فهرست مطالب

پژوهش های صنایع غذایی - سال بیست و نهم شماره 4 (زمستان 1398)
  • سال بیست و نهم شماره 4 (زمستان 1398)
  • تاریخ انتشار: 1398/11/01
  • تعداد عناوین: 14
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  • سعید میرعرب رضی، علی معتمد زادگان*، سید احمد شهیدی، علی رشیدی نژاد صفحات 1-12
    زمینه مطالعاتی

    ژل یک شبکه پلیمری سه بعدی با رطوبت بالا است که در مقابل فشار، مقاومت به جریان دارد.

    هدف

    هدف از این پژوهش تهیه ژل های بیوپلیمری بر پایه آلبومین و صمغ دانه ریحان با خواص فیزیکی و رئولوژیکی مطلوب می باشد.

    روش کار

    در این پژوهش تاثیر مقادیر مختلف صمغ دانه ریحان (0، 05/0، 1/0 و 3/0%) بر خصوصیات فیزیکی و بافت ژل حاصل از آلبومین تخم مرغ  (دمای °C 85) بررسی و تاثیر دما (افزایش دما از 5 به °C 90 و سپس کاهش دما از 90 به °C 5) نیز بر خصوصیات رئولوژیکی ژل حاصله بررسی شد.

    نتایج

    نتایج نشان داد که ظرفیت نگهداری آب ژل های تولیدی با افزایش غلظت صمغ دانه ریحان به صورت معنی داری افزایش یافت 05/0 > بررسی ویژگی های بافتی نشان داد که سختی ژل های تولیدی در نمونه حاوی 3/0% صمغ ریحان به صورت معنی داری بیشتر از سایر تیمارها بود 05/0> p. طبق نتایج بدست آمده با افزایش غلظت صمغ دانه ریحان در نمونه های ژل، پارامترL* کاهش پیدا کرد. نتایج آزمون کرنش متغیر نشان داد که ناحیه خطی ویسکوالاستیک در حدود کرنش 1/0% بود. بر اساس این نتایج، با افزایش غلظت صمغ دانه ریحان از 0 به 3/0% مقدار مدول های الاستیک و ویسکوز افزایش یافتند. علاوه بر این، مدول الاستیک در تمامی غلظت ها بزرگتر از مدول ویسکوز بود. در تمامی غلظت های مورد بررسی، در مرحله گرم کردن ژل از 5 به°C 90 مقدار مدول الاستیک به طور ملایمی کاهش یافت و با شروع مرحله سرد کردن ابتدا ثابت و سپس با شیب تندی افزایش یافت.

    نتیجه گیری نهایی

    با توجه به نتایج بدست آمده نمونه حاوی 3/0 درصد صمغ ریحان به عنوان بهترین نمونه انتخاب گردید.

    کلیدواژگان: آلبومین تخم مرغ، صمغ دانه ریحان، ژل، ویژگی های فیزیکی، ویژگی های رئولوژیکی
  • رویا ابکا خواجوئی*، جواد کرامت، ناصر همدمی صفحات 13-28
    زمینه مطالعاتی

    آلژینیک اسید و آلژینات ها مصارف مهمی در صنایع غذایی، پزشکی، داروسازی، دندانپزشکی و نساجی دارند.

    هدف

    هدف از این پژوهش بهینه سازی شرایط استخراج آلژینات سدیم از دیواره سلولی جلبک قهوه ای ایرانی (Nizimuddinia zanardini) می باشد.

    روشکار

    از آنجائیکه جلبک های قهوه ای دریای جنوب ایران (منطقه چابهار) دارای این پلیمر طبیعی اند، استخراج آلژینات سدیم در سه مرحله و با استفاده از محلول های اسیدی و قلیایی و به دنبال آن رسوب آلژینات سدیم توسط اتانول با استفاده از روش سطح پاسخ RSM)) بهینه سازی شد. برای بهینه سازی شرایط، در مرحله اسیدی تاثیر فاکتور های درجه حرارت استخراج با اسید کلریدریک 2/0 مولار در دامنه °C 25-60 و زمان استخراج در محدوده 5/0 تا 5/3 ساعت بر متغیر های وابسته شامل درصد بازده استخراج، میزان پلی فنل ها و مقدار پروتئین های آلژینات استخراج شده مورد مطالعه و بررسی قرار گرفت و پس از بهینه سازی این فاکتور ها در مرحله قلیایی، درجه حرارت استخراج با کربنات سدیم در بازه ی °C60 - 90، زمان استخراج در محدوده  2-4 ساعت و غلظت محلول در محدوده % 2 - 4 (وزنی/حجمی) به عنوان فاکتور های موثر بر درصد بازده استخراج، مقدار پلی فنل ها و ویسکوزیته ظاهری آلژینات استخراج شده، مورد مطالعه قرار گرفت و فاکتور ها بهینه سازی شدند.

    نتایج

    در مرحله اسیدی هر دو فاکتور درجه حرارت و زمان بر درصد بازده استخراج و کیفیت صمغ استخراجی (خلوص) تاثیر معنی دار دارند ودر مرحله قلیایی تمامی فاکتور ها بر بازده،  کیفیت و ویسکوزیته ظاهری پلیمر استخراجی تاثیر معنی دار دارند. شرایط بهینه استخراج آلژینات سدیم از جلبک قهوه ای (Nizimuddinia zanardini) به صورت زیر معرفی گردید. در مرحله اسیدی درجه حرارت:°C60، زمان: 3 ساعت و در مرحله قلیایی غلظت: % 3 (وزنی/حجمی)، درجه حرارت:°C60 و زمان: 3 ساعت.

    کلیدواژگان: آلژینات سدیم، بهینه سازی استخراج، پلی ساکارید، جلبک قهوه ای ایرانی، روش سطح پاسخ
  • منیره ارباب، ابراهیم علیزاده دوغیکلایی*، محسن شهریاری مقدم صفحات 29-43
    زمینه مطالعاتی

     امروزه کاربرد عصاره گیاهان دارویی بجای نگهدارنده های شیمیایی در محصولات شیلاتی رو به افزایش است.

    هدف

    مطالعه حاضر با هدف بررسی تاثیر عصاره های آبی و اتانولی دانه شنبلیله بر رشد استافیلوکوکوس اورئوس تلقیح شده (CFU/g103) در فیله کپور معمولی هنگام نگهداری در یخچال (C4) می باشد.

    روش کار

    عصاره ها با استفاده از حلال های آب و اتانول استخراج و در غلظت های 1، 5/2 و 4 درصد به فیله های تلقیح شده اضافه گردید. فراسنجه های شیمیایی (تیوباربیتوریک اسید و مجموع بازهای نیتروژنی فرار) و میکروبی (شمارش باکتری استافیلوکوکوس اورئوس، شمارش باکتری های کل و شمارش باکتریهای سرمادوست) در روزهای صفر، 3، 6، 9 و 12 اندازه گیری شدند.

    نتایج

    نتایج ارزیابی حسی به روش هدونیک نشان داد که فیله های حاوی 5/2 درصد عصاره آبی و اتانولی دارای خواص ارگانولیپتیکی بهتری بودند. نتایج نشان داد که تعداد باکتری استافیلوکوکوس اورئوس با گذشت زمان در تیمار شاهد افزایش و در تیمارهای حاوی عصاره کاهش یافت. به طوریکه غلظت 4 درصد عصاره های اتانولی و آبی موجب توقف رشد باکتری پس از 9 و 12 روز گردید. کمترین تعداد باکتری های کل و سرمادوست در فیله حاوی 4 درصد عصاره اتانولی مشاهده گردید. مقدار تیوباربیتوریک اسید و مجموع بازهای نیتروژنی فرار فیله ها طی نگهداری به تدریج افزایش یافت ولی این افزایش در تیمارهای حاوی عصاره کمتر بود.

    نتیجه گیری نهایی

    نتایج این تحقیق نشان داد که عصاره اتانولی دانه شنبلیله خواص ضد باکتری بیشتری نسبت به عصاره آبی دارد. لذا استفاده از عصاره اتانولی دانه شنبلیله در غلظت 4 درصد برای افزایش مدت ماندگاری فیله ماهی کپور معمولی توصیه می گردد.

    کلیدواژگان: استافیلوکوکوس اورئوس، ارزیابی حسی، عصاره دانه شنبلیله، کپور معمولی
  • رضا فتاحی، بابک قنبرزاده*، جلال دهقان نیا صفحات 45-57
    زمینه مطالعاتی

     افزودن محلول نانوامولسیون اسانس روغنی دارچین باعث بهبود برخی از ویژگی های فیزیکی شیمیایی وضدکپکی فیلم های امولسیونی گردد.

    هدف

    هدف از این مطلعه تهیه ماکروامولسیون اسانس روغنی دارچین با استفاده از روش هموژنیزاسیون برش بالا و افزایش در مقدار انرژی ورودی به محلول امولسیونی، از طریق هموژنیزاسیون ترکیبی برش بالا-فراصوت، برای کاهش اندازه قطرات امولسیون به کم تر ازnm 100بود.

    روش کار

    هر دو محلول امولسیونی حاوی غلظت های 25/0، 5/0 و 1 درصد اسانس روغنی دارچین به محلول تشکیل دهنده فیلم به طور جداگانه اضافه شدند و فیلم های نهایی به روش کاستینگ (تبخیر حلال) تهیه گردید. ویژگی های ریزساختاری فیلم ها با استفاده از تصاویر میکروسکوپ اتمی (AFM)  مورد بررسی قرار گرفت. از آزمون حرارتی، مکانیکی، پویا  (DMTA) برای بررسی مقاومت حرارتی فیلم ها استفاده گردید. به منظور آنالیزهای ضدمیکروبی فیلم ها از روش هاله ی عدم رشد استفاده شد.

    نتایج

    تصاویر حاصل از میکروسکوپ نیروی اتمی نشان دهنده پایداری بیشتر محلول نانوامولسیون در مقایسه با ماکروامولسیون در بستر فیلم امولسیونی بود، شاخص زبری فیلم نانوامولسیونی در بالاترین غلظت از اسانس روغنی nm) 86nm, Sq=80Sa=) تقریبا مشابه با فیلم کنترل بود ولی ناپایداری ماکروامولسیون اسانس روغنی دارچین در داخل بستر و در نتیجه مهاجرت به سطح فیلم در طی فرآیند خشک کردن، باعث ایجاد سطحی ناهموار گردید. ماهیت پلاستی سایزری اسانس روغنی دارچین و همچنین کاهش اندازه ی قطرات باعث کاهش بیشتر برهمکنش های بین زنجیره ای در بیوپلیمرگردید که در نتیجه ی آن دمای انتقال شیشه ای (Tg) و مدول ذخیره (E') براساس داده های آزمون حرارتی، مکانیکی، پویا کاهش بیشتری برای فیلم های حاوی نانوامولسیون در مقایسه با ماکروامولسیون نشان داد. کاهش در اندازه ی قطرات اسانس روغنی در محلول امولسیونی باعث افزایش دسترسی زیستی ترکیبات فعال ضدمیکروب اسانس دارچین گردید به گونه ای که شاخص ضدکپکی برای فیلم های ماکروامولسیونی حاوی % 1 اسانس روغنی دارچین در برابر آسپرژیلوس نایجرز و موکور راسموس به ترتیب از % 16/14 و 82/20 به % 81/18 و 25 در فیلم های نانوامولسیونی افزایش یافت.

    نتیجه گیری نهایی

    بهبود پایداری امولسیون در بستر فیلم امولسیونی نقش موثری در بهبود ویژگی های فیزیکی شیمیایی و همچنین اثرگذاری ضدمیکروبی داشت.

    کلیدواژگان: فیلم فعال، اسانس روغنی دارچین، دسترسی زیستی، ضدکپک
  • رامین مقصود زاده، عباس جلیل زاده* صفحات 59-69
    زمینه مطالعاتی

    بامیه یکی از شیرینی های سنتی است که به روش سرخ کردن عمیق تولید می شود و دارای محتوی روغن بالایی است.

    هدف پژوهش

    در این تحقیق پوشش دار کردن بامیه با استفاده از پوشش خوراکی پروتئین آب پنیر برای کاهش جذب روغن فراورده مورد مطالعه قرار گرفت.

    روش کار

    سه نوع پوشش با درصد های مختلف پروتئین آب پنیر در محلول سوسپانسیون کلوئیدی (25/0، 5/0 و 75/0 درصد) و با نسبت ثابتی از سوربیتول (5/0%) تهیه شدند و پوشش دهی با غوطه ورسازی بامیه ها در داخل محلول انجام شد. ویژگی های کیفی نمونه های بامیه شامل جذب روغن، رطوبت، اسیدیته و عدد پراکسید تعیین و ارزیابی حسی نمونه ها انجام شد.

    نتایج

    بامیه های پوشش داده شده با 25/0، 5/0 و 75/0 درصد پروتئین آب پنیر به ترتیب 10، 20 و 31 درصد جذب روغن کمتری در مقایسه با شاهد نشان دادند (05/0>P). در بامیه های پوشش داده شده با درصدهای مختلف پروتئین آب پنیر (25/0، 5/0 و 75/0 درصد)، باگذشت زمان نگهداری در روزهای مختلف نگهداری (1، 10، 20 و 30 روز)، افت رطوبت روند کاهشی نشان داد. اسیدیته و عدد پراکسید باگذشت زمان نگهداری در تمام نمونه ها افزایش یافت اما کمتر از بیشینه حد مجاز بود. نتایج ارزیابی حسی نشان داد نمونه های پوشش داده شده با درصدهای مختلف پروتئین آب پنیر، شکل ظاهری، رنگ، مزه و بافت بهتری در مقایسه با شاهد داشتند. نمونه های پوشش داده شده با 5/0 و 75/0 درصد پروتئین آب پنیر، پذیرش کلی بالاتری در مقایسه با سایر تیمارها نشان دادند.

    نتیجه گیری نهایی

    پوشش پروتئین آب پنیر می تواند به عنوان پوشش خوراکی جهت کاهش جذب روغن در بامیه مورد استفاده قرار گیرد.

    کلیدواژگان: بامیه، پوشش خوراکی، پروتئین آب پنیر، جذب روغن، سرخ کردن عمیق
  • نیما امامی، لیلا ناطقی*، محمدرضا اسحاقی صفحات 71-88
    زمینه مطالعاتی

     باقلوا یکی از مهمترین فرآورده های آردی است که به علت خواص حسی مطلوب و پایداری بالا، تولید آن رواج زیادی دارد. اما مصرف زیاد آن به دلیل کالری بالا، منجر به بروز مشکلاتی نظیر افزایش وزن و چاقی می شود.

    روش کار

    در این تحقیق تاثیر جایگزینی شکر در نسبت های 0، 20، 40، 60، 80 درصد توسط مخلوط کم کالری سوکرالوز و ایزومالت بر ویژگی های فیزیکی شیمیایی شامل اندازه گیری خاکستر، ساکارز، درصد پروتئین، درصد چربی، رطوبت، کالری و سختی بافت و رنگ سنجی طی 20 روز نگهداری و خواص حسی پس از 20 روز نگهداری، مورد مطالعه قرار گرفت.

    نتایج

    نتایج پژوهش حاضر نشان داد که با افزایش جایگزینی ساکارز با مخلوط سوکرالوز و ایزومالت میزان خاکستر، ساکارز، درصد پروتئین، درصد چربی، سختی بافت و کالری به طور معنی داری (05/0≥p) کاهش و رطوبت افزایش  یافت. ارزیابی تغییرات رنگ طی 20 روز نگهداری نشان داد که با افزایش نسبت جایگزینی پارامتر روشنایی (L*) به طور معنی داری افزایش یافت و پارامترهای قرمزی و زردی (a*) و (b*) به ترتیب کاهش و افزایش معنی داری را نشان دادند. از سوی دیگر ارزیابی خواص حسی نشان داد که بعد از شاهد تیمار حاوی20 % و 40 % سوکرالوز و ایزومالت از بالاترین قابلیت پذیرش حسی برخوردار بود و به عنوان تیمار برتر انتخاب شدند.

    نتیجه گیری نهایی

    نتایج نشان داد با استفاده از مخلوط (60 % شکر+ 40 % سوکرالوز و ایزومالت) می توان تا 40 درصد ساکارز مصرفی در فرمولاسیون نمونه شاهد را با مخلوط سوکرالوز و ایزومالت جایگزین نمود بدون اینکه اثر نامطلوب روی خواص فیزیکی شیمیایی، بافتی و حسی آن داشته باشد.

    کلیدواژگان: جایگزین شکر، باقلوا سنتی کرمانشاه، سوکرالوز، ایزومالت
  • زهرا سیار، هدا جعفریزاده مالمیری* صفحات 89-99
    زمینه مطالعاتی

     کورکومین به عنوان رنگدانه طبیعی موجود در زردچوبه دارای خواص منحصر به فردی می باشد که قابلیت استفاده از آن در فرمولاسیون های غذایی و دارویی را افزایش داده است. حلالیت پایین این ماده در سیستم های آبی از محدودیت های اصلی کاربرد کورکومین می باشد.

    هدف

    هدف از تحقیق حاضر تولید نانودیسپرسیون کورکومین در آب برای افزایش حلالیت آن می باشد.

    روش کار

    نانودیسپرسیون کورکومینتوسط روش نوین آب مادون بحرانی و روش متداول جایگزینی حلال بر پایه اتیل استات و با استفاده از امولسیفایر تویین20 تولید و ویژگی های فیزیکی شیمیایی، رئولوژیکی، پایداری فیزیکی، ضدمیکروبی و آنتی اکسیدانی نانودیسپرسیون های تولیدی با هم مقایسه گردید.

    نتایج

    نتایج آنالیز پراکندگی نور دینامیکی نشان داد که نانودیسپرسیون کورکومین تولیدی توسط روش نوین استفاده از آب مادون بحرانی دارای کمترین اندازه ذره (nm 1/10) و شاخص پراکندگی (06/0) و بیشترین قابلیت هدایت (ms/cm 401/0) و مقدار پتانسیل زتا (mV 8/15-) در مقایسه با روش جایگزینی حلال می باشد. نتایج حاصل همچنین نشان داد که نانودیسپرسیون کورکومین حاصل با روش نوین آب مادون بحرانی رنگ زرد روشن (55/2=b) با کدورت کمتر (NTU 063/0) و ویسکوزیته پایین در مقایسه با خواص مذکور نانودیسپرسیون کورکومین تولیدی با روش جایگزینی حلال است.

    نتیجه گیری نهایی
    نانودیسپرسیون تولید شده با  روش آب مادون بحرانی دارای بالاترین خاصیت آنتی اکسیدانی در مقایسه با محلول کورکومین در آب و خاصیت ضدباکتریایی در برابر باکتری های گرم مثبت و گرم منفی می باشد. علاوه بر این نانودیسپرسیون تولیدی با روش نوین یعنی آب مادون بحرانی، دارای پایداری فیزیکی در ظرف مدت زمان سه ماه می باشد.
    کلیدواژگان: نانودیسپرسیون، کورکومین، آب مادون بحرانی، جایگزینی حلال، پایداری
  • محمود حسین نیا، هادی الماسی*، محمد علیزاده خالد آباد صفحات 101-123
    زمینه مطالعاتی

    درون پوشانی یکی از روش های جدید افزایش پایداری ترکیبات زیست فعال در طی فراوری و نگهداری مواد غذایی محسوب می شود.

    هدف

    هدف از این پژوهش، ارزیابی و مقایسه کارایی صمغ عربی، ایزوله پروتئین آب پنیر و صمغ گوار در ریزپوشانی عصاره کاکوتی (Ziziphoraclinopodiodes) و تولید پودر ریزپوشینه بود.

    روش کار

    سه هیدروکلوئید مذکور به تنهایی یا در ترکیب با یکدیگر برای تولید میکروکپسول عصاره کاکوتی به وسیله روش اولتراسونیکاسیون مورد استفاده قرار گرفتند و نمونه ها با روش خشک کردن انجمادی به پودر تبدیل شدند. نتایج آنالیز نشان داد ریزپوشینه های پایدار شده به وسیله ایزوله پروتئین آب پنیر کمترین اندازه ذره (7/292 نانومتر) را دارا بودند. ترکیب صمغ عربی یا گوار با ایزوله پروتئین آب پنیر، کارآیی پلی ساکاریدها را بهبود بخشید. با در نظر گرفتن مقادیر راندمان انکپسولاسیون، اندازه ذرات، شاخص چند پخشی و پتانسیل زتا، سازگاری ایزوله پروتئین آب پنیر با صمغ عربی بیشتر از صمغ گوار بود. بیشترین کارآیی درون پوشانی (91/86 %) متعلق به نمونه صمغ عربی/ ایزوله پروتئین آب پنیر بود. زمانی که ایزوله پروتئین آب پنیر با صمغ عربی مخلوط شد، محتوای فنول کل و فعالیت آنتی اکسیدانی در بالاترین میزان خود بودند. شکل کروی ریزپوشینه ها برای تمامی نمونه ها بجز ترکیب صمغ گوار و  صمغ عربی که شکل نامشخصی داشت، به وسیله میکروسکوپ الکترونی روبشی مشاهده شد. آنالیز FT-IR ، شکل گیری برهمکنش های جدید بین مواد دیواره (بجز صمغ گوار) و اجزای عصاره کاکوتی را تایید کرد. آزمون XRD نشان داد که شاخص بلورینگی مواد دیواره بعد از ترکیب با عصاره کاکوتی کاهش می یابد اما نمونه های حاوی ایزوله پروتئین آب پنیر در مقابل تغییرات ساختاری مقاوم است.

    نتیجه گیری نهایی

    نتایج این پژوهش نشان داد که کارآیی ایزوله پروتئین آب پنیر در ریزپوشانی عصاره کاکوتی بیشتر از پلی ساکاریدها می باشد. اما توصیه می شود این مواد دیواره در ترکیب با یکدیگر به خصوص ترکیب صمغ عربی/ ایزوله پروتئین آب پنیر استفاده شوند تا بهترین نتیجه حاصل شود.

    کلیدواژگان: ریزپوشانی، عصاره کاکوتی، مواد دیواره، اندازه ذرات، مورفولوژی
  • حمید جهانگیر اصفهانی، ایمان شهابی قهفرخی، رحمت الله پورعطا صفحات 125-138
    زمینه مطالعاتی

    بررسی اثر اسید اولئیک و استفاده از پرتو فرابنفش به منظور اصلاح خصوصیات کاربردی فیلم نشاسته در بسته بندی مواد غذایی است.

    هدف

    نشاسته یکی از ارزان ترین زیست پلیمرهای پلی ساکاریدی است که به علت دسترسی آسان و زیست تخریب پذیری موردتوجه پژوهشگران قرار گرفته است، اما مشکل اصلی نشاسته مانند سایر پلی ساکاریدها، آب دوستی نسبتا بالای آن می باشد. مهم ترین هدف این پژوهش کاهش حساسیت فیلم نشاسته به آب با استفاده از اسید اولئیک و پرتو فرابنفش (UV-C) بود.

    روش کار

    در این پژوهش محلول فیلم نشاسته - اسید اولئیک در سه غلظت 6/0، 1 و 4/1 درصد (وزنی-وزنی نشاسته) و با استفاده از پرتو فرابنفش C در مدت زمان 60 دقیقه به منظور بهبود خصوصیات کاربردی آن در بسته بندی مواد غذایی اصلاح شد و فیلم آن به روش قالب گیری محلول تهیه شد. جهت بررسی خصوصیات کاربردی فیلم در بسته بندی مواد غذایی ضخامت، زاویه تماس، نفوذپذیری نسبت به بخارآب، جذب رطوبت، محتوای رطوبت و حلالیت فیلم ها مورد بررسی قرار گرفت. آزمون ها در قالب طرح کاملا تصادفی اجرا و نتایج آن به روش دانکن مورد مقایسه قرار گرفت.

    نتایج

    نتایج نشان داد که با افزایش غلظت اسید اولئیک تا حد معینی (1 درصد بر اساس وزن خشک نشاسته)، نفوذپذیری نسبت به بخارآب در کمترین حد و زاویه تماس در بیشترین مقدار قرار دارد. اگرچه افزایش غلظت اسید اولئیک تا مقدار مشخصی موجب افزایش آب گریزی شده است، اما درصورتی که امولسیون حاصل در بازه زمانی (60 دقیقه) تحت پرتو فرابنفش قرار گیرد، آب گریزی فیلم نشاسته به بیشترین حد می رسد. پارامترهای جذب رطوبت، محتوای رطوبت و حلالیت در آب فیلم های نشاسته با افزودن اسید اولئیک نیز کاهش یافت. تاثیر توام اسید اولئیک و پرتو فرابنفش نیز در کاهش خاصیت آب دوستی موثر بود ولی در کاهش محتوای رطوبت تاثیر چشمگیری نداشت.

    نتیجه گیری نهایی

    استفاده توام از اسید اولئیک (تا غلظت مشخص) و پرتو فرابنفش به صورت هم زمان موجب افزایش آب گریزی فیلم نشاسته می شود.

    کلیدواژگان: نشاسته، اسید اولئیک، پرتو فرابنفش، آب گریزی
  • مریم اسمعیلی، اصغر ابراهیم زاده*، حمید حسن پور، محمد باقر حسن پور اقدم صفحات 139-152
    زمینه مطالعاتی

    امروزه کنترل ضایعات پس از برداشت و اولویت دادن به استفاده از روش های سالم نسبت به استفاده از سموم شیمیایی در پرورش محصولات باغبانی ضروری است. در سال های اخیر، استفاده از پوشش های خوراکی مانند چیتوسان به منظور کاهش ضایعات پس از برداشت، کاهش سرعت متبولیسم محصول، افزایش عمر انبارمانی و کنترل رشد میکروبی در انواع میوه ها رواج پیدا کرده است.

    هدف

    هدف از پژوهش حاضر، تشخیص مناسب ترین غلظت چیتوسان در راستای حفظ خاصیت آنتی اکسیدانی محصول زغال اخته، شاخص های کمی، کیفی و ترکیب های آنتی اکسیدانی پس از برداشت میوه ها بود.

    روش کار

    میوه های  سالم و یکنواخت زغال اخته پس از برداشت با  غلظت های مختلف چیتوسان (5/0، 1 و 5/1 درصد)  بمدت 1 دقیقه تیمار شده و سپس در دمای 1±4 درجه سانتی گراد و به مدت 21 روز انبار شدند. نمونه برداری جهت مطالعات مختلف بعدی در روزهای 7، 14 و 21 صورت گرفت.

    نتایج

    نتایج آزمایش نشان داد که اثر متقابل زمان و غلظت چیتوسان بر میزان فعالیت آنزیم گایاکول پراکسیداز معنی دار نیست. با این حال تیمار چیتوسان در حفظ میزان اسیدیته قابل تیتراسیون، آنتوسیانین کل، فنل کل، فلاونوئید کل، خاصیت آنتی اکسیدانی و فعالیت آنزیم کاتالاز بیشترین تاثیر را داشت. همچنین فعالیت آنزیم های پلی فنل اکسیداز و فنیل آلانین آمونیالیاز در غلظت صفر درصد بیشتر بود.

    نتیجه گیری نهایی

      با توجه به نتایج کلی آزمایش، معلوم شد که تیمار 1 درصد چیتوسان نسبت به سایر غلظت های آن در حفظ صفات فیزیکوشیمیایی میوه های زغال اخته بهتر عمل نمود.

    کلیدواژگان: ارزش غدایی، چیتوسان، زغال اخته، صفات کمی و کیفی
  • طاهره نجف غفاری، سید حسین حسینی قابوس* صفحات 153-169
    زمینه مطالعاتی

    ماست از پر مصرف ترین فرآورده های تخمیری شیر است، که به دلیل ارزش تغذیه ای بالا تاثیر مثبتی در سلامتی انسان و اهمیت ویژه ای در رژیم غذایی افراد دارد.

    هدف

    هدف این پژوهش بررسی اثر تغییر مقدار چربی بر ویژگی های شیمیایی و رئولوژیکی ماست حاوی پودر سیب زمینی ترشی در طی زمان نگهداری می باشد.

    روش کار

    در این پژوهش از پودر سیب زمینی ترشی به مقدار 5/0، 1 و 5/1 درصد در فرمولاسیون ماست قالبی با 5/0، 1 و 5/1 درصد چربی استفاده و ویژگی های شیمیایی و رئولوژیکی نمونه های تهیه شده در مدت 21 روز نگهداری بررسی شد.

    نتایج

    اضافه کردن پودر سیب زمینی ترشی بر ویژگی های شیمیایی و رئولوژیکی ماست تاثیر معنی دار نداشت. نتایج نشان داد که pH نمونه های پرچرب تنها در انتهای دوره نگهداری به طور معنی داری بیشتر از pH ماست 5/0 درصد چربی بوده است. همچنین میزان اسیدیته در روز 14 نمونه ها به طور معنی داری افزایش یافت که البته این مقدار افزایش، در ماست پرچرب نسبت به ماست های 5/0 و 1 درصد چربی کمتر بوده است. در انتهای دوره نگهداری اسیدیته ماست 5/0 درصد چربی، به طور معنی داری بیشتر از ماست 1 و 5/1 درصد چربی بود. تیمار 5/1 درصد چربی با 5/1 درصد پودر سیب زمینی ترشی از نظر قوام و الاستیسیته بهترین تیمار بود.

    نتیجه گیری نهایی

    با افزایش مقدار پودر سیب زمینی ترشی و چربی، مدول افت در برابر تنش برشی افزایش یافت. به طور کلی با افزایش سرعت برش، ویسکوزیته نمونه ها کاهش یافت. همچنین با افزایش درصد چربی نمونه ها، ویسکوزیته آن ها در یک سرعت برش ثابت افزایش یافت. افزودن پودر سیب زمینی ترشی نیز ویسکوزیته را افزایش داد اما اثر چربی بر روی ویسکوزیته بیشتر بود.

    کلیدواژگان: سیب زمینی ترشی، ماست، رئولوژی، اینولین
  • مهسا نورالدینی، محسن اسماعیلی*، فروغ محترمی صفحات 171-184
    زمینه مطالعاتی

     افزودن اسانس پونه کوهی می تواند سبب بهبود خواص فیزیکی فیلم های بر پایه پودر بادمجان و ذرت شود.

    هدف

    هدف از این پژوهش تهیه فیلم های خوراکی پایه نشاسته و پودر بادمجان و بررسی افزودن غلظت های مختلف اسانس پونه کوهی بر روی خواص فیزیکی فیلم های تهیه شده می باشد.

    روش کار

    فیلم های خوراکی بر پایه نشاسته ذرت و پودر بادمجان به نسبت 1:1 تهیه شده و اسانس پونه کوهی در سطوح 1، 3 و 5% (وزنی/ وزنی) به آن ها افزوده شد. ضخامت، میزان رطوبت، دانسیته، خواص مکانیکی، رنگ، مقدار کدورت و عبور نور، حلالیت و شاخص تورم فیلم ها مورد ارزیابی قرار گرفت.

    نتایج

    ضخامت، شاخص تورم، پارامتر L*فیلم های حاوی اسانس بیشتر از فیلم های شاهد بود)05/0 (P<. با افزودن اسانس، مقاومت کششی، مدول یانگ، ازدیاد طول تا نقطه شکست، کدورت، میزان رطوبت، حلالیت و دانسیته فیلم ها به طور معنی داری)05/0 (P< کاهش یافت. اندازه گیری رنگ در فیلم ها نشان داد که با افزایش درصد اسانس، پارامترهای قرمزی (a*)، زردی (b*) و مقدار شفافیت فیلم ها افزایش یافتند. مقدار عبور نور در محدوده ی UV دارای مقدار ناچیز بوده و برای فیلم های شاهد بیشتر از فیلم های حاوی اسانس مشاهده شد.

    نتیجه گیری نهایی

    افزودن اسانس پونه کوهی به فیلم های خوراکی بر پایه نشاسته ذرت و پودر بادمجان سبب بهبود شفافیت و حلالیت در آب فیلم ها، همچنین موجب تضعیف خواص مکانیکی و نفوذپذیری به بخار آب گردید.

    کلیدواژگان: اسانس پونه کوهی، پودر بادمجان، فیلم خوراکی، نشاسته ذرت
  • حبیبه نعلبندی*، سید صادق سیدلو صفحات 185-200
    زمینه مطالعاتی

     اخیرا مصرف سیر خشک به صورت ورقه های خشک شده یا پودر افزایش پیدا کرده است.

    هدف

    در این تحقیق شرایط مختلف خشک شدن ورقه های سیر و رسیدن به کیفیت مطلوب از طریق شبیه سازی فرآیند خشک شدن بررسی شد.

    روش کار

    ابتدا معادلات انتقال جرم و گرما در طول خشک شدن همرفتی سیر روی هندسه سه بعدی ورقه های سیر به روش اجزاء محدود به صورت هم زمان حل شدند. سپس شبیه ساز توسعه یافته به صورت تجربی در شرایط مختلف اعتبار سنجی شد. هم زمان خواص مهندسی و کیفی ورقه های سیر مانند ضریب نفوذ موثر رطوبت، دانسیته ظاهری و تغییرات رنگ نمونه ها مطالعه شد. در نهایت با استفاده از شبیه ساز، موضوع کاهش انرژی مصرفی از طریق کاهش زمان کل فرآیند به همراه حفظ کیفیت ظاهری محصول، بر پایه اطلاعات خروجی از شبیه ساز از طریق به کارگیری دمای متغیر هوای گرم در طی فرآیند و در ضخامت های مختلف بررسی شد.

    نتایج

    شبیه ساز توسعه یافته با دقت بالایی توانست تغییرات نسبت رطوبت را در دماهای مختلف هوای گرم و ضخامت های متفاوت سیر پیش بینی کند. تغییر دمای هوای گرم و ضخامت نمونه ها تغییرات رنگ نهایی ورقه های سیر را تحت تاثیر قرار دادند؛ بطوری که کمترین تغییر رنگ کلی نمونه ها در دمای 50 درجه سلسیوس و در ضخامت 2 میلی متری ورقه های سیر حاصل شد. با استفاده از نرم افزار توسعه داده شده، اعمال شرایط متغیر در دمای هوای گرم مورد استفاده با حفظ خواص رنگی محصول، توانست مدت زمان انجام فرآیند را کاهش و به تبع آن راندمان عملیات خشک کنی را افزایش دهد.

    نتیجه گیری نهایی

    برای دستیابی به محصول خشک با کیفیت بالا و رنگ شفاف تر و نیز کاهش انرژی مصرفی از طریق کاهش زمان خشک شدن، باید از ورقه هایی با ضخامت کمتر و هوای گرمی با دمای متغیر در طول فرآیند بر اساس الگوی خروجی مدل توسعه یافته استفاده شود. شبیه ساز توسعه داده شده می تواند با دقت بالایی موارد مذکور را پیش بینی نماید.

    کلیدواژگان: خشک کردن، رنگ، سیر، شبیه سازی، کاربرد دمای متغیر، کیفیت
  • رومینا اکبر، مصطفی سلطانی*، مریم مصلحی شاد صفحات 201-215
    زمینه مطالعاتی

     شیره ی خرما در مقادیر خاص می تواند جایگزین مناسبی برای چربی ماست باشد.

    هدف

    استفاده از جایگزین های چربی شیر در تولید فرآورده های لبنی به منظور کاهش ابتلا به بیماری های قلبی و کاهش میزان کالری دریافتی بسیار موردتوجه است. با این حال محصولات لبنی تولید شده از شیر کم چرب یا شیر بدون چربی دارای نقایصی در زمینه ویژگی های بافتی و حسی هستند. در همین راستا، استفاده از جایگزین های چربی به عنوان بهبوددهنده بافت و طعم در فرمولاسیون محصولات لبنی توسعه یافته است. شیره خرما یکی از با ارزش ترین فرآورده های ثانویه خرما می باشد که سرشار از قندهای طبیعی نظیر فروکتوز و گلوکز است.هدف از این پژوهش دستیابی به مقادیر بهینه شیره خرما در تولید ماست بدون چربی است.

    روش کار

    در این پژوهش، 5 تیمار ماست در 3 تکرار از شیر کامل، شیر بدون چربی و افزودن شیره خرما با نسبت های 5، 10و 15 درصد حجمی به شیر بدون چربی تولید شد. تیمار های تولیدشده ی ماست در طی 22 روز در دمای°C 1± 4 نگهداری شده و ویژگی های فیزیکیشیمیایی، حسی و بافتی (سختی، کشسانی، چسبندگی و پیوستگی) آن ها در روزهای اول، هشتم، پانزدهم و بیست و دوم انبارداری مورد آزمایش قرار گرفت.

    نتایج

    نتایج آزمون های فیزیکیشیمیایی نشان داد که افزایش شیره خرما در تیمار های ماست موجب کاهش در اسیدیته، ویسکوزیته و ظرفیت نگهداری آب و افزایش pH و آب اندازی شد (05/0P<). با افزایش مقدار شیره خرما در تیمارهای ماست، ویژگی های حسی شامل ظاهر و رنگ، بافت و قوام و عطروطعم کاهش یافت (05/0P<). افزایش مقدار شیره خرما موجب کاهش در پارامترهای سختی، پیوستگی و چسبندگی و افزایش در پارامتر کشسانی در تیمارهای ماست دارای شیره خرما شد (05/0P<).

    نتیجه گیری نهایی

    درمجموع، استفاده از 5 درصد حجمی شیره خرما به جای چربی شیر در فرمولاسیون ماست، منجر به تولید بهترین تیمار ماست بدون چربی ازنظر ویژگی های فیزیکی شیمیایی، بافتی و حسی می شود.

    کلیدواژگان: شیر بدون چربی، شیره خرما، ماست، ویژگی های حسی، ویژگی های فیزیکی شیمیایی
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  • S Mirarab Razi, A Motamedzadegan *, SA Shahidi, A Rashidizadeh Pages 1-12
    Introduction

    Proteins and polysaccharides are well-known ingredients in food products which can interact with each other and alter the food properties. The interactions between proteins and polysaccharides depend on different parameters such as biopolymer type, pH, temperature, polysaccharide type, concentration of both protein and polysaccharide, and the concentration of cations present in the solution. Different conditions can have significant effects on the formation of such complexes or the associated thermodynamic incompatibilities (Rafe at el., 2012). Repulsive or attractive interactions can occur between proteins and polysaccharides and this interaction play an important role on various properties of the formed complexes (Razi et al., 2019a). The complex of protein and polysaccharide has various applications in different food systems such as emulsions, foams, and gels. When protein and polysaccharide mixtures are heated, the heat-induced gel can form, in which rheological and physical properties of gel samples are dependent on temperature, pH, ionic strength, biopolymer components, and polymer concentration (Rafe et al., 2012). Gel is a three-dimensional network with high humidity that resists to flow. Strong gels can be used in some of food products or delivery of active compounds in functional foods (Razi et al., 2018a). Egg white albumin (EWA) is one of the best ingredients for gel formation. A three-dimensional network can form during heat-induced gelation of EWA which can hold water at optimum conditions (Razi et al., 2018a). EWA has more than 40 different proteins, where ovalbumin contributes to about 54% w/w.The EWA gel properties can be improved with the addition of polysaccharides like basil seed gum (BSG) (Razi et al., 2018b). BSG is one of the newest polysaccharides that have recently been used in the food products for its different functionalities such as surface activity, emulsifying, stabilizing, foaming, thickening, and gelling properties (NajiTabasi and Razavi, 2017). Afsharnik et al. (2011) found that BSG chains was able to form a web network inside the protein matrix of milk proteins and reduce the amount of syneresis leading to an increase in the strength of a low-fat set yoghurt. This biopolymer can affect the functional properties of EWA by influencing upon the structure of food products (Razi et al., 2019a). Thus, the aim of the current study was to investigate the effect of different concentrations of BSG on the gelling properties of EWA. On the other hand, we wanted to introduce a gel system containing protein and polysaccharide which can be used in the food industry.

    Material and methods

    In the present study, the effect of different concentrations of basil seed gum (BSG; 0, 0.05, 0.1, and 0.3% w/v) on the gelling properties of egg white albumin (4% w/v) were studied. In order to form EWA gels, the samples were heated up to 85 °C in a water bath for 30 min, followed by storage at 4 °C for 24 h. Water holding capacity (WHC) was calculated after centrifuging the samples at 6000 rpm for 20 min. Textural properties of gel samples were analyzed using a texture analyzer equipped with cylindrical probe with the diameter of 12.1 mm, probe speed of 60 mm/min.  Gels color was reported using L*, a*, b* and Image g software. Rheological properties of the samples were analyzed by a rheomter (Physica, MCR 301, Anton Paar GmbH, Germany), with a parallel plate geometry. Amplitude sweep test was carried out at the strain range of 0.001 to 100 at 20 ˚C. During the temperature sweep test, the samples were heated from 5 to 95 ˚C in the rate of 1 ˚C/min. The physical and rheological properties of the manufactured EWA gels were examined under the influence of different concentrations of BSG. For this aim, all gel samples were prepared in triplicate in a completely randomized design and SPSS software was used to detect the significant differences.

    Results and discussion

    The results showed that water holding capacity of the gels increased as BSG concentration increased (p<0.05) and the lowest WHC belonged to the gel made with 4% EWA-0% BSG. These results could be due to a higher water bonding capacity of the samples in the case of the higher concentration of BSG. Although, the sample containing 0.3% BSG had a higher hardness compared to the other samples, no significant difference was observed between samples. The same trend was observed in gels cohesiveness (p>0.05). L* decreased due to the increase in BSG concentration. B* showed the same trend with L* but no significant differences were observed in a* (p>0.05). The strain sweep test showed that linear viscoelastic (LVE) region was about the strain of 0.1%. As BSG concentration increased from 0 to 0.3%, both storage and loss moduli increased too; whereas, storage modulus was higher than loss modulus in the case of all concentrations. With increasing the temperature from 5 to 90 ˚C, storage modulus decreased slightly while during cooling step it was stable at the first stage but then increased with a high slope, in the case of all samples. After heating and cooling of specimens in temperature sweep test, storage and loss modulus of gel sample containing 4% EWA and 0.3% BSG was significantly higher than other samples (p<0.05). Considering these results, it seems that hydrogen bonds play the main role in EWA and BSG interactions.

    Conclusion

    In different food products, proteins and polysaccharides exist together, both of which (either individually or combined together) can affect the texture, structure, shelf life, and stability of the food, due to their gelling, thickening, and surface-active properties. The finding of the current study can be useful for the manufacture of the food products containing proteins and polysaccharides, in which the interactions between the two biopolymers play an important role in regard to their properties of the final products. Furthermore, these results can help with choosing the best concentration of BSG where the addition of this novel polysaccharide to the protein-rich foods is considered. Overall, the results of this experiment indicated that BSG can improve the gelling properties of egg albumin, with 0.3% being the best concentration in terms of the favorable effects on both physical and rheological properties of the manufactured gels.

    Keywords: Egg albumin gels, Basil seed gum, Gel firmness, Physical properties, Rheological properties
  • R Abka Khajouei *, J Keramat, N Hamdami Pages 13-28
    Introduction

    Macroalgae are source of many polysaccharides. Based on their pigments content they are divided into brown, green and red algae having specific polysaccharide contents. Among them, brown algae (Phaeophyceae) are source of alginates and/or fucans or fucoidans (Percival and McDowell 1990, Torres et al., 2007). Alginates are anionic polysaccharide that existences in mixer of salt forms (Na+, Mg2+ and Ca2+) in cell walls of brown algae makes the tissues flexible and strong. They consist of (1,4) linked β-d-mannuronic acid (M) with 4C1 ring conformation and a-l-guluronic acid (G) with 1C4 ring conformation, the two uronic acids being in pyranosic conformation(Pawar and Edgar 2012, De Sousa et al., 2007). They offer three varying sequences identified as the blocks MG consisting of nearly equal proportion of both monomers with a high number of MG (or GM) dimmers, the blocks GG and the blocks MM (Haug and Larsen 1962). M/G ratio, length and distribution of sequences depend on the algae species but also on their growth conditions and geographic origins. It also determines the chemical and physical properties of alginates (Karaki et al., 2013). Indeed, their gelling properties are dependent on guluronic acid content and explained by the structural features of GG blocks where selective alkaline earth metal multivalent cations and notably Ca2+ take place by chelation. This phenomenon is known and explained as the “egg-box” model. The formed gel is not soluble in water. However, sodium alginate is a water-soluble polymer having generally pseudo plastic properties in solution (Draget and Taylor 2011). Polysaccharides have wide range of pharmacological activities and some of them are considered as antitumor, antihypertensive, immunomodulator as well as antioxidant agents. Their radical scavenger’s role can be used to inhibit oxidative damage in foods and improve their nutritional quality (Venugopal 2011, Yang et al., 2011).

    Material and methods

    Twenty-five gram of dried algae (Nizamuddinia zanardinii) was soaked under steering at room temperature for 24 h in 800 mL of 2% (v/v) formaldehyde to remove phenolic compounds and pigments. After that, the insoluble fraction was washed 3 times with MilliQ water and supplemented by 800 mL of 0.2 M HCL before to be incubated at different levels(25-60°C) for different extraction time periods(0.5-3 h) under stirring (250 rpm).After optimizing of acidic step, the suspension was then centrifuged (10000 g for 20 min at 20°C) and pellets with alginic acid were washed 3 times with MilliQ water before to be socked in a range from (2-4 % (w/v)) Na2CO3 solution for different levels (2-4 h) at different extraction time periods (60-90 °C). The mixture was centrifuged (10000 g for 30 min at 20°C) and the supernatant was precipitated with 3 volumes of ethanol 96 % (v/v). Pellets containing sodium alginate were dissolved in MilliQ water and precipitated with ethanol as described above. This step was repeated two times before to collect and freeze dried the sodium alginate. Response surface methodology (RSM) was used to study the effect of extraction temperature; X1 extraction time; X2 for acidic step and concentration; X1 , extraction time; X2,; extraction temperature X3 for alkaline step. A D-optimal design was employed for designing experimental data using Design-Expert 10.0.3 trial software (Stat-Ease Inc., Minneapolis, MN, USA).

    Results and discussion

    Both temperature and time factors have a significant effect on the extraction efficiency and the effect of temperature on extraction efficiency is higher than the effect of time in acidic step. There is also a significant interaction between the two variables of temperature and time. The extraction temperature had an increasing effect on alginate extraction efficiency. Chloridric acid disrupts the cell wall and releases alginate and also converts alginate salts in the cell wall into arginic acid. Increasing temperature causes further cellular breakdown and alginate extraction efficiency increases. With increasing time, the extraction efficiency increased. This increase can be due to the fact that the acid needs time to penetrate the cell wall, and as the time increases, the permeability increases, resulting in the extraction efficiency, so that the permeability is complete and the highest efficiency is obtained and After that, the extraction efficiency remains constant and even due to the long-lasting effect of acid, it causes de-polymerization and decreases the extraction efficiency. Increasing temperature increased the effect of time factor, meaning that the interaction of temperature and time had a significant effect on extraction efficiency. At low temperatures, the effect of time on the extraction efficiency is low because of the breakdown of the cell wall, but at higher temperatures, which contribute to the thermal breakdown of the cell wall, the effect of time variation is more evident. In alkaline step the effect of concentration on extraction efficiency was considered as a quadratic equation and as interaction with extraction time. By increasing the concentration of sodium carbonate, the extraction efficiency increases with an ascending slope. In other words, the amount of efficiency increases with an increase in direct concentration. Sodium carbonate causes the sodium substitution in carboxylic acid arginine groups and sodium alginate salts are obtained. Therefore, increasing concentration results in more calcium ion replacement and alginate extraction efficiency increases. This increase in extraction efficiency is increased to the extent that all carboxylic groups are replaced by sodium ion, and after that the extraction efficiency remains constant, and even due to the high concentration and de-polymerization of the alginate, it reduces the extraction efficiency. With increasing time of extraction with sodium carbonate, the extraction efficiency decreases with a second order gradient. Sodium ion has been completely replaced in argonic acid groups during the initial extraction hours, and if the extraction time is increased due to the prolonged contact, sodium alginate is obtained with an excess of sodium carbonate which has an alkaline pH and because of the adverse effect of this pH Extraction efficiency is reduced. The effect of temperature on extraction efficiency was considered as a first-order equation and as interaction with extraction time. As the temperature rises due to breaking of the bonds that may lead to the separation of sodium ions and also cause de-polymerization of the alginate, the extraction efficiency decreases.

    Conclusion

    Chloridric acid disrupts the cell wall and releases alginate and also converts alginate salts in the cell wall into alginic acid. the acid needs time to penetrate the cell wall. The results showed that in acidic step temperature and time are two major effective factors on yield and quality of extracted alginate. Sodium carbonate causes the sodium substitution in carboxylic acid arginine groups and sodium alginate salts are obtained. Sodium ion has been completely replaced in argonic acid groups during the initial extraction hours, in high temperature may lead to the separation of sodium ions and also cause de-polymerization of the alginate so in alkaline step, all factors have effect on yield, polyphenol and apparent viscosity of extracted polymer. The optimized conditions of extraction of sodium alginate from brown algae (Nizimuddinia zanardini)were as follows: temperature: 60 oC, time: 3 h (acidic step) and temperature: 60 oC, time: 3 h and concentration 3 % w/v (alkaline step).

    Keywords: Sodium alginate, Optimization of Extraction, Polysaccharide, Iranian brown algae, Response surface methodology
  • M Arbab, E Alizadeh *, M Shahriari Moghadam Pages 29-43
    Introduction

    Carp, as one of the freshwater fish species, has been one of the most widely cultured species all over the world due to its fast growth rate, easy cultivation, high feed efficiency ratio as well as high nutritional value. Spoilage is the degradation of food such that the food becomes unfit for human consumption. Among the various foods, fresh fish are highly perishable. Fish spoilage can be caused by a number of means, autolytic enzymatic, lipid oxidation and microbial which results in numerous undesirable metabolites being produced in the food that cause unwanted flavors and odors. Staphylococcus aureus is an opportunistic pathogen and is responsible for a wide range of human infections and food poisoning. In recent years, despite the use of antibiotics, diseases and deaths from food-borne diseases have increased due to the emergence of antibiotic resistant strains. As a result, the use of alternative methods to prevent the growth of microorganisms and limit the increase in their resistance seems necessary. Using plant extracts that inhibit their growth can be effective and safe alternatives to fight pathogens, especially those associated with food-borne diseases. Trigonella foenum-graecum (fenugreek) is an important medicinal plant and its leaves and seeds have been used in various illnesses. This plant is widely distributed throughout the world and mainly found on the Asia. Fenugreek seeds contain active ingredients such as flavonoids, fiber, amino acids, hepatoprotective protection against free radicals, and protection against breast and colon cancer. Therefore, the aim of the present study was to investigate the effect of aqueous and ethanolic extracts of Trigonella foenum-graecum (fenugreek) seed on growth of Staphylococcus aureus inoculated (10 3 CFU/g) in Cyprinus carpio fillet during storage in refrigerator (4˚C).

    Material and methods

    The fresh Common carp (Cyprrinus carpio) with average weight of 900 ± 50 g and average length of 30 cm were purchased from market (Zabol, South east of Iran) and transported in isothermal iceboxes to the fish product processing laboratory at University of Zabol. The fish were cleaned and filleted manually using a sterile scalp. Maximum acceptable concentration of aqueous and ethanolic extracts of Trigonella foenum-graecum (fenugreek) seed on the organoleptic properties of fillets was determined according to hedonic method. Fillet samples were randomly inoculated with Staphylococcus aureus (10 3(CFU/g) and then aqueous and ethanolic extracts of Trigonella foenum-graecum (fenugreek) seed were added to fillets according to: Treatement 1 (Ethanolic extract 1%), Treatement 2 (Aqueous extract 1%), Treatement 3 (Ethanolic extract 2.5%), Treatement 4 (Aqueous extract 2.5%), Treatement 5 (Ethanolic extract 4%), Treatement 6 (Aqueous extract 4%) and control (not treated with of Trigonella foenum-graecum (fenugreek) seed extract). Fish fillets individually packed in polyethylene packs and then stored in refrigerator (4˚C) for subsequent quality assessment. Chemical (pH, thiobarbituric acid (TBA) and total volatile basic nitrogen (TVB-N)) and microbial parameters (Staphylococcus aureus count, total viable counts (TVC) and psychrophilic viable count (PTC)) were measured at 0, 72, 144, 216 and 288 hours. All experiments were carried out in triplicate and the results are reported as the mean and standard deviation of these measurements. Data were analyzed using a one-way analysis of variance (ANOVA) with SPSS version 22 software. When differences were significant (P<0.05), the mean values were evaluated by Duncan's Multiple Range Test. Kruskal-Wallis test was used to sensory evaluation.

    Results and discussion

    In this study, the sensory evaluation was carried out to determine the maximum add concentration of aqueous and ethanolic extracts of Trigonella foenum-graecum (fenugreek) seed that had no negative effects on the sensory properties of common carp fillet. The results of sensory analysis showed that the overall acceptability of fillets containing 2.5% of aqueous and ethanolic extracts had better organoleptic properties. The growth rate of Staphylococcus aureus was significantly different between treatments and control during the experiment (without of the first 24 hours). All concentrations of extract were effective on the growth of Staphylococcus aureus inoculated in Cyprinus carpio fillet during storage. The Staphylococcus aureus count decreased with increasing the concentration of aqueous and ethanolic extracts of Trigonella foenum-graecum (fenugreek) seed during storage but the Staphylococcus aureus count increased in control. After 216 hours, the growth of Staphylococcus aureus was stopped in treatments containing high concentration extract. The 4% concentration of aqueous and ethanolic extracts of Trigonella foenum-graecum (fenugreek) seed were inhibited the Staphylococcus aureus growth after 216 and 288 hours respectively. The lowest number of TVC and PTC were observed in the fillet containing 4% of ethanolic extract of Trigonella foenum-graecum (fenugreek) seed. The shelf life of the control fillets was 216 hours while the treatments of 5 and 6 (4% concentration of aqueous and ethanolic extracts of Trigonella foenum-graecum (fenugreek) seed) were acceptable level after 288 hours. The TBA and TVB-N values of fillets gradually increased during storage but this increase was lower in treatments containing extract. The fillet containing 4% of ethanolic extract of Trigonella foenum-graecum (fenugreek) seed has lowest TBA and TVB-N values at the end of storage. Increasing the shelf life of fillets containing Trigonella foenum-graecum (fenugreek) seed extract can be due to the antibacterial and antioxidant properties of this plant seed.Trigonella foenum-graecum (fenugreek) seed extract is rich in polyphenolic flavonoids, which has antioxidant activity and can protect cellular structures from oxidative damage.

    Conclusion

    Aqueous and ethanolic extracts of Trigonella foenum-graecum (fenugreek) seed have been investigated as natural antimicrobial agents for food preservation. Based on the present study, the aqueous and ethanolic extracts of Trigonella foenum-graecum (fenugreek) seed improved the organoleptic properties and decreased the TBA and TVB-N values after treatment. High concentration of aqueous and ethanolic extracts of Trigonella foenum-graecum (fenugreek) seed greatly enhanced the shelf life of Cyprinus carpio fillets inoculated with Staphylococcus aureus during refrigerated storage. However, our results showed that ethanolic extract have more antibacterial properties than the aqueous extract and was more effective in slowing down the growth of bacteria. Thus, the use of ethanolic extract of Trigonella foenum-graecum (fenugreek) seed at concentration of 4% is recommended for increase the shelflife of Cyprinus carpio fillet during storage in refrigerator (4˚C).

    Keywords: Staphylococcus aureus, Sensory analysis, Fenugreek seed extract, Cyprinus carpio
  • R Fattahi, B Ghanbarzadeh *, J Dehghannia Pages 45-57
    Introduction

    In recent years, the tendency to use biodegradable polymers in food packaging has been increased due to enhanced awareness on the ecological and environmental problems and the contaminations of natural resources caused by non-degradable petrochemical-based polymers. In this regard, two types of biodegradable polymers have been investigated: edible and non-edible biopolymers. Carbohydrates and proteins or their combination with lipids usually are used for producing edible biopolymers (Noshirvani et al., 2018). Cinnamon essential oil (CEO) is a mixture of aldehyde, phenol and terpene active compounds, exhibiting antioxidant and wide spectrum antimicrobial properties against fungal spoilage. CEO is granted by the world health organization (WHO) expert committee as a non-toxic additive and flavoring agent, meanwhile CEO is widely applied in many food formulations thus it fits desirable taste (Ojagh et al., 2010). Mostly, synthetic antimicrobial and antioxidant compounds are directly added into the food products to control the microbial growth. This method may lead to the inactivation or evaporation of active agents and rapid migration into the bulk of the foods. Hence, the antimicrobial activity may be quickly lost by dilution below active concentration and also the flavor of the food may be changed. The incorporation of an antimicrobial compound in a polymer matrix and the production of active packaging potentially cause to gradual release of active agents, which may be promising approach to inhibit the microbial growth. Carboxymethyl cellulose (CMC) is a biodegradable semi-synthetic biopolymer. It is a linear anionic charge polysaccharide due to having many hydrophilic carboxyl groups. CMC produces high viscosity solution and transparent films with favorable properties from consumer point of view. The CMC-based films show good barrier properties against gases and lipophilic compounds, while showing poor inhibition against water vapor permeation, similar to other polysaccharide and protein-based films. In order to fix these defects and improve packaging properties, a number of approaches have been studied such as combination with other compatible biopolymers, using hydrophobic compounds (such as lipid and essential oil), cross linking agents and nanofillers. To our knowledge, there is no study on comparing the effects of nano and macro emulsion of cinnamon essential oil (CEO) on the physicochemical and antifungal properties of the active biopolymer based films. Therefore, the objectives of this work were (i) to produce the emulsified CMC-based films from CEO macroemulsions (ME) and nanoemulsions (NE) prepared by using Ultra-Turrax and Ultrasonication (ii) to compare the effects of these two types of the emulsified films on some physical features of the resulted films (iii) and to study the in-vitroefficiency of these films against Aspergillus niger and mucor racemous.

    Material and methods

    Macroemulsions (ME) were formed by adding different amounts (0.125, 0.25 or 0.5 gr) of Tween 80 equation with 50% W/W surfactant oil ratio (SOR) to 20 ml of double distilled water and followed by homogenization by Ultra-Turrax (JANKE & KUNKEL, Germany), at 20000 rpm for 1 min. Then, CEO was added at (0.25, 0.50 or 1 gr) equation with 0.25, 0.50 and 1% W/V (CEO/Emulsion) to each solution and mixed again for 2 min. Prepared ME were sonicated at the condition of 20 kHz frequency, 400 W input power and 70S amplitude for 10min by Ultrasonicator (FAPAN, Iran) to obtain nanoemulsions. In order to prevent the increase of emulsions temperature during sonication, the solutions were keeping in ice-water bath. Films were prepared as described by Dashipour et al. (2015), with slight modifications. First, 80 ml of double distilled water was heated in a water bath until temperature increased to about 85 , then, 1.5 g of CMC powder was added to hot water and mixed by magnetic stirrer(800 rpm) at 85 for 60 min. After that, glycerol was added at 0.75 w/w of CMC as a plasticizer and mixing continued for 10 min. Then, the solution temperature reduced to 60  in order to prevent the destruction of CEO active compounds. Having done that, the solution was mixed with 20 ml of macro and nano emulsions solution prepared in the previous section and agitated with magnetic stirrer (500 rpm) at 60  for 30 min to obtain homogeneous solutions. The film forming solutions were degassed with vacuum pump(DV-3E 250, JB,USA), at ambient condition for 5 min, then, 100 ml of the emulsified film forming solutions were poured into an even surface Teflon plates (PTFE) in the dimension of 15 15 cm and dried at 40  for 18 h in cold incubator to cast the films.

    Results and discussion

    The emulsified films based on carboxymethyl cellulose (CMC) containing macroemulsion (ME) and nanoemulsion (NE) of cinnamon essential oil (CEO) were prepared. The atomic force microscopy (AFM) images showed different morphology in the ME and NE films and more compact and uniform microstructure in the NE films than the ME one. Adding CEO led to more flexible films with lower glass transition temperature (Tg) and storage modulus (E'). Low droplet size in NE than ME led to brighter and yellowish films. Antifungal index against A. niger and M.racemous were 14.16% and 20.82 % in the ME films and 18.81% and 25 % in the NE ones. The antifungal activities of cinnamon essential oil (CEO) is related to their major phenolic or aldehyde such as eugenol and cinnamaldehyde constituents, respectively. Eugenol caused to killed microbial cells probably by two important mechanisms; leached out cell content by increasing the permeability of cellular membranes and released proton of hydroxyl groups causing to reduce proton gradient that resulted depletion energy polls in microbial cells. Another effective mechanism of cinnamaldehyde in microbial growth is its reaction with nucleophilic compound in microorganism's structure by higher electrophilic compounds such as carbonyl groups in cinnamaldehyde structure. The disruption of cytoplasmic membranes, the cytoplasm depletion, thedeformation of hyphal tips, the formation of short branches and the collapse of entire hyphaewere the major effect of essential oil on fungus, observed by transmission electron microscopy.

    Conclusion

    Comparing different physicochemical and antifungal properties of CMC films containing ME and NE of CEO showed significant differences. The decrease of droplet size by sonicator caused to better diffusion of CEO NE from cell membrane of microorganisms, resulting in improved antifungal efficiency. Microscopic images showed smooth and homogenous appearance with lower Sa and Sq of NE films. More interruption among biopolymer chains by nano droplets caused to the production of the films more extensible than ME films. Thermomechanical analysis confirmed more decrease in glass transition temperature (Tg) and storage modulus (Eʹ). This study introduced a new nano active packaging film with some improved functional characteristics.

    Keywords: Active film, Cinnamon essential oil, Bioavailability, Antifungal
  • R Maghsouzadeh, A Jalilzadeh * Pages 59-69
    Introduction

    Bamieh is one of the traditional confectionaries that are produced by deep frying, and it has high oil content. Coating of foods with edible coatings and films has been suggested to reduce oil absorption during the frying process. Films and edible coatings are natural polymers made from agricultural materials. Edible films are either formed as coatings or embedded in food components, limiting the migration of moisture, lipids, and color between food components to improve the quality of non-homogenous foods (Khawaldia et al., 2004). Edible coating is a surface polymer coating that reduces surface porosity and impedes the entry of oil into the food (Ziaeifar et al., 2008). Whey protein based films and coatings have been noticed in recent years because, in addition to being biodegradable, they utilize whey as a major by-product of cheese industry.   Moreover, they have excellent oxygen and water vapor barrier properties, and consequently can be used in food packaging. The aim of this study was to investigate the effect of whey protein based coating on qualitative characteristics of Bamieh during storage. In this research, coating of Bamieh coating using whey protein solution (0.25, 0.5 and 0.75% w/w) was studied in order to reduce the oil uptake of the product.

    Material and methods

    For preparing of Bamieh dogh, the raw materials, including flour and water, were mixed well with a small amount of vanilla, then the dough was spread on the table and cooled to ambient temperature. Then, it was poured into the mixer and the eggs and saffron were added and stirred well in the mixer to obtain a smooth and uniform dough. To prepare colloidal suspensions, the required concentrations of whey protein (80% purity produced by Agri Mark, USA) and sorbitol (70% purity Cargill, USA) were mixed with water and heated to 90℃. It was completely homogenized to give a transparent solution. The solution was cooled to ambient temperature and the Bamieh samples were coated by immersing in the solution (Garcia et al., 2007). Three types of coating frmulations with different percentages of whey protein were prepared (0.25, 0.5 and 0.75%) with a constant ratio of sorbitol (0.5%). Qualitative characteristics of Bamieh samples including oil uptake (by Soxhlet method, moisture (according to Iranian National Standard Procedure No. 2705), acidity (by titration method with 0.1N sodium hydroxide), peroxide value (According to AOAC method No. 965/33) and sensory evaluation of samples were investigated. All of analysis were performed with 3 replications and the results were reported as mean of 3 replicates.
     

    Results and discussion

    Analysis of oil uptake showed that, control samples had the highest oil uptake. By increasing the percentage of whey protein in the coating formulation, the oil uptake of Bamieh significantly decreased (P <0.05). Bamieh coated with 0.25%, 0.5% and 0.75% whey protein showed 10%, 20% and 31% lower oil uptake, respectively. This decrease in oil uptake in coated samples is due to the use of edible coating. Hydrocolloid coatings are able to physically prevent the penetration of oil into the nutrient due to the film-forming properties during heating. In the frying process due to the evaporation of moisture in the food, the oil replaces with water molecules. Thereby reducing the moisture content and increasing the oil content (Kester et al., 1986). Albert and Mittal (2002) showed that the use of hydrocolloids such as gelatin, gellan gum, capacaragine, methylcellulose, pectin, and whey protein isolate reduced the oil uptake in fried cereal products. The use of a plasticizer in the coating formulation contributes to the uniformity and enhances the coating's inhibitory property, reducing oil absorption and moisture outflow (Garcia et al. 2002). The results of moisture content analysis showed that Bamieh samples coated with different percentages of whey protein (0.25, 0.5 and 0.75%), had decreasing trend of moisture content during storage time on different days (1, 10, 20 and 30). During storage time, the acidity of all samples increased, which was higher in the coated samples compared to the control. However, the acidity of all samples was lower than the standard limit (0.2% maximum). The increased acidity is due to the hydrolysis of glycerol and the release of fatty acids that occur during the storage of edible oils and fats and oil-containing foods. The amount of hydrolysis depends on various factors such as the amount of food product moisture, the amount of oil, the storage temperature and the type of oil (Azadmard Damirchi, 1391). Analysis of peroxide values shoed that, the peroxide value of control and treated samples increased with different percentages of whey protein probably due to the oxidation of the oil in the samples during storage. All samples showed the highest peroxide value on day 30. Coating did not have significant effect on delaying oxidation. By coating the Bamieh with different percentages of coatings, the peroxide content in all samples were acceptable.
    Comparing of the scores obtained for different characteristics of appearance, color, taste, texture and overall acceptance between different treatments showed that samples coated with different percentages of whey protein had better appearance, color, taste and texture compared to control. As the percentage of whey protein in the coating increased, the appearance, color, texture and overall acceptability increased. The samples coated with 0.5% and 0.75% whey protein showed higher overall acceptability score compared to other treatments. Applying the coating before frying creates a uniform layer around the food and causes the fried products to reduce their crispness by preventing moisture transferred into the shell or absorbing moisture from the food (Jorjani and Hamrahi, 2015).

    Conclusion

    Coating of Bamieh with whey protein concentrate edible reduced the absorption of oil uptake but had no effect on the reduction of the final product acidity and peroxide value. Coating of Bamieh with whey protein based coating at a concentration of 0.5 and 0.75% produces a low oil content and desirable sensory properties in terms of appearance, color, taste and texture. SoWhey protein coatings can be used as an edible coating to reduce oil absorption in Bamieh.

    Keywords: Bamiyeh, Deep Frying, Edible coating, Oil uptake, Whey protein
  • N Emami, L Nateghi *, MR Eshaghi Pages 71-88
    Introduction

    Food science has meet new challenges in food production that could respond consumer’s tastes and at the same time improve. Lifestyle modifications related to change in the eating quality and quantity along with mental stress led to the prevalence of non-communicable diseases. Based on the consumer’s demand, food scientists are now focusing on developing low calorie/high-fiber functional foods. Baklava is one of the most important flour products with a widespread production due to its desirable sensory properties as well as high stability. Despite the benefits of sucrose as a natural sweetener with desirable performance characteristics, due to problems with blood pressure, heart disease, tooth decay, obesity and increased blood glucose and insulin levels, especially for harmful diabetics in addition, due to economic and technological issues, increasing research are under way to replace sugar with other sweeteners. One of the important issues regarding the replacement of sugar in food products is the choice of the type of sweetener to replace and how to preserve the quality of the product during the storage period (Gohari Ardabili et al 2005). Sugar is an essential ingredient in the preparation of various types of Baklava, which in addition to the role of sweetening has a great effect on the physical and chemical properties of the product (Specter and Setser 1994). There are many substitutes for sugar for use in baking products. For example, sucralose and isomalt are the natural substitutes for sugar in the baked goods. Considering the nutritional properties and high sugar content, sucralose and isomalt are used as a desirable substitute to sugar in food formulations to increase nutritional value and avoid sucrose complications. In this study, isomalt and sucralose were used as a replacement for sugar in Kermanshah's traditional Baklava production and physicochemical and sensory properties were studied. Physicochemical, textural and sensory analysis of Kermanshah's traditional Baklava including ash (Institute of Standards and Industrial Research of Iran 2015), sucrose (Institute of Standards and Industrial Research of Iran 2013), protein percentage (Institute of Standards and Industrial Research of Iran 2013), fat percentage (Institute of Standards and Industrial Research of Iran 2014), caloric (Institute of Standards and Industrial Research of Iran 2008) and texture hardness (Institute of Standards and Industrial Research of Iran 2013) & colorimetric (Saricoban and Yilmaz, 2010) for 20 days storage and sensory properties (Lee et al., 2008) on the first day of production, were studied. The results of the tests were analyzed using the Minitab 14 software using one-way analysis of variance Duncan's test.

    Material and methods

    In this study in order to produce Kermanshah's traditional Baklava first the dough Baklava. In the first stage solid materials which are egg (21.5 %), Milk (20.5 %), Peking powder (4 %), oil (16 %) and butter (4.2 %) were mixed in the mixer, then while mixer was working with a low speed, flour (33 %) and salt (0.8 %) was added so that the dough Baklava. After dough packaged in nylon bag and stored at refrigerator (4-6 °C) for about two hours. Then inner dough ingredients included pistachio powder (36.5%), almond powder (36.5%), cardamom (9%) and cinnamon (18%) pour in the dough and spread out material first by hand and then with a spoonful. Again the next layer of dough was applied to the material and the butter and liquid oil mixture was rubbed on it. Then the dough were placed in an oven Model TF1000 (Atlas Corporation) at 300C for 25 minute. Remove the beans from the oven to cool and add to the nectar and set the lid to allow the nectar to completely penetrate into the baklava (Institute of Standards and Industrial Research of Iran 2006). In order to produce nectar control first stage water (35 %), sugar (40 %), rose water (5 %), saffron (10 %) and lemon essence (1 %) were mixed then were placed in a stove for 15 minute and the syrup was poured hot on the baklava. For produce other treatment replacement of sugar in ratios of 0, 20, 40, 60, 80% by the low-calorie sucralose and isomalt mixture. It is worth mentioning sucralose was considered 650 times sweeter than sucrose (sugar) and isomalt is half times sweeter than sucrose and the rest compounds were considered as fixed compounds.

    Results and discussion

    The results of this research study showed that with increasing sucrose replacement by sucralose and isomalt mixture, the amount of ash, sucrose, protein percentage, fat percentage and calorie decreased significantly (p≤0.05) and moisture rate increased. Assessment of color changes during 20 days of storage showed that with increasing the replacement ratio, the light (L*) parameter significantly increased and redness (a*) and yellowness (b*) parameters significantly decreased and increased, respectively. Hardness of texture is measured by inserting a punch or rod into the food. Texture hardness is directly proportional to the magnitude of force required. The hardness decreased significantly on the first day with increasing sucrose replacement by sucralose and isomalt mixtures. As observed, increasing the shelf life significantly increases the texture hardness, this trend decreased with increasing substitution so that the treatment (20% sugar + 80% sucralose and isomalt mixture) had the least hardness after 20 days of storage. This is primarily due to the increase in sucrose substitution by sucralose and isomalt, the increased water uptake in baklava pastry and the decrease in texture hardness. During the storage period due to the release of water and the equilibrium of moisture treatments with the environment of all samples, it becomes harder than the first day (Gallagher et al. 2003). On the other hand, the sensory properties assessment showed that after control, the treatments containing 20% and 40% of sucralose and isomalt mixture had the highest sensory acceptability, and they were selected as the superior treatments.

    Conclusion

    The results revealed that by using the mixture (60% sugar + 40% sucralose and isomalt), the rate of sucrose consumed in the formulation of the control sample can be replaced by a mixture of sucralose and isomalt up to 40% without any adverse effect on its physicochemical, texture and sensory properties.

    Keywords: Sugar Replacement, Kermanshah's Traditional Baklava, Sucralose, Isomalt
  • Z Sayyar, H Jafarizadeh Malmiri * Pages 89-99
    Introduction

    Nowadays, the use of herbal medicines for the treatment of many diseases has attracted the attention of scientists (Abdullaev et al., 2004; Samarghandian and Borji 2014). Turmeric is one natural plant, which has a bioactive ingredient called curcumin. It has many medicinal and food applications due to its biological properties. Yellow pigment curcumin is a polyphenol from the diaryl heptanoids group (Anuchapreeda et al., 2011). Curcumin has different application in industry as cosmetic creams, wound glues, capsules, herbal toothpaste, and soaps. It is also used in the food industry for the preparation of soups, drinks and even pastels (Prasad et al., 2014; yallapu et al., 2013). Curcumin metabolism indicated that it has low poor solubility in the aqueous media, dramatically reduces cellular uptake and so-called bioavailability. In addition, it causes many problems in adding this valuable bioactive ingredient to water-based food and drug formulations (Sreekanth et al., 2011; Pan et al., 2011). In recent decades, nanotechnology has been able to solve this problem with bioactive compounds. Prepared nanodispersions of bioactive compounds are suggested ways to overcome this problem with low water solubility and low bioavailability bioactive (Anton et al., 2007; Mora-Huertas et al., 2011). Conventional methods of preparing nanodispersions using organic solvents may have undesirable effects. Therefore, green technology has recently been developed. Nowadays, using novel methods has advantages to prepare nanodispersions of bio-friendly bioactive materials such as subcritical water. In this method, water are used as a solvent because of its unique physico-chemical properties (Ravber et al., 2015). The aim of this study is to prepare curcumin nanodispersions with very fine particle size and high antimicrobial properties using water in subcritical conditions, for the first time, and a solvent replacement method. Finally, Zeta potential and particle distribution index (PDI) were compared. Also, the antioxidant and antimicrobial effects of prepared curcumin nanodispersions using these two methods were investigated.

    Material and methods

    Curcumin (97% purity), poly ethylene glycol (PEG, 4000 Dalton) and Tween 20 were provided from Merck Company (Darmstadt, Germany). Ethyl acetate (99.7%) as solvent was prepared from Samchun Pure Chemical Company (Seoul, Korea). Escherichia coli (PTCC 1270) and Staphylococcus aureus (PTCC 1112) were purchased from microbial Persian type culture collection (PTCC, Tehran, Iran). Nutrient Agar (NA) was provided from Biolife Company (Milan, Italy). Double distilled water was used to prepare all nanodispersions. Curcumin nanodispersions were prepared using solvent displacement and subcritical water. In subcritical water method, 1.5 mg of Tween 20 was mixed with 20 mg of curcumin then was added into the water, placed in a sealed teflon autoclave and heated at 120 °C for 2 h in an oven (Behdad Medical  Production Co., SP88, Tehran, Iran). The internal pressure of the autoclave was 1.5 bar. The Teflon autoclave with capacity of 100 mL, was designed and manufactured in our research laboratory. In solvent displacement method, 20 mg of curcumin was added into the ethyl acetate (10 mL) as solvent to produce the organic phase. On the other hand, 1.5 g Tween 20 was mixed into the distilled water (98.5 g) under a constant stirring (300 rpm) for 15 min to prepare aqueous solution. Organic phase was then slowly added into the aqueous solution and mixed using a conventional homogenizer at 300 rpm for 15 min. finally, the organic solvent was removed using a rotary evaporator (Eyela NE-1001, Tokya Rikakikai Co. Ltd, Tokyo, Japan) which it was adjusted at temperature, pressure and rotation speed of the 50 °C, 25 KPa and 100 rpm, respectively.

    Results and discussion

    Therefore, in the present study Curcumin nanodispersions using a novel subcritical water method and a traditional solvent displacement method using ethylacetate and utilizing Tween 20, as emulsifier, were prepared and the physico-chemical, rheological, stability, antioxidant and antimicrobial properties of the prepared Curcumin nanodispersions were evaluated. Dynamic Light Scattering analysis indicated that the produced nanodispersions using novel technique had minimum particle size (10.1 nm) and poly disperses index (0.06) and maximum conductivity (0.401 mS/cm) and zeta potential (-15.8 mV) values as compared to those of obtained by the solvent displacement method. The obtained results also indicated that the prepared pale yellow Curcumin nanodispersions (b=2.55) using subcritical water method had minimum turbidity (0.063 NTU) and viscosity. Furthermore, more stable (during three month) produced Curcumin nanodispersion using subcritical water method shown the highest antioxidant (57.6%) comparison to Curcumin in water (3%) and antibacterial activity against to the both studied Gram-positive and Gram-negative bacteria strains.

    Conclusion

    Curcumin nanodispersions were prepared using two methods as subcritical water and solvent displacement. The results showed a higher stability, lower viscosity, higher antioxidant and antimicrobial properties of curcumin nanodispersion prepared by the novel method as subcritical water. In addition to, organic solvents were eliminated in subcritical water method, also the amount of used emulsifier has decreased. Therefore, this method increases the economic justification of the process of production of curcumin nanodispersions then it decreases the concern about the health and environmental aspects of product consumption. Therefore, the use of this new method for preparing curcumin nanodispersions can be easily generalized and can be applied to prepare for other food and pharmaceutical nanodispersions.

    Keywords: Nanodispersion, Curcumin, Subcritical water, Solvent displacement, Stability
  • M Hoseinnia, H Almasi *, M Alizadeh Pages 101-123
    Introduction

    Due to the increasing of awareness and consumer demand for healthy and natural foods without synthetic preservatives, in the recent years the food industry has paid increasing attention to using natural preservatives. Plant extracts and essential oils (EO) are a broad class of natural food preservatives that are generally recognized as safe (GRAS). Microencapsulation is the most common technique that has been utilized to increase the stability of bioactive compounds. The benefits of microencapsulation of herbal extracts and essential oils includes: protection of flavor components from evaporation and destructive changes, promotion of easier handling, better mixing with food matrix, release controlling and increasing bioavailability (Donsi et al., 2011). Ziziphora clinopodiodes (known as Kakuti) is one of the most commonly consumed herbal plants belonging to the family of Lamiaceae and it is native to Turkey and Iran. The major phenolic compounds of Z. clinopodiodes essential oil (ZEO) or its extract (ZE) are include pulegone, 1,8-cineole, thymol, carvacrol, p-cymene and limonene (Sonboli et al., 2010). The functional properties of Z.clinopodiodes extract (ZE) and ZEO including strong antioxidant, antibacterial, antifungal and antiviral activities have been fully recognized in previous researches. The selection of a suitable wall material is critical to have a successful microencapsulation. Whey protein isolate (WPI), gum Arabic (GA) and guar gum (GG) are some of most frequently used biopolymers for encapsulation of bioactive compounds in food industry applications (Kuck et al., 2017). There is no report on the encapsulation of ZEO or ZE. The aim of this research was to evaluate and compare the potential of GA, WPI and GG either alone or in combination with each other in the microencapsulation of Ziziphora clinopodiodes extract (ZE) by ultrasonication method.

    Material and methods

    The GG, GA and WPI were used for encapsulation of ZE in the single form or in combination with each other. After encapsulation, the suspensions were freeze dried and the powder of microcapsules was used for further analyses. The particle size, zeta potential, and encapsulation efficiency were determined. Also, the total phenol content, antioxidant activity and color properties of microcapsules were analyzed. Structural and morphological properties of them were also characterized by FT-IR, XRD and SEM analyses. The one-way ANOVA method by using SPSS software was used for statistical analysis of obtained data.

    Results and discussion

    Particle size analysis showed that the WPI stabilized sample had the lowest particle size (292.7 nm). The performance of GA and GG was improved after combination with WPI. By considering encapsulation efficiency (EE%), particle size, PDI and Zeta potential values, the compatibility of WPI with GA was more than GG. The highest EE% (86.91%) belonged to GA/WPI sample. Total phenol content and antioxidant activity were in their maximum level for GA/WPI mixture. Among the used wall materials, GA had the highest Zeta potential (-20.5 mV). Since the isoelectric point of WPI is around pH 5 and pH of dispersions was about 7, the net charge of these microcapsules was also negative (-15.5 mV). GG is a weak polyelectrolyte and had the lowest Zeta potential (-6.6 mV). All of the powders had a whitish color. There was no significant difference between L* and a* values of samples (p˃0.05). But b* was increased significantly when WPI and GA were used instead of GG. Yellowish color of WPI and GA caused to increase b*. This yellow appearance was more distinct in GA in comparison to WPI. The initial TPC of ZE before enclosing in microcapsules was equal to 346.91 mg GAE.100g-1 DW. The TPC of all samples was lower than initial amount in fresh ZE. Between microcapsules, those that had the higher EE showed a higher TPC too. TPC of GA was higher than WPI followed by GG. When the mixture of wall materials was used, TPC was increased and the GA/WPI sample had the highest TPC (212.81 mg GAE.100g-1 DW). GG and GA/WPI with 21.67% and 32.11% respectively, had the lowest and highest antioxidant activity. Spherical shape of microcapsules was observed by SEM for all samples expect to GG/GA. WPI stabilized microcapsules exhibited the lowest particle size with uniform distribution. Polydispersity and mean diameter was higher for GA microcapsules and these parameters increased for GG microcapsules. FT-IR analysis confirmed the formation of new interactions between wall materials (expect to GG) and ZE ingredients. XRD test revealed that the crystallinity of wall materials was decreased after ZE incorporation but WPI contained samples were resistant against structural alterations. Crystallinity index of GG, GA and WPI coated microcapsules was equal to 6.54%, 23.13% and 9.76%, respectively. Crystallinity index of 11.5%, 25.21% and 19.66% was calculated for GG/GA, GG/WPI and GA/WPI microcapsules, respectively. By considering of applying similar sonication and drying conditions on all samples, these results indicate that the ZE incorporation had no distinct effect on crystallinity of WPI but it disrupt the structure of polysaccharide based encapsulating agents.

    Conclusion

    In this work the performance of different wall materials and their combinations was evaluated in microencapsulation of ZE. WPI and GA/WPI combination showed the lowest particle size and the best encapsulation efficiency, respectively. In the total phenolic content study, the mixture of GA/WPI performed better in protecting the ZE phenolic compounds leading to increase the antioxidant activity of microcapsules. SEM images indicated that the successful fabrication of microcapsules with GA, WPI and GG is possible but it is better to use their combination. The best morphological characteristics with spherical microparticles were obtained when WPI was mixed with GA. Formation of new interactions between GA, WPI and ZE ingredients was approved by FT-IR analysis. But XRD test indicated that these interactions lead to change in structural characteristics of biopolymers. However, in spite of new bond formation, WPI preserved its semi-crystalline structure when used alone or in combination with polysaccharides. Generally, by in comparison of individual wall materials, the WPI was the best encapsulating agent but its performance was increased via blending with other biopolymers. The compatibility of WPI with GA was more than GG and by considering the set of results; the combination of GA/WPI presented the best behavior. Further studies are required for exploring the performance of these microcapsules for their application in food formulation.

    Keywords: microencapsulation, Ziziphora clinopodiodes extract, wall materials, particle size, morphology
  • H Jahangir, I Shahabi, R Pourata Pages 125-138
    Introduction

    Today, the most of the food packaging materials are based on petroleum-derived polymers. They have caused many environmental pollutions in the world. One of the solutions to deal with the problem is development of edible and biodegradable films as substitutions of the petroleum based packaging materials. Among the bio-based materials which used in the food packaging, starch is interested as an ecofriendly material. It is due to acceptable film forming properties, easy access, renewability and low cost of starch. Nevertheless, high hydrophilic properties and weak mechanical properties have been limited its utilization as a commercial packaging material. The presence of hydroxyl groups in the starch chains create hydrogen bonds between starch and water. As well as the considerable free space between the starch chains facilitate the movement of the water molecules through this space. Many researches have been done to reduce hydrophilic properties of starch using chemical modification, irradiation, and composition with nanoparticles and other biopolymers. Most of the methods are based on blocking the hydroxyl groups of starch chains with hydrophobic agents, formation of emulsions and blocking of the pores.Other alternative procedure which used to improve the water barrier properties of hydrophilic films is producing composite films with adding hydrophobic components such as lipids and fatty acids.The starch based films have poor resistance to water vapour transmission. Their water vapor barrier properties might be improved by adding hydrophobic materials, such as lipids, into the film forming solutions. Fatty acids, such as oleic acid (OA) are lipid derivatives which have potentially improve the moisture barrier properties of hydrophilic films. OA is a yellow liquid at room temperature hence, it is easily miscible with biopolymer without needing to further heating treatment. As well as due to the polar nature of biopolymers, OA need to the surfactant to homogenous distribution in the matrix of biopolymers. On the other hand, OA is not very sensitive to oxidation which increases its safety in food packaging uses. In this study, the effects of different concentrations of OA and UV irradiation were investigated to improve the hydrophobicity of starch film.

    Material and methods

    In order to preparation of starch film, starch (5 wt. %) was added to distilled water. The resulting mixture was stirred at 85 ˚C for 15 min until the starch was gelatinized. Then, glycerol (40 wt. % of dry base) was added to the solution as a plasticizer. OA 0.6%, 1% and 1.4% (wt% of dry base) and Tween 80 as emulsifier (10% of the OA concentration), were mixed in 50 ˚C for 10 min. Then, 10 ml of distilled water was added to the solution, and then sonicated by ultrasonic homogenizer (Dr. Hielscher, Teltow, Germany) for 7 min. To prepare the uniform distributed film solution, the fatty acid emulsion was gradually added to the gelatinized starch solution. The resulting suspension was homogenized by magnetic stirrer and ultrasonic homogenizer for 10 and 7 minutes, respectively. Film forming solution was irradiated with UV-C as stirred during 60 minutes at a distance of 5 cm from the UV-C lamp. 43 g of each solution was casted into flat mold with a diameter of 15 cm. The samples were finally dried for 48 hours at room temperature. All films were conditioned at 50-55% relative humidity and room temperature for 48 hours before subjected to any tests.

    Results and discussion

    The contact angle of the starch based films was increased with increasing the OA content up to 1 wt%. After that it was decreased with increasing the OA. It was due to the plasticizing effect of OA at high concentration. The contact angle of the UV irradiated starch-OA were increased with increasing the OA content. Generally, the contact angle of the UV irradiated starch-OA films was drastically higher than virgin starch-OA films. However, the water vapor permeability (WVP) of the starch based films was decreased with increasing the OA content up to 1 wt% and increased at the high OA content film (i.e. 1.4 wt% dry based). But there was no significant difference between starch film and the starch-OA films. The WVP of the UV irradiated starch-OA were decreased with increasing the OA content. The WVP of the UV irradiated starch-OA films was higher than virgin starch-OA films. Nevertheless, there was no significant difference between WVP of UV irradiated starch-OA and starch film.Moisture content (MC) of the starch-OA film at the lower OA content (i.e. 0.6 wt% dry based) was the lowest. With increasing OA content MC of the starch-OA film increased that way there was no significant difference with starch film. But the MC of the UV irradiated film decreased with increasing the OA content up to 1 wt%. Moisture absorption (MA) of the starch-OA and UV irradiated starch-OA films were shown significant difference with virgin starch film. MA of the starch-OA films were independent from UV irradiation except starch-OA (0.6 wt%) which was increased with UV irradiation.There was no significant difference between the solubility of the starch, starch-OA, and UV irradiated starch-OA films in water except UV irradiated starch-OA contain 1.4 wt% OA.

    Conclusion

    Regard to results of the current study the low OA content in starch based film can be used as the appropriated method to solve the moisture sensitivity of starch based films. Furthermore, UV irradiation intensify the effect of OA on the moisture sensitivity of the starch based films. The most of characterizations of UV irradiated starch-OA films had been influenced by the content of formed the mono and disaccharides and the development of random cross-linkages during UV exposer process. The applied procedure is useful to develop more biodegradable and profitable packaging material, generally.

    Keywords: Starch, Oleic acid, Ultraviolet ray, Hydrophobic
  • M Esmaili, A Ebrahimzadeh *, H Hasanpour, MB Hassanpour Aghdam Pages 139-152
    Introduction

    Controlling the postharvest losses and the utilization of safe methods versus chemical compounds is a remarkable priority in the production of horticultural produce. Using techniques to preserve agricultural produce quality dates back to many decades ago (Paliath et al., 2009). This is essential to keep the visual characteristic and quality of products. In some ways, the procedures employed improve the quality and organoleptic properties of the crops. This is end goes to the reduced production charges and the higher incomes (Duan et al., 2007). Postharvest scientists are attempting to employ the materials to cover the fruits and to keep the harvest time quality or even to improve the quality and visual attributes. During the recent years, the application of edible coatings such as chitosan has been increased to reduce the postharvest loses, lowering the respiration rate, shelf life improvement, firmness keeping and for the control of microbial growth rates in fruit crops. Chitosan is an aliphatic organic polymer with a characterized antifungal (Allan and Hadwiger, 1979) property. Furthermore, chitosan coating lowers the respiration rate, prevents microbial growth and delays the fruit ripening by the control of CO2, O2 and ethylene exchange balance (EL Ghaouth et al., 1991). Moreover, low temperature storage intensifies the chitosan keeping qualities on stored fruits. Cornelian cherry fruits contain high amounts of ascorbic acid (vitamin C), organic acids, phenolics,taninns and some other bioactive compounds. Hence, the fruits have considerable nutritional and medicinal benefits effects (Moldovans et al., 2016). Furthermore, the fruits have precious antimicrobial properties (Asadov, 1990). In the present study, we tried to evaluate the effects of different chitosan concentration to keep the antioxidant potential of cornelian cherry and of the quality attributes during postharvest period.

    Material and methods

    Cornus mass L. fruits were harvested from an orchard from northwest of Iran (Hourand country). In advance, the fruits were homogenized for the size, color and shape and were transferred to the Lab. The fruits were treated with 0.5,1 and 1.5 % chitosan solution and distilled water as control for 1 minute. The fruits let too dry at ambient temperature and were stored at 4±1°C for 21 days. TSS, TA and pH were evaluated in fruit juice soon after. Samples were taken during the first, 7, 14 and 21th days after treatment. The fruits were kept at cold storage and immediately the common measurements like pH, TSS and TA were conducted. Then after the fruits were freezed in liquid nitrogen and kept in - 40 °C for further studies. Total phenolics, Flavonoids and anthocyanin were measured by folin- ciocaltea (Gallic acid as standard), flavonoids based on catechin and total anthocyanin by the absorbance difference in divers pH ratios, respectively. DPPH method was employed for the antioxidant potential of fruits. Besides CAT, GPX, PPO and PAL enzymes were quantified as well. The data were analyzed by SAS (ver.9.2) software as CRD with three replications. Excel 2013 was employed for the tables figuration and the means were compared by the Duncan's multiple range test.

    Results and discussion

    ANOVA results revealed that interaction of storage time × chitosan concentration meaningfully (P <0.01) influenced pH. TA and TSS of fruits. The top pH was acquired by 0.5% chitosan at the third week. Chitosan modifies fruit surface atmosphere and hence by the variations in CO2 and O2 alters the TA and pH values. Maturity stage influences TSS values and with ripening progress, TSS was increased (Gunduz et al., 2012). In a similar experiment, with chitosan concentration adding up, TSS increase was slowed down seemingly due to the hydrolytic changes in the starch content and water loss during the storage period (Kays, 1997).  Interaction of time and chitosan concentration was statistically influenced (P <0.01) total phenolics, flavonoids and total anthocyanin content. Total phenolics had the highest amount with 1.5% chitosan seemingly due to CO2 barrier induced by chitosan which reduces the phenolics oxidation. Moreover, chitosan coating activates PAL enzyme in phenolics biosynthesis (Romanazzi et al., 2017). Total flavonoids were increased by storage time, and by 1% of chitosan treatment. Flavonoids are crucial antioxidants and besides phenolics were increased in the fruits during the storage time and with SA treatment (Dokhanieh et al., 2013). Total anthocyanins followed the same pattern as well. Antioxidant potential of fruits was also impacted by storage time and chitosan as well (P <0.05). Antioxidant potential is directly related to phenolics, flavonoids and anthocyanins content of fruits and vegetables. So that, the increased total amounts of the mentioned metabolites resulted in improved DPPH activity. There is evidence that other coatings such CaCl2 and SA improved the metabolites and antioxidant potential (Dokhanieh et al., 2013; Soleimani-Aghdam et al., 2013).  CAT, PPO, GPX and PAL were influenced by the time× chitosan interaction as well. CAT activity was declined during the storage period. But, there was no significant difference between 0, 1 and 1.5% chitosan treatments. Chitosan application improves the selective permeability of membrane for CO2 and O2 exchange and hence reduce the phenolics oxidation. These all reduce the PPO activation and function (Duan et al., 2007). GPX activity was increased during the storage, So, that the highest GPX activity was belonged to the sampling at 21th days. PAL activity was responsive to the interaction of time × chitosan concentration and the enzyme activity was increased in time dependent pattern during the storage. The top data was recorded for the untreated fruits.

    Conclusions

    Cornelian cherry fruitsare rich in antioxidant compounds like phenolics, flavonoids, anthocyanins and ascorbic acid. During the storage period and like other horticultural products (fruits and vegetables), the nutritional and visual quality of cornelian cherry fruits reduces dramatically. Chitosan as an environment-friendly and non-chemical compound preserves the quality attributes of fruits. Over all, in the present experiment, chitosan treated fruits had more antioxidant potential and enzymatic activity than untreated ones. Moreover, chitosan improved the total quantities for phenolics, flavonoids and anthocyanins. DPPH antioxidant potential was improved by chitosan application. Furthermore, CAT, PPO and PAL were correspondingly responded to chitosan treatment in favor of fruits quality. In short, chitosan has a considerable potential to be considered as a good edible coating to improve the postharvest life and quality attributes of cornelian cherry fruits.

    Keywords: edible coatings, chitosan, cornelian cherry, antioxidant, quality attributes
  • T Najafabadi, S H Hoseini Ghaboos * Pages 153-169
    Introduction

    Consumers across the world are becoming more interested in foods with health promoting features as they gain more awareness of the links between food and health (Tamime et al., 2005). Yogurt is the most consuming fermented milk products, which has a positive effect on human health due to the high nutritional value and particular importance in the diet of individuals. Yogurt in Health and Disease Prevention examines the mechanisms by which yogurt, an important source of micro- and macronutrients, impacts human nutrition, overall health, and disease. Topics covered include yogurt consumption’s impact on overall diet quality, allergic disorders, gastrointestinal tract health, bone health, metabolic syndrome, diabetes, obesity, weight control, metabolism, age-related disorders, and cardiovascular health (Shah, 2017). Helianthus tuberosus L., commonly known as Jerusalem artichoke, produces fibrous roots with short rhizomes that end in underground caulinar tubers, which accumulate fructans, mainly inulin. The plant has four main uses: horticultural, fodder, bioethanol production, and inulin extraction (Rébora, 2008). This crop is highly tolerant to adverse weather conditions and various plant diseases and also grows well in poor land (Saengthongpinit & Sajjaanantakul, 2005). Among other plants rich in inulins, Jerusalem artichoke stands out as an interesting candidate for the industrial production as its tubers accumulate similar levels of inulin (16–20% of fresh tuber) as chicory roots (Franck, 2000) and could be cultivated at a low cost with low input of fertilisers on any type of soil and cool climatic conditions. However, the use of Jerusalem artichoke (JA) tubers for inulin extraction is less well known as they are commonly eaten as vegetable (Paseephol & Sherkat, 2009). Understanding of rheological properties of fruit juices are essential for quality control, process engineering application (designing and selection of proper equipment including heat exchangers, transport systems, evaporators and pumps), calculating energy usage and power requirement for mixing. Rheological information is valuable in product development (Salehi, 2019). Recently, viscometers have become a valuable and extensively used tool in the study of milk gel structure. Such measurements are sensitive to the initial stage of casein micelles aggregation and demonstrate that gelation begins well before any visual observation of coagulation. A point is reached during aggregation in which a three-dimensional cross-linked network of casein is formed and following this, coagulation can be observed rheologically (Shaker et al., 2000). The goal of this study is investigate on the effect of fat content changes on chemical and rheological properties of yogurt contains Jerusalem artichoke powder during storage.

    Material and methods

    In this study, Jerusalem artichoke powder to the amount of 0.5, 1 and 1.5% in yogurt formulation with 0.5, 1 and 1.5% fat was used, and its chemical and rheological characteristics was investigated during the 21 days. The cow milk (total solid nonfat 9%) was heated to 92 °C for 5 min then cooled to inoculation temperature (42 °C). Jerusalem artichoke tubers were washed with tap water and brushed to partially remove tuber skins. Tubers were then cut into ∼2 mm slices and dried at 45 °C in an electric oven with convection, until constant weight was achieved. Dried slices were then ground and passed through a 63-mesh sieve to obtain the Jerusalem artichoke flour. The pH was measured directly using a calibrated digital pH-meter (Lutron YK-2001 pH meter, Taiwan). The titratable acidity (TA) with respect to the percentage of lactic acid equivalent was determined by titration of the yogurt samples with 0.11 N NaOH in the presence of phenolphthalein. The viscosity of yogurt was measured using a rotational viscosimeter (Brookfield, USA). The rheological parameters of yogurt at shear rate of 40 s-1 were studied using spindle LV64 at 8°C. Each measurement was conducted in three repetitions. The experimental data were subjected to an analysis of variance (ANOVA) for a completely random design using a statistical analysis system (SPSS 21). Duncan’s multiple range tests were used to determine the difference among means at the level of 0.05 (Salehi, 2017).

    Results and discussion

    Addition of Jerusalem artichoke powder was not significantly effect on chemical and rheological characteristics of yogurt. The results showed that the pH of the higher in fat at the end of the maintenance period was significantly higher than the pH of yogurt with 0.5% fat. Also acidity of the samples at 14 days was significantly increased although for an amount of increase in higher fat yogurt in comparison with 0.5 and 1% fat yogurt is lower. At the end of the maintenance period, acidity of yogurt with 0.5% fat was significantly more than yogurt with 1 and 1.5 percent fat. According to consistency and elasticity, the samples with 1.5 % Jerusalem artichoke powder and 1.5 % fat was the best treatment. Rheological properties of plain yogurt during coagulation process, impact of fat content and preheat treatment of milk were studied by Shaker et al. (2000). Their results showed that the increasing in fat content leads to an increases in viscosity. The highest viscosity was manifested by milk heated at 137°C while the lowest value was exhibited by milk heated at 65°C. The process viscosity curves for three different stages are described by mathematical relationships. Finally, a two-parameter power law model was used to describe the flow behavior of the yogurt during coagulation.

    Conclusion

    Jerusalem artichoke flour resulted an interesting food ingredient due to its high content of prebiotics (inulin) and phenolics, which may be used as a powder substitute to increase the nutritional quality of dairy products. Rheological properties for foods, such as fermented dairy products, are important in the design of flow processes, quality control, storage and processing and in predicting the texture of foods. With increasing Jerusalem artichoke powder and fat content, loss modulus versus shear stress was increased. In general, with increasing shear rate the viscosity of samples were decreased. Also with increasing the percentage of samples fat, the viscosity in the constant shear rate was increased. The increase in viscosity at the highest fat content may be due to increase of total solids of the milk which has a significant effect on the firmness of yogurt gel. Addition of Jerusalem artichoke powder increases the viscosity but the effect of fat on the viscosity was more.

    Keywords: Inulin, Jerusalem artichoke, Rheology, Yogurt
  • M Nouraddini, M Esmaili *, F Mohtarami Pages 171-184
    Introduction

    Recently, the increase in synthetic polymers has been pushing researchers toward the development of new biodegradable and natural polymers, suitable for food packaging. To extend the shelf-life of foods and the preservation them from microbial spoilage and oxidation while reducing packaging waste, the tendency is to use natural materials such as edible films and coatings. (Khazaei et al., 2014). These films, as the carrier of the functional components like antioxidants, the antimicrobial agents, colorants, flavors and spices can improve both the capability and the functionality of the packaging materials (Ramos et al., 2012). Biodegradable and edible films can be prepared using proteins, carbohydrates, lipids or mixture of them. Among the natural and renewable resources, starch is one of the most important ingredients of films. It is commonly used in the packaging industry due to its abundance, low price, ability to form the edible films and biodegradability. The films based on starch are odorless, tasteless, colorless and transparent, while enjoying good gas barrier properties (Acosta et al., 2016; Šuput et al., 2015). In recent years, there is an increasing attention in developing edible films by agriculture crop flours and powders due to their availability, easy obtaining and low cost compared to pure components such as starch and proteins (Nouraddini et al., 2018). Among the agriculture crop, eggplant (Solanum melongena L.) is recognized for its high dietary fiber content, antioxidant capacity, oxygen radical scavenging capacity and minerals. Also, it has flavonoids and high amount of anthocyanin in peel (Niño-Medina et al., 2017). Eggplant powder has significant amount of protein, carbohydrates, fat and crude fiber (Nouraddini et al., 2018). In the last decades, the essential oils of  plants and spices have got attention to use as the antimicrobial and antioxidant agents, which can be added to the edible films (Jahed et al., 2017). Mentha longifolia essential oil and extract showed the antioxidant and antimicrobial activity (Farzaei et al., 2017; Gulluce et al., 2007). The antioxidant activity of Mentha longifolia EO and the extract might be related to its phenolic content such as phenolic acid, rosmarinic acid and polyphenols (Gulluce et al., 2007). According to our survey, there are no studies on the development of edible films using eggplant powder and Mentha longifolia essential oil. Therefore, the object of this study was to prepare the edible active films based on corn starch and eggplant powder incorporation with Mentha longifolia essential oil (0, 1, 3 and 5% w/w), in order to examine their physical properties.

    Material and methods

    For the extraction of Mentha longifolia essential oil, the dried samples were submitted to the hydro-distillation for approximately 3 h by a Clevenger. The obtained essential oil was kept in dark glass at 5 ºC. For the preparation of eggplant powder, the eggplants were sliced and dried in hot air oven at 50ºC for 24 h without peeling off the skin. Then the dried samples were grinded into powder and it stored in glass dishes at 4 ºC. The corn starch and eggplant powder based films were prepared at ratio of 1:1 by the casting method. The pH of solution was adjusted at 7.5 by NaOH and then it was stirred and heated at 85 ºC in a water bath. After that, the glycerol was added at 36% w/w/ and the solution was mixed for 30 min. Then the Mentha longifolia essential oil was added at different ratio (1, 3 and 5% w/w) to film solutions. The emulsion was homogenized with a Rotor-stator homogenizer and degassed using an ultrasonic homogenizer. The film samples solution was dried at room temperature for 48 h. Physical properties such as thickness, moisture content, density, mechanical properties, color, opacity and light transmittance values, solubility and swelling index of films were evaluated. All the tests were carried out in triplicate. The analysis of variance (ANOVA) was applied to the data and the means were compared by Duncan’s test using SPSS statistical software.

    Results and discussion

    The thickness, swelling index of films incorporated with essential oil were higher than control films (P<0.05). A decrease was observed in the density and moisture content of the films that incorporated with Mentha longifolia essential oil. The solubility in water of control films was the highest (67.61%), while the addition of Mentha longifolia essential oil, the solubility values significantly (P<0.05) decreased. The results showed that the lowest level of water vapor permeability was found for the control films (0.0023 ± 0.0009 g.mm/m2.h.Pa) and the highest was related to films containing 5% Mentha longifolia essential oil (0.0028 ± 0.0006). Results showed significant differences between color parameters (P<0.05). Color measurement of the edible films indicated that increasing the concentration of Mentha longifolia essential oil, increased the lightness (L*), redness (a*) and yellowness (b*) and decreased the ΔE of films. The addition of essential oil decreased the tensile strength, Young’s modulus and elongation at break of films. Light transmittance value at UV region was negligible and for control films were higher than other films and with an increase in the wavelength (visible light region), the light transmittance of the films increased. According to the results, the maximum light transmittance was related to control films. The evaluation of the opacity values revealed thatthe control films showed higher opacity compared to the films incorporated with essential oil.

    Conclusion

    The edible active films based on corn starch and eggplant powder with Mentha longifolia essential oil were successfully prepared. The addition of Mentha longifolia essential oil to edible films led to the formation of a film with good transparency and lightness characteristics. According to results the mechanical properties of films were decreased with the addition of essential oil. In general, addition of Mentha longifolia essential oil to edible films based on corn starch and eggplant powder improved the water solubility and transparency of films, furthermore it has negative effect on mechanical properties and water vapor permeability of films. According to the results obtained in this research, eggplant powder and corn starch based films with Mentha longifolia essential oil can be used in food packaging.

    Keywords: Mentha longifolia essential oil, Eggplant powder, Edible film, Corn starch
  • H Nalbandi *, SS Seidlou Pages 185-200
    Introduction

     Garlic "Allium Sativum L." is a relatively perishable product. Approximately 30% of this product is lost annually in the post-harvest stages due to the lack of suitable storage and convenient transportation facilities. It is rich in medicinal and food nutrition and is widely cultivated throughout the world, including Iran. Recently, dried garlic has been used as one of the ingredients and additives of cooked and semi-finished foods such as sauces and soups. Changing the pattern of consumption from the fresh garlic to the dried one has increased the demand for this product. Understanding the moisture and heat transfer mechanism during the drying is crucial to enhance the quality and reduce energy consumption. The quality changes of a dried product are functions of drying condition as like; drying air temperature, drying time, and the warmth of the product surface. By applying higher drying air temperature, shorter drying time and also in parallel with it, slightly lower energy consumption is achievable; however, it will result in higher quality changes. The objective of this study was developing a simulator for drying with variable air temperature to reduce the drying time and lowering energy consumption as well as maintaining the dried product quality at its highest possible level. 

    Materials and methods

    In the present study, the mathematical equations of mass and heat transfer during convection drying of garlic have been developed. The following assumptions were used to develop the mathematical model; 3-D transfer of heat and moisture is accrued; the air distribution is uniform inside the dryer; the distribution of initial moisture and temperature throughout the material is uniform; the product shrinkage is negligible during the drying process; heat transfer to the product through radiation is negligible and conductive heat transfer between trays and product was not included. Third type boundary condition was applied to all air-product interfaces and the equations were solved on three-dimensional geometry of garlic slices simultaneously with the Finite Element Method (FEM) using COMSOL MULTIPHYSICS 3.5 software under different drying air temperature. The temperature and moisture profiles were estimated in a garlic slice by the developed simulator. Mesh independence study was performed to establish an optimal mesh density that gives a solution with acceptable accuracy and four meshes, each containing 1430, 3364, 4362 and 12977 elements were used. The results indicated that mesh independence of numerical solution was obtained when the number of elements was above 4362. The developed simulator was validated by experimental study under different drying temperature conditions; 50, 60 and 70 °C; and different thicknesses of the samples; 2, 3 and 4 mm. At the same time, the engineering and qualitative properties associated with thermal processing of garlic slices were studied, such as the effective moisture diffusivity, apparent density and dry material density, and color changes of the samples. Eventually, by using the simulator, the issue of reducing energy consumption by reducing the total time of the drying along with preserving the apparent quality of the product was examined based on the output data from the simulator through the use of the variable temperature of hot air during the process and in different thicknesses. 

    Results and discussion

    The developed simulator was able to accurately predict changes in the moisture ratio at different temperatures of the hot air and the different thicknesses of the garlic product. The average error in estimating the moisture content at the hot air temperature of 50, 60 and 70 °C was 11%, 6%, and 34%, respectively. Based on the experimental results, the change in hot air temperature and samples thickness did not have a significant effect on the apparent density but affected the final color of garlic slices. The surface temperature of samples had a significant influence on the quality of the dried product; furthermore, the minimum and maximum changes in the color of the samples were observed when the surface temperature of slices was 50°C and 70°C, respectively. The use of drying air at 50 °C and 2 mm thick slices maintains the lightness of the samples and prevents the color changes of the samples during drying. However, the use of hot air at a lower temperature can prolong the drying time. Accordingly, by the developed simulator using the drying air with variable temperature for drying garlic slices was evaluated and the predicted surface temperature of sample was monitored during the drying process with the air temperature of 70°C and by the time that the surface temperature of sample was increased and reached 50°C, the hot air temperature was reduced and the drying process lasted from 30 minutes, with drying air at 50 °C. Despite the use of hot air with variable temperature, no noticeable changes were observed during drying compared to drying with an air temperature of 70 °C and drying time was prolonged only 3 minutes. At the same time, during the 25% of the total drying time the drying air with 20 °C lower than the usual has been used, which will reduce energy consumption. The results showed that by using this method, it is possible to dry the garlic slices in a shorter time. Also, by restricting the temperature rise of the product in the final stages of the process, the color change of the samples is prevented. On the other hand, due to the use of the variable temperature of the drying air, the drying time decreased about 43 minutes as compere with the drying of the sample with the air temperature of 50 °C, which had a significant effect on reducing energy consumption. Similar results were obtained in drying garlic slices with a thickness of 3 mm.
      

    Conclusion

     To achieve a high-quality dry product, more transparent color and reduced energy consumption by reducing the drying time, it was necessary to use slices with lower thickness and hot air with variable temperature during the process based on the developed output-model. The proper time to change the air temperature during the drying process was determined. The developed simulator can predict the items mentioned above, with high precision.

    Keywords: Color, Drying, Garlic, Quality, Simulation, Variable air temperature
  • R Akbar, M Soltani *, M Moslehi Shad Pages 201-215
    Introduction

    Yoghurt is a well-known dairy product manufactured by fermentation of milk with lactic acid bacteria (LAB). Due to production of bioactive peptides by LAB during fermentation, yoghurt has higher biological activity than milk (Pessione and Cirrincione, 2016). Specifically, some peptides in yoghurt have antioxidant activities and are effective in inhibition of lipid peroxidation and removal of free radicals (Nielsen et al., 2017). Milk acidification induces the formation of continuous gel networks by incorporation of aggregated protein molecules and fat globules. The fat globules serve as structure modifiers and influence the rheological properties of the composite gels. Gel strength depends on fat globule size and the extent of their surface interactions with the gel network (Kirimlidou et al, 2017). The physical properties and microstructure profile of the gels are reflected onto texture and sensory properties of yoghurt (Öztürk et al. 2018). Development of more nutritious yoghurt is an ongoing topic in dairy science. Incorporation of technically-emulsified oil formulations rich in mono- and polyunsaturated fatty acids in yoghurt may help to increase its health benefits (Baba et al, 2018). Reduction in consumption of dietary animal fat has been recommended by nutritionists due to the proven relationship between fat consumption and heart diseases. In this context, consumption of low or nonfat dairy products has increased because of recognition of their health benefits (Kucukoner and Haque 2003). Consumer trends have shown that consumption of healthful food supports healthy lifestyles and reduces the risk of disease (Asioli et al., 2017). These changes in consumer demand have driven the food industry to develop functional foods with health-beneficial effects (Vecchio et al., 2016). Low-calorie or low-fat dairy products have been available in EU or USA markets for a long time and their consumption have been increasing (Kucukoner and Haque 2003). Milk fat has an important role in the texture, flavour and colour development of dairy products. Fat reduction can cause some defects such as lack of flavour, weak body and poor texture (Haque and Ji 2003). Although the manufacture of low- or nonfat dairy products has been possible for many years, the use of fat replacers in the manufacture of dairy products is still novel. Fat replacers, which decrease the calorific value of food, can be used to solve some physical and organoleptic problems originating from low-fat levels in the final products. Fat replacers consist of mixtures of lipid originated fat substitutes, protein or carbohydrate originated fat mimetic or their combinations (Huyghebaert et al. 1996).  Using fat replacers as improver of texture and flavor have developed in the formulation of dairy products. Date molasses is one of the most valuable secondary products of the date that rich in natural sugars such as fructose and glucose. This product contains significant amount of iron which can increase red blood cells and reduce the risk of anemia. In this context, the aim of this study was to investigate the effect of using different rates of date molasses as a fat replacer on the physicochemical, texture and sensory properties of yoghurt manufactured from non-fat milk.

    Material and methods

    In this research, two yoghurt samples were manufactured from whole milk (3%) and skim milk (<0.1%) as control samples and three yoghurt samples were manufactured with addition of date molasses in different concentrations of of 5, 10 and 15 % (w/w) to non-fat milk. All yoghurt samples were manufactured in three replicates. Skim milk powder (2% w/v) was added to all treatments in order to increasing the total solid of final product. The mixtures were then pasteurized at 90°C for 5 min and cooled to 43 ± 1°C, inoculated with 3% of starter culture (w/v), dispersed into plastic cups (200 ml), and incubated at 42± 1°C until pH 4.6. Following incubation, Yoghurt samples were stored in refrigerator (4±1°C) for 22 days and their physicochemical, texture and sensory properties were evaluated at 1st, 8th, 15th and 22th day of storage.

    Results and discussion

    Physicochemical analysis showed that increasing the rate of date molasses in yoghurt samples caused to decrease in acidity, viscosity and water holding capacity and increase in pH and syneresis (P<0.05). The yoghurt samples manufactured from different rates of date molasses had higher pH and syneresis and lower acidity, water holding capacity and viscosity compared with yoghurt samples manufacture from full-fat milk (P<0.05). On the other hand, with increasing the rate of date molasses in yoghurt samples, sensory properties including appearance and colour, texture and consistency and odour and falvour decreased (P<0.05). Increasing the amount of date molasses caused to decrease in hardness, cohesiveness and adhesiveness and increase in springiness of yoghurt samples (P<0.05). Results of fat, protein and dry matter analysis on the first day of storage in the yoghurt treatments indicated that, as expected, an increase in date molasses in the yogurt treatments resulted in increase in the dry matter. On the other hand, protein content in yoghurt treatments decreased with increasing the rate of date molasses. Also, according to the rate of milk fat used, control full-fat yoghurt had the highest fat content among the treatments.  In terms of sensory properties, with increasing the date molasses, total sensory desirability of yoghurt samples decreased. In this context, the yoghurt containing 5% (w/w) of date molasses received the highest acceptability compared with other samples manufactured using date molasses. Moreover, increasing the rates of date molasses in the manufacture of non-fat yoghurt samples caused to decrease in hardness, cohesiveness and adhesiveness and increase in springiness values of them (P<0.05).

    Conclusion

    In this study, the effect of using different rates of date molasses on different quality characteristics of yoghurt manufactured from non-fat milk during 22 days of storage was evaluated. The results of different analysis showed that date molasses can be used in certain quantities in the manufacture of non-fat yoghurt. In conclusion, using 5% (w/w) of date molasses instead of milk fat led to the best result in manufacture of non-fat yoghurt in terms of physicochemical, texture and sensory properties. Analysis of texture characteristics is considered as a useful procedure for assessing the hardness, adhesiveness, cohesiveness and springiness in yoghurt. The results of texture analysis showed that increasing the date molasses rates in date molasses-enriched yoghurt samples resulted in increase in springiness and decrease in hardness, cohesiveness and adhesiveness.

    Keywords: Date molasses, Physicochemical properties, Sensory properties, Skim milk, Yoghurt