فهرست مطالب

  • سال پانزدهم شماره 5 (پیاپی 59، آذر و دی 1398)
  • تاریخ انتشار: 1398/07/29
  • تعداد عناوین: 12
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  • فاطمه فرزانه مقدم، جواد سرگلزایی*، شادی بلوریان صفحات 529-542

    آنتی اکسیدان های طبیعی اصولا ترکیبات فنولی، پلی فنولی و کاروتنوئیدی هستند که در میوه درخت عناب یافت می شود. هدف از این مطالعه بهینه سازی شرایط استخراج ترکیبات فنولیک از میوه عناب به دو روش حلالی و روش سیال فوق بحرانی کربن دی اکسید جهت یافتن نقاط بهینه استخراج و کاهش میزان حلال مصرفی و ارزیابی فعالیت آنتی اکسیدانی عصاره های استخراجی می باشد. در روش استخراج با حلال از طرح باکس بنکن با سه متغیر دما، زمان و نسبت حلال و در روش فوق بحرانی از طرح مرکب مرکزی با دو متغیر دما و فشار جهت بهینه سازی استفاده شده است. دما، زمان و نسبت حلال ها در روش استخراج با حلال برای رسیدن به حداکثر میزان فنول کل به ترتیب برابر oC54/43،  hr46/3 و 92/44 درصد به دست آمد و نسبت حلال و دما بیشترین تاثیر را بر میزان فنول کل دارا بودند. همچنین دما و فشار در روش فوق بحرانی برای رسیدن به حداکثر میزان فنول کل برابر oC19/34 و bar 323 حاصل شد. میزان فنول کل استخراجی در نقطه بهینه در روش استخراج با حلال برابر 21/26 و در روش فوق بحرانی برابر 74/22 میلی گرم گالیک اسید به گرم عصاره خشک بود. در خصوص خاصیت آنتی اکسیدانی نیز IC50 در نقطه بهینه در روش استخراج با حلال برابر 6/581 و در روش فوق بحرانی برابر 8/532 بود. در هر دو روش میزان فنول کل رابطه مستقیم با فعالیت آنتی اکسیدانی داشت و روش فوق بحرانی با وجود برخورداری از میزان فنول کمتر دارای قدرت آنتی اکسیدانی بیشتری بود.

    کلیدواژگان: میوه عناب، بهینه سازی، ترکیبات فنولی، روش فوق بحرانی، خاصیت آنتی اکسیدانی
  • مصطفی کاشانی نژاد، مسعود نجف نجفی*، محسن قدس روحانی، مرتضی کاشانی نژاد صفحات 543-563

    در این پژوهش اثر کنسانتره پروتئین شیر (mpc)، پودر آب پنیر (cwp) و صمغ کنجاک (kg) بر روی ویژگی های فیزیکوشیمیایی، رئولوژیکی و حسی ماست چکیده مورد بررسی قرار گرفت و سپس این خصوصیات با استفاده از روش های تحلیل مولفه اصلی و رگرسیون حداقل مربعات جزئی مقایسه گردید. نتایج آزمون های فیزیکوشیمیایی نشان داد که با افزایش میزان mpc و کاهش cwp، تغییرات pH پس از 5 روز و آب اندازی نمونه ها کاهش یافت. بر طبق نتایج حاصل از آزمون اکسترژن برگشتی- آنالیز پروفیل بافت، با افزایش میزان صمغ کنجاک سختی، چسبندگی و نیروی چسبندگی نمونه ها نیز به طور معنی داری به ویژه برای نمونه های حاوی cwp بالاتر افزایش یافت در حالی که در مقادیر بالای صمغ کنجاک با افزایش میزان mpc و کاهش میزان cwp پیوستگی نمونه ها کاهش نشان داد. بر اساس آزمون کرنش متغیر نیز با افزایش میزان صمغ کنجاک، G' LVE، G" LVE، γc، τy، τf و Gf نمونه ها نیز به طور معنی داری برای نمونه های حاوی cwp بالاتر افزایش یافت. همچنین نتایج حاصل از بررسی همبستگی بین خصوصیات حسی، فیزیکوشیمیایی و رئولوژیکی نشان داد که رابطه ای نزدیک بین امتیاز مزه ترش با پذیرش کلی نمونه ها وجود داشت که این امر نشان دهنده اهمیت بیشتر امتیاز مزه ترش در بین صفات اندازه گیری شده برای پذیرش کلی مصرف کنندگان بود.

    کلیدواژگان: آزمون اکسترژن برگشتی آنالیز پروفیل بافت، آزمون کرنش متغیر، پودر آب پنیر، کنسانتره پروتئین شیر
  • سید محمد امام*، امیرمحمد رضایی پور، ابوالفضل فورگی نژاد صفحات 565-575

    مغز پسته یکی از مهمترین محصولات صادراتی ایران محسوب می شود. بنابراین درجه بندی دقیق آن از اهمیت زیادی برخوردار است. این محصول بر اساس استاندارد ملی ایران، با شمارش تعداد پسته در 100 گرم به سه دسته درشت، متوسط و ریز تقسیم می شود. در این مقاله با استفاده از روش ماشین بینایی، از تعدای مغز پسته با اندازه و شکل های کاملا تصادفی تصویربرداری و ذخیره سازی در رایانه انجام شد. سپس، عملیات پردازش تصویر شامل بهبود عکس مغز پسته ها جهت افزایش دقت لبه یابی صورت گرفت. جهت استخراج ابعاد هندسی شامل بزرگترین قطر و مساحت، فرآیند کالیبراسیون دقیق با یک صفحه شطرنجی انجام شد. در استاندارد ملی ایران توجهی به سالم یا شکسته بودن مغز پسته جهت درجه بندی این محصول نشده است. لذا در این تحقیق، روش سری فوریه برای استخراج ویژگی های مورفولوژیکی مغز پسته شامل گردی، کشیدگی، تقارن، مثلثی و مربعی بودن با استفاده از توصیف گرهای مرتبه پایین مورد استفاده قرار گرفته است. با توجه به نتایج حاصل از عملیات کالیبراسیون، دقت اندازه گیری با میانگین خطای 09/0 میلی متر حاصل شد. با توجه به نتایج آزمایش تجربی مشاهده می شود، با استفاده از پردازش تصویر و تکنیک سری فوریه، امکان بهبود استاندارد فعلی از نظر افزایش سرعت، کاهش هزینه ها و افزودن پارامترهای شکل مغز پسته جهت تعیین میزان سالم بودن این محصول، امکان پذیر است.

    کلیدواژگان: مغز پسته، ماشین بینایی، سری فوریه، درجه بندی
  • فاطمه سعادت، سید هادی رضوی*، هوشنگ علیزاده صفحات 577-582

    گیاهان روغنی انرژی را به شکل لیپیدهای خنثی در اندامک هایی به نام اجسام روغنی (Oil Body) ذخیره می‏کنند. این اندامک‏ها تری اسیل گلیسرول را تا زمان جوانه زنی در شرایط و تنش‏های مختلف محیطی حفظ می‏کنند. در سال‏های اخیر اجسام روغنی به عنوان امولسیون روغن در آب در صنایع دارویی، غذایی و آرایشی بهداشتی مورد توجه قرار گرفته‏اند. همچنین این اندامک‏ها ابزاری کارآمد در تخلیص، تثبیت و دارورسانی محصولات بیوتکنولوژی محسوب می‏شوند. متداول‏ترین روش جداسازی اجسام روغنی از گیاهان استفاده از محیط‏های آبی است که علیرغم تمام مزایایی که نسبت به استفاده از حلال‏های آلی دارند، از بازده پایین‏تری برخوردار هستند. این مقاله به بررسی کارایی دو حلال بافر فسفات (1/0 مولار، 5/7= pH) و آب مقطر در استخراج آبی اجسام روغنی دانه‏های کلزا می‏پردازد. برای این منظور بذور گیاه کلزا (Brassica napus. L) از موسسه اصلاح بذر و نهال ایران تهیه گردیدند. سپس پودر کلزا در حلال‎ها به نسبت 1 به 10 (وزنی/ حجمی) به مدت 12 ساعت در دمای اتاق مخلوط شدند. این مرحله 3 بار تکرار گردید. عصاره به دست آمده در دور 10 هزار g به مدت 15 دقیقه در دمای 4 درجه سانتی گراد سانتریفوژ گردید. لایه شناور با دقت برداشته شده و در بافر اولیه حل گردید و pH آن به 5/8 رسانده شد تا پروتئین‏های تخریب شده حذف گردند. در نهایت، لایه کرمی مجددا بازیابی شده و در یک دهم حجم اولیه از بافر اوره 9 مولار (pH=7.5) برای 10 دقیقه ترکیب شد تا پروتئین‏های غیراختصاصی از اجسام روغنی جدا گردند. اجسام روغنی تخلیص شده در زیر میکروسکوپ نوری بررسی گردیدند. براساس نتایج میکروسکوپی و ماکروسکوپی، کارایی بافر فسفات بدلیل قابلیت حفظ pH قلیایی در طی استخراج بهتر از آب مقطر بوده و ذرات روغنی استخراج شده با این بافر از پایداری بیشتری برخوردار هستند. از طرف دیگر، بافر فسفات بدلیل ایجاد فشار اسمزی و افزایش حلالیت پروتئین‏های غشایی کارایی تخلیص را تا دو برابر افزایش می‏دهد. این نتایج بیش از پیش اهمیت حضور پروتئین های غشایی در تشکیل و تثبیت اجسام روغنی را مشخص می سازد.

    کلیدواژگان: پایداری، امولسیفایر، پروتئین ‏های غشایی، بهینه‏ سازی، بافر فسفات
  • الهام رنجبر ندامانی، علیرضا صادقی ماهونک*، محمد قربانی، شارلوت جاکوبسن، وحید خوری صفحات 583-596

    در این پژوهش، از روش سطح پاسخ برای بهینه سازی و مدلسازی شرایط هیدرولیز پروتئین های نخود کاجان (Cajanus cajan) (لپه) توسط پپسین و تولید پروتئین های هیدرولیز شده با ویژگی های آنتی اکسیدانی و تغذیه ای استفاده شد. هیدرولیز در نسبت آنزیم به سوبسترا 1، 2 و 3 درصد(وزنی- وزنی)، دماهای 30، 35 و 40 درجه سانتی گراد و زمان های 2، 5/3 و 5 ساعت انجام، و توانایی مهار رادیکال آزاد 2و2 دی فنیل 1 پیکیریل هیدرازیل، قدرت احیاء کنندگی، مهار رادیکال هیدروکسیل و ظرفیت آنتی اکسیدانی کل به عنوان متغیرهای وابسته بررسی شد. شرایط بهینه هیدرولیز برای دستیابی به بیشترین میزان فعالیت آنتی اکسیدانی، نسبت آنزیم به سوبسترا 15/2 درصد، دمای 9/39 درجه سانتی گراد و زمان 52/4 ساعت بود. پروتئین هیدرولیز شده دارای مقادیر زیادی از آمینواسیدهای آنتی اکسیدان گلوتامیک اسید و فنیل آلانین بود و از نظر وجود آمینواسیدهای ضروری دارای کیفیت تغذیه ای مناسبی بود. نتایج بررسی توزیع وزن مولکولی (به روش FPLC) نشان داد که وزن مولکولی بیشتر پپتیدهای تولید شده کمتر از 10 کیلودالتون است که بیشترین تاثیر را در فعالیت آنتی اکسیدانی دارند. نتایج نشان داد که از پروتئین های هیدرولیز شده نخود کاجان توسط پپسین می توان به عنوان آنتی اکسیدان طبیعی و همچنین به عنوان منبع آمینواسیدهای ضروری استفاده کرد.

    کلیدواژگان: پروتئین هیدرولیز شده، پپسین، آنتی اکسیدان، نخود، پپتیدهای زیست فعال
  • مژگان کریمی رضاآباد، آی ناز خدانظری*، سید مهدی حسینی صفحات 597-611

    در این مطالعه اثر فیلم و پوشش کیتوزان تحت شرایط بسته بندی در خلاء و بسته بندی در اتمسفر بر کیفیت فیله ماهی شعری معمولی (Lethrinus nebulosus) طی نگهداری در یخچال به مدت 12 روز مورد بررسی قرار گرفت. محلول کیتوزان با حل کردن 2% وزنی/ حجمی کیتوزان در اسید استیک 1% حجمی/ حجمی به دست آمد. فیله های ماهی به وسیله فیلم و پوشش کیتوزان تیمار و سپس بسته بندی (معمولی و تحت خلاء) شدند. آنالیزهای شیمیایی، میکروبی و حسی هر 3 روز یک بار به مدت 12روز انجام شد. میزان بازهای ازته فرار، اسیدهای چرب آزاد، تری متیل آمین، pH و باکتری های کل در نمونه پوشش کیتوزان و بسته بندی تحت خلاء کمتر از نمونه شاهد بود. در انتهای دوره نگهداری نمونه فیلم کیتوزان و بسته بندی تحت خلاء کمترین مقدار (22/1 میلی گرم مالون آلدهید بر کیلوگرم گوشت) تیوباربیتوریک اسید را دارا بود. کمترین و بیشترین مقدار باکتری های سرما دوست به ترتیب در نمونه های پوشش کیتوزان و بسته بندی تحت خلاء (log10 cfu/g 25/6) و شاهد (log10 cfu/g 70/8) در روز 12 مشاهده شد. نتایج آنالیز حسی فیله های خام و پخته شده نشان داد که نمونه های دارای پوشش و فیلم کیتوزان همراه و بدون بسته بندی تحت خلاء بهترین امتیاز را دارا بودند. نتایج به دست آمده از آنالیز رنگ نمونه ها نیز بیان کننده همین مطلب است. با توجه به نتایج به دست آمده می توان نتیجه گیری کرد که استفاده از فیلم و پوشش کیتوزان همراه با بسته بندی تحت خلاء باعث حفظ ویژگی های شیمیایی، میکروبی و حسی فیله ماهی شعری معمولی می شود.

    کلیدواژگان: بسته بندی تحت خلاء، Lethrinus nebulosus، فیلم، پوشش
  • رضا مبصرفر، سیدعلی مرتضوی* صفحات 613-622

    دوغ نوعی نوشیدنی تخمیری لبنی است که اساس تهیه آن، مخلوط کردن ماست با آب و نمک است. یکی از مشکلات اساسی دوغ، تغییرات کیفی آن در طی دوره نگهداری است که عمدتا به علت فعالیت میکروارگانیسم ها و در نتیجه کاهش pH رخ می دهد. در این پژوهش، تاثیر کاهش لاکتوز بر زمان ماندگاری، ویژگی های طعمی و حسی دوغ تولیدی در سه بازه زمانی روز اول، بیست و سوم و چهل و ششم پس از زمان تولید دوغ در مقایسه با دوغ های شاهد بررسی گردید. میزان استالدهید نیز به وسیله ی کروماتوگرافی گازی اندازه گیری شد. در این مطالعه شیر در سه روز متوالی از فیلترهایUltra filtration (UF)  عبور داده شد و میزان لاکتوز آن تا حدود 2% کاهش یافت. سپس مرحله تخمیر و استاندارد کردن دوغ ها از نظر چربی و ماده خشک بدون چربی انجام شد. کلیه آزمون ها با سه تکرار و با استفاده از آزمون LSD در سطح اطمینان 95% مقایسه میانگین ها انجام شد. نتایج نشان داد که در طول دوره نگهداری دوغ، میزان اسیدیته، pH و استالدهید دوغ تولیدی کمتر از دوغ شاهد شد؛ افزون بر این خواص حسی و طعمی آن نیز به میزان قابل توجهی بهبود یافت. هدف اصلی پژوهش افزایش زمان ماندگاری و بهبود خواص حسی و کیفیت دوغ بود؛ بر اساس یافته های این پژوهش به نظر می رسد که کاهش لاکتوز و به دنبال آن کاهش فعالیت باکتری های لاکتیکی می تواند نقش اساسی در افزایش زمان ماندگاری، ایفا کند.

    کلیدواژگان: دوغ، کاهش لاکتوز، اولترافیلتراسیون، کروماتوگرافی گازی، استالدهید
  • پرویز احمدی قشلاق، سیدصادق سیدلو هریس*، حبیبه نعلبندی صفحات 623-634

    استفاده از امواج مادون قرمز برای خشک کردن محصولات کشاورزی و غذایی موجب کاهش مصرف انرژی و مدت زمان خشک کردن و افزایش کیفیت محصول نهایی می گردد. در این تحقیق مراحل تغییر خشک کن مادون قرمز منفرد موجود، به دستگاه ترکیبی مادون قرمز- هوای گرم انجام و دستگاه مذکور ساخته شد. سپس برای ارزیابی سیستم در خشک کردن موز و بر اساس مبانی علمی موجود و نیز نیاز بازار مصرف، تاثیر مشخصه هایی مانند ضخامت ورقه های موز (4 و 6 میلی متر) و دمای سطح محصول (55، 65 و 75 درجه سانتی گراد) روی سینتیک خشک شدن و خواص کیفی محصول نهایی مطالعه شد. هم چنین جهت سهولت استفاده از نتایج آزمون ها، مدل های ریاضی مختلف روی داده های آزمایش برازش و مناسب ترین مدل توسعه داده شد. بر اساس نتایج حاصله، افزایش دما از 55 به 75 درجه سانتی گراد و نیز کاهش ضخامت نمونه ها تاثیر معنی داری روی تغییرات رنگ نمونه ها و زمان خشک شدن داشت ولی اثر فاکتورهای مذکور روی دانسیته نمونه ها غیرمعنی دار بود. به عبارت دیگر استفاده از دمای 55 درجه سانتی گراد موجب تولید بهترین محصول خشک از نظر کیفیت ظاهری شد. با توجه به خصوصیات کیفی مناسب استحصالی و مقایسه آن با داده های مرتبط با روش خشک کردن هوای گرم مشاهده شد که روش ترکیبی از دیدگاه تغییرات کیفی و زمان خشک شدن از ارجحیت برخوردار است. مقایسه مدل های ریاضی نشان داد که مدل پیج انتخاب مناسبی برای پیش بینی سینتیک خشک شدن موز تحت شرایط مورد مطالعه می باشد.

    کلیدواژگان: مدل ریاضی، موز، خشک کن ترکیبی مادون قرمز- هوای گرم، خواص کیفی
  • محبوبه داراپور، بهزاد ناصحی*، حسن برزگر، حسین جوینده صفحات 635-647

    سالانه مقادیر زیادی از پسماند کارخانه های فرآوری محصولات کشاورزی وارد چرخه ضایعات می شوند. این در حالی است که برخی از آنها سرشار از فیبر و ترکیبات فعال زیستی هستند، بنابر این پژوهش برای به کارگیری آنها به عنوان ترکیبات عملگرا در غنی سازی محصولات غذایی از اهمیت زیادی برخوردار است. در این راستا در این پژوهش اثر فیبر باگاس نیشکر (25- صفر درصد)، پلی ساکارید محلول سویا (2- صفر درصد) و زمان سرخ کردن (5-2 دقیقه) بر خصوصیات فیزیکوشیمیایی و حسی دونات مورد بررسی قرار گرفت. نتایج حاکی از آن است که افزایش فیبر باگاس نیشکر سبب افزایش مقدار رطوبت، چربی، سفتی، چسبندگی و صمغی بودن و کاهش حجم مخصوص، تخلخل و شاخص روشنایی پوسته و مغز تیمارها می شود. هم چنین افزایش زمان سرخ کردن نیز سبب افزایش سفتی، چسبندگی، صمغی بودن و کاهش محتوی رطوبت، تخلخل و شاخص روشنایی پوسته شد. علاوه بر این با افزایش درصد این منبع فیبری، پذیرش کلی فرآورده کاهش یافت. با این حال پلی ساکارید محلول سویا اثر معنی داری بر ویژگی های فیزیکوشیمیایی و حسی دونات نداشت. تحلیل آماری و بهینه یابی با طرح مرکب مرکزی چرخش پذیر حاکی از آن است که اگر تیمار حاوی 09/9 درصد فیبر باگاس نیشکر و 78/0 درصد پلی ساکارید محلول سویا طی 60/2 دقیقه سرخ شود، نمونه ای به دست می آید که دارای مطلوب ترین کیفیت است. بررسی ویژگی های نمونه بهینه نشان داد که مقدار رطوبت، فیبر، عناصر آهن و روی، پذیرش کلی و نرمی بافت بیشتر نسبت به نمونه کنترل داشت.

    کلیدواژگان: فیبر باگاس نیشکر، پلی ساکارید محلول سویا، غنی سازی، دونات
  • سارا کرم زاده، سارا انصاری* صفحات 649-665

    در این پژوهش از روش سطح پاسخ و طرح باکس- بنکن برای بهینه سازی شرایط استخراج به کمک امواج مایکروویو پکتین حاصل از پوست بادنجان استفاده شد و خصوصیات فیزیکوشیمیایی پکتین استخراجی مورد بررسی قرار گرفت. فاکتورهای مستقل مورد بررسی در این تحقیق شامل توان (360، 450 و 540 وات)، زمان (1، 5/2 و 4 دقیقه) و pH (1، 2 و 3) بودند. راندمان استخراج، درجه استریفیکاسیون، میزان گالاکتورونیک اسید و فعالیت امولسیفایری پکتین های استخراج شده به ترتیب 20/2 تا 16/17 درصد، 20/20 تا 23/36 درصد، 3/51 تا 7/74 درصد و 87/1 تا 64/21 درصد به دست آمد. نتایج تحقیق حاضر نشان دادکه با افزایش توان، افزایش زمان وکاهش pH، راندمان استخراج پکتین افزایش، درحالیکه درجه استریفیکاسیون کاهش یافت. میزان گالاکتورونیک اسید و فعالیت امولسیفایری با افزایش توان تا 450 وات و زمان پرتودهی تا 3 دقیقه ابتدا سیر صعودی و سپس نزولی داشت. شرایط بهینه برای دستیابی به حداکثر راندمان استخراج، میزان گالاکتورونیک اسید و فعالیت امولسیفایری در توان 360 وات، زمان 4 دقیقه و pH برابر با 0/1 بوده که در این شرایط پاسخ های فوق به ترتیب برابر با 81/18، 81/70 و 68/2 درصد پیش بینی شدند. همچنین مشاهدات نشان داد که با افزایش غلظت رفتار جریان محلول پکتین از نیوتونی به سودوپلاستیک تغییر کرد. از طرفی پایداری امولسیون پکتین استخراجی، در دمای 4 درجه بیشتر از 23 درجه سلسیوس بوده است. بر مبنای نتایج این تحقیق مایکروویو به عنوان یک روش نوین و با کارایی بالا برای استخراج پکتین از پوست بادنجان می باشد.

    کلیدواژگان: پکتین، پوست بادنجان، بهینه سازی، خصوصیات فیزیکوشیمیایی
  • نرجس بادفر، سیدعلی جعفرپور*، مهدی عبدالهی صفحات 667-677

    در این پژوهش از ماهی کپور نقره ای (Hypophthalmichthys molitrix) جهت تولید سوریمی استفاده شد و اثر پراکسید هیدروژن (H2O2)، دفعات شستشو و نسبت آب به گوشت در چهار تیمار (یک بار شستشو،1:3، 3%؛ یک بار شستشو،1:3، 2%؛ دوبار شستشو،1:2، 1%؛ سه بار شستشو،1:2، 1%) بر ویژگی های رئولوژیکی سوریمی مطالعه شد. طبق نتایج، نمودارهای آزمون های رئولوژیکی روبش فرکانسی، روبش تنشی و روبش دمایی از روند نسبتا یکسانی برخوردار بودند. طی فرآیند تشکیل ژل بر اثر حرارت در تمامی تیمارها، کم ترین مقدار G’(مدول ذخیره) بین 50 تا 52 درجه سانتی گراد ثبت شد. سپس با افزایش دما از 52 تا 62 درجه سانتی گراد منحنی G’ (مدول ذخیره) روند افزایشی داشته و از دمای 62 تا 80 درجه سانتی گراد منحنی روند نسبتا یکنواخت داشت. تغییرات در نمودار "G روند مشابه ای با G’ نشان داد.که این تغییرات منطبق با الگوی نمودار زاویه فازی تاخیری بود. در آزمون خزش-بازیابی، کم ترین و بیش ترین کرنش به ترتیب مربوط به نمونه شاهد و نمونه 5 (1% H2O2 ، 1:2 ، دو بار شستشو) بود. در مرحله بازیافت و پس از طی مدت زمان 300 ثانیه کرنش ایجاد شده در هیچکدام از نمونه ها به حالت اولیه خود نرسید که بدین معنی است که در مواد ویسکوالاستیک بازیافت تنش اعمال شده به صورت نسبی بوده و بخشی از ساختار دیگر قابل بازیافت نیست. نتیجه گیری کلی این که حضور H2O2 ، طی فرآیند شستشوی گوشت چرخ شده، فاقد اثر منفی معنی دار بر ویژگی های رئولوژیکی سوریمی تهیه شده بود.

    کلیدواژگان: کپور نقره ای، پراکسید هیدروژن، ویژگی های رئولوژیکی
  • غلامرضا چگینی*، ایمان حسن زاده صفحات 679-690

    در این مطالعه به منظور بررسی اثر خشک کردن برنج نیم پز شده با استفاده از روش جت برخوردی، سینیتیک خشک شدن همراه با صفات شاخص سفیدی و اختلاف رنگ مورد بررسی قرار گرفت. بدین منظور نمونه ها پس از خیساندن (در دمای 70 درجه سلسیوس به مدت 5 ساعت) به مدت 20 و 25 دقیقه بخاردهی شده و در دماهای 90، 100 و 110 درجه سلسیوس با سرعت هوای 15 و 20 متر بر ثانیه خشکانیده شدند پس از آن شاخص های کمی (L ، a و b) سیستم رنگ سنجی CIELAB اندازه گیری گردید. نتایج حاصل از تجزیه و تحلیل آماری حاکی از آن است که دمای هوای خشک کن نسبت به دو پارامتر مدت بخاردهی و سرعت هوا تاثیر بیشتری بر رنگ برنج نیم پز شده داشت. بیشترین مقدار سفیدی 884/63 و کمترین مقدار اختلاف رنگ 432/29 در مدت بخاردهی 20 دقیقه، سرعت هوا 15 متر بر ثانیه و دما 90 درجه سلسیوس به دست آمد.

    کلیدواژگان: جت برخوردی، برنج نیم پز شده، شاخص سفیدی، اختلاف رنگ
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  • Fatemeh Farzaneh Moghaddam, Javad Sargolzaei*, Shadi Bolourian Pages 529-542
    Introduction

    The term antioxidant is said to be compounds that are delaying or preventing oxidization of a substance at their own presence, which leads to reach a stabilized food quality (Collins, 2005). Natural antioxidants are often phenolic compounds that exist in all parts of a plant. These compounds are secondary metabolites that can inhibit active oxygen species by giving hydrogen atoms and converting them into more stable non-radical compounds due to oxidation and reduction properties. They also have the ability to chelate the metals (Wijngaard et al., 2009 and Erasto et al., 2007). Regarding the positive effects of natural antioxidants, many studies have been conducted to extract, identify and apply them from various herbal sources. Edible fruit jujube is a member of the Ramanaceae family, known in Iran as the jujube. The plants of the family are jujube flowers, which are all diploid and have 24 chromosomes. The jujube tree has been cultivated in China for thousands of years ago and is used as a medicine, food and food flavoring, also distributed in tropical and subtropical regions of Europe, Australia and South Asia. (Su et. al., 2005, Yan et. al., 2002, Preeti et al. 2014). Phenolic compounds have a high potential for antioxidants and a natural source of antioxidants. The antioxidant capacity of the Jujube is due to its antioxidant compounds such as flavonoids, total phenolic, anthocyanins and ascorbic acid. Zhao et al., 2014) and Zhang et al., 2010). Shell, pulp and fruit jujube seeds have a wide range of phenolic compounds and have long been used as a drug and flavor agent (Zhang et. al., 2010, Mahajan et al., 2009). Many studies have investigated the effects of Jujube fruit and its juice on the prevention and treatment of diseases such as digestive disorders, weakness, obesity, liver problems, diabetes, skin infections, Infections, Anemia, and Allergies have been reported (Gao et al., 2015 and 2013, Kim et al., 2011, Verma, 2016, Li et al., 2012). In a study by Wang et al. on Jujube fruit, 22 compounds were identified in ethanol jujube extracts (Wang et al., 2014). Zhang et al. The study that they carried out showed that the antioxidant activity of the jujube is due to its antioxidant compounds, such as flavonoids, total phenolic, anthocyanidins and ascorbic acid (Zhang et al., 2010). Italian scientists influence the phenolic compounds of jujube fruit extract on breast cancer cells (Plastina et al., 2012). During a study conducted in Egypt, the effect of jujube fruit on obesity, lipid profile and liver function were examined. (Mostafa et al., 2013). In another study on juvenile fruit phenolic compounds, the effect of jujube on seizure treatment was evaluated and the results showed that jujube has protective properties against seizure, oxidative stress and other disorders. Pahuja et al., 2011).In this research, extraction of phenolic compounds of Ziziphus Jujuba extracts has been performed using the supercritical carbon dioxide fluid method and optimization of the extracted compounds and the measurement of the antioxidant activity of Jujube fruit.

    Materials and methods

    Jujube fruit was prepared from Birjand in late August. Chemical materials such as pure ethanol, reagent Folin-Cictalto, sodium carbonate and free radical molecules from German-German corporations and Sigma Aldrich, and laboratory glassware and instruments such as volumetric balloons, refrigerators and freezers, spatula, vertex, buret, pipettes, calibrated cylinders, Filter paper, Falcon, Human Dimension, Mesh 30, Funnel and Arlene were provided. The freshly purchased fruits were separated from the tree before drying. After separating the jujube grain, the fruit was dried at 40°C in a digital-powered oven (volume 5 liters made by Binder Company in Germany), and dried with the aid of a home-made mill. For particles of uniform size, the resulting powder was sown using a mesh 30 and kept in a refrigerator at -20°C until it was extracted.

    Results & discussion

    Generally, according to the results of both solvent extraction and supercritical fluid extraction (SFE) methods, the total amount of phenolic extraction at the optimal point in terms of mg Gallic acid to gram of dry extract in the solvent extraction and in the supercritical method were 26.21 and 2.24, respectively. Comparison of the obtained values ​​at the optimal point of both methods indicated that the solvent method shows higher values of the total phenol content and it has been more successful. However, due to the insignificant differences in total extraction phenol content between the two methods, the supercritical method can be described as a better way to extract phenolic compounds, since the supercritical method was less effective than antioxidant power despite the presence of phenol,  because in the supercritical method, the selectivity can be increased and the target compounds can be isolated by adjusting the temperature and pressure which increases the purity and increase the antioxidant property, and the purpose of the extraction of phenolic compounds. On the other hand, due to the low amount of organic solvent used in this method and the reduction of health and environmental risks, the supercritical method can be introduced as an effective method for extraction of phenolic compounds from Ziziphus Jujube fruit, which reduces the consumption of organic solvent and causes in an efficiency equal with solvent method approximately. In general, according to the amount of total phenolic extraction in both methods, it can be said that Jujube has higher phenol content than other herbs and it can be introduced as a natural antioxidant at the commercial level.

    Keywords: Ziziphus Jujuba, Optimization, phenolic compounds, supercritical fluid, antioxidant activity
  • Mostafa Kashaninejad*, Masoud Najaf Najafi*, Mohsen Ghods Rohani, Morteza Kashaninejad Pages 543-563
    Introduction

    Labane or concentrated yoghurt is a semi-solid product which is being producedd by dehydration of yoghurt or separation of water and some water-soluble solids from yoghurt. High nutritional value, long shelf life, more desirable taste and texture and feasibility to produce other product are the reasons for high acceptance among customers. There are wide ranges of production methods from traditional methods which are tedious, such as separation of whey by fabric bags, to complicated time-consuming methods which also contaminate product and reduce its nutritional value. These cause demand to establish more suitable methods such as “wheyless process” by dried milk, concentrated milk protein or concentrated whey protein. On the other hand, one of the methods for enhancing firmness and textural properties of yoghurts, similar to other dairy products is utilization of hydrocolloids. These components are used for enhancing rheological an textural properties of food and commonly used as additives for increasing viscosity, gel forming ability, enhancing physical stability, film forming ability, controlling crystallization, postponing syneresis and textural improvement. Konjac gum (KG) is a neutral polysaccharide that derived from Amorphophallus konjac C. Koch tuber, which is well known in east countries during centuries. Ability to hold water and reduction of cholesterol and glucose are the reasons for grossing demand of this gum. So due to the importance of labane produced through wheyless process, the effect of different ingredients of formulation such as milk protein concentrate, cheese whey powder and konjac gum on physicochemical, rheological and sensory properties of labane was investigated and compared these properties by using Principal component analysis (PCA) and Partial least squares regression (PLS regression).

    Materials and methods

    Cow milk was purchased from local market (Mashhad, Iran). Dried skim milk, milk protein concentrate, cheese whey powder   and commercial starter provided from Khorasan Razavi Pegah Company (ABY1, Christian Hansen, Horsholm, Denmark) and KG purchased from Food Chem. (China). In order to concentrate the milk, 3% dried skim milk was added to1 Kg milk. Then, according to the experimental design (table 2), MPC and CWP added to milk at 0, 4, 6 and 8% levels which reached the total solid of milk to 21.5%. KG with percentage of 0, 0.05, 0.1, 0.15, and 0.2% was added to the mixture at 40˚C. The mixtures were homogenized at 50˚C and pasteurized at 90˚C for 1 min. and then cooled to 43-45˚C. The mixtures were incubated at 43-45˚C for 3-4 hours after addition of starter. Then the samples were slowly stirred and packed in polyethylene bags after reaching to suitable pH. The samples were transfered to refrigerator for 24 hours then the tests were conducted. PH was measured according to AOAC 2005 official method NO. 935.42.25 gr of samples were centrifuged at 4˚C for 10 min. at 4500 rpm. Syneresis was evaluated as parentage of separated serum. Texture analyzer was used for combination of back extrusion and texture profile analysis (TPA) test. 50 mm in diameter cylinder with 10 mm in height and probe with 4 mm diameter and 100 mm height with the speed of 1 mm/s were used to conduct the test. Dynamic rheological parameters were evaluated by rheometer (Parphysica). The devise was equipped by 50mm diameter parallel plate with 2 mm gap. Eheo plus/32 version V3.40 software was used to measure elastic modulus (G’), loss modulus (G”) and η*.

    Results & discussion

    Results showed that none of the linear, quadratic and interaction effect of MPC, CWP and KG was significant on pH of the samples at the first day. Results represented that the pH of the samples was varied from 0.36 to 0.94 after 5 days and only linear effect of MPC and CWP (at 99% level of confidence) and interaction effect of CWP-KG (at 95% level of confidence) were significant on that. The effect of MPC and CWP and interaction effect of MPC-KG, CWP-KG and CWP-MPC-KG were significant on syneresis at 99% of confidence. Results showed that hardness of the samples varied between 3.25-9.58 N and the interaction effects of MPC-KG, CWP-KG and CWP-MPC-KG were significant at 99% of confidence. None of the linear, quadratic and interaction effect of CWP, MPC and KG was not significant on springiness of the samples (p>0.05). In strain sweep test, two separated regions were distinguishable: linear viscoelastic (LVE) region that elastic and viscous modulus (G’ and G”) were constant and G’ was higher than G” which showed the solid like behavior, and non-LVE region that G’ and G” decreased by increasing strain and led to a crossover point (flowing point) which G” goes over the G’ and liquid-like behavior shows itself. In this test, strain corresponding to start of the non-LVE region and sharp reduction of G’ define as critical strain (γc) and the corresponding stress of this point defined as critical stress (τc).Results represented that G’LVE and G” LVE of the samples varied from 22.54 to 750.1 and 11.01 to 242.1 Pa, respectively and the selected model (cubic x quadratic) showed that the interaction effect of MPC-KG, CWP-KG and CWP-MPC-KG on G’LVE and G” LVE was significant at 99% of confidence while the interaction effect of CWP-MPC was only meaningful on G” LVE. Results also showed that the variation trend of G’LVE and G” LVE was the same by alteration MPC, CWP and KG in a way that both of these parameters were increased by increasing KG. The effect of MPC-KG and CWP-KG was significant on γc and τc at 95% confidence and also, in addition to mentioned effect, the interaction effect of CWP-MPC was significant only on γc. Increasing KG increased γc at higher amount of CWP and lower amount MPC which can be concluded that increasing KG amplified the gel strength. Also, the results of the correlation study between sensory and instrumental measures showed that there was a close relationship between the score of sour taste and the overall acceptance of samples, which showed that among the measured characteristics, sour taste score is more important than other parameters.

    Keywords: Strain sweep test, Modified texture profile analysis, back extrusion, Cheese whey powder, Milk protein concentrate
  • Seyyed Mohammad Emam*, Amirmohammad Rezaiepoor, Aboalfazl Foorginejad Pages 565-575
    Introduction

    Pistachio cereals are one of the most important products in the export sector. Therefore, accurate grading of pistachios is very important. By counting the number of pistachios in 100gr according to the national standard of Iran, this product is classified into three categories of large, medium and small.

    Materials and methods

    In this paper, the image of some pistachio cereals with different random size and shape was taken and stored in computers using the machine vision technique. Then, the image processing operations consisted of improving the pistachio images to increase the accuracy of edge detection was done. The exact calibration process was performed with a chessboard plate was conducted to extract the geometrical dimensions including the largest diameter and area. In the national standard of Iran, intact or broken pistachios are not considered to grade this product. Therefore, in this research, Fourier series method is used to extract morphological characteristics of pistachio cereals including roundness, elongation, asymmetry, triangularity and squareness using the low order descriptors. According to the results of the calibration operation, the dimensional measurement of pistachios with an average error of 0.09 mm is possible

     Results &Discussion

    According to the experimental results, it is possible to improve the current standard of pistachio using image processing and fourier series techniques in terms of increasing measurement speed, reducing costs, and adding the shape characteristics of pistachios to determine the amount of intact or broken pistachios.

    Keywords: Pistachio, Machine vision, Fourier series, Grading
  • Fatemeh Saadat, Seyed Hadi Razavi*, Houshang Alizadeh Pages 577-582
    Introduction

    Oil plants store energy in the form of neutral lipids in the organelles called oil bodies. These organelles save triacylglycerol until seed germination. In recent years, the oil bodies have been considered as an oil/water emulsion in the pharmaceutical, food, and cosmetic industries. These organelles are also effective tool for purifying, stabilizing and delivery of biotechnology products. Aqueous extraction processing (AEP) is the most common method for oil body extraction. Despite all advantages compared to organic solvent extraction, the yield of AEP still needs to be optimized. Therefore, this study surveys the efficacy of two solvents, phosphate buffer and distilled water in the oil bodies' extraction from rapeseed.

    Materials and methods

    Brassica napus L. seeds were obtained from seed and plant improvement institute, Iran. To compare the efficacy of solvents, 0.1 M phosphate buffer (pH 7.5) and distilled water were used for extraction. The ground rapeseed was suspended in the buffers in a ratio of 1:10 (w/v) and stirred for 12 hours at room temperature. This step was repeated three times. Then, the extract was centrifuged at 10,000 g for 15 minutes at 4 ° C. The floating layer was carefully removed and dissolved again in the initial solvent and the pH was adjusted to 8.5 to precipitate the deflated proteins. Finally, the cream layer was retrieved using centrifuges and one-tenth of the initial buffer volume was applied to the 9 M urea buffer (pH 7.5) for 10 minutes to separate non-specific proteins from oil bodies. The purified oil-bodies were monitored under light microscopy.

    Results and discussion

    According to the microscopic and macroscopic results, the stability of oil particles and efficiency of extraction would be higher by phosphate buffer due to maintaining a constant alkaline pH during the extraction. Moreover, the presence of different salts in the phosphate buffer increases the purification yield up to twice times as a result of providing osmotic pressure and increasing solubility of membrane proteins. These results emphasize the importance of membrane proteins on the formation and stabilization of oil bodies.

    Keywords: Constancy, Emulsifier, Membrane proteins, Optimization, Phosphate buffer
  • Elham Ranjbar Nadamani, Alireza Sadeghi Mahoonak*, Mohammad Ghorbani, Sharlot Jakobson, Vahid Khori Pages 583-596
    Introduction

    Proteins are being hydrolyzed to generate various properties such as antioxidant activity and nutritional values. Enzymatic hydrolysis is carried out in milder condition and is more controllable. The produced protein hydrolysates’ properties are dependent to the hydrolysis condition. So by optimizing the hydrolysis conditions, proteins with higher antioxidant abilities are achieved. Response surface method is a statistical way to optimize and model the process more efficiently. The aim of present study was to optimize and model the hydrolysis condition to produce and antioxidant protein hydrolysate with high nutritional value   from Cajanus cajan by pepsin.

    Materials and methods

    First, Cajanus cajan’s proteins solubility was measured. After reaching the pHs with the most and least solubility, protein extraction was carries out by using NaOH and HCl. Enzyme concentration (1, 2, 3%), temperature (30, 35, 40 °C) and time (2, 3.5, 5 h) as independent variables were given to the Design Expert software and protein hydrolysis was done in a shaker incubator according to the 20 treatments suggested by the software. 1, 1- diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, hydroxyl radical scavenging activity, Reducing power and total antioxidant activity were measured as dependent variables. Antioxidant assays were modeled by the software and the optimum condition was evaluated. The obtained optimum condition was validated by repeating the antioxidant assays for the protein hydrolysate produced in the optimum condition. The amino acid profile of the protein hydrolysate was measured using HPLC-MS and chemical score was measures. Then, the molecular weight distribution of the protein concentrate and protein hydrolysate was evaluated by FPLC. Chemical composition of the samples was also measured.

     Results & discussion

    The optimum condition for achieving antioxidant protein hydrolysate was enzyme concentration 2.15%, temperature 39.99 °C and time 4.52 h. Model validation results for this point were including DPPH scavenging activity 58.49%, reducing power 0.31 nm, hydroxyl radical scavenging activity 38.2% and total antioxidant capacity 0.63 nm. The protein concentrate consisted of 215.84 mg/g hydrophobic and 57.04 mg/g of them were aromatic amino acids. These amino acids are responsible for antioxidant activity of the protein hydrolysates. Chemical scores for essential amino acids were good. Most of the peptides in the protein hydrolysate had molecular weights below 10 kD that is considered to have antioxidant activities. Hydrolysis also increased the protein and ash content while fat and water content decreased compared to the Cajanus cajan’s flour and protein concentrate. Results showed that Cajanus cajan’s protein hydrolysate can be a good source of antioxidants and play a positive role in human nutrition.

    Keywords: Protein hydrolysate, Pepsin, Antioxidant, Pea, Bioactive peptides
  • Mozhgan Karimi, Ainaz Khodanazary*, seyyed mehdi hosseini Pages 597-611
    Introduction

    The Spangled emperor (Lethrinus nebulosus) is one of the valued fish species in Persian Gulf, which due to its high nutritional quality and excellent sensory properties, is preferred by the customers in the south of Iran. Because this species is consumed domestically, it is very important to extend its shelf life, which is normally quite limited when kept refrigerated. Vacuum packaging (VP) is one of the methods of the natural preservation in order to delay the degradation and maintain the quality of the products longer. VP is widely used as a supplement to ice or refrigeration to decrease the supply of oxygen to the aerobic bacteria in the flesh to extend the shelf life of product. Chitosan have been used in seafood products to inhibit the growth of bacteria in stored fish in refrigerator and retarded the oxidation of unsaturated fatty acids in fish muscle before vacuum packaging. Chitosan, a linear polysaccharide of randomly distributed β-(1-4)-linked D-glucosamine and N-acetyl-D-glucosamine, is a biocompatible polysaccharide obtained from deacetylation of chitin. Edible coating is a thin layer of edible material formed as a coating on a food, while an edible film is a preformed thin layer which once formed can be placed on or between food components. In food industry, chitosan coatings have been used successfully because of some advantages such as edibility, biodegradability, aesthetic appearance and barrier properties, being nontoxic and non-polluting, as well as carrier of foods additives (i.e.: antioxidants, antimicrobials). Therefore, these coatings can retain quality of raw, frozen and processed foods including fish items by preventing bacterial growth and delaying lipid oxidation.

    Materials and methods

    Lethrinus nebulosus with an average weight of 500 g was caught with gill net in the Persian Gulf, Khorramshahr, Iran in July 2016. Fish samples were placed in crushed ice with a fish/ ice ratio 1:3 (w/w) and transported to the fish processing laboratory with 2-3 h after catch. They were washed with tap water and two fillets were obtained from each fish after removing the head and gutted. Chitosan solution was prepared with 1% (w/v) chitosan (Sigma Chemical Co., medium molecular weight, viscosity 200-800 cP) in 1% v/v acetic acid. To achieve complete dispersion of chitosan, the solution was stirred at room temperature to dissolve completely. Glycerol was added at 0.75 ml/g concentration as a plasticizer and stirred for 10 min. All films were obtained by casting 100 ml film forming solution on a nonstick surface (16*27cm), dried at ambient temperature (20˚C) until a firm surface but still with adhesive properties was obtained. After evaporation the films were peeled off from the plates. Fillet samples were randomly assigned into four treatment lots consisting of: one control lot (un-coated), second lots packaged with VP, third lots wrapped with films prior to VP, fourth lots immersed for 30 s in chitosan solution. Then the fish fillets were removed and allowed to drain for 2 h at ambient temperature (20˚C) in order to form the edible coating. All samples were stored at 4±1˚C for 12 days. Chemical, microbiological and sensorial analyses were performed at 3-day intervals to determine the overall quality of fish.

    Results and discussion

    Combination of vacuum packaging and chitosan treated samples effectively retarded the TVB-N and TMA values and inhibited the growth of total viable count and psychrophilic count bacteria during refrigerated storage. Therefore, to extend the shelf life and delay the deterioration of fresh Spangled emperor fillets during refrigerated storage, chitosan coating prior to vacuum packaging is more appropriate. These coatings and films also showed antioxidant effects, since TBA and FFA values was lower than control samples at the end of the storage. There was no significant difference between coating and film in reducing TBA of fillets and bacterial contamination. Therefore, chitosan coating and film prior to vacuum packaging provides a type of active packaging that can be utilized as a safe preservative for fish under refrigerated storage.

    Keywords: Vacuum packaging, Lethrinus nebulousus, Film, Coating
  • Reza Mobasserfar, Seyed Ali Mortazavi* Pages 613-622
    Introduction

    Doogh is one of the most important and most widely consuming fermented traditional Iranian milk products, which is being prepared from the healthy milk by using the activity of certain lactic acid bacteria and molds under the especial conditions. Streptococcus thermophilus and Lactobacillus bulgaricus are used as starter culture for milk fermentation. The fermented dairy products have long storage life and constitute an important part of the milk's per capita consumption. For this reason, studying the different methods in order to improve the quality of these products is crucial. By considering the fact that the strong thermal treatments damage some components of milk such as protein and vitamins, using the membrane filterations decrease the need to impose the intense thermal conditions which result into the relative loss of nutrients. On the other hand, using the membrane filters not only increase SNF (solid non-fat) and the percentage of protein but also lead into the production of less-lactose milk as well, the production of less-lactose products, in addition to their nutritional value for some people, have especial benefits for improving the quality. As follows, UF filters in 10-2-10-1 diameter separate the bacteria, fats and protein when milk is passing with a pressure about 1-10 bar but also they pass the minerals such as salts and water which are being removed as permeate and the concentrated milk is called “Retentate”.

    Materials and methods

    Materials provided in this study were including: Starter culture (No: 505 form Danisco, USA), Lactic acid (1.00366) with a degree of purity level more than 95%, NaH2PO4*2H2O (1.06345) plus the cultures' environment and the chemical substances from MERCK Company. HPLC system (Agilent, 1100 series, USA), Rheometer (Anton, MCR300, Austria), Milk analyzer bar (Azmalaban, MCC, Iran), pH meter (Knick,766, Germany), Digital scale 0.001 (AND,GF4000, Japan), Psychrometer (Sartorius, MA45, Germany), Oven (memmert, UM400, Germany), Centrifuge (Funke Gerber, Nova safety, Germany), Kjeldahl (Gerhardt, KB, Germany), Refrigerated incubator (WTW,TS606-6/2-i, Austria), Incubator (memmert, BM400, Germany),  Autoclave (RT-2, Reyhan Teb, Iran). In the present study the effect of a decrease in lactose percentage on the durability, flavor and sensory (organoleptic) properties of produced doogh on the 1st, 23rd and 46th day’s after production time in comparison to control ones, was  investigated. The changes of acetaldehyde levels were measured using Gas chromatography mass spectroscopy. In this study, milk was passed through UF filters in three consecutive days and its lactose level was decreased by about 2%. After that fermentation and standardization of doogh based on the amount of fat and solid-nonfat has been done. All tests were repeated 3 times and the comparison of averages has been done by using LSD test (p= 0.05 %). Results were expressed as mean ± SE. Values were the average of triplicate experiments. Significant differences between the results were calculated by analysis of variance (ANOVA) with the help of SPSS software version 20. Differences at P<0.05 were considered to be significant. Also the obtained data for the rheological experiments was processed using software such as Excel 2010 and SPSS software version 20 to determine an appropriate mathematical model. And in this case, the linear and nonlinear regressions were used.

    Results & discussion

    Results showed that by increasing the storage time, the acidity and pH changes and the acetaldehyde amount of produced doogh was less than those of the control samples. Additionally flavor and sensory properties improved considerably. Based on the findings of this research, it seems that the reduction of lactose and the decrease of lactic acid bacterial activity can play an important role in increasing the durability time, improving the sensory properties and enhancing the quality of doogh. It was determined that the decrease of lactose using ultrafiltration to the control sample not only indicates the significant changes in most considered variables but also there are these kinds of changes during the durability time. In addition, the significant and slow changes of pH to the control sample due to the decrease of lactic bacteria activities show the least qualitative and flavor changes over the durability time. And also it was specified that by increasing the activities of lactic bacteria, the amount of acetaldehyde will increase but by decreasing this activity, the level of acetaldehyde will decline. This issue has a direct relationship with the changes of lactose's amount. The post-filtration doogh due to its high amount of proteins shows high viscosity and concentration and for this reason, the attention of panelists in the sensory evaluation was directed toward choosing the post-filtration doogh instead of the pre-filtration one. Therefore, it can be concluded that the decrease of lactose using ultrafiltration has a main role in improving the quality of the product and also the tendency of the consumers.

    Keywords: Doogh, Lactose, Ultrafiltration, Gas chromatography, Acetaldehyde
  • Parviz Ahmadi gheshlagh, Seiied Sadegh Seiiedlou*, Habibeh Nalbandi Pages 623-634
    Introduction

    Thin layer drying of agricultural products using an infrared dryer (IR) is one of the interesting and low cost methods of dehydration. Quality of dried products could be increased if the engineering aspects and proper selection of performance parameters be well considered in the designing of a dryer. The dryer that uses two or more drying methods in combination, produces in the most cases the higher quality product with lower energy consumption.

    Materials and methods

    In this study, an available IR dryer was modified and a combined IR and hot- air dryer was constructed. According to the reported quality factors in the literatures and market desire, the developed dryer performance was evaluated during the drying of banana slices. The studied factors were the effects of the thickness of slices (4 and 6 mm) and the surface temperature of the product (55, 65 and 75 °C) on the drying kinetic and quality of the dried product.  Some various mathematical models were fitted to the experimental data and results and among them the best fitted model was selected.

    Results & discussion

    Based on the results, the different surface temperature and thickness of the slices had a significant effect on the drying time and color changes of the samples. However, they did not affect the density of samples. Drying time of the banana slices (to reach the moisture ratio of 0.04) with the thickness of 4 mm was 155, 105 and 80 min at the surface temperatures of 55, 65 and 75 °C, respectively. At the thickness of 6 mm, the drying time was 230, 130 and 100 min, respectively at the mentioned temperature. The minimum color change were observed at the thickness of 4 mm (ΔE=32.41) and surface temperature of 55°C (ΔE= 28.99). The samples dried at the temperature of 55 °C had the best quality. Evaluation of the various mathematical models indicated that the Page model is the most suitable to predict the drying kinetic of banana slices under the studied condition. Comparing the obtained results with the reported ones for just hot-air or IR drying of banana slices; it is obvious that in point of product quality and drying time, the combined IR and hot- air dryer has better conditions

    Keywords: Mathematical Model, Banana, Combined IR, Hot-Air Dryer, Qualitative Properties
  • Mahbobe Darapoor, Behzad Nasehi*, Hassan Barzegar, Hossein Joyandeh Pages 635-647
    Introduction

    By-products have traditionally been used as animal feed and are considered agricultural waste. However, they are rich in fiber and bioactive compounds, and efforts have been made to utilize them as functional ingredients and for the enrichment of food products. On the other hand, the intake of a sufficient amount of dietary fiber can regulate the flow of intestines, prevent and treat diabetes, cardiovascular and intestinal cancers. In this regard, in recent decades, there has been a tendency to seek new sources of dietary fiber and natural antioxidants, such as agricultural byproduct that were considered. In this regard, sugar cane bagasse, which has chemical compounds such as cellulose, hemicellulose, lignin, as well as phenolic compounds, waxes and minerals. Currently, bagasse used to production Cement (Tian et al., 2016), sand and grains (Sales et al., 2010), Chipboard (Garzon-Barrero et al., 2016), enzymes (Bocchini et al., 2005), single proteins (Rodriguez et al., 1992), vanillin (Mathew & Abraham, 2005), succinic acids (Chen et al., 2016), citric acid (Zhoghi et al., 2013), lactic acid (Laopaiboon et al., 2010). Donut is the only wheat industrial product that has a lot of attractive sensory features in spite of its high fat content. Therefore, one of the goals of the researchers in recent years has been finding solutions to improve its quality by reducing the absorption of oil or increasing the health components such as fiber. Therefore, this study was conducted to investigate the possibility of production of functional donuts that enriched with bagasse.

    Materials and methods

    In this study, in order to optimize the formulation of donuts with two varieties of sugarcane bagasse fiber (0-25%), soybean soluble polysaccharide (0-2%) and frying time (2-5 minutes) on the physicochemical characteristics of donuts  and sensory properties by using mini-tab software  (version 16) and  central composite rotatable design (CCRD)  was investigated. The mean comparison was performed using Fisher test at 95% probability level. Bagasse were treated according to the method of Gao et al. (2013). Donuts were prepared according to the formulation by Nouri et al., 2017. Ingredients used in control donut formulation were consisted of 100 g of wheat flour (9  g/100g proteins, (Arde jonob Co., Khuzestan, Iran), 38 g of water, 9g of Shortening (Behshahr Industrial Co., Tehran, Iran), 13g of Egg, 13g of water for yeast, 6.3g of sugar, 6.3g of nonfat dried milk powder (Pegah Co., khozestan, Iran), 3g of active dried yeast (Nabmayeh, Khozestan, Iran), 1.6g of Vanilla extract (AbyazChimieEssence and Colour Co., Tehran, Iran), 1.6g of baking powder (Soheil Powder, Tehran, Iran), and 1.6g of Salt. The volume of the donuts was determined using the rapeseed displacement AACC method 10-05 (AACC, 2000). Moisture content of donuts crumb was measured using a Heraeus oven (model UT 5042, Germany) at 105 ºC for 3.5 h (Kim et al., 2015). The fat content of dried donuts was determined by Soxhlet extraction with petroleum ether for 5 h (Melito & Farkas, 2012). Firmness and springiness were measured in triplicate using a TA.XT2i Texture Analyzer (Stable Micro Systems, Goldalming, UK). The donuts were evaluated for over all acceptance of based on a five-point hedonic scale. The scale of values ranged from “dislike extremely” (score 1) to “like extremely” (score 5). And lightness was evaluated with Konica Minolta colorimeter.

    Results and discussion

    The results showed that most of the proposed models in this study were proportional and meaningful from R2 and R2 (Adj). Also, the lack of fit these model were meaningless and their coefficient of variation was also appropriate. So, bagasse fiber increased moisture, hardness, cohesiveness and gumminess, fat, crust and crumb a, fiber and decreased specific volume, crust L. Increasing frying time increases hardness, cohesiveness, gumminess, and decreases crust L and moisture. Soybean soluble polysaccharide had no significant effect on these cases. According to the panelists, donuts containing bagasse fiber were harder and less chewable and had a darker color than the control sample. Response surface methodology described that donuts with optimum formulation of 9.09% bagasse fiber and 0.78% soybean soluble polysaccharide and the frying time of 2 minutes and 36 seconds would be the most desirable sample that has acceptable consumer characteristics. Investigating the optimal sample composition showed that iron and zinc mineral elements, fiber, fat, and total acceptance were higher than the control sample. However, no significant difference was observed in the control and optimum sample protein content. Also, with increasing durability, the moisture content of the product decreases. On the other hand, the specific volume of the control sample during the days of storage did not have a significant difference at 5% level. While the optimum sample volume in the days of shelf life has decreased. There was no significant difference between the control and optimum sample peroxidase in the first and third days, while on the fifth day, both were significantly decreased. The examination of texture characteristics suggests that the donut crumb of controlled and optimized was harder during the storage period, while the optimum sample was softer than the control sample.

    Keywords: Sugarcane, donut, Dietary fiber, Functional, Optimization
  • Sara Karamzadeh, Sara Ansari* Pages 649-665
    Introduction

    Pectin is a complex mixture of polysaccharides in the primary cell wall of plants which is a polymer of α-galacturonic acid, to which neutral sugar is connected to form aside chain. Pectin is a natural food additive used extensively in the food industry as thickener, texturizer, emulsifier, stabilizer and gelling agent. In 2018, the world market demand for pectin was in excess of 60,000 tons and Europe was estimated to have the largest market with 31,000 tons (valued about US$420). In Iran, about one hundred tons of pectin is consumed annually in the food and pharmaceutical industries, all of which are supplied from abroad, and due to its price in the world market is of considerable magnitude. Therefore, the study of its production within the country could be of great importance. During processing and canning of eggplant, its cap and skin are discarded as waste which can be considered as a valuable ingredient in the food industry. The main objective of this study was to develop an MAE (Microwave assisted extraction) of pectin from eggplant peel and investigate the effect of process variables (microwave power, irradiation time and pH) and the response (extraction yield, degree of esterification, galacturonic acid content and emulsifying activity); and to obtain optimum conditions for maximum extraction yield of pectin from eggplant peel. The response surface methodology (RSM) using Box-Behnken design was employed in this study.

    Material and methods

    Eggplant peels were provided by Yek-o-Yek factory as an unwanted by-product. Then, the peels were divided into small pieces and dried in hot air oven at 65 °C until it attains constant weight. The peels were then grinded and passed through a 40-mesh sieve to obtain powdered sample. The independent variables examined were microwave power (360–450–540 W), irradiation time (1–2.5–4 min) and solution pH (1–2–3). MAE of pectin was performed in an ordinary household microwave oven with a total of 17 treatments according to RSM. About 5 g of dried eggplant peel powder was weighed and placed into a 250 ml beaker, 75 ml distilled water (the liquid-solid ratio 15:1 v/w) containing different pH values was added and exposed to microwave radiation at different powers for the selected irradiation times. After microwave heating, the mixture in the beaker was allowed to be cooled down and filtered using filter paper (Whatman no-1). The filtered extract was centrifuged and the supernatant was precipitated with an equal volume of 98% (v/v) ethanol. The coagulated pectin mass was washed with 98% (v/v) ethanol for two times and dried in oven at 60 ° C until it attains constant weight. The pectin extraction yield was calculated by dividing the weight of dried pectin to the weight of dried eggplant peel powder. Galactoronic acid content of pectins was determined using the meta-hydroxydiphenyl method. The esterification degree of the pectins was determined by the titrimetric method with minor modifications. The emulsifying activity (EA) of the eggplant peel pectins were analyzed according to the method by Dalev & Simeonova (1995). Optimum extraction conditions to achieve maximum extraction efficiency, degree of esterification, galacturonic acid content and emulsifying activity were determined. Then, the stability of the oil-based emulsion prepared by mixing 0.5% w/w solution of pectin extracted in optimal conditions and corn oil, were examined at 4 and 23 ° C. In addition, the behavior of pectin extracted under optimal conditions (at concentrations of 0.1, 0.2, 1 and 2%) and its spectra using a Fourier transform infrared spectrometer (FTIR) were investigated.

    Results and discussion

    The results indicated that the extraction efficiency, esterification degree, the amount of galacturonic acid, and the emulsifying activity of the pectins extracted were 2.20- 17.16%, 20.20- 36.13%, 51.3- 74.7%, and 1.87- 21.64%, respectively. With increasing microwave power, irradiation time and decrease of solution pH the extraction efficiency of pectin extracted increased, while esterification degree decreased. The amount of galacturonic acid and emulsifying activity showed an upward trend up to microwave power of 450 watts and the irradiation time of 3 minutes after which demonstrated a downward trend. The optimum conditions for reach to the maximum extraction yield, galacturonic acid content and emulsifying activity were in microwave power of 360 W, irradiation time of 4 min and pH of 1 that at these conditions, the extraction yield of 16.17, galacturonic acid content of 70.81 and emulsifying activity of 2.68 were predicted. Also, these observations indicated that with increase in concentration, the flow behavior of pectin solutions was changed from Newtonian to pseudo-plastic. In addition the stability of pectin-stabilized emulsion at 4°C was more than 23°C. In general, this study showed that the microwave method could be used as a novel and high-performance method for extracting pectin from eggplant peel.

    Keywords: Pectin, Eggplant peel, Optimization, Physicochemical properties
  • Narjes Badfar, Seyed Ali Jafarpour*, Mahdi Abdolahi Pages 667-677
    Introduction

    There is an expanding market for surimi in the world, and much interest in surimi throughout the seafood and food industry by the rapid growth in popularity of surimi-based products. This interest justifies an investigation into the applicability of freshwater fish species such as Silver carp, as an alternative fish resource, for surimi and surimi based products. Rheology concerns the flow and deformation of substances and, in particular, to their behavior in the transient area between solids and fluids. Moreover, rheology attempts to define a relationship between the stress acting on a given material and the resulting deformation and/or flow that takes place. Rheological properties are determined by measuring force and deformation as a function of time. Rheological evaluation is a useful technique for gathering information on the textural characteristics of surimi and kamaboko. It describes the surimi dynamic characteristics in the form of storage modulus (G′), loss modulus (G″), and phase angle (δ).

    Materials and methods

    Whole Silver carp fish were gutted and the head removed, Fillets were minced by a meat mincer with a mesh size of 3 mm, then mince washed one, two and three times at ratio of 1:3 and 1:2 (mince: water) and dewatered. The mince was turned into surimi in a food processor operated for 2 min. salt (2%) was sprinkled over the mince. Ice water was also sprinkled over the mince to adjust the moisture content of the paste to 80 mL/ 100 g.
    Dynamic tests using a rheometer (MCR-301, Anton Paar- Germany) were carried out on the surimi gel after setting. The region of linear viscoelasticity of the surimi paste was determined by both stress and frequency sweep tests. The thermorheological behavior of Silver carp surimi was evaluated using a temperature sweep test and reported using sol-gel transition thermographs. The stress of 100 Pa was considered as the stress and the frequency of 1 Hz was considered as the frequency in the frequency sweep test, then Temperature sweep test involved heating the surimi samples from 10 to 90°C. Also Crip-recovery test was performed on the surimi in 300 seconds.

    Results & discussion

    Rheological tests: Frequency sweep, Stress sweep and Temperature sweep  graphs were relatively similar and in all samples affected by H2O2 and the control sample, the lowest value of G' was recorded between 50 and 52°C. Then, with increasing temperature from 52 to 62°C, the curve G' increased and the curve was stable at temperatures up to 80°C. Changes in the G' graphs can be attributed to the process of forming the gel by heating. Changes in the G" graph showed a similar trend with G’. In the creep-recovery test, the lowest and most strain were belonged to the control and sample 5 (1% H2O2, 1: 2, twice washing). Studying the figure of Creep-recovery test showed the samples affected by H2O2 had more resistance against applied stress in compression with control sample which expressed the effect of H2O2 on creating more and effective covalence cross-linking resulting more stable and constant gel network. During Surimi's heating, there are several reactions that involve various mechanisms, such as protein gelation. About Surimi, the observed macroscopic changes are related to the effect of temperature on proteins. The presence of H2O2 during the washing process did not have a significant negative effect on rheological properties of Surimi.

    Keywords: Silver carp, Hydrogen peroxide, Rheological properties
  • Gholamreza chegini*, Iman Hassanzadeh Pages 679-690
    Introduction

    One of the common rice in Asia and Africa is parboiled (semi-cooked) rice. In parboiled rice, three processes will be added in comparison to white rice which includes: soaking, steaming and drying. The parboiled rice has a different color than white rice, which is probably the parboiled rice brown color is due to the diffusion of shell color in the grain's endosperm. Changes in the color of parboiled rice increase with increasing soaking temperature, increasing the duration of steaming and also increasing the hydration pressure of the grain. Increasing the temperature of the water during the soaking stage increases the absorption of shell color and absorption of colored materials, including the enrichment of folic acid, which has a negative effect on the whiteness of rice grain. The important process of parboiled rice production is steaming and drying which change color and transfer residual moisture of rice. One of the drying methods that is being used in food and agriculture industry is Air Jet Impingement Drying (AJID) by rapid drying rate and high performance .In air jet impingement dryer, hot air passes in up and down of product with high pressure as heat and mass transfer increases as drying time is decreased. In this research the effect of drying parboiled rice using air jet impingement dryer, drying kinetics with whiteness index and color difference was evaluated.

    Materials and methods

    Samples were steamed after soaking for 20 and 25 minutes and at temperatures of 90, 100 and 110  with air velocity of 15 and 20  were dried. The quantitative indicators CIELAB color system (L, a and b) were measured. The Air jet dryer contained a 3 kW air fan by air speed of 1-28 m/s, a 13.5 kW heater by air temperature of 250 , an inverter for control and measuring of air velocity and K type thermocouple. For control and measuring of air velocity two plenum chamber (a plate for direction of air to nozzle) used by a control valve, temperature circuit control, an aluminum drying chamber and two nozzles. Fan transfer air to heater then transfer to plenum chamber then to nozzle at final the hot air directly contact on product.

    Results and discussion

    The results showed that with increase of air velocity from 15 m/s to 20 m/s in 90  air temperature average value of whiteness index was decrease from 61.952 to 57/088. With steaming time of 25 minutes, air velocity 15 m/s and the temperature 100   minimum whiteness index was 48.537. The maximum average value of whiteness index and the minimum average value of color differences were 63.884 and 29.432, respectively was obtained with steaming time 20 minutes, air velocity 15 m/s and the temperature 90 . By increase of temperature and air velocity in steaming time 25 minutes were drying rate increases, in this condition rice drying rate more effected by change temperature. The results showed that change of temperature had significant effect on color in comparison to steaming time and air velocity. With decreases of parameters: air velocity, steaming time and air temperature parboiled rice samples with higher whiteness index was obtained. The results of statistical analysis showed that dryer air temperature have more effects than steaming time and air velocity parameters on the color changes of parboiled rice. Also drying rate decreased by moisture reduction and Increasing of both temperature and air velocity were significant effective in color index. The results of regression analysis showed that drying rate significantly decreases with decrease of moisture.

    Keywords: Jet Impingement dryer, parboiled rice, Whiteness Index, Color Difference