فهرست مطالب

پژوهش های صنایع غذایی - سال سی‌ام شماره 1 (بهار 1399)
  • سال سی‌ام شماره 1 (بهار 1399)
  • تاریخ انتشار: 1399/03/12
  • تعداد عناوین: 15
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  • ویدا برین، لیلا روفه گری نژاد* صفحات 1-14
    زمینه مطالعاتی

    افزودن پروتئین های لبنی به دوغ علاوه بر افزایش ارزش تغذیه ای و سلامتی بخشی محصول می تواند منجر به تولید دوغ پایدار با خواص ریولوژیکی بهتر گردد.

    هدف

    این پژوهش با هدف تاثیر آنزیم ترانس گلوتامیناز و کازیینات سدیم بر بهبود ویژگی های کیفی و پایداری دوغ انجام گرفت.

    روش کار

    به این منظور با بکارگیری روش آماری سطح پاسخ و طرح مرکب مرکزی، تاثیر آنزیم ترانس گلوتامیناز در محدوده صفر تا  5 واحد به ازاء هر گرم پروتئین و کازیینات سدیم در محدوده صفر تا 1 درصد بر روی اسیدیته، دو فازه شدن، ویسکوزیته و ویژگی های حسی دوغ بررسی شد.

    نتایج

    نتایج نشان داد که استفاده از ترانس گلوتامیناز افزایش معنی داری بر روی اسیدیته داشته در صورتی که اثر کازیینات سدیم معنی دار نبود. ترانس گلوتامیناز و کازیینات سدیم بر ویژگی های حسی و ویسکوزیته افزایش معنی دار و بر میزان دوفازه شدن کاهش معنی داری داشتند. با انجام بهینه سازی برای تولید محصول با پایداری بالا همراه با بیشترین مقبولیت حسی، مقادیر بهینه ترانس گلوتامیناز و کازیینات سدیم به ترتیب 30/4 واحد به ازاء هر گرم پروتئین و 71/0 درصد محاسبه شد. مقایسه نمونه بهینه و شاهد نشان داد که نمونه بهینه ویسکوزیته و مقبولیت حسی بالاتر با حداقل دو فازه شدن را داشت. هم چنین تیمار با ترانس گلوتامیناز و کازیینات سدیم باعث کاهش اندازه ذرات و منفی شدن پتانسیل زتا شد.

    نتیجه گیری نهایی

    در مجموع نتایج حاصل نشان داد با بکارگیری کازیینات سدیم و آنزیم  ترانس گلوتامیناز میکروبی می توان دوغ پایدار با ویژگی های مطلوب از نظر خواص فیزیکی شیمیایی و حسی با قابلیت نگهداری طولانی مدت تولید نمود.

    کلیدواژگان: ترانس گلوتامیناز، دوغ، روش سطح پاسخ، کازئینات سدیم
  • اقدس شاهی مریدی، عبدالمجید میرزاعلیان دستجردی* صفحات 15-28
    زمینه مطالعاتی

     استفاده از عصاره یا اسانس های گیاهی می تواند موجب بهبود شاخص های بیوشیمیایی و افزایش عمرقفسه ای میوه شود.

    هدف

    این تحقیق به منظور تعیین اثرات عصاره برگ چندل (Rhizophora mucronata) و اکالیپتوس (Eucalyptus spp.) روی فعالیت آنتی اکسیدانی میوه موز انجام شد.

    روش کار

    میوه در مرحله سبز بالغ از یک باغ تجاری واقع در بخش زرآباد، شهرستان کنارک، استان سیستان و بلوچستان برداشت شد. میوه ها پس از انتقال به آزمایشگاه دانشگاه هرمزگان، ضدعفونی، شستشو و خشک شدن در دمای اتاق، با محلول های عصاره اتانولی برگ چندل و اکالیپتوس در سه غلظت صفر، 500 و 1000 میکروگرم/ لیتر به مدت 10 دقیقه تیمار شدند. سپس میوه ها در مدت های صفر، 7، 14 و 21 روز در دمای 1± ºC 25 و رطوبت نسبی 80 تا 90% نگهداری شدند.

    نتایج

    نتایج نشان داد میوه های تیمارشده در مقایسه با میوه های شاهد کیفیت بهتری داشتند. موثرترین تیمار در حفظ میزان فنل کل در میوه های تیمار شده با عصاره اکالیپتوس غلظت 1000 میکروگرم/ لیتر با مقدار 79/10 میلی گرم گالیک اسید/ 100 گرم وزن تازه و کمترین میزان مالون دی آلدهید (29/0 نانو مول/ گرم وزن تازه)، در میوه های تیمار شده با عصاره اکالیپتوس غلظت 500 میکروگرم/ لیتر ثبت گردید در حالی که میزان مالون دی آلدهید در نمونه شاهد نسبت به این تیمار 7/51% بیشتر بود. همچنین بیشترین فعالیت آنزیمی پراکسیداز (72/7 واحد/ میلی لیتر/ دقیقه) در میوه های تیمار شده با عصاره چندل با غلظت 1000 میکروگرم/ لیتر و بالاترین فعالیت آنتی اکسیدانی (90/11%) و کمترین فعالیت آنزیمی پلی فنل اکسیداز (22/11 واحد/ میلی لیتر/ دقیقه) در عصاره چندل با غلظت 500 میکروگرم/ لیتر مشاهده شد. این مطالعه نشان داد که عصاره های گیاهی استفاده شده در حفظ کیفیت بیوشیمیایی میوه موز به واسطه کاهش سرعت مکانیسم های رسیدن، اثر قابل ملاحظه ای داشتند. همچنین کاربرد مواد زیستی و گیاهی  به دلیل ایمنی بالای سلامت در مقایسه با مواد شیمیایی، نزد مصرف کننده پذیرش بهتری خواهد داشت.

    کلیدواژگان: پلی فنل اکسیداز، عمر قفسه ای، فسادپذیر، فنل کل، کیفیت بیوشیمیایی
  • ثریا صالحی، آی ناز خدانظری*، اسحاق زمانی صفحات 29-41
    زمینه مطالعاتی

     میگوی سفید سرتیز بدون پوست به منظور ارزیابی کاهش کیفیت و تازگی در یخ و یخچال به مدت 16 روز نگهداری شدند.

    هدف

    هدف از مطالعه حاضر، تاثیر دماهای مختلف (یخ و یخچال) بر تغییرات ویژگی های کیفی میگوی سفید سرتیز بود.

    روش کار

    آنالیزهای فیزیکوشیمیایی (TVBN، pH، TBA و FFA)، میکروبی (بار باکتریایی مزوفیل، سرمادوست، انتروباکتریاسه، استافیلوکوکوس و باکتری های تولید کننده H2S) و ارزیابی حسی در روز های 0، 4، 8، 12 و 16 نگهداری انجام شدند.

    نتایج

    تغییرات شاخص فیزیکوشیمیایی در کل دوره نگهداری مشاهد شد. تغییرات ارزیابی حسی به طور معنی دار طی دوره نگهداری مشاهده شد و همبستگی معنی دار  نزدیک به 800/0 در میگوی سفید سرتیز نگهداری شده در یخ و یخچال طی زمان نگهداری مشاهده شد که نشان دهنده کاهش کیفیت میگو می باشد. آنالیز رگرسیون با استفاده از محدوده قابل قبول برای باکتری های مزوفیل (log cfu/g 7) نشان داد که ماندگاری میگوی سفید سرتیز بدون پوست نگهداری شده در یخ و یخچال به ترتیب 7 و 4 روز تخمین زده شده است.

    نتیجه گیری نهایی

    آنالیزهای TVBN، میکروبی و حسی همبستگی خیلی بالایی با زمان نگهداری دارد و ممکن است به عنوان شاخص های مناسب برای ارزیابی فساد میگوی سفید سرتیز بدون پوست نگهداری شده در یخ و یخچال بررسی شود.

    کلیدواژگان: Metapenaeus affinis، ماندگاری، خواص کیفی، سردسازی
  • مریم فتاحی، لیلا نجفیان*، مهدی چرمچیان لنگرودی صفحات 43-59
    زمینه مطالعاتی

    کنگر یکی از گیاهان با خواص سلامت بخشی بالا می باشد و به طور معمول قبل از مصرف تحت فرآیند حرارتی قرار می گیرد.

    هدف

    این آزمایش به منظور تعیین روش مناسب پخت ساقه کنگر جهت حفظ کیفیت و ترکیبات سلامت بخش این گیاه انجام گرفت.

    روش کار

    در این تحقیق تاثیر روش های مختلف پخت (جوشاندن، بخار پز کردن و مایکروویو) در سه سطح زمانی بر ویژگی های آنتی اکسیدانی ساقه کنگر مورد استفاده قرار گرفت.محتوای فنول کل، محتوای فلاونویید کل، مهاررادیکالDPPH، ظرفیت آنتی اکسیدانی کل و قدرت احیا کنندگی یون آهن همچنین ترکیبات شیمیایی و ویژگی های حسی نمونه ها مورد ارزیابی قرار گرفتند.

    نتایج

    روش پخت بر محتوای فنل کل و فلاونویید کل و فعالیت آنتی اکسیدانی به طور معنی داری موثر است (05/0 >P). محتوای فنل کل و فلاونویید کل ساقه کنگر تحت فرآیند مایکروویو در زمان های 2 و 4 دقیقه و فرآیند بخار پز در زمان 5 دقیقه نسبت به نمونه های ساقه کنگر تازه افزایش و در فرآیند آب پز به طور معنی داری کاهش یافت (05/0 >P). فعالیت آنتی اکسیدانی ساقه کنگر در فرآیندهای پخت مایکروویو در زمان 2 دقیقه و بخار پز در زمان 5 دقیقه بالاترین میزان را نشان داد. ترکیبات شیمیایی نمونه هایی که تحت فرآیند حرارتی قرار گرفتند به جز رطوبت در مقایسه با کنگر تازه اختلاف معنی داری نشان ندادند (05/0 >P). در ارزیابی حسی نیز روش مایکرویو در زمان 2 دقیقه و بخار پز در زمان 5 دقیقه بالاترین پذیرش کلی را کسب نمودند.

    نتیجه گیری نهایی

    با توجه به نتایج بدست آمده، روش مایکروویوو بخار پز در زمان کوتاه جهت پخت ساقه کنگر و استفاده بهینه از ترکیبات مفید و سلامت بخش این گیاه پیشنهاد می گردد.

    کلیدواژگان: ترکیبات فنلی، روشهای پخت، کنگر، ویژگیهای آنتیاکسیدانی
  • لیلا ناطقی* صفحات 61-80
    زمینه مطالعاتی

     امروزه استفاده از فیبرهای رژیمی به علت اثرات سلامت بخشی آن و استفاده از هیدروکلوییدها به دلیل بهبود خواص کیفی آن در محصولات پخت مورد توجه قرار گرفته است.

    هدف

    این پژوهش، به منظور بررسی اثرات جایگزین کردن آرد گندم با فیبر سبوس جو و صمغ کتیرا بر خواص کیفی نان تست انجام شد.

    روش کار

    فیبر سبوس جو در دو سطح (4 و 8 درصد) و صمغ کتیرا در دو سطح  (5/0 و 1 درصد) به صورت جداگانه و به صورت توام شامل 75/0 درصد صمغ کتیرا + 6 درصد فیبر سبوس جو و  25/0 درصد صمغ کتیرا + 2 درصد فیبر سبوس جو) در فرمولاسیون نان تست مورد استفاده قرار گرفت. ویژگیهای فیزیکی شیمیایی شامل حجم نان، درصد رطوبت، درصد خاکستر،pH ، درصد چربی، رنگ (روشنی، قرمزی و زردی)، سفتی بافت، خصوصیات حسی 2 ساعت پس از تولید و بیاتی در بازه های زمانی 1، 2 و 3 روز پس از پخت مورد ارزیابی قرار گرفتند.

    نتایج

    اختلاف معنی داری در شاخص درصد چربی و pH تیمارها در مقایسه با تیمار شاهد مشاهده نگردید. با استفاده از صمغ کتیرا و فیبر سبوس جو و افزایش غلظت آن ها میزان حجم نان، درصد رطوبت، درصد خاکستر، شاخص زردی و قرمزی و امتیازات حسی ارزیاب ها به طور معنی داری افزایش و شاخص روشنایی، سفتی بافت و بیاتی کاهش یافت.

    نتیجه گیری نهایی

    استفاده توام صمغ کتیرا 75/0 درصد و فیبر سبوس جو 6 درصد باعث افزایش حجم نان های تست و کاهش بیاتی نسبت به نمونه شاهد گردید.

    کلیدواژگان: بافت، رنگ، صمغ کتیرا، فیبر سبوس جو، نان تست
  • نیر اسماعیلی، رحیم نقش بند حسنی*، فریبرز زارع نهندی صفحات 81-97
    زمینه مطالعاتی

    میوه زغال اخته بالاترین مقادیر آنتوسیانین ها، فنل ها و فعالیت آنتی اکسیدانی را در میان بسیاری از میوه های دیگر به خود اختصاص داده است.میزان ترکیبات شیمیایی و کیفیت میوه بستگی به عوامل متعددی دارد که یکی از مهمترین آن ها زمان برداشت است.

    هدف

    این پژوهش به منظور بررسی اثر زمان برداشت بر برخی ویژگی های شیمیایی و خواص آنتی اکسیدانی میوه های زغال اخته طی انبارمانیآن انجام گرفت.

    روش کار

    برای این منظورمیوه یک ژنوتیپ تجاری زغال اخته در دو زمان برداشت (برداشت اول با میوه به رنگ قرمز روشن  و برداشت دوم با میوه به رنگ قرمز تیره) برداشت شد. به منظور بررسی ویژگی های مختلف شیمیایی از قبیل میزان فنل کل ، فلاونویید کل، تانن های محلول، آنتوسیانین کل، کاروتنویید کل ، ظرفیت آنتی اکسیدانی کل و میزان مالون دی آلدهید طی نگهداری (0، 7، 14 و 21 روز) مورد ارزیابی قرار گرفتند.

    نتایج

    با پیشرفت مرحله بلوغ و رسیدگی میوه در طول انبارمانی، میزان ترکیبات فنلی و فلاونوییدکل، آنتوسیانین ها با افزایش طول دوره نگهداری در انبار در برداشت اول نسبت به برداشت دوم به طور معنی داری (01/0 <P) افزایش یافته، ولی ظرفیت آنتی اکسیدانی با افزایش مدت زمان انبارمانی روند کاهشی داشته (01/0 <P) به طوری که در میوه های برداشت اول به میزان  1/41 % و میوه های برداشت دوم 71 %  کاهش یافت. همچنین با تاخیر در برداشت (دوم) و افزایش زمان نگهداری (هفته سوم) میوه ها، محتوای کاروتنوییدها افزایش پیدا کردند. در طول انبارمانی میزان تانن های محلول میوه به طور معنی داری (01/0 <P) کاهش پیدا کرده، در حالی که میزان مالون دی آلدهید میوه ها افزایش پیدا کردند. با تاخیر در برداشت میوه میزان تانن های محلول کاهش یافت. در حالی که محتوای مالون دی آلدهید تحت تاثیر زمان برداشت قرار نگرفت.

    نتیجه گیری کلی

    بطور کلی میوه های مربوط به برداشت دوم در مقایسه با میوه های برداشت اول دارای مقادیر بیشتری از نظر ترکیبات کاروتنوییدی و فعالیت آنتی اکسیدانی در مقایسه با سایر ترکیبات بیوشیمیایی میوه زغال اخته در طول دوره انبار مانی بودند. مطابق نتایج حاصله مناسبترین زمان انبار مانی با قابلیت مناسب آنتی اکسیدانی  برای میوه های زمان برداشت اول هفته اول انبارمانی (هفت روز) و برای میوه های برداشت دوم تا هفته دوم انبارمانی (چهارده روز) بودند.

    کلیدواژگان: انبارمانی، آنتی اکسیدان های میوه، پراکسیداسیون لیپیدی، رسیدگی میوه
  • شهین زمردی*، سمیرا فرامرزی صفحات 99-111
    زمینه مطالعاتی

     دونات نوعی اسنک سرخ شده شیرین است که به صورت شیمیایی یا تخمیری یا تلفیق این دو تهیه شده و در دمای بالا سرخ می شود. هدف در این پژوهش، بررسی تاثیر پودر دانه کتان و امولسیفایر داتم بر خواص کیفی و حسی دونات بود.

    روش کار

    پودر دانه کتان در چهار سطح صفر، 5، 10 و 15 % (وزن آرد گندم) و امولسیفایر داتم در سه سطح صفر، 25/0 و 5/0 % در تهیه دونات استفاده شد. بر روی نمونه ها پس از 7 روز نگهداری درسردخانه، آزمایش های رطوبت، خاکستر، پروتئین، حجم مخصوص، درصد تخلخل، اندیس های رنگ پوسته، سختی بافت و ویژگی های حسی شامل شکل، سختی بافت، قابلیت جویدن و طعم با روش های معمول تعیین شد.

    نتایج

    نتایج تجزیه آماری داده ها نشان داد که با افزایش پودر دانه کتان در فرمولاسیون دونات، رطوبت 8/33 %، سختی بافت 6/41 % و مولفه a* حدود 8/93 % افزایش و تخلخل 27 %، حجم مخصوص 1/57 % و شاخص L* در حدود 18% کاهش پیدا کرد. با افزایش امولسیفایر نیز در فرمولاسیون دونات، رطوبت 8 %، تخلخل 7/11 %، حجم مخصوص 34 % و شاخص L* 6/7 % افزایش ولی سختی بافت 5/17 % و مولفه a* حدود 5/47 % کاهش پیدا کرد. بر اساس نتایج ارزیابی حسی، پودر دانه کتان در سطح 5 تا 10 % تاثیر نامطلوبی بر صفات حسی دونات نداشت ولی مقدار 15 % تاثیر کاهشی بر امتیازدهی داوران به صفات حسی داشت. در حالی که افزودن امولسیفایر داتم منجر به بهبود صفات حسی از نظر ارزیابان گردید.

    نتیجه گیری نهایی

    بر اساس نتایج حاصل از این پژوهش، استفاده از 10 تا 5 % پودر دانه کتان و 5/0 % امولسیفایر داتم در تهیه دونات با خصوصیات کمی و کیفی قابل قبول، پیشنهاد می شود.

    کلیدواژگان: امولسیفایر داتم (DATEM)، پودر دانه کتان، دونات، خواص کیفی
  • سبا بلقیسی* صفحات 113-124
    زمینه مطالعاتی

     تعیین ویژگی های فیزیکی شیمیایی و میکروبی استاندارد در محصولات غذایی حایز اهمیت است. از آنجاییکه ترکیب شیمیایی عسل با توجه به منشاء گیاهی آن متفاوت است، ضروری است ویژگی های آن مطابق با این عوامل بطور دوره ای بررسی و تجدید نظر شود.

    روش کار

    ویژگی های فیزیکی شیمیایی (رطوبت، مواد جامد محلول، pH، اسیدیته،هدایت الکتریکی، خاکستر، قندهای احیا کننده، ساکارز، نسبت فروکتوز به گلوکز، فعالیت دیاستازی، هیدروکسی متیل فورفورال و پرولین) و ویژگی های میکروبی (کپک، مخمر و کلستریدیوم احیاکننده سولفیت) 30 نمونه عسل از منابع گیاهی مختلف (گون، کنار، آویشن، بهارنارنج و چهل گیاه) مورد ارزیابی قرار گرفتند و با ویژگی های تعریف شده در استاندارد بین المللی کدکس مقایسه شدند.

    نتایج

    میزان رطوبت عسل بهارنارنج نسبت به سایر گونه های گیاهی بالاتر بوده است و با حد مجاز استاندارد بین المللی کدکس (بیشینه 20%) مطابقت نداشته است. هم چنین میزان ساکارز در نمونه های عسل گون، کنار، آویشن و چهل گیاه بالاتر از حد مجاز استاندارد بین المللی کدکس (بیشینه 5%) بود. میزان هیدروکسی متیل فورفورال در تمام نمونه ها به استثناء عسل بهار نارنج از حد مجاز (بیشینه mg/kg40) بالاتر بوده است. دیاستاز در نمونه های عسل گون، کنار، آویشن و چهل گیاه کمتر از حد استاندارد (کمینه G08) بود. پرولین در تمام نمونه ها به استثناء گون و کنار در محدوده مجاز استاندارد بین المللی کدکس (کمینهmg/kg180) قرار داشت. میزان آلودگی میکروبی کپک، مخمر و کلستریدیوم احیاکننده سولفیت نمونه های عسل وابسته به منشا گیاهی نبوده و اختلاف معنی دار بین نمونه ها مشاهده نشد (05/0>P).

    نتیجه گیری کلی

    با توجه به نتایج به دست آمده پیشنهاد می شود استانداردهای موجود در زمینه ویژگی های فیزیکی شیمیایی عسل با توجه به منشاگیاهی آن مورد بازنگری و بررسی قرار گرفته و در تعیین حدود قابل قبول هر ویژگی، منشا گیاهی مد نظر قرار گیرد.

    کلیدواژگان: ایران، فیزیکی شیمیایی، عسل، منشاگیاهی، میکروبی
  • عاطفه پورجاهد*، حبیب الله عباسی، نسیم صفاریان صفحات 125-136
    زمینه مطالعاتی

     در سال‎های اخیر، از فیتواسترول‎ها، به منظور کاهش جذب کلسترول در رژیم غذایی استفاده شده است. نقطه ذوب بالا و نامحلول بودن آن‎ها در آب و روغن، افزودن فیتواسترول‎ها را به مواد غذایی با مشکل مواجه می‎کند.

    هدف

    هدف از این پژوهش بهبود خصوصیات فیزیکی و شیمیایی فیتواسترول‎ها به کمک نانولیپوزوم‎ها است.

    روش کار

    در این مطالعه، نانولیپوزوم‎های حاوی بتا- سیتواسترول از غلظت‎های مختلف لسیتین سویا و کلسترول به روش هیدراسیون لایه نازک تهیه شد و برای کاهش اندازه ذره از هموژنایزر اولتراسونیک استفاده گردید. طیف‎سنجی مادون قرمز (FTIR) برای مطالعه برهم‎کنش گروه‎های عاملی مواد افزودنی مختلف در ترکیب نانولیپوزوم‎ها استفاده گردید. نتایج نشان داد که برهم‎کنش بین بتا- سیتواسترول و نانولیپوزوم‎ها از نوع پیوند هیدروژنی است. میانگین قطر حجمی ذرات، شاخص پراکندگی، پتانسیل زتا، پایداری فیزیکی و pH نانولیپوزوم‎های تولید شده بررسی گردید.

    نتایج

    میانگین قطر حجمی ذرات بین 90 تا 100 نانومتر بود. افزودن کلسترول به نمونه‎ها، میانگین قطر حجمی نانولیپوزم‎ها را به مقداری کم و به صورت معناداری (05/0>P) افزایش داد، با این حال، موجب کاهش معنادار پتانسیل زتا (05/0>P) و پایداری بیشتر نمونه‎ها در دماهای مختلف گردید. همچنین pH نمونه‎ها به محدوده خنثی نزدیک بود که ثابت می‎کند استفاده از این نانولیپوزوم‎ها تاثیری در تغییر pH مواد غذایی ندارد.

    نتیجه گیری نهایی

    بهترین نتایج برای نمونه حاوی 06/0 گرم کلسترول به دست آمد که علیرغم اندازه ذره تا حدودی بزرگ‎تر، از نظر پتانسیل زتا، پایداری فیزیکی و pH،مطلوب‎تر از سایر نمونه‎ها بود.

    کلیدواژگان: بتا- سیتواسترول، نانولیپوزوم، اندازه ذره، پایداری
  • سمیه رحیمی*، سولماز صارم نژاد صفحات 137-150
    زمینه مطالعاتی

     امروزه توجه محققین به فرمولاسیون و تولید محصولات غذایی فراسودمند جلب شده است. با توجه به اینکه نان سهم عمده ای از تامین انرژی روزانه افراد جامعه را بر عهده دارد ، می توان طی پروسه تولید این فراورده، این محصول را با  بسیاری از ترکیبات فراسودمند  غنی نمود.

    هدف

    هدف این تحقیق بررسی اثر تخمیر بر میزان ترکیبات فراسودمند آرد مالت برنج قهوه ای بود.

    روش کار

    آرد مالت برنج قهوه ای توسط هر یک از میکروارگانیسم های لاکتوباسیلوسساکیی ولاکتوباسیلوس  سانفرانسیسنسیس در دو حالت جداگانهو مخلوط (یک بار با دانسیته نوری 45/1  معادل CFU/ml   108× 5/0 و  بار دیگر با دانسیته نوری 9/2 معادل CFU/ml  108) در حضور مخمر نانوایی تا رسیدن به  pH  9/4 تخمیر شده و تغییرات غلظت ترکیبات فراسودمند شامل ترکیبات فنولی آزاد و باند شده، ظرفیت آنتی اکسیدانی، میزان گاما آمینو بوتیریک اسید و آمینواسیدهای آزاد در نمونه های خمیر ترش مطالعه شد. از خمیر تخمیر شده با مخمر نانوایی بعنوان شاهد استفاده شد.

    نتایج

    بر اساس نتایج حاصله، تخمیر با دو میکروارگانیسم جه بصورت تکی و چه به صورت مخلوط به ترتیب باعث افزایش و کاهش معنی دار میزان ترکیبات فنولی آزاد و باند شده نسبت به میزان این ترکیبات در آرد مالت برنج قهوه ای شد (05/0≤P. فنول های آزاد خمیرترش تخمیر شده با لاکتوباسیلوس ساکیی بیشترین ظرفیت آنتی اکسیدانی را از خود نشان داد، درحالیکه بالاترین ظرفیت آنتی اکسیدانی ترکیبات فنولی باند شده، مربوط به خمیر حاوی مخلوط دو میکروارگانیسمبا دانسیته نوری 45/ 1 بود. خمیر ترش تخمیر شده با  لاکتوباسیلوس ساکیی همچنینبیشترین میزان گاما آمینوبوتیریک اسید و آمینواسیدهای آزاد را داشت.

    نتیجه گیری نهایی

    با توجه به نتایج، باکتری لاکتوباسیلوس ساکیی را می توان به عنوان یک باکتری لاکتیکی مناسب جهت تخمیر آرد مالت برنج قهوه ای با هدف تولید ترکیبات فراسودمند بویژه گاما آمینوبوتیریک اسید  به صنایع تولید خمیر ترش معرفی نمود.

    کلیدواژگان: آرد مالت برنج قهوه ای، فراسودمند، گاما-آمینوبوتیریک اسید، لاکتو باسیلوس ساکئی، لاکتو باسیلوس سانفرانسیسنسیس
  • آزاده مردانی قهفرخی، رضا فرهوش*، علی شریف صفحات 151-166
    زمینه مطالعاتی

     بررسی مکانیسم فعالیت برخی آنتی اکسیدان های فنلی با استفاده از روابط سینتیکی.

    هدف

    تعیین مکانیسم فعالیت آنتی اکسیدانی اسید جنتیسیک در روغن های زیتون و سویا.

    روش کار

    در این پژوهش فرایند خوداکسایشی روغن های تخلیص شده زیتون و سویا در حضور غلظت های 02/0، 04/0، 08/0، 16/0 و 32/0 درصد اسید جنتیسیک و در دماهای 60، 80، 100 و 120 درجه سانتیگراد با پایش عدد پراکسید و محاسبه پارامترهای سینتیکی مختلف از قبیل فاکتور حمایتی (F) ، نسبت سرعت اکسایش (ORR) و فعالیت آنتی اکسیدان (A) ارزیابی گردید و مکانیسم فعالیت اسید جنتیسیک با استفاده از این روابط سینتیکی مشخص گردید.

    نتایج

    بررسی مکانیسم فعالیت آنتی اکسیدانی اسید جنتیسیک توسط پارامترهای سینتیکی گویای شرکت این ترکیب در واکنش اصلی پایانی اکسایش (ROO• + InH ® ROOH + In•)  در رقابت با واکنش مرحله انتشار فرایند اکسایش روغن ها(ROO• + RH ® ROOH + R•) بود. در روغن سویا به دلیل درصد بالاتر اسید های چند غیراشباعی افزایش غلظت اسید جنتیسیک تا سطوح بالا، موجب افزایش فعالیت آنتی اکسیدانی این ترکیب گردید، در حالی که در روغن زیتون به سبب بالاتر بودن مقادیر اسید چرب تک غیراشباع آن (اسید اولییک)، افزایش غلظت حالت پرواکسیدانی به اسید جنتیسیک بخشید و شرکت این آنتی اکسیدان در واکنش جانبی (InH + ROOH ® In• + R• + H2O) را به دنبال داشت.

    نتیجه گیری نهایی

    اسید جنتیسیک به عنوان یک آنتی اکسیدان فنلی بدون تولید رادیکال های آزاد فعال و مضر توانایی کاهش سرعت فرایند اکسایش در روغن های زیتون و سویا را دارا بود.

    کلیدواژگان: اسید جنتیسیک، روغن های گیاهی، مکانیسم فعالیت آنتی اکسیدانی
  • راضیه رضوی، رضا اسماعیل زاده کناری* صفحات 167-182
    زمینه مطالعاتی

     شیر پر مصرف ترین محصول لبنی در جهان است که معمولا جهت افزایش ایمنی و عمر ماندگاری تحت فرآیندهای حرارتی پاستوریزاسیون و استرلیزاسیون قرار می گیرد. فرآیند حرارتی می تواند باعث تغییر شکل ناخواسته پروتئین، قهوه ای شدن غیر آنزیمی، از بین رفتن ویتامین ها و ترکیبات معطر فرار، کاهش نقطه ذوب و تغییر در عطر و طعم شود. تکنولوژی اولتراسوند نوعی فرآیند غیر حرارتی است که در سال های اخیر توجه بسیاری را به خود جلب نموده است.

    هدف

    در این پژوهش شیر تازه گاو در 3 دمای 45، 55 و 65 درجه سانتیگراد و سه زمان 5، 10 و 15 دقیقه با استفاده از دستگاه اولتراسوند نوع پروب (توان 350 وات) در دو شدت 50 و 75 درصد و حمام اولتراسوند (توان 280 وات) تیمار شد.

    روش کار

    اعمال فرآیند حرارتی در نمونه شاهد به مدت 10 دقیقه در دمای 90 درجه سانتیگراد انجام شد. شمارش کلی باکتری ها، شمارش کلی کپک و مخمر، شمارش کلیفرم ها، شمارش باکتری های سایکروفیل و اشرشیاکلی برای شیر خام، شیر شاهد و شیر تیمار شده با اولتراسوند انجام شد.

    نتایج

    مشخص گردید که با افزایش دما و زمان اولتراسوند اکسایش چربی شیر افزایش یافته است. نمونه شیر تیمار شده با حمام اولتراسوند کمترین اندیس پراکسید (meq O2/Kg oil01/0±19/0) و اندیس اسید تیوباربیتوریک (µg/Kg0/0±03/0) را داشت. در شرایط سونیکاسیون یکسان تاثیر افزایش دما از 45 تا 65 درجه سانتیگراد بر تخریب ویتامین های شیر بیشتر از تاثیر شدت و نوع اولتراسوند بود و بیشترین تخریب ویتامین های تیامین (µg/100g 06/0±80/10)، ریبوفلاوین (mg/100g 68/0±55/97) و رتینول (µg/100g 09/0±9/14) در نمونه شاهد اتفاق افتاد. اولتراسوند بخوبی توانست بار میکروبی شیر را کاهش دهد و تغییرات کمتری از نظر کاهش ویتامین ها نسبت به روش حرارت دهی متداول در شیر ایجاد نماید که از این حیث دستگاه اولتراسوند نوع پروب در شدت 75% موثرتر عمل نموده است.

    نتیجه گیری نهایی

    استفاده از اولتراسوند نوع پروب در دمای 55 درجه سانتیگراد با شدت 75% و به مدت 10 دقیقه به عنوان یک فرآیند غیر مخرب برای پاستوریزه کردن شیر توصیه می شود.

    کلیدواژگان: اکسیداسیون چربی، اولتراسوند، بار میکروبی، حرارت دهی، ویتامین
  • حسین غفاری ستوبادی*، حسین حسن پور کهنمویی، نعمان مرغوب، خسرو محمدی قرمزگلی صفحات 183-194
    زمینه مطالعاتی

     تعیین خواص انواع محصولات کشاورزی برای استفاده در طراحی و بهینه سازی ماشین ها و سامانه های پس از برداشت در راستای کاهش ضایعات و افزایش ماندگاری، کیفیت و توان رقابت با محصولات خارجی، امری ضروری است. امروزه به دلیل نیاز روز افزون کشور و به منظور حفظ سلامت جامعه استفاده از میوه تازه و با کیفیت مناسب ضروری به نظر می‏رسد. از طرفی سالانه درصد بالایی از محصولات میوه ای به دلیل وجود آسیب‏های مکانیکی تلف می شوند و یا کیفیت آن ها کاهش می‏یابد.

    هدف

    در این مطالعه برخی خواص مکانیکی مشارکت کننده در آسیب مکانیکی شامل انرژی نفوذ، نیروی نفوذ و ضریب برجهندگی میوه خرمالو تعیین شدند.

    روش کار

    در این پژوهش آزمایش هایی جهت تعیین این خواص مکانیکی دو رقم میوه خرمالو به نام های D. Kakiو D. Virginiana در سه زمان برداشت (نارس، نیمه رسیده و رسیده)  و سه سرعت بارگذاری 50، 100 و 200 میلی‏متر بر دقیقه با استفاده از دستگاه آزمون بافت انجام شد و برای به دست آوردن ضریب برجهندگی که می تواند معیاری برای تعیین میزان کوفتگی خرمالو‏باشد، از روش صوتی ابداعی استفاده شد. بدین منظور میوه های خرمالو از سه ارتفاع 10، 20 و 30 سانتی متری بر روی صفحه صلب دستگاه به صورت آزاد رها شدند.

    نتایج

    میانگین نیروی مورد نیاز برای نفوذ کردن به رقم D.virginianaبیشتر از رقم D.Kakiبود و با افزایش سرعت بارگذاری میانگین نیروی مورد نیاز برای نفوذ به هر دو رقم خرمالو افزایش یافت. با افزایش رسیدگی محصول میانگین انرژی نفوذ کاهش و با افزایش سرعت بارگذاری میانگین نیروی نفوذی افزایش یافت. تفاوت مقادیر میانگین ضریب برجهندگی میوه های خرمالو که از سه ارتفاع متفاوت رها شده بودند، در هر سه زمان برداشت و برای هر دو رقم در سطح احتمال یک درصد معنی‏دار بود. از آن جایی که ضریب برجهندگی معیاری از کوفتگی می باشد بنابراین ضریب برجهندگی کوچک تر بیانگر انرژی جذب شده بیشتر توسط میوه و احتمال صدمه کوفتگی بیشتر است. زمانی که خرمالو به صورت نارس و یا حداقل نیمه رسیده (بلوغ تجاری) روانه بازار شود، صدمات مکانیکی به طور قابل توجهی کاهش می‏یابد.

    کلیدواژگان: انرژی نفوذ، خرمالو، صدمه مکانیکی، ضریب برجهندگی، نیروی نفوذ
  • محسن زندی*، علی گنجلو، ماندانا بی مکر صفحات 195-210
    زمینه مطالعاتی

     مشخصه ظاهری میوه ها بر ارزش تجاری، ترجیح و انتخاب مصرف کننده موثر است. درجه بندی میوه در صنایع بسته بندی بسیار ضروری می باشد، زیرا تقاضای زیادی برای میوه های مرغوب و با کیفیت در بازار وجود دارد.

    هدف

    هدف ایجاد یک سیستم درجه بندی میوه بر اساس کیفیت آن طی نگهداری با استفاده از خصیصه های رنگی و با کمک تکنیک تجزیه و تحلیل تصویر است.

    روش کار

    درجه بندی میوه های زالزالک به سه درجه کیفی (A، B و C) طی نگهداری در شرایط مختلف (یخچالی، سردخانه و محیط) با استفاده از تکنیک تجزیه و تحلیل تصویر انجام شد. برای مقایسه نتایج تجزیه و تحلیل تصویر و طبقه بندی بصری، خصوصیات فیزیکی شیمیایی و هندسی میوه تعیین شد. پارامترهای کیفی رنگی (L*، a*، b*، c*، h* و) پارامترهای هندسی، افت وزن، سفتی بافت، میزان مواد جامد محلول (TSS)، pH، اسیدیته قابل تیتر (TA) و شاخص رسیدگی (RPI) فاکتورهای اندازه گیری شده است. تجزیه و تحلیل مولفه اصلی به منظور ارزیابی ارتباط بین متغیرها استفاده شد.

    نتایج

    اولین همبستگی بین پارامترهای فیزیکی شیمیایی و رنگی انجام گردید که همبستگی بالای بین تمامی متغیرها به جز خصیصه  وجود داشت؛ پارامترهای فیزیکی شیمیایی و رنگی توانستند تغییرات را با قابلیت اطمینان 2/94 درصد توصیف نمایند. با استفاده از پارامترهای رنگی و بدون حضور پارامترهای فیزیکی شیمیایی، تغییرات را با قابلیت اطمینان 4/97 درصد توصیف گردید. از دو سیستم طبقه بندی تحلیل تفکیک خطی (LDA) و تحلیل تفکیک درجه دو (QDA) برای ارزیابی کارایی سیستم بینایی استفاده شد. نتایج نشان داد که دو سیستم طبقه بندی تحلیل تفکیک خطی و تحلیل تفکیک درجه دو قادرند تا زالزالک ها را با دقت 99 و 5/99 درصد به درجه کیفی درست خود طبقه بندی نماید.

    نتیجه گیری نهایی

    بنابراین روش پیشنهادی جدید امکان طبقه بندی سریع و دقیق میوه ها بر اساس درجه کیفی فراهم می آورد؛ و می توان آن را به راحتی در کارخانه های فرآوری کاربردی نمود.

    کلیدواژگان: زالزالک، پردازش تصویر، خصیصه های رنگی، پارامترهای فیزیکی شیمیایی، درجه بندی کیفی
  • امیرافشار اصدق، اصغر خسروشاهی اصل*، سجاد پیرسا صفحات 211-226
    زمینه مطالعاتی

     افزودن اسانس زنیان و بتاکاروتن خصوصیات فیلم پکتین را کاملا تحت تاثیر قرار داده و در مجموع باعث بهبود ویژگی های فیزیکی شیمیایی و مکانیکی فیلم شد.

    هدف

    در این تحقیق فیلم زیست تخریب پذیر پکتین/زنیان/بتاکاروتن تهیه شد و اثر همزمان اسانس زنیان و رنگدانه بتاکاروتن روی ویژگی های فیزیکی شیمیایی و مکانیکی فیلم تهیه شده مورد بررسی قرار گرفت. برای بررسی اثر اسانس زنیان در سطوح 5/0-0 درصد و رنگدانه بتاکاروتن در سطوح 03/0-0 درصد از طرح مرکب مرکزی استفاده شد.

    روش کار

    برای آماده سازی فیلم 2 درصد وزنی/حجمی پکتین در 100میلی لیتر آب دیونیزه به مدت 12 ساعت در دمای 30 درجه سانتیگراد با همزن مغناطیسی مخلوط شد، پس از سرد شدن 40 درصد وزنی/وزنی ماده خشک گلیسرول اضافه شد و محلول به مدت 10 دقیقه با همزن مخلوط شد و به این ترتیب فیلم شاهد (بدون بتاکاروتن و زنیان) تهیه شد. برای تهیه فیلم های حاوی اسانس زنیان بعد از مخلوط شدن گلیسرول به محلول حاصل اسانس در غلطت های 25/0 و5/0 درصد ماده خشک پکتین به همراه 5 درصد حجمی/حجمی ماده خشک، تویین 80 به عنوان امولسیفایر اضافه سپس توسط همزن با دور9000 در دقیقه به مدت 5 دقیقه مخلوط شد. برای تهیه فیلم های حاوی بتاکاروتن ابتدا کریستال های بتا در غلظت های 015/0 و 03/ 0درصد در 20 میلی لیتر کلروفرم حل شد و به حجم 100میلی با آب مقطر رسیده به همراه 5 درصد تویین طبق روش فوق با همزن با دور 13000 به مدت 2دقیقه با پلیمر مخلوط شد. جهت تهیه فیلم های ترکیبی (اسانس و بتاکاروتن) مخلوط پلیمر/اسانس/بتاکاروتن طبق روش فوق آماده شد با این تفاوت که مدت زمان مخلوط شدن با همزن به 5 دقیقه افزایش یافت.

    نتایج

    نتایج آزمون FTIR نشان دهنده برهمکنش جدید بین اسانس زنیان و بتاکاروتن بود. پراش اشعه ایکس نیز تایید کرد که میزان کریستالی شدن فیلم با افزودن بتاکاروتن افزایش یافت. افزودن اسانس بر کدورت فیلم ها تاثیر معنی دار داشت، به طوریکه بیشترین مقدار کدورت در فیلم حاوی 5/0 درصد اسانس ایجاد شد، از طرفی دیگر افزایش مقدار بتاکاروتن تا 015/0 درصد باعث کاهش مقدار کدورت شد ولی در غلظت های بالاتر افزایش کدروت را به همراه داشت. در نتایج حاصل از خواص مکانیکی، خاصیت کشسانی با افزودن اسانس سیر صعودی نشان داد، از طرفی بتاکاروتن و اسانس زنیان در غلظت های پایین باعث کاهش استحکام کششی و مدول الاستیک شدند، ولی در غلظت های بالاتر به بهبود خواص مکانیکی کمک کردند.

    نتیجه گیری نهایی

    با توجه به اینکه رنگدانه بتاکاروتن در شرایط مختلف محصولات غذایی تغییر رنگ می دهد در ادامه میتوان از این فیلم ها برای بسته بندی هوشمند محصولات غذایی استفاده کرد.

    کلیدواژگان: اسانس زنیان، بتاکاروتن، خواص مکانیکی، فیلم خوراکی زیست تخریب پذیر
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  • V. Barin, L. Roufegarinezhad * Pages 1-14
    Introduction

    “Doogh” is a native beverage in Iran and has in important share in beverage industry (Zomorodi and Kianfar 2018). It can be made by yoghurt dilution or direct acidification of milk. Traditionally, doogh is made by mixing yogurt, water, and a little salt as well as some aqueous extracts of local herbs. However, Doogh, like other acidic dairy beverages has a serious problem because of its low pH, which causes phase separation, and leads to casein accumulation and gives a product with an undesirable, non-uniform appearance (Sanli et al., 2011). On the other hand, heat treatments such as pasteurization have a key importance in the production of dairy products because this is a common step in the processing of milk products. The heat treatment exposes reactive groups on the protein, which were previously inaccessible, and this, in turn, affects the rheological properties of the products (Joudaki et al., 2013). It has been reported that polysaccharide hydrocolloids addition could be prevent phase separation in doogh during storage. But creation undesirable taste in the higher concentration is a seriouse problem (Tsevdou et al., 2013). The enhancement of food texture with enzymes has gained increasing importance as an alternative to conventional processing strategies for protein containing foods. Microbial transglutaminase or glutaminyl-peptide-amine γ-glutamyl transferase (mTGase, EC 2.3.2.13) is a calcium independent enzyme. It forms covalent crosslinks of inter- or intra-molecular ε-(γ-glutamine)-lysine isopeptidic bonds by catalyzing an acyl transfer reaction between a γ-carboxyamide group in protein-bound glutamine residues (acyl donor) and an ε-amino group in a protein-bound lysine residue (acyl acceptor) (Lorenzen et al., 2002). Microbial transglutaminase represents an interesting tool for texture modification of protein-containing foods. Since 1998, this enzyme with “No. GRN 000095” was approved by the FDA as “Generally Recognized as Safe (GRAS)” and there are confirmed documents for MTGase in the US, Japan and Europe as a safe ingredient in different types of processed foods (Ardelean et al., 2012). Acid gels, such as yogurt, made from enzyme-treated milk are characterized by reduced syneresis and improved viscosity. In this study, effect of sodium caseinate on functionality of transglutaminase was assayed too.   Concerning milk proteins, casein monomers can be easily cross-linked by mTGase, whereas whey proteins only polymerize after heat treatment or in the presence of reducing agents. The literature on mTGase-induced cross-linking on casein micelles, caseins or caseinates, whey proteins or milk, has been reviewed recently (Barbaros et al., 2012). The aim of this study was to investigate the effect of transglutaminase enzyme and sodium caseinate to improve quality and stability characteristics of Doogh.

    Material and methods

    This study was carried out to improve the quality and stability properties of Doogh using sodium caseinate (at 0, 0.5 and 1%) and microbial transglutaminase (at 0, 5, 10 u/g protein). For this purpose, after pasteurization and homogenization of raw milk (0.6 % fat), sodium caseinate and microbial transglutaminase added at 45 and 50oC, respectively. Heating of treated milk was performed after 2 h (72oC- 15 s) to inactive enzyme. Fermentation was carried out by adding starter culture (yogurt starter culture consist of Lactobacillus bulgaricus and Streptococcus thermophiles) and incubation was performed at 42oC until 12 h. Finally, prepared yogurt mixed with potable water at 1:1 ratio and 0.65% salt added to mixture. The pasteurized treated samples were assayed for physicochemical and sensory properties. Acidity was measured through titration with sodium hydroxide as Dornic degree and viscosity was assayed at ambient temperature by a rotational Brokfield viscometer. Phase separation of the different formulations was carried out in 250 mL glass tubes for 30 days at 5 oC storage. Evaluation of the sensory attributes of the produced Dooghs with various formulations in terms of taste, consistency, appearance, smell and color was carried out by 30 untrained panelists and the average of scores as overall acceptability were used for statistical analyses. In the second phase, based on the obtained results, optimized sample was selected using response surface methodology in central composite design and particle size distribution (determined by dynamic light scattering) and zeta potential tests were measured.

    Results and discussion

    The results showed that the use of transglutaminase increased significantly effect on acidity, while the effect of sodium caseinate was not significant. Transglutaminase and sodium caseinate had a significantly increase effect on sensory properties and viscosity, while phase separation decreased significantly. Optimization of formula was performed based on tranglutaminase, sodium caseinate and acidity in range, phase separation in minimize, apparent viscosity and overall acceptability in maximize. The importance of all of factors was selected the same. And optimum content of transglutaminase and sodium caseinate to have high stability product were calculated 4.30U/g Protein and 0.71% respectively through optimization with desirability 0.928. In optimum situation phase separation and apparent viscosity were obtained 2.15% and 29.10 cP, respectively. Optimum overall acceptability was acquired 4.25. Comparison of optimum and control samples showed that the optimum sample had higher viscosity (6.01 cP in control and 29.10 cP in optimized sample) and overall acceptability (1.55 in control and 4.25 in optimized sample) with at least phase separation (2.95% in control and 2.15% in optimized sample). Applying transglutaminase and sodium caseinate also reduced particle size (10.05 nm in control and 3.55 nm in optimized sample) and zeta potential (11.4 mV in control and -21.2 mV nm in optimized sample).

    Conclusion

    Generally, according to the obtained results, it can be said that applying MTG and sodium caseinate, is possible to produce the stable Doogh with desired properties in terms of physicochemical and sensory properties and long storage duration.

    Keywords: Doogh, Response Surface Methodology, Sodium Caseinate, Transglutaminase
  • A. Shahi, A. Mirzaei * Pages 15-28
    Introduction

    Banana (Musa spp.) is one of the most important commercial tropical fruits traded. Fruit is perishable and have a relatively short shelf life due to physiological characteristics at the time of ripening. Due to these characteristics postharvest losses of fresh banana fruits have been estimated to be very high, especially in developing countries, and their postharvest life can be very short (Yahia, 2011). Polyphenol oxidase is considered the enzyme responsible for quality deterioration and browning in fresh banana fruits during postharvest period. Browning reaction of banana fruit results from the enzymatic oxidation of phenolic substrates by polyphenol oxidase leading to the production of black or brown pigments which is the cause of enzymatic browning in fruit (Tapre and Jain, 2016). Antioxidant properties of essential oils and plant extracts were obtained from a reduction of enzymatic browning and fruit shelf life extension (Ranasinghe et al., 2002; Yahia, 2011). Treatment with basil essential oil inhibited anthracnose and crown rot and extending storage life of banana as well as eucalyptus oil-enrichment reduced fruit decay and maintained fruit quality of strawberries. The composite edible coatings of gum arabic enriched with lemongrass showed the synergistic effects and the greatest potential to control anthracnose and improved postharvest quality of fruit banana (Tzortzakis and Economakis, 2007). Thyme essential oil treatment induced the activities of peroxidase, phenylalanine ammonia lyase and chitinase which all play an important role in disease resistance in avocado fruit (Sellamuthu et al., 2013). Ethanol extract of Rhizophora mucronata reduced the growth of Penicillium pupurogenome, Penicillium chrysogenum, Penicillium notatum, Penicillium niger, Penicillium alternata and Penicillium italicum in vitro (Rastegar and Gozari, 2017). Mangrove leaf extracts were inhibited Penicillium digitatum of growth. Mangrove leaf extracts, in 20, 40, 60 and 80 Percent concentration, the mentioned extract were shown inhibition effect on mold pathogen growth (Alizadeh Behbahani et al., 2012). Therefore, the objective of the present experiment was to evaluate doses of red mangrove and eucalyptus ethanolic extracts from leaves on the effective control of the polyphenol oxidase activity and enzymatic browning and maintenance ofantioxidant capacity of fresh banana fruit.

    Material and methods

    Banana fruits (Musa,genome group AAA and subgroup Cavendish) at the mature green stage were harvested from a commercial orchard in Zarabad (Sistan and Bluchestan Province) and were transferred to the postharvest laboratory of hormozgan university. The selected fruits were randomized before being used for plant extract treatments. Ethanolic extracts of red mangrove (Rhizophora mucronata) and eucalyptus (Eucalyptus spp.) leaves in concentrations (0, 500 and 1000 µg/L) for ten minutes. According to the method used by De León-Zapata et al. (2015), the extracts were prepared by adding 5 g of dried leaf powder to 50 ml ethanol (96%). The extracts were stored in opaque vials at 4 °C before using them on fresh banana fruits. Then, the liquid extracts on the surface layer of the fresh banana fruits were left to evaporate, and the fruits were stored at (25°C ±1 and 80-90% relative humidity) for 0, 7, 14 and 21 days. Several parameters were measured every 7 days during the storage time. These were the antioxidant activity, total phenol content, malondialdehyde, peroxidase and polyphenol oxidase activity. The current study was carried out as a factorial assay and was based on a completely randomized design with three replications. Data were processed by ANOVA using the SAS software version 9.4. Significant differences were identified by using LSD test at 1% probability level.

    Results and discussion

    The results showed that the processed fruits had better quality compared to the control fruits. The most effective treatment for maintaining the total phenol content in fruits was the eucalyptus leaf extract at a concentration of 1000 μg/L with 10.79 mg gallic acid/100 g fresh weight. Phenolic content was higher in fruits at harvest time (15.85 mg gallic acid/100 g fresh weight). Lowest total phenol content was observed in untreated fruits (7.11 mg gallic acid/100 g fresh weight) after 21 days. With ripening, total phenol content decreased in fresh banana fruit. Phenolic compounds and tannins which are responsible for astringency taste of unripe fruits, decreased with ripening mainly due to polymerization. The highest antioxidant activity (11.9%) and the lowest amount of malondialdehyde (0.29 nmol/g fresh weight) were achieved in fruits treated with 500 μg/L Eucalyptus leaf extract, while the lowest amount of antioxidant activity (5.82%) and the highest amount of malondialdehyde (0.44 nmol/g fresh weight) were achieved in the control sample. Also, the highest enzymatic activity of peroxidase (7.72 unit/mL/min) was observed in fruits treated with 1000 μg/L mangrove leaf extract. The lowest activity of polyphenol oxidase (11.22 unit/mL/min) was observed in fruits treated with 500 μg/L mangrove leaf extract. The results showed that the extending of postharvest life of banana fruits from 0 to 21 days significantly enhanced the activity of polyphenol oxidase and peroxidase enzymes. Enzymatic browning reaction of banana fruit is usually caused by polyphenol oxidase and peroxidase enzymes, following cell damage caused by senescence. The study indicated the beneficial effect of extracts of red mangrove and eucalyptus leaves by postharvest immersion on antioxidant capacity and enzyme activity of fresh banana fruit.

    Conclusion

    Ethanol extracts of red mangrove and eucalyptus treatments maintained greater total phenol content and antioxidant activity, reduced malondialdehyde, peroxidase and polyphenol oxidase activity in fresh banana fruit during ripening. This study showed that the ethanolic plant extracts have a significant effect on preserving the biochemical properties of banana fruits by reducing the rate of mechanisms involved in ripening. Also, the use of plant materials are more acceptable by the consumer due to their higher health safety compared to chemical agents.

    Keywords: Biochemical quality, Perishable, Polyphenol oxidase, Shelf life, Total phenol
  • S. Salehi, A. Khodanazary * Pages 29-41
    Introduction

    Shrimp is one of the popular seafood consumed in the Iran. In Abadan (West Iran), Metapenaeus affinis, called as king prawn, are caught from marine water (Persian Gulf), processed and sold in the local market or exported. There is a reduction quality due to microbiological and enzymes activities during postmortem storage, which result in undesired odors and off-flavors over time, causing ultimate rejection by the consumer and making shrimp unfit for consumption. Specific spoilage organisms, a few members of the microbial community of freshly caught or processed seafood, produce various volatile compounds such as trimethylamine (TMA) and total volatile nitrogen bases (TVB-N), which could function as indicators of spoilage. Physicochemical indexes (pH, trimethylamine (TMA), total volatile nitrogen bases (TVB-N) and thiobarbitoric acid reactive substances (TBARS) are used to evaluate the freshness of fishery products. White shrimp (Metapenaeus affinis) is a warm-water speciesnative to the eastern Pacific coast from the Gulf of California, Mexico tonorthern Peru. The world aquaculture production of white shrimp was about 4.2 million tonnes with a global market value of USD24.4 billion in 2016. Currently, Pacific white shrimp is themost important species economically, and it is accounted for about 70%of the total shrimp production in the world due to its high nutrient content of amino acids, peptides, polyunsaturated fatty acids, and other useful substances. However, because shrimp is subject to natural contamination by many bacterial species and contain a large amount of non-protein nitrogenous compounds and autolytic enzymes, it is highly perishable and its post-mortem changes occur rapidly, which result in an obvious off-taste and soft texture. In general, sea-food microbiota originates from the skin or intestines of the processed objects, and contamination occurs during the successive steps of food processing. Shrimp spoilage is attributed mainly to the uncontrolled growth and subsequent various metabolic activities of microbiota. It is commonly assumed that only specific spoilage organisms (SSO) participate in the spoilage process, and they produce metabolites that result in off-odors and off-flavors. The identification of SSO that are responsible for spoilage re-quires sensory, microbiological and chemical studies. The growth of SSO results in the breakdown of macromolecules in shrimp, which causes the tissue of shrimp to lose its elasticity and produce off-odors. The modification of microbiota would lead to the change in pattern andprocess of spoilage in shrimp. Therefore, the aim of the present assay is to investigate of different temperatures (ice and refrigerator) on peeled shrimp Metapenaeus affinis.

    Material and methods

    Freshly caught shrimp Metapenaeus affinis were collected from the Persian Gulf in Khozestan (south Iran). The average weight of shrimp was 15.26±0.05 g per shrimp. Immediately after collection, samples were cooled with ice and transported to the Department of Marine Natural Resources, Khorramshahr University of Marine Science and Technology within 1h. The ratio of shrimp to ice was 1:3 (w/w). Upon arrival, shrimp were peeled and washed in cold water. After draining, shrimp weighing approximately 200 g were packed in a zip bag and were stored at ice and refrigerator. Shrimp samples were kept in ice in a plastic container with drain holes. Shrimp were re-iced daily to maintain the same ratio. All samples were taken for microbiological, physicochemical, and sensory analyses every 4 days for up to 16 days. Average were compared through an Analysis of Variance (ANOVA) and effects were considered significant (by Duncan´s test) when p-value £0.05. Pearson correlation analysis with 95% of confidence interval was used to determine the relationship between time of iced storage and quality parameters.

    Results and discussion

    Variations in physicochemical index were observed throughout the storage period. Sensory analysis attributes exhibited significant variations and correlations close 0.800 with time storage, which is a showing of the shrimps´ loss of freshness. A regression analysis using the acceptability limit mesophilic counts (7 log cfu/g) yielded a shelf life for white shrimp stored on ice and refrigerator of 7 and 4 days respectively.

    Conclusion

    The TVBN, microbiological and sensory analysis displayed very strong correlations with storage time, and they may be considered suitable indicators for evaluating white shrimp spoilage stored on ice and refrigerator.

    Keywords: Metapenaeus affinis, Shelf life, Quality properties, Chilling
  • M. Fathi, L. Najafian *, M .Charmchiyan Pages 43-59
    Introduction

    In recent years, increasing attention has been paid by humans to the role of diet in human health. Epidemiological researches have demonstrated that a high intake of plant-originated foods is strongly associated with a reduced risk of a number of chronic diseases, such as atherosclerosis and cancer, neurodegenerative diseases, including Parkinson's and Alzheimer's diseases (Şengül et al., 2014). These beneficial effects have been partly attributed to the compounds present in plants that possess antioxidant activity. Antioxidant compounds, which are found in plants (fruits, vegetables, medicinal herbs, etc.), are free radical scavenging molecules, such as phenolic compounds (e.g., phenolic acids, flavonoids, stilbenes, quinones, coumarins, lignans, tannins), nitrogen compounds (amines, alkaloids, betalains), vitamins (C, E), endogenous metabolites, and terpenoids (including carotenoids) (Cai et al., 2004).Artichoke is one of the plants with high health properties and usually heat treated before consumption. Stems of artichoke present significant antioxidant activity (Pereira et al., 2013), and for this purpose they are the main ingredients in many dietary supplements and drugs. In particular, stems and leaves are the most common plant part used for therapeutic purposes, since they have numerous medicinal properties including antitumor, antioxidant, antibacterial, antifungal, and hepatoprotective effects and so forth, mostly attributed to their high content of phenolic compounds (Zhu et al., 2004). Vegetables are commonly cooked by different cooking processes, including steaming, boiling in water or microwaving, before being consumed. These processes change the physical and chemical properties of vegetables. Cooking processes may have an effect on the antioxidant content of food due to antioxidant release, destruction, or creation of redox-active metabolites (Wachtel-calor et al., 2008) Antioxidant compounds, such as ascorbic acid and some carotenoids, are very sensitive to heat and storage. On the other hand, polyphenols have shown a certain stability when exposed to high temperatures. Turkmen et al., (2005) reported that after cooking, total antioxidant activity increased or did not change depending on the type of vegetable but not type of cooking. Zhang and Hamauzu (2004) showed that cooking affected the antioxidant compound contents of broccoli. Ismail and et al., (2004) demonstrated that heating decreased the total phenolic content in some vegetables such as swamp cabbage, kale, spinach, cabbage, and shallots. Important parameters in the cooking quality of vegetables, which may strongly influence consumer preferences, are texture and color. Thus, the aim of the current study was to investigate the effects of different cooking methods (boiling, steaming, and microwaving) on artichoke stem. The antioxidant capacity, and physical characteristic changes after cooking were also investigated.

    Material and methods

    In this research, the effects of different cooking methods (boiling, steaming and microwaving) in three levels of time on the antioxidant properties of the artichoke stem were used. Fresh artichoke was used in this research and obtained from a market in Sari, Iran and immediately cleaned by removed manually non edible parts with a sharp knife. Artichoke carefully washed with water (in consumer conditions), dried air and stems were cut into almost equal small pieces, mixed well. The samples were taken and divided into four portions. One portion was kept raw as control and stored at 4 ◦C in the refrigerator in home consumer conditions, others were subjected for four thermally treatments in triplicate. The best cooking times were determined as previously described and according to common cooking techniques [9] which conducted by trained researchers (Boiling 5, 10 and 15 min, steaming 5, 10 and 15 min, Microwaving 2, 4 and 6 min). Cooking conditions were examined, with a preliminary experiment in our laboratory. Then, total phenol content, total flavonoid content, DPPH radical scavenging, total antioxidant capacity and ferric reducing power and also chemical composition and sensory properties of samples were evaluated.

    Result and discussion

    The results showed that boiling at all times caused a significant increase in moisture content in the samples (P<0.05). Steaming also increased the moisture content of the samples, but this increase was not significant (P<0.05). There was no significant difference between the control and the cooked samples by microwave in 5 minutes (P<0.05). The fat content of the samples varied from 0.11 to 0.16%. Methods and cooking times did not have a significant effect on fat and protein (P<0.05). Protein levels also varied from 1.2 to 7.2%. Also, there was no significant difference between the amount of ash of the control sample and in boiled, steamed and microwaved samples at different times (P<0.05) except the microwaved sample in 6 minutes, which ash content was 1.9%. The cooking method has a significant effect on total phenol content, total flavonoid and antioxidant activity (P<0.05). The total phenol content and total flavonoid content of the artichoke stem under microwave processing at 2 and 4 min and the steaming process at 5 minutes increased compared to fresh artichoke stem samples and the boiling process decreased significantly (p <0.05). In boiling method, stems are immersed in water and in the loss of phenolic compounds because of leaching (leakage of compounds into water from artichoke). The antioxidant activity of the stem in the microwave cooking process at 2 min and steaming at 5 min showed the highest activity. In the reducing power assays, the antioxidants present in the artichoke stems convert the oxidized form of iron (Fe+3) in ferric chloride to the ferrous (Fe+2) form. The reducing power of the microwave method was significantly higher than other methods (P<0.05). In the sensory evaluation, the microwave method for 2 min and steaming for 5 min obtained the highest overall acceptance. Therefore, the microwaving and steaming methods are recommended in short time for cooking of artichoke and the optimal use of the valuable and useful compounds of this plant.

    Conclusion

    Therefore, microwave and steaming methods in short time for cooking artichoke stem and optimal use of the beneficial compounds and health of this plant are recommended. In addition, artichoke stems of the studied genotypes showed different bioactive compound profiles and significant antioxidant properties, and could be further used in the food and nutraceuticals industries as a cheap source of phenolic compounds and antioxidants.

    Keywords: Phenolic compounds, Cooking methods, Artichoke, Antioxidant properties
  • L. Nateghi * Pages 61-80
    Introduction

    Bread is one of the oldest foods that it is widely used in the world. Since the quality properties of breads are great interest to consumers. Bread during the storage period has undesirable physicochemical changes that it's called staling. Increase in hardness of bread core during the storage period is one of the most important to the staling index that the main reason for this is starch retrogradation (Guarda et al. 2004). It is recommended to delay staling by various pathways including additives such as proteins, carbohydrates, enzymes, fats, fibers, emulsifiers and hydrocolloids (gums) (Rajabzadeh, 2008). Today, the usage of dietary fiber is one of interest for food consumers due to its beneficial, physiological effects.  Its importance in reducing fat and blood sugar, reducing the risk of colon and gastrointestinal cancers and treating obesity is well known (Basman and Köksel, 1999). Oat bran is a soluble dietary fiber source and its known for its high beta-glucan levels. It is effective in lowering cholesterol and slowing glycemic responses (Klopfenstein, 1988). For a long time ago flour and bran of oat has been used in breakfast cereals or bakery products (Webster, 1986). Adding sources of fiber to the bread formula is often accompanied by problems in the properties of the dough and the quality of the bread. Adding fiber reduces the volume, hardness and darkness of the bread color and sometimes changes the taste (wang et al., 2002). Negative effects of fiber on bread structure is related to the decrease in gluten content and the increase in bran particles in bread texture (Verbeken et al. 2003). Due to low consumption of fiber in the daily diet that is usually lower than the recommended dose (30 grams of fiber per day), enriching bread with fiber can play an important role in achieving its health benefits (wang et al., 2002). The use of hydrocolloids increasing in recent years due to the desirable characteristics of baking (Kiumarsi, 1997). Tragacanth gum, as one of the herbal gums, is ejected from several species of Astragalus. Tragacanth is listed as a quality hydrocolloid in the GRAS list and is one of the food additives (Kiumarsi, 1997). This gum has wide application properties in the food industry, especially in the baking products, it has wide application properties including emulsifying properties, stability and thickening in food products (Verbeken et al. 2003). In this research, the effects of replacing oat bran fiber (4 and 8%), as well as tragacanth gum (0.5% and 1%) alone and in combination include 0.75% tragacanth gum + 6% oat bran fiber and 0.25% tragacanth gum + 2% oat bran fiber were used in preparation and formulation of toast bread formulation.  

    Material and methods

    Six treatments were designed according to a completely randomized design. The physicochemical tests included: bread volume, moisture content, ash, pH, fat percentage, colorimetric (brightness index (L*), redness index (a*), jaundice index (b*), hardness, sensory characteristics (Volume, Shape, Crust color, cooking uniformity, Crust Properties, Crack and tear properties, Hollow and grainy properties, Crump color, Aroma, Taste, Chewiness, Texture) were analyzed 2 hours after production and staling at 1, 2 and 3 days intervals were evaluated in three replications. The results of the tests were analyzed by Duncan's one-way mean comparison at 95% confidence level and training. Sensory data also evaluated using Kruskal-Wallis nonparametric test, charts were drawn with Excel software version 2013. 

    Results and discussion

    The results showed that there was none significant difference in fat percentage index and pH of treatments compared to control (p>0.05). By increasing the amount of tragacanth gum, as well as oat bran fiber ash percentage, jaundice and redness index significantly increased and brightness index, texture hardness and staling significantly (P ≤ 0.05) decreased. By using tragacanth gum and oat bran fiber and increase their concentration the moisture content of toast bread compare to the control significantly (P≤0.05) increased. In fact, the addition of tragacanth gum significantly increased the absorption of water in the dough as compared to the control, which is due to the hydrophilic nature of the hydrocolloids, including tragacanth gum. Oat bran fiber due to the high protein content of beta-glucan, it is also able to absorb a large amount of water in the early stages of dough preparation and increase the amount of water used to make the dough. This increase in water absorption caused decreases the hardness of the bread texture. Reason of staling decrease by adding oat bran fiber it is also due to the presence of starch degrading enzymes such as amylase, which causes delay in the staling and hardening of the bread's kernel. The results of the evaluation of the volume of tested treatments showed that the use of oat barley fiber alone increased the bread volume up to 4%, and decreased the bread volume in quantities higher than 4%. The reason for reducing volume by increasing the amount of oat bran fiber can be due to less airborne bubbles during the mixing of the dough and thus to reduce the volume of the samples. The use of tragacanth gum and increase its concentration also increased the specific volume of the toast breads compared to the control sample. Tragacanth gum due to the presence of hydroxyl groups in their structure, they can interact with the water molecules in the bread dough, which increases the viscosity of the dough, develops the dough and, consequently, improves the maintenance of gases and increases the volume of the product. The highest proportion of volume belonged to the treatment containing 0.75% tragacanth gum and 6% oat bran fiber and then the treatment containing 0.25% tragacanth gum and 2% oat bran fiber. The sensory evaluation results showed that all sensory features were evaluated including volume, shape, crust color, cooking uniformity, crust properties, crack and tear properties, hollow and grainy properties, crump color, aroma, taste, chewiness, texture did not have a significant difference with the control sample and even got higher score.

    Conclusion

    Toasting treatment containing 0.75% tragacanth gum and 6% oat bran fiber due to having more volume, less stale and desirable sensory properties were introduced as superior treatment. Therefore, the use of tragacanth gum and oat bran fiber can improve the qualitative (physicochemical and sensory properties) of the toast bread.

    Keywords: Texture, Color, Tragacanth Gum, Oat bran fiber, Toast bread
  • N. Esmaeli, R .Naghshband *, F. Zare Pages 81-97
    Introduction

    Cornelian cherry fruits are considered as natural antioxidant source and fruits are quite rich in anthocyanins, flavonoids, flavanols, tannins, carotenoids, vitamins, organic acids and phenolics acids. Leaves, flowers and fruits have been used in traditional medicine. Earlier investigations on physical and chemical properties of cornelian cherry fruits and flowers, their antioxidant and cytotoxic efficacy reported phenol, ascorbic acid, anthocyanin and high concentration of essential minerals (Ca, K, Mg) contents (Eyde, 1988). Consumers usually prefer attractive fruits in markets. However, serious quality losses are encountered in fresh-consumed fruits throughout the shelf life. Flesh softening, decays, deteriorate in taste, flavor and aroma are the basic problems experienced in shelves. Such losses are directly proportional to pre and post-harvest practices (maturity stage, harvest damages and storage conditions - temperature, relative humidity) (Lurie, 2003). When the fresh-consumed fruits were harvested at optimal maturity stage, less quality losses are experienced throughout the cold storage and shelf life of the fruits. Thus, postharvest quality losses increase in fruits not able to be harvested at optimal maturity. It was reported in previous studies that maturity stage had significant effects on storage or shelf life performance of litchi, sweet cherries, banana, plums, peaches and apples (Lata, 2007). Study of the antioxidant properties of fruits during different stages of maturity is essential for obtaining high-quality product and extending shelf life. Harvest maturity and storage time are main factors that may lead to changes in sensory and nutritional qualities of cornelian cherries (Gunduz et al. 2013). Cornelian cherry fruit are frequently harvested at dark red stages, when their flavor is most desirable. Consumers do not usually eat cornelian cherry at any of the other maturation stages. Therefore, the effect of ripening and storage time on nutritional quality is a major issue (Soleimani et al. 2013). This research was conducted to investigate the effect of harvesting time on some physicochemical and antioxidant properties of Cornelian cherry fruits during its storage period.

    Material and methods

    Fruit were harvested commercially at 2 stages of harvesting time (first harvest, fruit with light red color and second with dark red) from a commercial orchard at Kalybar area of east Azerbaijan province. In each harvest time fruit picked from four direction of a cornelian cherry tree and then transferred to postharvest laboratory of department of horticulture sciences of university of Tabriz. After preliminary evaluation of harvested fruit and selection of intact fruit among them they divided to two group: one group were used to evaluate of the qualitative characteristics before storage and the other fruit were transferred to storage at a temperature of 4 °C and a relative humidity of 80-85% for 21 days. The study was carried out as a factorial experiment based on completely randomized design in order to study of various chemical properties such as total phenol, total flavonoid, soluble tannins, total anthocyanin, total carotenoids, total antioxidant capacity and malondialdehyde levels during storage (0, 7, 14 and 21 days).

    Results and discussion

    The results showed that with progress in fruit maturity during storage, the amount of phenolic and flavonoid compounds, anthocyanins increased significantly (P<0.01) with the increase in the storage period in the first harvest compared to the second harvest, but the antioxidant capacity of fruit had a more significant (P<0.01) decreasing trend by the storage time than second harvest fruit. Anthocyanins are the major phenolic components of soft berry fruits, and their antioxidant activity has been found to be closely related to total phenolic content (Lopiero et al. 2005). The phenolic content and composition of fruits depend on environmental factors as well as post-harvest processing conditions (Lurie, 2003). Anthocyanin is a pigment responsible for red color development. Le Piero et al. (2005) reported increased anthocyanin pigment accumulation with the progress of ripening. Thus, anthocyanin pigment accumulation went on in early harvested fruits (H1) throughout the storage. However, anthocyanin pigment degradation was observed in full-ripe fruits. The phenolic compounds use in plant defense mechanisms, to counteract reactive oxygen species, in order to survive and prevent molecular damage, and damaging by microorganisms, insects and herbivores (Hopkins, 1999). Also, the carotenoids content increased by delay in harvest time and by prolonging the storage time of fruits. During the storage period, the amount of fruit soluble tannins decreased significantly (P<0.01), while the malondialdehyde content of the fruits increased. With delay in harvest the amount of soluble tannins of fruits reduced. Total antioxidant activity of fruit increased by the progress in fruit maturity stage during storage time as it decreased by the storage time for both maturity stages. The antioxidant activity of phenolics is mainly due to their redox properties, which allow them to act as reducing agents, hydrogen donors and singlet oxygen quenchers (Lurie, 2003). Taken together, our results have suggested that OA treatment significantly enhanced the antioxidant activity of the cornelian cherry fruits. It has been reported that the DPPH• scavenging activity is mainly attributed to the phenols, flavonoids, anthocyanins as well as ascorbic acid contents in cornelian cherry fruits (Dokhanieh et al. 2013).  Lipid peroxidation as MDA content is a secondary end product of oxidative lipid degradation, has become the system of choice for estimating lipid peroxidation of fruit increased by storage period as the highest amount was observed by the end of storage period. Formation of lipid peroxides, their degradation, and the roles of these hydroperoxides may play in cellular metabolism and the most accurate approach to measure lipid peroxidation is to directly quantify the primary hydroperoxide products (Hodges et al. 1999).

    Conclusion

    In general, cornelian cherry fruit chemical composition and its antioxidant capacity affected by harvest maturity and storage time as fruit of the second harvest had higher amount of carotenoids and antioxidant capacity content compared to other constituents, than first harvest fruit during storage time. Progress in harvest maturity was accompanied by increased total phenol, flavonoid, anthocyanin and carotenoid contents as well as improved DPPH scavenging capacity. Our data suggested that the fruit of second harvest enhanced antioxidant potential could be due to the activation of biosynthesis of most of antioxidant compounds in fruit compared to first harvest during cold storage period.

    Keywords: Storage time, Fruit antioxidants, Lipid peroxidation, Fruit ripening
  • Sh .Zomorrodi *, S. Faramarzi Pages 99-111
    Introduction

    Doughnut is a sweet sparkling snack which is produced chemically or by fermented or by combination of two methods. It is fried at high temperature. Doughnut is among the most popular sweeteners of wheat flour because of its high taste and high energy (Tan & Mitral 2006). Due to the high demand and the mechanization of Doughnut production, it is necessary to add suitable food additives to improve its nutritional value and enhance the technological and sensory properties of such a product. One of the compounds that can be used as a functional material in the baking industry is flaxseed (Linum usitalissmum). Flaxseed is known as a functional food, because it cantains α-linolenic acid (omega-3) and essential amino acids such as methionine and tryptophan. Fiber is another important ingredient in flaxseed, which reduces blood cholesterol, regulates blood sugar and prevents constipation and reduces the risk of colon cancer (Ganorkar & Jain 2013). Technological and textural properties of Doughnut can be improved by using various emulsifiers, such as DATEM (EC472), in addition to improving the nutritional value of this product using flaxseed, texture and consumer satisfaction. DATEM is a derivative of glycerol esterified with edible fatty acids, mono and di-tartaric acid (Dehgan Tnha et al. 2013). Bagherzade et al. (2018) the effects of the emulsifier diacetyl tartaric acid ester of monoglycerides (DATEM) and of the enzyme maltogenic α-amylase separately and combined on the quality and organoleptic properties of pan bread investigated. The results showed that emulsifier DATEM and α-amylase were effective in reducing density. In this regard, combined effects had better result than individual effect of them. Addition of enzyme and/or DATEM emulsifier improved the organoleptic quality of pan bread through reducing firmness and increasing flavor, chewiness, and porosity as compared to control samples.  The aim of this study was to investigate the effect of flaxseed powder as a functional food and DATEM as emulsifier on qualitative and sensory properties of Doughnut.

    Material and methods

    Thesamples were prepared according to the method described by Entazari et al. (2017). After 7 days of storage at cold room, the moisture content was meseared by drying in an oven at 103 ± 2 ºC, ash by burning in an electric furnace at 550 ºC to produce white color residue, protein using Kjeldahl method, specific volume using the seed displacemen method (AACC 2000), and the porosity and shell color indexes by Image J software (Wilderjans et al. 2008) and The texture was determined using a instran (Dehgan Tnha et al. 2013). Sensory properties were evaluated by 10 trained panelists. The attribute evaluation coefficient was from very bad (1) to very good (5). The results were analyzed using a completely randomized design with factorial trial with two factors and three replications using MSTAT-C software. The first factor was the amount of flaxseed powder in 4 levels (0, 5, 10 and 15%), and the second factor was the amount of DATEM as emulsifier in three levels (0, 0.25 and 50%).

    Results and discussion

    The results showed that by increasing the amount of flaxseed powder in the Doughnut formulation, the moisture content increased (Table 4). This can be due to high water absorption ability of fiber in flaxseed (Ganorkar and Jain 2013). In this regard, the increase in moisture reported by Ganorkar and Jain (2013) in Cookie, Xu et al. (2014) and Marpalle et al. (2014) in Bread and Ayubi (2018) in cup cake containing flaxseed powder. Addition of DATAM as emulsifier, the moisture content of product increased (Table 4). Similar results have been reported by Dahgan Tnha et al. (2013). Also, the addition of flaxseed powder resulted in decreased porosity and specific volume of the final product after frying process. This can be due to presence of water soluble proteins in flaxseed which reduces the strength of gluten network and as a result the dough is not going to be able to retain the gas produced during baking process. In this regard, Khorsand et al. (2018) showed that with increasing soy flour and lentil flour, the porosity and specific volume of Doughnut decreased. Ayoubi (2018) also reported similar results with increasing the amount of flaxseed powder in a cupcake. Increasing DATEM as emulsifier improved the porosity and specific volume of Doughnut (Table 5). This can be due to the size reduction and the increase in the number of gas cells and its uniform distribution in the product texture (Ziobro et al. 2012). Brooker (2003) also stated that the addition of emulsifiers to the formulation of the baking products would uniformly distribute air bubbles, improve the specific volume and texture of the final product. The hardness of the samples increased with increasing flaxseed powder and decreased with increasing the DATEM as emulsifier (P <0.05). With increasing flaxseed powder, the apparent brightness decreased and the redness of the Doughnut shell increased (P <0.01). The presence of protein and sugars in flaxseed powder, increaseted brownishness color in samples due to the Millard reaction. The darkening of the bread crust color with the replacement of wheat flour with flaxseed powder reported by Ayubi (2018), Xu et al. (2014) and Mentes et al. (2008). While with increasing of DATEM as emulsifiers, the L* index increased and redness (a*) of the shell surface of Doughnut samples decreased (Table 6). The ability of Homogenization and create very fine emulsion droplets by DATEM as emulsifiers, resulted in whitening of the Doughnut (Kim and Walker 1992). Also, with increasing the flaxseed powder in the product formulation, the sensory score of the samples decreased. According to the opinion of the panelists, the treatments containing 5-10% of flaxseed powder had a better flavor than the control sample (Table 7). Probably the reason for the increase in the flavor of the Doughnut contaning less amounts of flaxseed powder was the presence of nutritional compounds, unsaturated fatty acids and aromatic compounds in flaxseed, but at higher concentrations, due to the presence of fiber and gumy compounds, the flavor of the product is covered. The similar results reported by Ganorkar and Jain (2013) on the cookie containing flaxseed. With increasing the DATEM as emulsifier in Doughnut, the score of sensory evalulation of samples increased (Table 7). The overall acceptance score of Doughnut containing 0.25 and 0.5% DATEM compared to the control sample was higher (Table 7), which was in agreement with the results obtained by Dehghan Tnha et al. (2013).

    Conclusion

    According to the results obtained in this study, the use of 5 to 10% of flaxseed powder and 0.5% of DATEM as emulsifier for production of Doughnut with acceptable qualitative and quantitative properties is recommended.

    Keywords: Doughnut, DATEM emulsifier, Flaxseed powder, Qualitative properties
  • S. Belgheisi * Pages 113-124
    Introduction

    Honey is one of the most economically important bee products (Apismellifera) that is produced as a natural chemical from plants. Honey quality is mainly determined by its physicochemical and microbial properties, and the physicochemical properties of honey are specified in national and international standards. Honey ripening, harvest season, production and processing methods, climatic conditions, storage time and storage location and source of nectar (single or multiple flowers) have important effects on the quality, composition and biochemical properties of honey. These factors can have different physico-chemical properties. The main properties of honey are moisture, electrical conductivity, ash, reducing and non-reducing sugars, acidity, diastatic activity, hydroxymethylmorphoreal and proline content. In other words, the standards of honey in terms of microbial and health contamination of this product are deficient. In fact, many studies have been reported on the physicochemical properties of honey, but studies on microbial contamination are scarce. In this study, physicochemical properties (moisture, acidity, pH, soluble solids, diastase activity, electrical conductivity, ash, reducing sugars before and after hydrolysis, fructose to glucose ratio, sucrose, proline and hydroxymethylmfurfural), and microbial properties ( Mold, Yeast, and sulphite reducing Clostridium) in 30 honey samples of different plant origin (Milkvetch , Jujube, Thymes, Orange blossom, Multi flower) were analysed and compared with the Codex standard in order to classify different honeys and to specify the characteristics of each honey.

    Material and methods

    In this study, 30 samples of honey with different plant sources (24 single flower and 6 multi flower) produced by Karnica bee were collected from Alborz province with the assistance of the Ministry of Agriculture's Ministry of Agriculture during 2017-2018. For this purpose, 10 beekeepers were selected from the Alborz Agricultural Jihad Organization. Honey samples were then harvested by random sampling and packed in glass bottles (500 g) and stored    at -180C in the dark until the test. Physicochemical properties (moisture, soluble solids, pH, acidity, electrical conductivity, ash, reducing sugars, sucrose, fructose to glucose ratio, diastatic activity, hydroxymethylfurfural and proline) and microbial properties (Mold,Yeast, sulphite reducing Clostridium) were evaluated from various plant sources (Milkvetch , Jujube, Thymes, Orange blossom, Multi flower) and compared with the characteristics defined in the International Codex Standards.

    Results and discussion

    There was no significant difference in soluble solids content of Milkvetch and Multi flower samples (P>0.05). While other samples showed significant differences (p <0.05).Honey samples beside the highest soluble solids and Orange blossom honey had the least soluble solids. The amount of soluble solids is related to the amount of sugar in honey and is an important indicator in the diagnosis of fraud. There was a significant difference between pH and acidity in different honey samples of different plant origin (P<0.05). Orange blossom had the lowest pH and acidity and the honey had the highest pH and acidity. High acidity is the indicator of fermentation of sugars to organic acids. Electrical conductivity was significantly different in honey samples of different plant origin (P<0.05). The electrical conductivity of Jujube was above the permissible limit (0.8 ms/cm) and other samples were within acceptable range. The electrical conductivity of Jujube was higher than the permitted limit (0.8 ms/cm) and other samples were within acceptable range, indicating that the honey samples were rich in flower pollen. Ash content in honey of different plant origin was not significantly different (P> 0.05). The amount of ash was related to total minerals in honey and it was dependent on environmental, geographical and vegetative conditions. There was a significant difference in the amount of sugars before and after hydrolysis of the studied honey samples (P<0.05). Orange blossom honey had the highest and the Jujube honey had the least amount of reducing sugars. The Orange blossom hony had the lowest sucrose content and the Jujube honey had the highest sucrose content. Sucrose content of Milkvetch, Jujube, Thymes, Orange blossom, and Multi flower honeis was exceeded as specified in Codex standard (maximum 5%). Fructose to glucose ratio was not significantly different in Milkvetch, and Jujubehoneies (P>0.05), while the other samples had significant differences (P<0.05). The ratio of fructose to glucose was lower than the standard level (0.9) in Milkvetch, and Jujubehoneies. The results show that Orange blossom honey with higher fructose to glucose ratio has fewer tendencies to crystallization than other types of honey. Sucrose content in Milkvetch, Jujube, Thymes, andMulti flower honey samples exceeded the International Standard Codex limit (maximum 5%) (Codex 2001) and may be indicative of honey bee feeding or premature harvesting. Hydroxy methyl furfural content was not significantly different in Milkvetch, and Thymes honeis (P>0.05), while other samples showed significant differences (P<0.05). In all honey samples with the exception of Orange blossom the levels of hydroxymethylfurfural were higher than the maximum (40 mg / kg). Diastatic activity of the up and down specimens were not significantly different (P> 0.05), while the other samples had a significant difference (P<0.05). Samples of Astragalus, Quercus, Thyme and Multi flower had lower diastase activity than standard (minimum G0 8) and only the samples of spring honey were within acceptable range. Proline content in honey samples of different plant origin was significantly different (P<0.05). Honey samples except of Milkvetch, and Jujube honeis had the proline content within the allowed range (minimum 180 m /kg). The amount of mold, and yeast in the analyzed honey samples was generally low, and the amount of sulphite reducing Clostridium was negative in all samples. Microbial contamination of honey samples was not dependent on plant origin and no significant differences were observed between the samples.

    Conclusion

    The physicochemical properties (moisture, soluble solids, acidity, pH, electrical conductivity, ash, sucrose, fructose to glucose ratio, hydroxymethylfurfural and proline) were dependent on the plant origin of the honeycomb but, the microbial properties (Mold, Yeast, and sulphite reducing Clostridium) was not dependent on the origin of honey. Based on the results, it is recommended to review the standards regarding the physicochemical properties of honey with regard to its plant origin and to determine the acceptable limit standards for each of the attributes, to consider the origin of honey samples.

    Keywords: Iran, Physicochemical, Honey, Plant origin, Microbial
  • A. Pourjahed*, H. Abbasi, N. Saffarian Pages 125-136
    Introduction

    Natural sterols and stanolols in plant cell membranes are known as phytosterols. In recent years, interest in the use of phytosterols in dietary compounds to reduce cholesterol has increased. Diet provides a daily amount of phytoestrol 500-180 mg, which is not enough to lower blood cholesterol. The main mechanism of action of phytosterol in reducing cholesterol is interfering with the dissolution of cholesterol in the intestinal micelles which leads to a decrease in cholesterol absorption. These compounds also reduce the risk of gastric cancer, prevent tumor growth, improve inflammatory diseases, and prevent atherosclerosis. Taking two to three grams of phytosterol per day can lead to approximately a 10% decrease in blood cholesterol levels and a 15% decrease in low density lipoproteins. Phytosterol is a white, water-insoluble, high-melting powder that is difficult to dissolve in fats and oils, which makes it difficult to add phytosterol to foods.Phospholipids are cell membrane constituents with a hydrophilic end and one or more hydrophobic tails; they also have antioxidant activity. These compounds are used to make carriers called nanoliposomes that have in recent years been an important carrier in the pharmaceutical and food industries for the coating and release of hydrophilic or lipophilic active compounds such as vitamin A, Vitamin E and vitamin C, ascorbic acid, micronutrients, omega-3 essential fatty acids, medium chain fatty acids - vitamin C, cinnamon oil, polyphenols including catechin, curcumin and other active ingredients. Nanoliposomes are colloidal structures formed from one or more spheres consisting of two lipid layers that surround the aquatic environment. This structure of liposomes provides special properties, such as spontaneous sealing in the aqueous medium, which makes them suitable carriers for active compounds in the field of medicine, immunology, diagnosis, substances Manufactures cosmetics, cleaning and food industries. Nanoliposomes provide greater surface area than liposomes, and improve bioavailability and targeted targeting of embedded materials. In the design of nanoliposomes used in the food industry, two important parameters must be taken into account; the first parameter, the stability of nanoliposomes, in order to increase the shelf life and storage of the food and the second parameter, the composition of their structure should not be compromised. Make a difference in the texture and taste of the food.Reducing the size of liposomes to nanosize can reduce their stability. For this reason, the addition of stabilizers can extend the life and stability of these nanocarriers.Adding Cholesterol to Phospholipids Increases Stability of Nanoliposomes by reducing lipid membrane permeability and membrane stiffness. Nanoliposomes have shown good potential to encapsulate and stabilize molecules against a wide range of environmental conditions and to protect them from degradation.The main purpose of this study was to incorporate phytosterol into nanoliposomal formulations in order to improve its dispersion in aqueous and aqueous media, to select the optimal formulation from soybean-cholesterol formulation. Different concentrations of cholesterol were used as stabilizers. Mean particle volume diameter, dispersion index, zeta potential, physical stability and pH were studied as important parameters. The use of edible grade compounds in the preparation of nanoliposomes and the overlay of the beneficial phytoestrol compound is the most important advantage of this study over other studies. According to studies done, no research into the intrinsic phytosterol content of edible materials was found. In this study, ultrasonic homogenizer was used to reduce particle size and more efficient loading of phytosterol into nanoliposomes.

    Material and methods

    In this study, β-sitosterol containing nanoliposomes were prepared from different concentrations of soy-lecithin and cholesterol by thin layer hydration method. The ultrasonic homogenizer was used to reduce the particle size. Fourier-transform infrared spectroscopy (FTIR) was performed to investigate the possible interaction between beta-cytosterol and the prepared nanoliposomal carriers. Particle size, polydispersity index and zeta potential of nanoliposomes were analyzed according to cholesterol content of samples. Also, pH and stability of nanoliposomes in different temperatures were analyzed according to cholesterol content.

    Results and discussion

    The results demonstrated that the interaction between β-sitosterol and nanoliposomes is a hydrogen bond type. The tension created in the area of the OH bond stretch proved to be a hydrogen bond between lecithin, cholesterol and β-sitosterol. The mean particle diameter, polydispersity index, zeta potential, physical stability and pH of the nanoliposomes were investigated. The size of nanoliposomes can vary depending on the physical conditions such as temperature, chemical conditions such as pH as well as the type of phospholipid, the type of carrier and the type of stabilizer. The mean particle diameter was between 90 and 100 nm. Although the addition of cholesterol to the samples slightly increased the mean particle diameter of nanoliposomes (P<0.05), it reduced the zeta potential (P<0.05) and increased the stability of the samples at different temperatures. Cholesterol addition, although it has led to an increase in the particle size and dispersion index of nanoliposomes, these effects are negligible. Increasing the cholesterol level decreased the pH in the range of 6.88 to 6.51; the proximity of pH to neutral range in these samples is an advantage. The pH of the samples was close to the neutral range, which proves that the use of these nanoliposomes does not affect the pH of the food stuffs. Statistical analysis of physical stability test showed that samples with higher cholesterol percentage showed longer stability at different temperatures.

    Conclusion

    The use of thin layer hydration and ultrasonic homogenizer resulted in the formation of particles with an average volume diameter of about 100 nm and lower which, however, increased cholesterol and had a mild and slight effect on increasing particle size and distribution; In the prepared samples, it reduced the zeta potential and consequently increased the stability of the samples. It is also a measure of the stability of the specimens at different temperatures predicted for optimal storage and use. The best results for a sample containing 0.06 g cholesterol were obtained. Although the size of the particle was slightly larger than other samples, zeta potential, physical stability and pH were more favorable than other ones.

    Keywords: β-sitosterol, Nanoliposomes, Particle size, Stability
  • S. Rahimi*, S Saramnezhad Pages 137-150
    Introduction

    Nowadays, by increasing the awareness of people on the importance of healthy diet and its effects on prevention of many diseases, researchers have been focused on the formulation and production of functional foods for their positive effects on improving the health. Regarding to the role of  bread in supplying a major part of the daily energy of community members, it is possible to fortify this product during production process with many functional compounds. Brown rice has high fiber content and is known as a rich source of vitamins and antioxidants due to the presence of bran layer on the seed. Many studies have shown that germination can improve the concentration of functional compounds such as gamma- aminobutyric acid, phenolic compounds and antioxidants in brown rice, so it can be used for production of functional foods or fortification . One of  the important processes during the bread making is fermentation. Regarding to  the probable effects of fermentationon on the concentration of functional compounds in sourdough, in the present project the effect of fermenting the malted or germinated brown rice flour by  two lactic acid bactria, Lactobacillus sakei and Lactobacillus sanfranciscensis, seperately and in  the co-culture form besides the baker,s yeast was investigated and the potential of resulted sour doughs for using in the formulation of functional fermented products such as bread was determined.

    Materials and methods

    The brown rice sample was steeped for 24 hours at 30 ᵒC, then germinated for 48 hours at the same temperature of steeping. The germinated sample was dried to approximately 10% moisture content then ground and sieved to 40 mesh flour.The resulted flour samples were fermented with each of Lactobacillus sakei and Lactobacillus sanfranciscensis, seperately and in  the co-culture form (once with  the optical density of 2.9 or 10 8 CFU/ml and another time with  the optical density of 1.45 or 0.5 ×108 CFU/ml) in the presence of baker,s yeast till reaching to pH=4.9, then changes in the concentrations of the functional compounds such as free and bound phenolic compounds and their related DPPH free radical scavenging capacity, gamma-aminobutyric acid and free amino acids contents of sourdough samples was studied. The gamma-amino butyric acid and amino acid profile were measured by HPLC method, free and bound phenolic compounds were determined by using of folin ciocalteu reagent and DPPH radical scavenging capacities were measured by using of spectrophotometric method in all of the samples. A dough sample which was fermented only by Baker,s yeast (Saccharomyces cerevisiae) was used as control. The effect of each independent variable on the concentration of functional compounds was determined by using of one way ANOVA, by SPSS software (version 20 ). All data were first checked for their normal distribution and also the homogeneity of variances. Duncan, s multiple range test was used for comparing the means at α=0.05 significant level. All tests were performed in triplicate other than amino acid profile determination.

    Results and discussion

    According to the obtained results, fermenting with L.sakei and L.sanfranciscensis separately or in the co-culture form, caused significant increase and decrease of free and bound phenolic compounds respectively compared to those of malted brown rice flour (p≤0.05). The highest free phenolics content was observed at sourdoughs containing the mixture of lactic acid bacteria with OD of 2.9 and 1.45. Free phenolic compounds of sourdough sample which wasfermented by L.sakei, showed the highest antioxidant capacity, whilst the highest free DPPH radical scavenging activity of bound phenolic compounds was obsereved in sourdough that was fermented with the mixture of L.sanfranciscensis and L.sakei with optical density of 1.45. In general, the results indicated on the higher antioxidant activity of free and bound phenolic compounds of L. sakei fermented sample and sourdough containing the mixture of L. sakei and L. sanfranciscensis with optical density of 1.45 respectively. The type of microbial flora for fermenting the dough had significant effect on GABA synthesis. The control sample and the sour dough fermented by L. sakei had the lowest and the highest GABA contents respectively. It seems that the difference in the GABA contents of the samples with different starters is related to the presence and amount of glutamate decarboxylase (GAD) in samples. The mentioned enzyme converts the glutamate to GABA. Also, fermenting of sourdough with L.sakei, resulted in the most free amino acids contents. The highest essential amino acid contents was observed at sour dough fermented by the mixture of L.sakei and L. sanfranciscensis with OD of 2.9.

    Conclusion

    Considering the obtained results, L.sakei bacteria can be suggested to sourdough industry as a suitable lactic acid bacteria for fermentation of malted brown rice flour with the aim of improving its functional compounds specially gamma-amino butyric acid. Gamma-amino butyric acid widely known as GABA, is a 4-carbon nonproteinogenic amino acid that is ubiquitous in microorganisms, plants, animals, and humans. It has been reported to possess numerous physiological functions in different organisms. It serves as a major inhibitory neurotransmitter in the central nervous system in humans and animals by mediating inhibitory synaptic currents between the pre- and postsynaptic membrane. It provides beneficial effects for human health by regulating blood pressure and the heart rate, helping with recovery from chronic alcohol-related symptoms, alleviating pain and anxiety, controlling stress and inhibiting cancer cell proliferation. According to  the scientific articles, L.sakei is a microorganism with short lag phase and high growth rate among other Lactobacilli microorganisms. This bacteria is able to inactivate pathogens and spoilage microorganisms through acid and bacteriocin production and there is no report on its toxic or pathogenic effects, so it is mostly used for fermentation of sausages as starter culture. In the present study, based on the obtained results, the type of the fermenting microorganism and its concentration in the dough affected the functional properties of the resulted sourdough, also using of  L.sakei for fermenting the malted brown rice flour with the aim of producing a functional sour dough, resulted in improving of  the  gamma-amino butyric  acid concentration and DPPH radical scavenging capacity, so producing of a functional bread rich in  gamma-amino butyric acid, free amino acids and free phenolic compounds with antioxidant activity would be possible.

    Keywords: Gamma- aminobutyric acid, Functional, L.sakei, L.sanfranciscensis, Malted brown rice flour
  • A .Mardani, R. Farhosh *, A .Sharif Pages 151-166
    Introduction

    Lipid oxidation is the oxidative deterioration of unsaturated fatty acids via an autocatalytic radical chain process that leads to the deterioration both the sensory and nutritional quality of lipids. Lipid oxidation has adversely consequences for the quality of lipid and human health by producing a wide range of harmful reactive radicals. Using antioxidants is the most important defense means to delay or slow rate of lipids oxidation by scavenge chain-propagating peroxyl radicals. Recently, the interest in natural antioxidants has been increased due to the reported toxicologically negative effects of the synthetic antioxidants.The most powerful types of natural antioxidants are the phenolic acids, which are widely found as secondary metabolites in plant kingdom acids. A relationship between the antioxidant activities and the structures of the phenolic acids were the object of a number of investigations. The number of hydroxyl groups and the position of these groups in the phenolic ring have a significant influence in antioxidant activity of phenolic acids. The activity increases in the following order: monohydroxyo< dihydroxy< trihydroxy. Gentisic acid (2,5-dihydroxybenzoic acid) is one of the interesting subset of dihydroxybenzoic acids, present in many natural sources such as citrus fruits, grapes, olive, peanuts and herbs. The antioxidant activity of the Gentisic acid was the object of lot investigations. Gentisic acid has been reported to has anxiolytic, antirheumatic, anticarcinogenetic, anti-inflammatory and antimutagenic properties. The capacity of Gentisic acid to prevent lipid oxidation is related to its mechanism of antioxidant activity. The relative positions of the two hydroxyl groups in Gentisic acid phenolic ring have significantly influence in antioxidant property.

    Material and methods

    Purifed triacylglycerols of sunflower and olive oils were obtained by removing all pro- and anti- oxidants by adsorption chromatography: 130 g of oils were purified twice by passing in a glass column (25 × 2.5 cm i.d), packed with 70 g of aluminum oxide 60 activated at 200 °C for 3 h in bottom and, 15 g of silica gel activated at 160 C for 3 h in upper layer. Triacylglycerols were drawn in dark through the column by suction without solvent. Then soybean and olive oil samples, containing different concentrations of the Gentisic acid (0.02, 0.04, 0.08, 0.16 and 0.32 wt. %) were prepared by adding aliquots of its solutions in purified acetone. The solvent was removed under nitrogen. 1-mm layer of the prepared oils samples (4 g) were oxidized in a Petri dish having a diameter of 9 cm Under these conditions, the process took place in a kinetic regime, i.e., at a sufficiently high oxygen concentration which the diffusion rate does not influence the oxidation rate. Oxidation was performed in dark at 60, 80, 100 and 120 °C.The oxidation process was followed by withdrawing samples at certain time intervals and subjecting them to spectrophotometric determination of the peroxide value (PV) as primary oxidation products and different kinetic parameters i.e. stabilizing factor (F), oxidation rate ratio (ORR), and antioxidant activity (A). In order to PV measurement, the vegetable oil samples (≤0.01–0.30 g) were added to a glass tube containing 9.8mL chloroform–methanol (7:3 v/v) and were vortexed for 2–4 s. 50mL of ammonium thiocyanate solution (30 % w/v) was added the sample was mixed on a vortex mixer for 2–4s. Then iron (II) chloride solution [50mL, (0.4g barium chloride dehydrate dissolved in 50mL H2O) + (0.5 g FeSO4·7H2O dissolved in 50mL H2O) + 2mL 10 M HCl], with the precipitate, barium sulfate, filtered off to produce a clear solution]) were added, and the sample was vortexed for 2-4 s. After 5min incubation at room temperature, the absorbance of the sample was read against a blank sample (containing all the reagents except the sample) at 500nm (UV-VIS spectrophotometer, Model 160A Shimadzu, Kyoto, Japan). Results were reported as milliequivalents of oxygen per kilogram of oil. Kinetic curves of peroxide accumulation were plotted. The x-coordinate of intersection point of two straight lines fitted on the initiation and propagation stages of the oil oxidation was calculated as induction period (IP). Mechanism of antioxidative action was determined according to kinetic parameters and the based on the participation of Gentisic acid molecules and radicals in a series of reactions).

    Results and discussion

    Gentisic acid as a phenolic antioxidant was effectiveness during autoxidation in both lipid systems (i.e. olive and soybean oil) without reactive free radicals production. The dependence of the parameter F on antioxidant concentration is linear only in the case of Gentisic acid-inhibited sunflower oil oxidation that showed the participation of antioxidant molecules mainly in reaction 7. The absence of F linearity in other treatments (α-Resorcylic acid in both olive and sunflower oils oxidation and Gentisic acid in olive oil oxidation) is due to the participation of the inhibitors molecules in the side reactions other than the main reaction of chain termination 7, namelyreaction 11 or/and 12. The mean rate of antioxidant consumption increased as the unsaturation degree of the soybean oil increased. Despite having the more appropriate performance in the olive oil sample, which normally contains higher amounts of oleic acid. The overall performance of Gentisic acid was attributed to the main reaction of chain termination (ROO• + InH ® ROOH + In•) as competed with the main oxidation reaction of chain propagation (ROO• + RH ® ROOH + R•). Due to the higher percentage of non-saturated fatty acids in soybean oil, antioxidant activity of gentisic acid promoted with increased concentrations, while in olive oil because higher content of monosaturated fatty acid (e.g. oleic acid), Gentisic acid participate in side oxidation reactions (InH + ROOH ® In • + R • + H2O) as prooxidant in high concentration.

    Conclusion

    The present study was performed to elucidate the mechanism of antioxidative action of Gentisic acid. It was concluded that Gentisic acid as a phenolic antioxidant was effectiveness during autoxidation in both lipid systems (i.e. olive and soybean oil) without reactive free radicals production. The mean rate of antioxidant consumption increased as the unsaturation degree of the oil system increased. Despite having the more appropriate performance in the olive oil sample, which normally contains higher amounts of oleic acid.

    Keywords: Gentisic acid, Vegetable oils, Mechanism of antioxidant activity
  • R. Razavi, R. Esmailzadeh * Pages 167-182
    Introduction

    Milk is the most consumable dairy product in the world which is predominantly treated to heat pasteurization and sterilization processes to increase safety and shelf life (Meshref 2008). Heat treatment can cause undesirable protein denaturation, non-enzymatic browning, loss of vitamins and volatile flavor compounds, freezing point depression, and flavour changes. Due to using high temperature of heat in this process, the nutritional composition and sensory properties of milk are changed (Herceg et al., 2012). Today, there is interest in use of high-intensity ultrasound waves with a mild heat treatment process to deactivate microbes and enzymes leading to spoilage and degradation of safety in foods. The aim of this study was to evaluate the effect of ultrasound process as an alternative for high temperature heat process on microbial count, lipid oxidation as qualitative parameter and vitamins as nutritional characteristics of milk.

    Materials and methods

    Fresh milk was prepared from the Firoozkandeh cow farm (Sari-Mazandaran-Iran) and transferred to the laboratory in cold conditions then it was treated by ultrasonication techniques at 3 temperature levels of 45, 55 and 65 ° C and duration 5, 10 and 15 min using ultrasound probe type (350 W) in two intensities of 50 and 75% and ultrasound bath (280 W). The control sample was heated at 90 ° C for 10 min. Total viable count of bacteria, total count of mold and yeast, count of coliforms, psychrophilic bacteria and Escherichia coli in raw milk, control milk and treated milk with ultrasound were measured. Plates with 30 to 300 colonies were selected to count of colonies and microbial changes of milk samples were reported based on Log CFU/ml. The effect of thermo sonication on the lipid oxidation of milk was evaluated by measuring peroxide value and thiobarbituric acid value. Riboflavin and thiamine as water-soluble vitamins and retinol and tocopherol were measured as lipid-soluble vitamins by HPLC method.

    Results and discussion

    It was found that an increase in ultrasonication temperature from 45 to 65°C and duration from 5 to 15 min, increased lipid oxidation of milk and the samples treated with ultrasound bath had the least amount of peroxide value (0.019±0.01 meq O2/Kg oil) and thiobarbituric acid value (0.03±0.0 µg/Kg). Raw milk has the least oxidation because no heat process was applied to it. The presence of air bubbles during sonication and solid particles of milk leads to the formation of nuclei for free radicals and intensifies the oxidation process. The formation of primary and secondary compounds resulting from fat oxidation depends on the variables of ultrasound treatment, the time and temperature of treatment with ultrasound, as well as the type and intensity of ultrasound. When sound waves pass through a liquid; in each section of the fluid, a continuous compression occurs and an exponential cycle occurs. Because of the sound energy cannot be absorbed by molecules, the fluid is drawn to one side and the cavitation phenomenon occurs, which is associated with the formation of small gas bubbles. The collision of gas bubbles encounters the formation of other waves. Given that the effects of ultrasound depend on the number and severity of explosive bubbles inside the liquid over time and type of treatment environment. In same sonication condition the effect of increasing in temperature on vitamin degradation was higher than that of ultrasound type, and the highest levels of thiamin (10.80±0.06 µg/100g), riboflavin (97.55±0.68mg/100g) and retinol (14.9±0.09µg/100g) degradation occurred in the control sample. The effect of temperature on riboflavin and thiamine amount was significant (P<0.05) and with increasing in temperature riboflavin and thiamine amount decreased and there was a significant difference (P<0.05). The ultrasound process was effective in reducing riboflavin and thiamine amount, resulting in a decrease in their amount, and the probe type of ultrasound caused the most vitamin degradation. The separate and interaction effects of each factor were not significant on retinol content. The retinol content decreased with increasing in temperature but the difference was not statistically significant. The reason for the decrease in tocopherol during sonication treatment can be attributed to the anti-radical properties of vitamin E. Also, the effect of ultrasound on water-soluble vitamins and lipid-soluble soluble vitamins showed lower levels of degradation of these vitamins compared with conventional heat-treated specimens. Very few studies have investigated the direct and indirect effects of ultrasound on the nutritional value of food, and the use of ultrasound at low temperatures reduces the probability of nutrient degradation. Increasing in time of ultrasound was effective in reducing the count of microorganisms but it had a statistically significant effect (P<0.05) on reducing the number of Escherichia coli, mold and yeast. Ultrasound type and ultrasound temperature had a significant effect on the total viable count of bacteria, coliforms, mold and yeast and psychrophilic bacteria (P<0.05). Probe type ultrasound is very suitable for the 75% oscillation range in the destruction of a variety of microorganisms, but increases the fat oxidation. The effect of none of the studied variables on count of Escherichia coli was statistically significant (P<0.05). When probe type of ultrasound used, the antimicrobial effect of sonication increased with increasing in intensity of ultrasound due to the cavitation effect. Increasing the time of ultrasound process has reduced the number of bacteria and in this regard, probe ultrasound has been more effective than ultrasound bath, which is consistent with the results of the present study. In addition to the cavitation phenomenon, ultrasound application results in a change in permeability of the membrane. Entering high amounts of water into the microbial cells can easily damage the cells.

    Conclusion

    The results showed that ultrasound has been able to reduce the microbial load of milk and it made fewer changes in vitamins than milk treated with conventional method. In this regard, the ultrasound probe has been more effective at 75% intensity. The use of ultrasound probe type at 55 ° C and 75% intensity for 10 minutes is recommended as a non-destructive process for milk pasteurization.

    Keywords: lipid oxidation, ultrasound, microbial load, heating, vitamin
  • H. Ghaffari *, H. Hassanpor, N. Marghoub, Kh. Mohammadi Pages 183-194
    Introduction

    Fruit and vegetables are an important component of the human diet and consumers usually expect such products to have premium quality. The texture is a major quality attribute that influences consumer acceptance, shelf life, resistance, and transportability. Also, the quality of fruits and vegetables can be determined by their external and internal characteristics. Recognition of agricultural product characteristics may help to design new machines, industrial processes to reduce the damages (Tavakkoli hashtjin, 2003). The first step in the codification of qualitative standards for the agricultural product is the recognition of different properties and different modifications of these products caused by various factors (Mohsenin 1986). Persimmon (Diospyros) is a member of Ebenaceae family and originated from China and Japan. D. Lotus, D.Virginiana and D.Kaki are three important persimmon cultivars in Iran. According to the FAO statistics, the Iran persimmon harvested area was about 1692 ha in 2017. In this year Iran produced about 24326 tons of persimmon (with an average yield of 14.3 ton/ha) which ranked 11th in the world. Although many researchers conducted some investigations on the mechanical properties of agricultural products, but studies on persimmon mechanical properties have been very limited. Hezbavi et al. (2008) studied the physical and mechanical responses of Japanese cultivar of persimmon (D.Kaki) and reported that there was a significant difference in all mechanical properties between soft and stiff persimmon, except fruit deformation. Altuntas et al (2013) determined the physical, mechanical and chemical properties of medlar during physiological maturity and ripening period. The physical properties such as geometric mean diameter, sphericity, bulk and true densities, porosity, projected area and color characteristics were measured during physiological maturity and ripening period of medlar. Mechanical properties such as rupture force, deformation and rupture energy and chemical properties (total soluble solid content, titratable acidity and pH) of medlar fruit were determined.  The results of Altuntas et al. (2010) have shown that the correlation coefficients between the physical parameters of persimmon fruits were significant. The coefficient of static friction was greater on plywood as compared to the chipboard and galvanized metal surfaces. They reported that the required force for punching persimmons along the Y-axis was higher than along the X-axis. Review of literature showed that the effect of harvesting time, cultivar and loading speed of D.Kaki and D.virginiana persimmon cultivars on some mechanical properties and coefficient of restitution of persimmon have not been studied. Therefore, in this research, some mechanical properties of two persimmon cultivars (D.Kaki and D.virginiana) at three harvests time (immature, semi-mature and mature) and coefficient of restitution were studied.

    Material and methods

    In this study, some tests were conducted to determine these mechanical properties of two persimmon varieties   D. Virginiana and D. Kaki at the three harvest times with three different loading speeds of 50, 100 and 200 mm/min using fruit texture analyzer and to obtain resilience coefficient used an invented device equipped with sonic sensor, so that it can be used as a criteria for bruising damage. The persimmon fruits (D.Kaki and D.virginiana) at three harvest times were provided from gardens of East Azarbaijan province. Then, the samples were transferred to the biophysical and mechanical lab of university of Tabriz. The moisture content of fruits was determined by the standard method (ASAE 1998). The acoustic test was used to determine the resilience coefficient that is a criterion for determining persimmon bruising damage. For this purpose, persimmons were dropped from three heights 10, 20 and 30 cm on the plate equipped with an acoustic sensor located underneath that plate. The amplitude-time curve was obtained using Praat software for each drop test. According to this curve, rebound time (the time required for the first and second peaks of curve) was determined.

    Results and discussion

    According to the results, the main effects of variety, harvesting time and speed of loading and also interaction of variety*harvesting time were significant at the probability level of 1% and the other interactions were not significant. It means, in general, as expected, the mean values of puncture force ​​for the two varieties, at three harvesting times and in three different loading speeds, had a significant effect at the probability level of 1%. The reason for the significance of interaction of variety*harvesting time is the behavior of puncture force at different times of harvesting persimmons. The results showed that the required mean value of puncture force in D. Virginiana variety was greater than D. Kaki variety and the average force required to punch the persimmon fruit, with Magness Taylor probe for the first harvesting time (immature stage) is nearly doubled compared with the third harvesting (mature stage). It shows that if persimmon has been marketed in the immature stage or in semi-mature stage, mechanical damage can be decreased to one-half value. By increasing the loading speed, the average force required to punch the persimmon increased. The average energy required to punch of persimmon fruit, using Magness Taylor probe for the first harvesting time (immature stage) is nearly doubled in comparison with the second harvesting  time (semi-mature stage) and nearly tripled in comparison with the third harvesting time (mature stage). By increasing the loading speeds, the average energy required to punch the persimmon fruit  increased and also the same results were obtained for three harvesting stages. It can be concluded that, for example, during sorting operation, whatever Persimmon move at a slower speed, minimum energy can cause  mechanical damage. When the product getting ripe the mean value of puncture energy decreased and by increasing loading speeds the mean value of puncture force increased. The difference between mean values of resilience coefficients of fruits released from different heights at the three different harvest times for both two varieties was significant at the probability level of 1%.

    Keywords: Resilience coefficient, Mechanical damage, Persimmon, Puncture energy, Puncture force
  • M. Zandi *, A. Ghanjloo, M. Bimakr Pages 195-210
    Introduction

    The crucial sensory characteristic of fruits is appearance that impacts their market value, the consumer’s preference and choice (Afsharnia et al., 2017). The task of fruit grading is vital in the packaging industry because there is a great demand for high quality fruits in the market (Liming and Yanchao 2010). Optical sensors have been used for grading, sorting, and fruit quality detection of different crops (Mohammadi et al., 2015). Today, in various agricultural commodity grading systems, computer vision has become an alternative to visual inspection being objective, consistent, rapid, and economical (Chai et al., 2014). Color is the major attribute to assess quality of agricultural products more than any other single factor (Moallem et al., 2017). It represents the degree of maturity, sugar content, acidity, and taste. For instance, in fresh fruit market such as apples and peaches, darker red color represents higher quality fruit than does light red (Cardenas-Perez et al., 2017). Computer vision is a non-destructive method that can be used for inspection and has found to be applicable in both the food industry and precision agriculture, including the inspection and grading of fruits and vegetables (Wan et al., 2018). This paper proposes an automatic and effective hawthorn fruit grading system based on computer vision-based algorithm. Blasco et al. (2008) developed a computer visionbased machine for detecting and removing unwanted material and sorting the pomegranate arils by color. Liming and Yanchao (2009) developed an automated strawberry grading system using image processing technique and graded the strawberry adopting one or two or three indices among shape, color and size. Okamoto and Lee (2009) developed an image processing method to detect green citrus fruit in individual trees to apply for crop yield estimation at a much earlier stage of growth (Mohammadi et al., 2015).

    Material and methods

    Grading of hawthorn fruits into three quality grades (A, B and C) was conducted by image analysis technique. Physicochemical and geometrical properties of fruits were determined to compare the results of image analysis and visual classification. Color quality parameters (L∗,a∗,b∗,c∗,h∗,∆E) geometrical parameters, weight loss, firmness, total soluble solid (TSS), pH, treatable acidity (TA) and ripening index (RPI) were the measured factors. TSS content was directly measured from the obtained juice using a refractometer. From the same juice the titratable acidity (TA) was determined. The hawthorn firmness was measured by means of a penetration test using a Texturometer Analyzer. In this study, a machine vision algorithm was developed to capture the images of the hawthorn samples, and then it extracted the feature color value to classify quality grade of the hawthorn fruits. For this work RGB images were captured with a resolution of 1936 × 1288 pixels and stored on the computer in TIFF format. Different color spaces have been compared in previous works in which it was concluded that the CIELab space is the most appropriate for the measurement of fruit color. From each image, squares from the equatorial area of the fruit were cropped, trying to obtain the greatest possible area but avoiding areas with excessively bright pixels. For the calibration process and image analysis, conversions were performed by using the color space converter plugin for the public domain image processing application ImageJ software. Next, the values of chroma (C*) and hue angle (h*) were also calculated. Principal component analysis (PCA) was used to analyze the dataset obtained from the study of the hawthorn storage. The first set of 200 hawthorns was arranged in a matrix of 14 variables (TSS ،TA ،F ،WL ،φ،Dg ،MDL ، RPI ، L∗ ،a∗،b∗ ،∆E ، C∗ and h∗) ×200 averaged measurements. This matrix was used to calculate the Pearson correlation matrix, variable contributions, factorial loadings, eigenvalues, and percentage of variance of the principal components related to the original variables. Later, a second model was built including only the color variables and was used to classify the hawthorns into quality grade.

    Results and discussion

    Principal component analysis was used to evaluate the correlation between variables. A first correlation was performed between physicochemical and color parameters and variables correlated correctly between each other except for L*, but both described the samples variability with 94.2% reliability. Using only color parameters, the samples were described accurately with 97.4% reliability. Two classifiers based on linear (LDA) and quadratic discriminant analysis (QDA) were used to assess the applicability of vision system. Color parameters obtained by means of CVS under laboratory conditions provided an adequate classification of the quality grade of hawthorn fruits and showed a good correlation with the flesh physicochemical parameters measured. LDA and QDA were capable of classifying hawthorn in their correct quality grade with 99% and 99.5% accuracy, respectively.

    Conclusion

    The current study used image analysis technique to classify hawthorn fruits into three commercially quality grade (A, B and C). The written algorithm captured an image, eliminated the noises, obtained binary image, removed the noise, and ultimately extracted the color features. This demonstrates that it is possible to create a reliable and objective method for the non-destructive evaluation of quality grade. The selection of variables performed using PCA and the classification model built by means of LDA and QDA allowed adequate classification of the hawthorn according to quality grade using only L∗ ،a∗،b∗ ،∆E ، C∗ and h∗. Thus, it was concluded that external color features of hawthorn fruits can be potentially used to classify the fruits with a proper probability.

    Keywords: hawthorn, image processing, color characterize, physicochemical properties, quality grading
  • A .Asdagh, A. Khosrowshahi Asl *, S. Pirsa Pages 211-226
    Introduction

    Addition of female essential oil and beta-carotene completely affected the properties of pectin film and overall improved the physicochemical and mechanical properties of the film.Purpose Pectin has good film forming properties but due to its hydrophilic nature it has high solubility and low elasticity. Therefore, in this paper biodegradable film of pectin / adenine / beta carotene was prepared and the simultaneous effect of essential oil of adenine and Beta carotene pigments were studied on the physicochemical and mechanical properties of the prepared film. The central composite design was used to study the effect of the essential oils on the levels of 0.5% and beta carotene pigments on the levels of 0.03%. Thirteen films were prepared and the tests were performed on them.MethodTo prepare 2% w / v pectin film in 100 ml of deionized water for 12 h at 30 ° C, stirred with magnetic stirrer, after cooling 40% w / w of glycerol dry matter was added and the solution was added. The mixture was stirred for 10 minutes and the control film (without beta-carotene and adenine) was prepared. To prepare films containing feminine essential oil after mixing glycerol with the solution of essential oil in 0.25 and 0.5% pectin dry matter plus 5% vol / vol dry matter, Tween 80 as an emulsifier was then added by stirring. Mixed at 9000 rpm for 5 minutes. For preparation of beta-carotene films, the beta crystals were first dissolved in concentrations of 0.015 and 0.03% in 20 ml of chloroform and reached 100 ml with distilled water and 5% tween as described above. The 13000 was mixed with the polymer for 2 minutes. The polymer / essential oil / beta-carotene mixture was prepared according to the above method for the preparation of hybrid films (essential oil and beta-carotene) but the mixing time was increased to 5 minutes.ResultsThe results of FTIR test showed a new interaction between female essential oil and beta-carotene. X-ray diffraction also confirmed that the crystallization rate of the film increased with the addition of beta-carotene. The essential oil and beta-carotene reduced the water solubility of the films, the effect of the essential oil was higher due to the bonding between phenolic compounds of high molecular weight with the polymeric pectin molecules. The addition of essential oil had a significant effect on the turbidity of the films, with the highest amount of turbidity in the film containing 0.5% of the essential oil, on the other hand, increasing the beta-carotene content to 0.015% reduced the turbidity but at concentrations Higher yields increased opacity. In the results of mechanical properties, tensile properties by addition of ascending garlic essence showed that on the other hand, beta-carotene and femoral oils at low concentrations reduced tensile strength and elastic modulus, but at higher concentrations helped to improve mechanical properties.ConclusionAs the beta-carotene pigment changes in different food conditions, these films can then be used for smart packaging of food products.

    Material and methods

    The pectin film was prepared with slight modifications according to the method of Nisar et al. (2018). For preparation of 2% w / v pectin film in 100 ml of deionized water was mixed with magnetic stirrer for 12 h at 30 ° C, after cooling to 40% w / w glycerol was added and the solution was stirred for 10 min. The minute was mixed with the stirrer and the control film (without beta-carotene and adenine) was prepared. To prepare films containing feminine essential oil after mixing glycerol with the essential oil solution at 0.25 and 0.5% pectin dry matter plus 5% vol / vol dry matter, Tween 80 as an emulsifier was then added by stirring. Mixed at 9000 rpm for 5 minutes. For the preparation of beta-carotene films, the beta crystals were first dissolved in concentrations of 0.015 and 0.03% in 20 ml of chloroform and reached 100 ml with distilled water and 5% tween as described above. The 13000 was mixed with the polymer for 2 minutes. The polymer / essential oil / beta-carotene mixture was prepared according to the above method for preparation of composite films (essential oil and beta-carotene) but the mixing time was increased to 5 minutes. It was then poured into 25 ml solutions in plastic plates at 25 ° C and kept in a sachet bag for 72 hours until finally tested (Doxia 2014).

    Results and discussion

    In the present study, edible film containing pectin polymer based on adipose and beta carotene was prepared. Adding essential oils and beta-carotene decreased the solubility, which could be attributed to their hydrophobicity. The effect of adding essential oil on film opacity made a significant difference, with the highest amount of opacity for the film containing 0.5% of the essential oil, due to the decreased transparency and glassy state of the films as a result of the addition of essential oil. The decrease in transparency was also due to an uneven surface during drying of the film, where the essential oil accumulated on the film surface and caused a heterogeneous surface in the film. Increasing the amount of beta-carotene to 0.015% reduced the amount of turbidity but had the opposite effect at higher concentrations. Addition of essential oil increased elasticity and interaction of high concentrations of essential oil (0.5% level) and beta-carotene (0.03%) increased tensile strength and elastic modulus and improved mechanical properties performance. The results of XRD analysis showed an increase in the crystallinity of the pectin film containing essential oil due to the addition of beta-carotene. The chemical structure and molecular interaction of the synergistic effect of female essential oil and beta-carotene on pectin film were confirmed by FTIR and XRD .

    Conclusion

    The present study showed that it is possible to use admixture and beta-carotene in degradable pectin film which can decrease solubility, increase total phenol content and improve the mechanical properties of the film, so it is better to increase the film content. Used shelf life and improved quality properties in foods such as butter.

    Keywords: Biodegradable Edible Film, Beta-carotene, Carum copticum essential oil, Mechanical Properties