فهرست مطالب

پژوهشهای علوم و صنایع غذایی ایران - سال شانزدهم شماره 2 (پیاپی 62، خرداد و تیر 1399)
  • سال شانزدهم شماره 2 (پیاپی 62، خرداد و تیر 1399)
  • تاریخ انتشار: 1399/03/18
  • تعداد عناوین: 12
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  • شیما نصیری، سامان آبدانان مهدی زاده*، مریم نداف زاده صفحات 171-191

    توسعه نقاط قهوه ای رنگ تاثیر قابل توجهی بر بافت، رنگ و طعم میوه موز دارد به طوری که ظهور این لکه ها کیفیت میوه را کاهش داده و بازارپسندی آن را تحت تاثیر قرار می دهد. در این پژوهش تغییرات مجموعه ای از پارامترهای رنگی (قرمز (R)، سبز (G)، آبی (B)، عامل روشنایی (L)، تغییرات رنگ از سبز به قرمز (a)، تغییرات رنگ از آبی به زرد (b)، فام رنگ (h)، اشباع (s)، مقدار روشنایی (v)، کروما (C)، زاویه شیب نمودار دستگاه مختصات دوبعدی a وb در فضای رنگی Lab (H))، ابعادی (قطر، شعاع انحنا، طول بزرگ و طول کوچک) و شیمیایی (کل مواد جامد محلول (TSS)، pH و اسیدیته کل قابل تیتراسیون) 5 گروه میوه موز (متفاوت از لحاظ شکل ظاهری) در روزهای صفر، 2، 4و 6 (بعد از انبارمانی) مورد بررسی قرار گرفت. در این مطالعه نشان داده شد که با به کارگیری پارامترهای غیرمخرب در توسعه مدل رگرسیون فرآیند گاوسی (GPR)، کیفیت میوه موز و همچنین میزان بازارپسندی (پذیرش کلی میوه) آن در خلال انبارمانی قابل ارزیابی و پیش‎بینی (با ضریب همبستگی 91/0، MAPE (47/20)، RMSE (43/0)، SRE (71/0) و RAV (20/0)) است؛ بدین ترتیب با استفاده از روش پیشنهاد شده در این تحقیق می توان مطابق با تقاضای مصرف کننده، محصول مورد نیاز را به بازار عرضه نمود و از این طریق هزینه های اقتصادی را به طور چشمگیری کاهش داد.

    کلیدواژگان: انبارمانی، پذیرش کلی میوه، پردازش تصاویر دیجیتالی، رگرسیون فرآیند گاوسی، موز
  • مهری ذوالفقاری، اسحاق زکی پور رحیم آبادی*، مهین ریگی، مجید علیپور صفحات 193-205

    هدف این مطالعه بررسی اثر نگهدارندگی محلول های نمک- شکر بر کیفیت فیش فینگرهای تهیه شده از فیله کپور نقره ای هنگام نگهداری در یخچال (C4) بود. برای این منظور، ابتدا فیله ها با محلول های رقیق 10 درصد نمک و شکر تیمار گردیده و پس از آن، اقدام به تهیه فیش فینگر گردید. تیمارهای تحقیق عبارت بودند از: فیش فینگرهای بدون تیمار با محلول نمک و شکر (شاهد)، فیش فینگرهای تیمار شده با محلول نمک/ شکر (به نسبت 50:50، تیمار 1)، فیش فینگرهای تیمار شده با محلول نمک/ شکر (به نسبت 25:75، تیمار 2) و فیش فینگرهای تیمار شده با محلول نمکی (تیمار 3). نمونه ها سپس در بسته های پلاستیکی بسته بندی شده و به مدت 15 روز در یخچال نگهداری گردیدند. شاخص های شیمیایی، میکروبی (TVCو PTC) و ارزیابی حسی (بافت، بو، طعم، رنگ و مطلوبیت کل) در روزهای صفر، 3، 6، 9، 12 و 15 اندازه گیری گردیدند.نتایج نشان دادند که مقدار پراکساید، تیوبابیتوریک اسید و مجموع بازهای نیتروژنی فرار در همه تیمارها به طور معنی داری افزایش یافت (05/0<p). نمونه های تیمار شده با محلول شکر دارای مقدار TBA اولیه کمتری در مقایسه با سایر نمونه ها بودند. کمترین میزان بار باکتریایی کل در روز 15ام نگهداری در یخچال در تیمار شماره 2 مشاهده گردید (8/5 Log CFU/g). مقادیر بار باکتریایی در تمامی تیمارها تا پایان روز 15 ام، از حد قابل قابل پیشنهادی، تجاوز نکرد. بر اساس نتایج اخذ شده، تیمار محصولات شیلاتی با محلول های نمک و شکر، باعث افزایش زمان ماندگاری آن ها می گردد. همچنین، بر اساس نتایج حاصل از ارزیابی حسی، تیمار شماره 2 به عنوان بهترین تیمار به لحاظ مقبولیت فاکتورهای حسی توسط ارزیاب ها انتخاب گردید. زمان ماندگاری مطلوب برای تیمار 2، 15 روز تعیین گردید.

    کلیدواژگان: فیش فینگر، کپور نقره ای، خصوصیات کیفی، نمک، شکر
  • نگین زنگنه، حسن برزگر*، بهروز علیزاده بهبهانی، محمدامین مهرنیا صفحات 207-220

    ریزجلبک اسپیرولینا پلاتنسیس (Spirulina platensis) حاوی مواد مغذی منحصر به فرد و فوق العاده ای است که می توان از آن در تولید مواد غذایی عملگر استفاده کرد. از آنجایی که علم و دانش مرتبط با غنی سازی کیک اسفنجی به عنوان یک محصول پرطرفدار میان اقشار مختلف جامعه (به ویژه کودکان) محدود می باشد، لذا هدف از این پژوهش، تولید کیک اسفنجی غنی شده با ریزجلبک اسپیرولینا پلاتنسیس و بررسی ویژگی های تغذیه ای، فیزیکوشیمیایی و حسی این فرآورده بود. در این پژوهش تجربی، اثر افزودن ریزجلبک اسپیرولینا پلاتنسیس در چهار سطح (صفر، 5/0، 1 و 5/1 درصد بر اساس وزن آرد) بر ویژگی های تغذیه ای (پروتیین، چربی، آهن، روی و مس)، خواص فیزیکوشیمیایی (رطوبت، pH، فنل کل، پتانسیل آنتی اکسیدانی، تخلخل، بافت، رنگ) و ویژگی های حسی (عطر و بو، رنگ، بافت، طعم و مزه، قابلیت جویدن و پذیرش) نمونه های کیک اسفنجی بررسی شد. نتایج نشان داد میزان پروتیین، چربی، مواد معدنی و دیگر ویژگی های تغذیه ای با افزایش درصد ریزجلبک اسپیرولینا پلاتنسیس افزایش یافت. میزان تخلخل نمونه های کیک اسفنجی با افزایش درصد ریزجلبک اسپیرولینا پلاتنسیس کاهش یافت و با افزایش درصد ریزجلبک اسپیرولینا پلاتنسیس پارامترهای بافتی (سفتی، پیوستگی و صمغی شدن) در روزهای 1، 5 و 10 روز پس از پخت افزایش یافت. نتایج رنگ سنجی نشان داد که اثر اسپیرولینا پلاتنسیس بر شاخص های رنگی پوسته و مغز(L*، a* وb*) معنی‎دار بود (05/0<p). ارزیابی حسی نمونه ها نشان داد افزودن ریزجلبک اسپیرولینا پلاتنسیس به کیک اسفنجی در سطح 5/0 درصد، سبب کسب بیشترین امتیاز پذیرش کلی شد.

    کلیدواژگان: اسپیرولینا پلاتنسیس، پارامترهای بافتی، کیک اسفنجی، ویژگی های حسی
  • مرضیه امیدی میرزائی، محمد حجتی*، بهروز علیزاده بهبهانی، محمد نوشاد صفحات 221-233

    در طب سنتی ایران از دانه های گشنیز به طور گسترده به منظور درمان بیماری استفاده می شود. هدف از این پژوهش، شناسایی ترکیبات شیمیایی، قدرت آنتی اکسیدانی و بررسی فعالیت ضدمیکروبی اسانس دانه گشنیز بود. ترکیبات شیمیایی اسانس دانه گشنیز با دستگاه کروماتوگرافی گازی متصل به طیف سنجی جرمی شناسایی شد. فنول کل و قدرت آنتی اکسیدانی به ترتیب با روش های فولین سیوکالتو، رادیکال هایABTS  و DPPH اندازه گیری گردید. قدرت آنتی اکسیدانی اسانس با آنتی اکسیدان سنتزی  BHAدر غلظت 100 میکروگرم بر میلی لیتر مقایسه شد. فعالیت ضدمیکروبی اسانس دانه گشنیز با روش های انتشار در آگار به کمک دیسک (کربی- بویر)، حداقل غلظت مهارکنندگی و حداقل غلظت کشندگی برای باکتری های باسیلوس سریوس، سالمونلا تیفی، اشرشیا کلی و سودوموناس آیروژینوزا تعیین گردید. براساس نتایج آنالیزهای شیمیایی، اسانس دانه گشنیز غنی از مونوترپن های اکسیژن دار (94/89%) بود. ترکیب عمده اسانس دانه گشنیز لینالول (75/76%) بود. بیشترین درصد مهار رادیکال آزاد برای DPPH، 75/53% و برای ABTS، 60/66% در غلظت ppm 900 مشاهده شد. مقدار فنول کل موجود در اسانس mg GAE/g 02/0± 04/38 بود. نتایج نشان داد که بیشترین و کمترین قطر هاله عدم رشد به ترتیب مربوط به باکتری باسیلوس سریوس (30/30 میلی متر) و سالمونلا تیفی (15/23میلی متر) بود. حداقل غلظت مهارکنندگی اسانس دانه گشنیز برای باکتری های باسیلوس سریوس، اشرشیا کلی، سودوموناس ایروژینوز و سالمونلا تیفی به ترتیب برابر با 2، 4، 4 و4 میلی گرم بر میلی لیتر بود. به طورکلی نتایج نشان داد که اسانس دانه گشنیز داری فعالیت آنتی اکسیدانی کمتر از آنتی اکسیدان سنتزی BHA بود.

    کلیدواژگان: ضدباکتریایی، دانه گشنیز، آنتی بیوتیک جنتامایسین، آنتی اکسیدان سنتزی
  • مریم ماندگاری، عبدالمجید میرزاعلیان دستجردی*، لاله مشرف، مریم تاتاری صفحات 235-249

    شکل ظاهری میوه مهمترین شاخص ارزیابی بازارپسندی آن است. وجود هرگونه علایم آلودگی، پوسیدگی و نرم شدگی طی انبارمانی باعث کاهش بازارپسندی آن می شود. به منظور ارزیابی اثرات تیمار طبیعی و دما بر ویژگی های کمی و کیفی در مرحله پس از برداشت آریل انار، آزمایشی در قالب آزمایش فاکتوریل بر پایه طرح کاملا تصادفی در مرکز تحقیقات کشاورزی و منابع طبیعی اصفهان انجام گرفت. در این پژوهش عوامل مورد بررسی شامل نیتریک اکسید به عنوان ترکیب طبیعی (با غلظت های صفر، 5 و10 میکرومولار) و دما (2، 4 و 8 درجه سانتی گراد) بود. خواص مختلف کیفی میوه درفاصله زمانی هفت روز مورد ارزیابی قرار گرفتند. بر اساس نتایج به دست آمده، غلظت 10 میکرومولار نیتریک اکسید و نگهداری در دمای 8 درجه سانتی گراد نقش موثرتری را نسبت به سایر تیمارها بر ویژگی های افت وزن، حفظ مواد جامد محلول، اسید آسکوربیک، فنل کل، آنتوسیانین، آنزیم پراکسیداز، شاخص طعم و ظرفیت آنتی اکسیدان داشت و به طور چشمگیری باعث کاهش محتوای مالون دی آلدهید و نشت الکترولیت در طول انبارمانی شد. با گذشت زمان میزان فعالیت آنزیم پلی فنل اکسیداز در تمام تیمارها افزایش یافت. اما آریل های تیمار شده کمترین میزان فعالیت آنزیم را داشتند. آریل های تیمارشده با 10 میکرومولار نیتریک اکسید در دمای 8 درجه سانتی گراد بالاترین کیفیت ظاهری را داشتند.

    کلیدواژگان: آنتی اکسیدان، بازارپسندی، پلی فنل اکسیداز، مواد جامد محلول
  • اسماعیل خزایی، میرخلیل ‍پیروزی فرد*، فریبا زینالی، محمد علیزاده خالدآبادی صفحات 251-269

    انواع  سوسیس و کالباس در بسته بندی های تحت خلاء از جمله فرآورده های گوشتی هستند که به دلیل تنوع، راحتی در مصرف و اقتصادی بودن رایج می باشند. مهمترین مشکل عمده تولید، نگهداری و فروش این نوع فراورده های گوشتی، آب اندازی (سینرسیس) آنها درون بسته بندی تحت خلاء است. آب اندازی بسته علاوه بر ظاهر ناپسند، منجر به تسریع رشد و تکثیر میکروبی و تغییرات نامطلوب در عطر و طعم محصول می گردد. در این پژوهش عوامل مختلفی از جمله اثر سطوح مختلف کیتوزان و نشاسته اصلاح شده سیب زمینی در فرمولاسیون، بر روی میزان آب اندازی، pH، جمعیت میکروبی و ارزیابی حسی در دو نوع محصول ژامبون گوشت گاو و ژامبون گوشت مرغ در طول مدت زمان نگهداری مورد بررسی قرار گرفت. در ادامه اثر روش بسته بندی تحت خلاء و میزان خلاء ایجاد شده در بسته بر روی میزان آب اندازی بررسی گردید. نتایج نشان داد افزودن کیتوزان و نشاسته اصلاح شده سیب زمینی به طور معنی داری باعث کاهش آب اندازی محصول در طول مدت نگهداری می شوند در حالی که در تمامی نمونه ها با افزایش مدت زمان نگهداری میزان آب اندازی افزایش یافت (05/0<p). کیتوزان به دلیل اثرات ضدمیکروبی باعث کاهش جمعیت میکروبی و مانع کاهش pH گردید. طبق نتایج ارزیابی حسی در طول مدت زمان نگهداری کیفیت حسی نمونه ها به طور معنی داری دچار افت گردید در حالی که کیتوزان اثرات مثبت معنی داری بر روی پارامترهای حسی در طول مدت زمان نگهداری داشت(05/0 <p). همچنین نتایج نشان داد که آب اندازی ژامبون ها تحت تاثیر نوع بسته بندی و میزان خلاء نیز قرار دارد به گونه ای که بسته بندی Skin نسبت به بسته بندی های تحت خلاء ساده میزان آب اندازی کمتری از خود نشان دادند و با افزایش میزان خلاء بسته بندی، میزان آب اندازی افزایش معنی داری داشت (05/0<p). نتایج نشان داد نشاسته سیب زمینی 5% و کیتوزان 6/0% و بسته بندی Skin در میزان خلاء 30 میلی بار باعث کاهش آب اندازی از 7/1 به 3/1 گردید. در مجموع می توان نتیجه گرفت که با افزوده نشاسته اصلاح شده سیب زمینی و کیتوزان به فرمولاسیون و همچنین استفاده از بسته بندی Skin با میزان خلاء کمتر می توان میزان آب اندازی فراورده های گوشتی را به میزان قابل توجهی کاهش داد.

    کلیدواژگان: ژامبون، آباندازی، نشاسته اصلاح شده سیبزمینی، کیتوزان، بستهبندی تحت خلاء
  • اعظم ستاری، جعفر محمدزاده میلانی*، زینب رفتنی امیری، علی پاکدین پاریزی صفحات 271-286

    بتاگلوکان یک پلی ساکارید خطی، بدون انشعاب، غیرنشاسته ای و محلول در آب است که در دیواره سلولی غلات به ویژه یولاف وجود دارد. با توجه به تاثیر فعالیت آنزیمی بر پایداری لیپیدهای یولاف لازم است که این آنزیم ها در طی فرآوری یولاف غیر‏فعال شوند. یکی از روش های موجود برای غیرفعال کردن آنزیم ها، فرآیند هیدروترمال است. در این پژوهش فرایند هیدروترمال با اتوکلاو در دماهای110 ، 120 و 130 درجه سانتی گراد در دو زمان 10 و 20 دقیقه بر روی آرد یولاف انجام شد و بتاگلوکان استخراجی از آن به روش آبی از نظر خواص فیزیکو شیمیایی و عملکردی و نیز ریولوژیکی مورد برررسی قرار گرفت. بتاگلوکان حاصل از آرد یولاف هیدروترمال شده در 120 درجه سانتی گراد به مدت 10 دقیقه بالاترین حلالیت را در 25 درجه سانتی گراد و کمترین حلالیت را در دمای 50 درجه سانتی گراد و  تیمار 120 درجه سانتی گراد به مدت 20 دقیقه بیشترین حلالیت را در 75 درجه سانتی گراد داشت. میزان کف کنندگی بتاگلوکان استخراجی از آرد یولاف هیدروترمال شده در دمای 130درجه سانتی گراد به مدت 10 دقیقه، از سایر تیمارها کمتر بود و بتاگلوکان حاصل از تیمار هیدروترمال شده در دمای 110 درجه سانتی گراد به مدت 10 دقیقه از ثبات کف بالاتری برخوردار بود. در بررسی خصوصیات ریولوژیکی، تاثیر سرعت برشی بر میزان ویسکوزیته نشان داد که با افزایش سرعت برشی، میزان ویسکوزیته در تمامی نمونه ها کاهش یافت و بیشترین مقدار ویسکوزیته را بتاگلوکان حاصل از آرد یولاف هیدروترمال شده در دمای 120 درجه سانتی گراد به مدت 10 دقیقه داشت. در آزمون نوسانی شامل روبش دما، پارامترهای اندازه گیری شده شامل مدول الاستیک G′ و مدول ویسکوز G′′ بودند که مقدار G′ و G′′ در نمونه بتاگلوکان استخراجی از آرد یولاف هیدروترمال شده در تمامی نمونه ها کاهش یافت و نیز مدول الاستیک و ویسکوز بتاگلوکان استخراج شده از آرد هیدروترمال شده در دمای 120 درجه به مدت 10 دقیقه از سایر تیمارها بیشتر بود. در روبش فرکانس در فرکانس های پایین تر، G′′ از G′ بزرگتر است و هر دو با افزایش فرکانس افزایش می یابند و مقدار G′ وG′′ و η* بتاگلوکان استخراج شده از آرد هیدروترمال شده در دمای 120 درجه به مدت 10 دقیقه از سایر تیمارها در فرکانس 1 و 10 هرتز بیشتر بود.

    کلیدواژگان: بتاگلوکان، یولاف، خصوصیات رئولوژیکی، فرآیند هیدروترمال
  • فروزان جعفری، نفیسه زمین دار*، محمد گلی، زهرا قربانی صفحات 287-299

    گوشت شتر ارزش تغذیه ای بالا و طعم مشابه با سایر منابع گوشت قرمز دارد. در این پژوهش به منظور بهبود ویژگی های بافتی تاثیر افزودن محلول های ماریناد (5 سطح)، زمان (2 سطح) و فرایند اولتراسیون (2 سطح) بر روی گوشت شتر بر پایه طرح کاملا تصادفی مورد بررسی قرار گرفت. قطعات گوشت به دو گروه تقسیم شد و یک گروه تحت فرایند اولتراسیون قرار گرفت. پنج گروه محلول ماریناد (عصاره زنجبیل 30%، عصاره زنجبیل 30%+ 5/0%، %1 و 5/1% اسیدسیتریک و آب مقطر (شاهد)) تهیه شد. قطعات گوشت در داخل محلول ها در دمای C 1±4 داخل کیسه های پلی اتیلنی خوابانده شد. پس از طی 24 و 48 ساعت خصوصیات فیزیکوشیمیایی، شاخص های رنگ (a*،b*  وL*)، بافت و ساختار میکروسکوپی نمونه ها مورد ارزیابی قرار گرفت. نمونه های ماریناد شده در عصاره زنجبیل 30% و 5/1% اسیدسیتریک، کمترین میزان pH (بعد از ماریناد و بعد از پخت) و بیشترین میزان افت پخت را نسبت به نمونه شاهد داشتند (05/0(P<. برای نمونه های گوشت ماریناد شده در عصاره زنجبیل 30%، بالاترین میزان شاخصa*، b* و L* نسبت به نمونه شاهد گزارش شد (05/0<p). زمان و اولتراسیون در بهبود ویژگی های بافتی تاثیرگذار بودند. تصاویر میکروسکوپ الکترونی ایجاد تغییرات در ساختار داخلی پروتیین های گوشت و افزایش فضای خالی بین میوفیبریل ها پس از 48 ساعت را نشان داد. استفاده همزمان از عصاره زنجبیل، اسیدسیتریک و اولتراسوند گزینه مناسب تری جهت افزایش تردی گوشت نسبت به نمونه شاهد بود.

    کلیدواژگان: گوشت شتر، اولتراسیون، ماریناد، اسیدسیتریک
  • لیلا محصولی، حنان لشکری* صفحات 301-311

    دسر بر پایه شیر، یکی از فرآورده های لبنی است که علاوه بر ارزش تغذیه ایی، در سبد کالای مصرف کننده تنوع ایجاد می کند. مهم ترین ویژگی دسرها انرژی بالای آنها و احساس خوشایندی است که به واسطه نوع ترکیبات آن در مصرف کننده ایجاد می شود. از شکر به عنوان شیرین کننده در تولید دسرها استفاده می شود. شیره انگور حاوی مقادیر بالایی قند طبیعی، مواد معدنی، ویتامین، اسیدهای آلی و آنتی اکسیدان ها است، بنابراین می توان از شیره انگور به عنوان شیرین کننده جایگزین شکر استفاده کرد. به منظور کاهش میزان ساکارز دسر و جایگزینی آن با شیره انگور، از نسبت های مختلف (0، 5، 5/7 و 10%) شیره انگور در دسر استفاده شد. 4 نمونه تولید شده بعد از 48 ساعت نگهداری در دمای 6 درجه سانتی گراد تحت آزمون های فیزیکوشیمیایی (تعیین ماده خشک، اسیدیته، pH، ساکارز، چربی، میزان به دام اندازی رادیکال های آزاد، ارزیابی بافت، ارزیابی رنگ، آزمون های میکروبی (شمارش کلی میکروارگانسیم ها، کپک و مخمر، اشرشیاکلی و استافیلوکوکوس اوریوس) و ارزیابی حسی قرار گرفتند. داده ها با نرم افزار  SPSSآنالیز و میانگین ها با آزمون چنددامنه ای دانکن (05/0>P) مقایسه شدند. نتایج نشان داد که افزایش غلظت شیره انگور در نمونه های دسر باعث افزایش معنی دار (05/0>P) میزان اسیدیته (98/13%)، شاخص a و b، درصد بازدارندگی رادیکال های آزاد (94/25%) و کاهش معنی دار (05/0>P) ساکارز (40/95%)، چربی (18/5%)، pH (94/2) و شاخص L گردید. افزایش غلظت شیره انگور تاثیر معنی داری (05/0>P) بر شاخص های بافت، شمارش کلی باکتری ها و کپک و مخمر نمونه ها نشان نداد. ارزیابی حسی نشان داد که افزودن شیره انگور در نمونه های دسر لبنی بر فاکتور بافت تاثیر معنی داری نداشته و موجب افزایش امتیاز سایر فاکتورهای حسی گردید. دسر حاوی 10 درصد شیره انگور در فاکتورهای بو، شیرینی، بافت، رنگ و پذیرش کلی بالاترین امتیاز را به دست آورد و با توجه به استاندارد بودن همه ویژگی های آن، به عنوان بهترین تیمار تعیین گردید.

    کلیدواژگان: ارزیابی حسی، دسر لبنی، شیره انگور، ویژگی های فیزیکوشیمیایی
  • مهسا فریدنیا، علی محمدی ثانی، مسعود نجف نجفی* صفحات 313-322

    هدف از این پژوهش تولید پودر عصاره چغندر قرمز به عنوان منبع ترکیبات زیست فعال و رنگی با استفاده از فرآیندهای خشک کردن انجمادی و پاششی بود. برای این منظور، ایزوله پروتیین آب پنیر (WPI) و مالتودکسترین با DE برابر 20-18 در نسبت های مختلف (100: 0، 75: 25، 50: 50، 25: 75 و 0: 100) به عنوان مواد دیواره برای درون پوشانی عصاره مورد استفاده قرار گرفتند. در همه تیمارها بریکس محلول خوراک 10 درصد ثابت نگه داشته شد. پودرهای تولیدی از لحاظ کارآیی درون پوشانی، محتوی رطوبت، حلالیت در آب و محتوی فنول کل مورد ارزیابی قرار گرفتند. نتایج نشان داد که با افزایش WPI تا سطح 50 درصد (نسبت 50:50)، کارآیی درون پوشانی به طور معنی داری (05/0>p) افزایش یافت. همچنین کارآیی درون پوشانی روش خشک کردن پاششی بالاتر بود (05/0>p). در نمونه های خشک شده به روش انجمادی و پاششی، کمترین مقدار رطوبت در نمونه های تیمار شده با 100 درصد مالتودکسترین مشاهده شد. افزایش نسبت مالتودکسترین به طور معنی داری حلالیت پودرها در آب را افزایش داد (05/0>p). ارزیابی محتوی ترکیبات فنولی نشان داد که پودرهای عصاره چغندر قرمز تهیه شده با خشک کن انجمادی بالاترین میزان فنول کل را داشتند. همچنین پودرهای به دست آمده از نسبت 50: 50 مالتودکسترین به WPI از بیشترین محتوی فنول کل برخوردار بودند.

    کلیدواژگان: خشک کردن انجمادی، خشک کردن پاششی، چغندر قرمز، ایزوله پروتئین آب پنیر، مالتودکسترین
  • حیدر ناصری، عیسی حزباوی*، فیض الله شهبازی صفحات 323-330

    شیر بازساخته یک محصول جایگزین شیر است. اجزای شیر بازساخته به راحتی قابل تنظیم تر از شیر است. نسبت اجزای شیر به طور مستقیم بر کیفیت محصول تاثیر می گذارد. با استفاده از هدایت الکتریکی می توان اطلاعات ارزشمندی در مورد کیفیت مواد مختلف از جمله مواد غذایی به دست آورد و به وسیله این روش، به عنوان یک ابزار ساده و کاربردی، کیفیت بسیاری از مواد غذایی را کنترل نمود. هدف از انجام این تحقیق بررسی هدایت الکتریکی شیر بازساخته تحت تاثیر دما، درصد پروتیین و درصد لاکتوز است. برای بررسی اثر درصد پروتیین (1، 2 و 3 درصد)، درصد لاکتوز یا قند (4، 6 و 8 درصد) بر هدایت الکتریکی شیر از پودر شیر خشک که خالص و بدون مکمل غذایی می باشد، در این تحقیق استفاده شد. برای افزایش درصد لاکتوز پودر شیر خشک از پودر لاکتوز، برای افزایش پروتیین از پودر کازیینات سدیم و برای به حجم رساندن نمونه ها از آب مقطر استفاده شد. کل آزمایشات در 3 سطح دمایی (50، 55 و 60 درجه سلسیوس) صورت گرفت. نتایج نشان داد که متغیرهای دما، درصد پروتیین و درصد لاکتوز بر هدایت الکتریکی شیر بازساخته تاثیر معنی داری داشتند. با افزایش درصد پروتیین و دمای شیر بازساخته، هدایت الکتریکی آن به طور معنی دار افزایش یافت. با افزایش درصد لاکتوز، هدایت الکتریکی شیر بازساخته به طور معنی دار کاهش یافت. بیشترین و کمترین مقدار هدایت الکتریکی شیر بازساخته به ترتیب mS/cm 7/5 در دمای 60 درجه سلسیوس، لاکتوز 4 درصد و پروتیین 3 درصد و mS/cm 31/2 در دمای 50 درجه سلسیوس، لاکتوز 8 درصد و پروتیین 1 درصد حاصل شد.

    کلیدواژگان: درصد پروتئین، درصد لاکتوز، شیر بازساخته، هدایت الکتریکی
  • محمدابراهیم محمدپور میر، سارا نانواکناری، کامیار موقرنژاد* صفحات 331-341

    برنج یکی از گیاهان مهم تیره غلات است و غذای اصلی اکثر مردم دنیا به شمار می آید. خشک کردن برنج بعد از برداشت، به جهت غیرفعال کردن عاملین فساد، امری مهم و ضروری است. در این تحقیق به منظور بررسی اثر توان مایکروویو بر روی سینتیک خشک شدن شلتوک، ضریب نفوذ موثر رطوبت، درصد برنج سالم و کیفیت برنج از یک خشک کن مایکروویو استفاده شده است. به منظور خشک کردن شلتوک از رطوبت اولیه 21 درصد تا رطوبت نهایی 11 درصد از 3 توان270، 360 و 450 وات استفاده شد. همچنین مدل سازی سینتیک خشک شدن شلتوک در خشک کن مایکروویو با استفاده از 2 شبکه عصبی MLP و RBF انجام شد. نتایج حاصل از این بررسی بدین صورت بوده که حداکثر و حداقل زمان خشک شدن به ترتیب در توان 270 و 450 وات و برابر با 42 و 20 دقیقه بوده است.  با افزایش توان مایکروویو میزان شکستگی افزایش یافته و درصد برنج سالم کاهش می یابد. و همچنین خشک کردن برنج توسط خشک کن مایکروویو تاثیری بر روی کیفیت برنج نداشته است. از نتایج مدل سازی انجام شده می توان دریافت که شبکه RBF با تابع انتقال گوسی با شاخص پراکندگی و تعداد نورون بالا بهترین عملکرد را در قیاس با سایر حالات طراحی شده در شبکه RBF داشته است و شبکه  MLP با الگوریتم آموزش لونبرگ مارکوارت و تابع انتقال تانژانت سیگمویید با تعداد نورون پایین قادر بوده مدل سازی سینتیک خشک شدن را به خوبی انجام دهد. به طور کلی شبکه عصبی MLP عملکرد بهتری نسبت به شبکه عصبی RBF داشته است و میزان خطا و ضریب همبستگی آن به ترتیب کمتر و بیشتر از شبکه عصبی RBF بوده است.

    کلیدواژگان: خشک کن مایکروویو، درصد برنج سالم، سینتیک خشک کردن شلتوک، شبکه عصبی، ضریب نفوذ موثر رطوبت، کیفیت برنج
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  • Shima Nasiri, Saman Abdanan Mehdizadeh*, Maryam Nadafzadeh Pages 171-191
    Introduction

    The development of brown spots on banana peel has a notable effect on the texture, color and taste of this fruit. So that the appearance of these spots reduces the quality of the fruit and affect its sale market. In recent years, in order to evaluate the quality and classification of agricultural products, the various systems based on computer vision technology have been widely considered. These systems as the computer image analysis methods have been successful in measuring the visual quality of different products (Riyadi et al., 2007; Roseleena et al., 2011; Rodriguez-pulido et al. 2012). According to research by Probha and Kumar (2015), the extracted color properties from the banana image were more effective than other features in identifying the different stages of the banana ripening. Also, Mendoza and Aguilera (2004) detected the different stages of banana ripening based on the color, texture parameters and the distribution of brown spots on banana peel using image processing technique with a precision of 98%. Nadafzadeh et al. (2018) designed a non-linear mathematical model using the Genetic Programming (GP) to predicting and evaluating the activity of polyphenol oxidase enzymes (PPO) and peroxides (POD) during the browning process of the banana peel; using the extracted parameters from image as inputs of proposed model, the correlation coefficients to predicting of PPO and POD enzymes were obtained 0.98 and 0.97, respectively.The aim of this study was to investigate the changes of color, dimensions and chemical parameters of several banana fruit groups (different in terms of appearance) as well as their marketability (the total acceptance of fruit) by Gaussian regression model (GPR) during the storage period. Therefore, using the proposed method in this research, the required product can be available according to the consumer demand.

    Materials and Methods

    In this study, one hundred banana samples were prepared from a market on the first day of the experiments. Samples were different in terms of shape and size, and were classified into 5 different groups. Group A had small size and curvature; B group compared to Group A had more curvature; the curvature of the samples in the group C was high, and in terms of size were medium. While the size of the bananas in group D was large, they had a small curvature. Also, the features of the group E were similar to the group D, but the curvature was greater in this group (group E). All of the samples were kept at the ambient temperature (25° C) away from the direct light for 7 days. During the days of experiments (days 0, 2, 4 and 6), five samples were examined from each group: after taking images of samples under the constant light conditions, and performing of manual measurements, they were subjected to destructive tests (laboratory tests) and sensory tests. After the images acquisition of samples, the preprocessing operations such as image enhancement, noise removal by the area opening, and the implementation of the image segmentation process using the method of Otsu adaptive thresholding were conducted (Gonzalez et al., 2004). Finally, 11 color parameters (R, G, B, L, a, b, h, s, v, C, H) and 4 dimensional characteristics (diameter, curvature radius, long and small length) were extracted from each image. In the laboratory method, the TSS value was measured by a digital refractometer, and amount of pH and acidity were also measured by a fruit juice analysis titrator. Eventually, in order to investigate the changes of measured parameters, statistical analysis was performed in a randomized complete block design by SAS 9.3 software at a significance level of 5% using Duncan's multiple comparison test.

    Results and discussion

    Gradually along with the appearance of dark spots on the banana peel, many of the qualitative parameters such as the color, dimensions and chemical features were changed during the storage period. According to results of the Duncan's multiple range test, the values of color coordinates R, G, B, L, b, h, v, C, and H gradually reduced, and the values of these parameters were significant in all the experiments days (p<0.05). The parameter S also had a decreasing trend during the storage period, and the changes of this parameter was significant in the first days of the experiments compared to the ending days; during this period, the color parameter a increased significantly. Due to the changes of the banana fruit texture, the amount of the curvature radius, the small and large lengths, total soluble solids, pH and total titration acidity gradually decreased. Based on the results of the statistical analysis, there were no significant differences between dimensional parameters measured by non-destructive method and manual measurement (p>0.05). It is worth noting that in this study, the spent time to conduct the manual measurements of the dimensional parameters of a banana sample was 510 seconds, while all of these measurements were performed using a digital image processing method at 1.015 seconds. Therefore, it can be said that when the number of samples is high, using of the proposed method is also very cost-effective in terms of time, and it has high accuracy during the measurement. In the sensory evaluation, the results show that the best and most acceptable group of bananas were groups C, D and E, which had long size and low curvature; these groups of bananas had delicious texture, desirable flavor and low levels of brown spots on their peel. In the following, the non-destructive parameters were used to the development of Gaussian regression model (GPR), and finally, it was shown that the quality of banana fruit as well as its marketability (the total acceptance of fruit) are predictable during the storage period by GPR with a correlation coefficient of 0.91, MAPE (20.47), RMSE (0.43), SRE (0.71) and RAV (0.20).The appearance quality of the banana fruit is very effective in its acceptability for customer. In this research, the image processing technique as a non-destructive method was used to extract a set of color (R, G, B, L, a, b, h, s, v, C and H) and morphological properties (diameter, curvature radius, long length and small length) from banana image in order to evaluate its quality during storage. According to the results of Duncan's statistical analysis at the probability level of 5% and Pearson correlation results, the most suitable parameters were chosen to apply in Gaussian regression model. The results showed that the image processing technique is capable to evaluating the changes of color and dimensional parameters of banana fruit, and also the proposed model have a satisfactory performance (R2=0.91) in predicting the overall acceptance parameter of the banana.

    Keywords: Storing period, Acceptability, Digital image processing, Gaussian process regression, Banana
  • Mehri Zolfaghari, Eshagh Zakipour Rahimabadi*, Mahin Rigi, Majid Alipour Pages 193-205
    Introduction

    Seafood is among the very perishable foodstuffs. For this reason, a lot of researches have focused on improving the quality of fish and increasing the shelf-life of fishery products, including the use of edible films, modified atmosphere, freezing and control of temperature. Storage in the refrigerator is one of the methods used in fish supply centers to keep quality and extend the product shelf-life. The storage of fish and seafood in the refrigerator decreases the enzymatic and chemical activity and activity of microorganisms. However, undesirable changes occur during refrigerator storage, which leads to a decrease in quality. Therefore, it is necessary to maintain the product quality by combining protective factors. The aim of the present study was to evaluate the preservation effects of salt/sugar solutions treatment on quality of fish fingers made from silver carp (Hypophthalmichthys molitrix) fillets during refrigerated storage (4ºC).

    Materials and methods

    The prepared fillets (about 100 g in weight) were soaked in cold 10% salt/sugar solutions for 30 min, allowed to drain for 15 min in refrigerator and after bone separation were minced. Fish fingers were prepared after adding the ingredients and mixing, and then packaged and stored in refrigerator for 15 days. The treatments of study were as: fish fingers without any treatment (control sample), samples made from treated fillet with salt/sugar solution(50 / 50) (T2), samples made from treated fillet with salt/sugar solution (75 / 25) (T3) and fish fingers made from treated fillet with salt solution (100 %) (T4). Physicochemical, microbial (TVC and PTC) and sensory characteristics were measured at days 0, 3, 6, 9, 12 and 15.

    Results and discussion

    PV, TBA and TVB-N values were increased significantly in all treatments (p<0.05). Lowest TVC count was obtained in treatment 2 at day 15 (5.8 log CFU/g). According to the obtained results, treatment 2 was the best treatment in sensory characteristics. Osmotic treatment increased the shelf-life of fillets and their products, due to the effect of preventing these solutions against the growth of spoilage bacteria, which ultimately resulted in the reduction of corrosive products such as TBA and TVB- N. The results of this study showed that osmotic solutions have the potential to replace the thermal and chemical treatments to produce a quality and healthy product with an apparent consumer sentiment.

    Keywords: Fish finger, Silver carp, Quality characteristics, Salt, Sugar
  • Negin Zanganeh, Behrooz Alizadeh Behbahani, Mohammadamin Mehrnia Pages 207-220
    Introduction

    Spirulina platensis belongs to the Division of Cyanobacteria and the family of Oscillatoriaceae. It is autotroph and photo-synthesizer and can be reproduced through double cell division. Spirulina platensis is a filamentous blue-green multi-cellular microalgae naturally occurring in the tropical and alkaline lakes of America, Mexico, Asia and central Africa. It contains unique and extraordinary nutrients which can be used in the production of functional foods. Among bakery and flour products, cake has a relatively high diversity and long shelf-life and is famous among a variety of people, especially children. Since the knowledge associated with the enrichment of sponge cake, as a popular product among different communities (in particular, children) is limited, the aim of the present research is to produce a sponge cake enriched with spirulina platensis, and to examine its nutritional, physicochemical and sensory properties.

    Materials and methods

    In this research, the effect of Spirulina platensis at four levels (0, 0.5, 1 and 1.5%) was investigated on the nutritional properties (protein, fat, iron, zinc and copper contents), physicochemical properties (moisture content, pH, total phenol content, antioxidant potential, textural properties and color indices) and sensory attributes (odor, color, texture, flavor and taste, chewiness and total acceptance) of the sponge cake samples prepared with wheat flour.

    Results and discussion

    Results showed that algae powder was rich in protein (56.33%) and iron (13.18 ppm). The addition of Spirulina platensis to the sponge cake caused reduction in its moisture content during storage (days 1, 5 and 10). The results also revealed that the different levels of algae addition brought about significant differences in the moisture content of the samples (p<0.05). The results also indicated that the protein, fat and mineral contents as well as other nutritional properties of the sponge cake increased as the algae content was elevated. The total phenol content of the cake samples was also raised with an increase in the algae powder level, compared with the control. This could be attributed to the large amounts of phytochemical and biological active substances such as flavonoids, sterols and other phenolic compounds. The results demonstrated that the porosity values of the control and the sample containing 1.5% of the algae were not significantly (p<0.05) different. The percentage of porosity was equal to 24.94, 37.99, 33.39 and 27.81 in the control and the samples containing 0.5, 1 and 1.5% of Spirulina platensis. Overall, the sample with 0.5% of the algae and the control had the highest and lowest porosity percentage respectively. As the algae level rose, the textural parameters (hardness, cohesiveness and gumminess) of the sponge cake increased on days 1, 5 and 10 of the storage period. The colorimetry results showed that the effect of Spirulina platensis was significant (p<0.05) on color parameters (L*, a* and b*). Sensory evaluation revealed that the sponge cake with 0.5% of the microalgae was the most acceptable among the samples. The green color of the cake crumb was attractive to the panelists and a comparison between the total sensory scores indicated that the incorporation of Spirulina platensis into the sponge cake was desirable from the panelists` points of view. The results of this study demonstrated that the addition of Spirulina platensis to sponge cake for the enrichment of this product, caused an increase in its protein and mineral contents, antioxidant potential, in addition to other functional ingredients naturally occurring in this algae. The results revealed that different levels of this algae (0.5, 1, and 1.5%) did not significantly affect the cake texture, however, had a significant impact on its color. Incorporation of Spirulina platensis into sponge cake reduced its L*, a* and b*, which was highly noticed by the panelists. Therefore, it can be declared that enrichment of sponge cake, as a popular product among different people of societies, particularly children, is a desirable and easy way of transferring the useful and valuable compounds of this algae to human.

    Keywords: Spirulina platensis, Textural properties, Sponge cake, Sensory properties
  • Marzieh Omeidi Myrzai, Mohammad Hojjati*, Behrooz Alizadeh Behbahani, Mohhamad Noshad Pages 221-233
    Introduction

    Essential oils and secondary metabolites of plants have too many uses in medicine as well as food and hygiene industries. The herbal essential oils include different health features including antioxidant and antibacterial activities. Several forms of the activated oxygen, also known as reactive oxygen species (ROS), include free radicals and non-free radical species. In traditional Iranian medicine, coriander seeds are widely used to treat the disease. The objectives of this paper were to identify the chemical compounds and to measure the phenol content and the antioxidant potential of coriander seed essential oil in addition to its free radical scavenging activity. The other aim of this work was to investigate the antimicrobial of coriander seed essential oil on Bacillus cereus, Salmonella typhi, Escherichia coli and Pseudomonas aeruginosa “in vitro”.

    Materials and methods

    In this research, the coriander seed essential oil (100 g) was extraction using water-distillation method with clevenger apparatus. Afterwards, coriander seed essential oil was collected in vials which had already been weighed by a 0.0001 balance and stored at 4 °C until testing. Chemical composition of coriander seed essential oil was determined using gas chromatography. The antioxidant activity was determined by 2,2’-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) di-ammonium salt (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicles, respectively. The method of Folin-Ciocalteu was performed through determination of TPC. The result was reported as mg of gallic acid/g of the dried coriander seed essential oil. The antioxidant potential of the essential oil was compared with BHA synthetic antioxidant at a concentration of 100 μg/ml. Antibacterial activity of coriander essential oil was determined by disc diffusion agar (Kirby-Bauer test), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods.

    Results and discussion

    Based on the results of chemical analysis, the coriander seed essential oil was rich in oxygenated monoterpenes (89.94%). The main compound of coriander seed essential oil was Linalool (76.75%). The highest percentage of free radical scavenging for DPPH was 53.5% and for ABTS 66.6% at 900 ppm concentration. The total phenol content essential oil was 38.04 ± 0.02 mg GAE/g. The result show that, the most sensitive and the most resistant bacteria with diameter inhibition zone 30.30 mm and 23.15 mm were Bacillus cereus and Salmonella typhi respectively. MIC of coriander seed essential oil for Bacillus cereus, Salmonella typhi, Escherichia coli and Pseudomonas aeruginosa was 2, 4, 4 and 4 mg/ml respectively. MBC of coriander seed essential oil for Bacillus cereus, Salmonella typhi, Escherichia coli and Pseudomonas aeruginosa was 512, > 512, > 512 and 512 mg/ml respectively. In general, the results indicated that the coriander seed essential oil was effective on microorganisms; nevertheless, the extent of its effectiveness varied depending on the type of microorganism. The gram-positive bacteria are more sensitive to essential oil rather than gram-negative ones. The higher resistance of gram-negative bacteria to the essential oils of medicinal plants could be attributed to the more complex structure of the cell membrane of these bacteria compared with the single layer structure of the gram-positive ones. The results of this study revealed that coriander seed essential oil had less antioxidant activity than synthetic antioxidant BHA. Antibacterial activity of the essential oil was higher than the gentamicin antibiotic. Regarding the chemical compositions identified in the coriander seed essential oil, these compositions could be employed as an important economical source uses in medicine as we as food and hygiene industries.

    Keywords: Antibacterial activity, Coriander seed, Gentamicin antibiotic, Synthetic antioxidant
  • Maryam Mandegari, Abdolmajid Mirzaalian dasgerdi*, Laleh Mosharaf, Maryam Tatari Pages 235-249
    Introduction

    Pomegranate (Punica granatum L.) is an important horticultural fruit that is generally very well adapted to the Mediterranean climate. Arils are the edible part of this fruit, being rich in anthocyanins and bioactive compounds such as phenolic compounds and flavonoids which act as antioxidants and free radical scavengers. Susceptibility to chilling injury in pomegranate fruits is a major limiting factor in storing fruits at low temperatures. Below 5 °C, pomegranate fruits show symptoms such as surface pitting, browning, discoloration, and decay. The control of temperature is an effective tool for extending the shelf life of fresh horticultural products. Oxidative stress, as caused by an excess of reactive oxygen species (ROS), is usually associated with chilling injury in fruits. Nitric oxide (NO) is an important gas molecule, the involvement of which in many physiological processes can protect plant cells against oxidative stress by reducing the accumulation of ROS. Postharvest studies have shown that the application of NO gas can extend the storage life of a range of horticultural produce by delaying ripening or senescence. Due to the high number of pomegranate cultivars in Iran, limited amounts of information exist on how the qualitative characteristics of arils in the Malas pomegranate can be affected by nitric oxide and different temperatures during storage. The Malas cultivar comprises a large share of pomegranate exports from Iran. In this research, the positive effects of nitric oxide were examined on reducing the chilling injury and maintaining the fruit quality of pomegranate. The application of this treatment at different concentrations and different storage temperatures led to variable effects on the qualitative characteristics of arils in the Malas pomegranate.

    Materials and methods

    Malas pomegranate fruits were harvested commercially from Isfahan Province and were transferred to the Food Industry Laboratory of Isfahan Natural Resources Research. The fresh arils were separated from fruit tissues and were immersed in solutions of nitric oxide (0, 5 and 10 μM/L) for 5 min. After draining, the arils were placed in packaging films of polyethylene and were immediately stored at 2, 4 and 8 °C for 21 days. Several parameters were measured every 7 days during the storage time. These were the weight loss, total soluble solids, titratable acidity, TSS/TA, acid ascorbic, total phenol, total anthocyanin content, antioxidant activity, MA, ion leakage, POD, PPO activity and sensory evaluation. The current study was carried out as a factorial assay and was based on a completely randomized design with three replications. Data were processed by ANOVA using the SAS software version 9.4. Significant differences were identified using Duncan’s test at 1% probability level.

    Results and discussion

    Results showed that the total anthocyanin content, total phenol, antioxidant activity, and titratable acidity decreased during storage time. The control group and the treatment with low temperatures significantly reduced the qualitative characteristics of arils during storage. The water content of arils treated with 5 and 10 μM nitric oxide was maintained considerably for 21 days during storage. According to these results, unlike titratable acidity and ascorbic acid which decreased in both treated and untreated fruits, there was an increase in the total soluble solids and POD activity of arils during storage. However, nitric oxide reduced the rate of these changes, whether it be the decrease or increase in the measured parameters. During the experiment, the control samples showed lower values of quality regarding all parameters. The use of nitric oxide in fruits reduced lipid peroxidation and ion leakage significantly, whereas the antioxidant activity increased. The decrease in ion leakage was observed most notably in fruits that were treated with 10 μM nitric oxide. Furthermore, low temperatures managed to disrupt the metabolic balance of reactive oxygen species, leading to the accumulation and destruction of antioxidant enzymes. In the present study, exogenous treatments with nitric oxide at 5 and 10 μM significantly reduced the lipid peroxidation content and electrolyte leakage of arils being stored at cold temperatures, compared to untreated arils. Nitric oxide suppressed the activity of polyphenol oxidase (PPO) and preserved the physical appearance and the internal quality of pomegranate arils. The decrease in phenolic compounds (29.32%) and antioxidant activity (39.91%), besides the increase in lipid peroxidation (38.37%) and ion leakage (36.98%), caused deteriorations in the appearance and organoleptic properties of the control samples. To alleviate these problems, nitric oxide has beneficial effects on maintaining the anthocyanin content of pomegranate arils by partially inhibiting PPO enzyme activity during storage. It prolongs the postharvest life, helps to preserve the quality of pomegranate arils, suppresses the formation of ethylene, reduces the respiratory rate and controls weight loss, in addition to maintaining the firmness of fruits. Delaying the changes in peel color and TSS are also considered as useful effects of nitric oxide on pomegranate arils. Nitric oxide impeded the process of senescence by slowing down PPO-related activities, thereby maintaining the total phenolic content of pomegranate arils.
    In conclusion, the application of nitric oxide was observed to reduce ion leakage and PPO activity in pomegranate arils, while also maintaining the quality of arils. Ultimately, the use of 10 µM nitric oxide at 8 °C can be suggested as the most optimum treatment herein.

    Keywords: Antioxidant activity, Fruit quality, Polyphenol oxidase, Pomegranate arils
  • Esmail Khazaei, Mikhalil Piruzifard*, Fariba Zeynali, Mohammad Alizadekhaledabadi Pages 251-269
    Introduction

    Meat and meat products are important sources of protein, fat, essential amino acids, minerals and vitamins, and other nutrients. Bologna sausage, a cooked meat product, is one of the most accepted processed meat products and is consumed and enjoyed worldwide. Among the meat products, sausage and bologna in vacuum packages due to their variety, easy to use applications and being economical, have become commonplace. The most important problem with the production, storage, and sale of this kind of meat products is their syneresis in the vacuum packages. In addition to an unpleasant appearance, syneresis leads to accelerating microbial growth and undesirable changes in the flavor and odor of the product.The addition of functional ingredients helps to modify the overall technological and sensorial characteristics of a meat system such as water holding capacity (WHC), fat holding capacity, and texture properties and decrease the syneresis. Syneresis and purge are seen as a result of retrogradation of starch and this is very common in sliced and vacuum-packed meat products. Storage of meat products containing high-amylose starches, at low temperatures from around –1 °C to 0 °C for a prolonged time also favors retrogradation. The level of retrogradation depends on the type of starch and wheat starch demonstrating the greatest tendency towards retrogradation. Chitosan is a natural cationic polysaccharide antibacterial activity and antioxidant properties in muscle foods during storage. The aim of this study was Investigation the addition of functional ingredients such as chitosan and potato modified starch in the formulation on the amount of syneresis, pH, total microbial count and sensory evaluation in two type of products including beef ham and chicken ham were examined during storage. Then, the effect of vacuum packaging type and the amount of vacuum created in the package on the amount of syneresis were investigated.

    Material and methods

    In this study, first various factors such as three levels of chitosan (0, 0.3 and 0.6%) and replace the wheat starch with three levels of potato modified (0, 5 and 10%) in the formulation on the amount of syneresis, pH, total microbial count and sensory evaluation in two type of products including beef ham and chicken ham were examined during storage time (1, 15 and 30 days). In this part of the study, samples with the least syneresis were selected. After that various factors of packaging such as two types of vacuum packaging(simple vacuum pack and skin pack) and the amount of vacuum(5 and 30 millibars) created in the package on the amount of syneresis were examined during storage(1, 15 and 30 days). Wheat starch, potato starch, and chitosan were purchased, respectively, from Faradane Company, KMC Company, and Sinaseven Company. The chicken meat was purchased from Fileh Amol Company. The beef was purchased from the Minerva Company of Brazil. All steps of samples’ preparation were performed in the Kalleh Amol Meat company. The chicken ham samples in this study consisted of 90% of the chicken meat and beef ham samples consisted of 90% of beef. Vacuum packaging was done using the machines which were manufactured by the German company Multivac. Syneresis was measured using the method suggested by Cesare et al. (e 2013).  The initial weight of the ham slices before vacuum-packed was measured (P1); on the day of the analysis, the packaging was opened and the slices were dried with a disposable absorbent towel, then the dried ham slices were weighed again (P2). Syneresis was expressed as Syneresis= (P1- P2) ×100/P1. This study was conducted in a completely randomized design and Duncan multi-ranged test was used to determine differences between samples at 95% confidence level.

    Results and discussion

    According to the results of analysis of variance, there was no significant difference between the syneresis of beef and chicken ham. The effect of storage time was significant on the syneresis and the syneresis rate increased with increasing storage time. Also, the results showed that adding chitosan and potato modified starch significantly (p<0.05) reduced the product's syneresis during storage. Potato starch has more water storage capacity and more amylopectin than wheat starch. For this reason, potato starch has a weaker retrogradation and less syneresis. Chitosan is a cationic polysaccharide with water-absorbing polar groups. Chitosan also was prevented from decreasing the product’s pH during storage time, that this result showed the antimicrobial effect of chitosan on acid lactic bacteria, especially in 15 and 30 days of storage. For that reason, chitosan prevents product’s pH to reach to its isoelectric pH. According to the sensory evaluation results, during the maintenance period, the sensory quality decreased significantly while chitosan had a significant positive effect on sensory parameters during storage time (P<0.05). The type of vacuum packaging and the amount of vacuum created in the package showed a significant effect on the amount of samples’ syneresis. Skin packaging showed less syneresis rates than simple vacuum packages. This result can be due to two reasons: one is the shrinkage of the product in the package, and the other is the amount of the film packing tangency on the surface of the products. So that by increasing the amount of vacuum, syneresis value increased significantly. Increasing the negative pressure inside the package caused increase the mechanical pressure by the packaging film on the product. In total, it can be concluded that with the addition of modified potato starch and chitosan to the formulation, as well as the use of lower-vacuum Skin packaging, the amount of syneresis of meat products can be significantly reduced.

    Keywords: Ham, Syneresis, Potato Modified Starch, Chitosan, Vacuum Packaging
  • Azam Sattari, Jafar Mohammadzadeh Milani*, Zeynab Raftani Amiri, Ali Pakdin Parizi Pages 271-286
    Introduction

    Oat establishes a healthy basis for food products. It has gained relevance in human nutrition because it is one of the few cereals with a high content of soluble fiber namely β -glucan, and is a good source of proteins, vitamins, and minerals (Butt et al., 2008). β-glucan is one such polysaccharide that has received much attention from the past few years due to its several health beneficial properties, including the ability to remove free radicals in a way identical to antioxidants (Gardiner, 2000). β-glucan is an unbranched polysaccharide consisting of β-D-glucopyranose units linked through (1→4) and (1→3) glycosidic bonds in cereals and (1→6) glycosidic bonds in fungal sources (Ahmad et al., 2016). β-glucan from different sources vary in their molecular structure, chain conformation, solubility, number of β- (1→3)- or β-(1→6)-linkage, and thus different biological activities (Descroix et al., 2006). β-glucan is regarded as an important functional ingredient to lower serum cholesterol, promote weight management, reduce glycemic response, enhance immune system, besides having a prebiotic effect (Zhu et al., 2016; Shah et al., 2016). β–glucan from barley and oat at a 3 g/day dosage as recommended by FDA would reduce cardiovascular disease risk including a reduction in blood glucose and also has satiety effects. Therefore, in order to meet the demands of people related to diets that have a low glycemic index and antioxidant property, non-starch polysaccharides like β-glucan can be used as an ingredient in the products to develop new functional foods (Lee et al., 2016). Oat grain’s fat content is more than that of wheat and it is full of lipase, lipoxygenase, and other hydrolytic enzymes. Over time, enzymes lead to the hydrolysis of the fats present in the oat that make the rancidity taste. Due to the effect of enzyme activity on the stability of oat flakes, these enzymes need to be deactivated during oat processing. One of the methods for disabling enzymes is a hydrothermal process (Doehlert et al., 2010). In this study, the effect of the hydrothermal process using autoclave on the physical and rheological properties of oat β-glucans at different times and temperatures has been investigated.

    Materials and methods

    In this study, beta-glucan was extracted from oats using the hot water extraction method. Hulled oat grains, it put into the autoclave for hydrothermal processing, at three different temperatures of 110, 120 and 130°Ϲ in two different times (10 and 20 minutes) intervals, to measure the effect of time and temperature on physicochemical and functional and rheological properties of β-glucan. After extraction, the physiochemical and functional properties of extracted β-glucan such as solubility, foaming, foaming stability and rheological properties were tested. In order to measure the moisture, ash and protein content, the standard methods (AOAC, 2005) were used. The fat content of the flour was measured by the standard AACC method 25-30. The starch was determined by polarimetry method. For solubility measurement, according to Betancur-Anoka (2003) method, after preparing 90 ml of 1% w / v solution from each sample β-glucan, it was divided into 3 equal parts. Then each of them was placed in a warm bath of 25, 50 and 75 °C for 30 minutes. After centrifuging for 15 minutes at about 8000 g, 10 ml of the upper clear solution was transferred to an oven at 125 °C to reach a constant weight. Finally, solubility percentage at different temperatures was calculated.The foaming capacity and foam stability were studied using the temelli method (1997). For this purpose, 2.5 g, β-glucans was dissolved in 100 mL distilled water. The resulting solution was mixed vigorously for 2 min using a hand held food mixer at high speed in a stainless steel bowl with straight sides and volumes were recorded before and after whipping. To determine foaming capacity, foams were slowly transferred to a 1000 mL graduated cylinder and the volume of foam that remained after staying at 25 ± 2°C for 2 h was expressed as a percentage of the initial foam volume (Temelli et al. 1997; Ashraf Khan et al., 2016). β -Glucan gum solutions were prepared in duplicate in the desired concentration (1.0% of gum, w/w) using distilled water. The rheological properties of the samples were studied by an Anton Paar Physica Rheometer (Physica, MCR 301, Anton Paar GmbH, Germany), with a parallel plate geometry.

    Results and discussion

    β-glucan obtained from hydrothermal process on oat flour at 120°C for 10 minutes had the highest solubility at 25°C and the lowest solubility at 50°C, and 130°C treatment for 10 minutes had the highest solubility at 75°C from hydrothermal process on oat flour at 120°C for 10 minutes had the highest solubility at 25°C, and the treatment of 110°C for 10 minutes and also the treatment of 120°C for 20 minutes had the highest solubility at 50°C and 75°C. The amount of foam in treatment at 130°C for 10 minutes were lower than other treatments and the treatment at 110°C for 10 minutes had the highest foaming stability. In the study of rheological properties, the effect of shear rate on viscosity showed by increasing the shear rate, viscosity decreased in all samples. β-glucan from hydrothermal process on oat flour at 120°C for 10 minutes, had the highest amount of viscosity. In the temperature sweep the parameters included G′ modulus and G″ modulus, the amount of G′ and G″ in β -glucan sample that extracted from hydrothermal process on oat flour were decreased in all samples. Also, G′ and G″ of extracted β-Glucan from hydrothermal process on oat flour at 120°C for 10 minutes was higher than other treatments. In the frequency sweep, at a lower frequency, the amount of G″ was more than G′, and both of them were increased by an increasing frequency and the amount of G′, G″ and η* at 120°C for 10 minutes was higher than other treatments in the frequency of 1 and 10 (Hz). The results showed that the hydrothermal process had a significant effect on the properties and functional properties of β -glucan. Extracted β -glucan sample at 120°C for 10 minutes had the highest solubility at 25°C, and the sample had the lowest solubility at 50°C. The sample treated at 120°C for 20 minutes had the highest solubility at 75°C. The foaming capacity of the sample at 130°C for 10 minutes was lower than other treatments and the treatment at 110°C for 10 minutes had the highest foaming stability. In the study of rheological properties, the effect of shear rate on viscosity decreased in all samples and the treatment of 120°C for 10 minutes had the highest amount of viscosity. In temperature sweep measurement, the amount of G′ and G″ were decreased in all samples and at 120°C for 10 minutes it had the highest amount of G′ and G″. In the frequency sweep, at a lower frequency, the amount of G″ was more than G′, and both of them were increased by an increasing frequency and the amount of G′, G″ and η* at 120°C for 10 minutes was higher than other treatments in the frequency of 1 and 10 (Hz).

    Keywords: B-glucan, oat, hydrothermal processing, rheological properties
  • Foroozan Jafari, Nafiseh Zamindar*, Mohammad Goli, Zahra Ghorbani Pages 287-299
    Introductıon

    In developing countries, camel meat is used to provide nutrients, proteins, vitamins, and minerals but it usually has a tough texture. Marinating meat may improve its flavor and tenderness. It has been shown that plant enzymes such as papain, ginger, and Cucumis increase the meat's tenderness and improve the flavor and aroma of the products.Ginger extract (GE) could improve the tenderness of camel meat by “Zingibain”. Marination in acidic solutions has been used both traditionally and industrially for the tenderization and flavoring of meat (Abdeldaiem and Hoda., 2013; Tsai et al., 2012). The tenderization effect of marination on meat have been examined by using organic acids such as citric acid (Aktas et al., 2003; Berge et al., 2001; Ke et al., 2009; Kim et al., 2013; Ke, 2006; Ke et al. 2009).The objective of this study was to evaluate the effect of ultrasound and marination with different concentrations of citric acid and Ginger extract 30% on the physicochemical characteristics of camel meat.

    Materials and methods

    Fresh ginger rhizome (Zingiber officinalis roscoe) purchased from a local market was washed, peeled, sliced and immediately homogenized with an equal quantity of chilled and distilled water (4ºC) for 2 min to extract the crude enzyme. The homogenate was filtered through Buchner funnel and the water to get the GE. Marinade solutions were prepared by the addition of 0.5, 1 and 1.5% citric acid to 30% GE, and distilled water was used as control. To prepare the required 30% GE, the crude fresh GE was diluted with distilled water (He et al., 2015).The portions from Biceps femoris muscles of aged male camel carcasses (4 years of age) were prepared according to the method described by Abdeldaiem et al (2013). Uniform sized (3×3×3 cm) of aged camel meat chunks were dipped in the curing solutions at the ratio of 3:1(meat: liquid) and immersed in the polyethylene bags and kept at 4±1°C for 24 and 48 h (Abdeldaeim et al., 2014; Garge et al., 2006).The pH values were measured directly using a probe-type electrode (Naveena et al., 2004). Uptake of the marinade (%) was measured according to the method described by Garg et al (2006) and Hosseini et al (2012).The color measurements; lightness (L*), redness (a*) and yellowness (b*) were performed at the surface of the marinated meat samples (Barbut, 2004).Cooking loss of meat samples was determined so that He et al (2015) and Kim et al (1995) described.Shear force values of cooked samples were determined using texture analyzer with Warner-Bratzler shear apparatus, while muscular fibers were almost parallel to the force as normally occurs during chewing. Six meat cores (1.27 cm diameter) parallel to muscle fiber were sheared once through the center by a warner-Bratzler shear attachment using 50 kg compression load cell and 200 mm/min cross-head speed (Karimi et al., 2008; Hosseini et al., 2012).After 24 and 48 h marination, samples were prepared for (SEM) as described by Naveena et al (2004).A completely randomized design in a factorial experiment with 3 replications was employed by using analysis of variance (ANOVA) to study the effect of ultra-sonication, and time on the physicochemical properties of camel meat. Least significant difference (LSD) test was used to determine differences between treatments means (P<0.05). Data were analyzed using the procedure of SAS version 8 (Burke et al., 2003)

    Results and discussion

    Ultrasonication caused a decrease in pH while increasing marination time caused an increase in pH of all samples compared with control. Cooked samples showed higher pH compering with raw marinated samples. Ultration and increasing marination time caused a significant increase in marinade uptake due to structural changes. Application of ultrasound, the higher concentration of acid in marinade solution and longer marination period resulted in lower shear forces of meat samples.Marination by 30% GE in addition to 1.5% citric acid and ultration illustrated maximum tenderness, lower pH and L*-value but caused less water holding capacity and higher cooking loss.

    Keywords: Camel meat, Ultrasound, Marinade, Citric acid
  • Liela Mahsouli, Hannan Lashkari* Pages 301-311
    Introduction

    Milk-based dessert is one of the dairy products which in addition to the nutritional value, makes a variety in the consumer basket of goods. The most important property of desserts is their high energy and a pleasant feeling that is created by the consumer due to its ingredients. These products contain mainly milk, thickeners, sugar, flavoring compounds and colorant, and have a jelly structure. Sugar is used as a sweetener in the production of desserts. The grape juice concentrate is one of the traditional products of Iran's grapevine region, which accounts for about 5 to 20 percent of Iranian grapes used to make grape juice concentrate. Grape juice concentrate contains high levels of natural sugars, minerals, vitamins, organic acids and antioxidants. Therefore, grape juice concentrate can be used as a sugar replacer sweetener. 

    Materials and Methods

    In order to reduce the amount of sucrose in dessert and its replacement with grape juice concentrate, different ratio of grape juice concentrate (0, 5, 7.5 and 10%) were used. To prepare dessert samples, wheat starch was first added to milk at 4%w/w, and then 0.5%w/w gelatin and sugar were added and mixed until all ingredients were completely dissolved in the milk. Then, it was heated to 95°C and stirred at 270 rpm for 15 minutes, then cooled to 40 °C, and grape juice concentrate and water were added. The mixture was finally filled into the dishes. Samples were subjected to physicochemical, microbial and sensory evaluation after 48 hours of storage at 4 °Ċ. The AOAC (2000) methods were used for measuring the moisture content and fat. The amount of carbohydrate, acidity, and pH were calculated based on method of Ebrahimi et al (2018). To measure the free radicals inhibition by DPPH, method Kamkar (2009) was followed. The color analysis was performed based on the method of Hosseini et al (2019). The parameters of color include L* (lightness), a* (redness) and b* (yellowness) were measured. Texture parameters include hardness (N), cohesiveness, springiness (cm), gumminess (N), chewiness (N.cm), adhesiveness were determined by texture analyzer as described by AOAC (2000). The sensory attributes were evaluated by 15 panelists. A five-point hedonic scale rating (1= very bad, 2=bad, 3= neither bad nor good, 4= good, 5= very good) was carried out. Data analyzed with SPSS software and means were compared with Duncan multiple range test.

    Results and discussion

    The results showed that the increase in the amount of grape juice concentrate in dessert samples caused a significant (p< 0.05) increase in acidity, hardness, total solid, a*, and b* value, and percentage antioxidant activity and a significant (p<0.05) decrease in fat, sucrose, pH and L* index. Grape juice concentrate has no significant (p˃0.05) effect on the texture indexes, total count, mold and yeast. The results of microbial tests showed that the total bacterial count increased in samples of grape juice compared to control (p <0.05) but mold and yeast counts were not significantly different in dessert dairy samples (p˃0.05). It should be noted that the microbial count of the samples is in accordance with the standard dairy dessert No. 14725. Sensory evaluation indicated that the addition of grape juice concentrate in the dessert samples did not have any significant effect on the textural characteristics but increased the score of other sensory factors. The sample containing 10% of grape concentrate juice obtained the highest score in odor, sweetness, color, and acceptance, and since its other characteristics were standard, it was selected as the best treatment.

    Keywords: dairy dessert, Grape Juice Concentrate, Physicochemical Properties, Sensorial Atribiute
  • Mahsa Faridnia, Ali Mohammadi sani, Masoud Najaf Najafi* Pages 313-322
    Introduction

    Natural substances with plant sources are rich in bioactive and useful compounds that promote health and improve the physicochemical properties of food products. Compounds such as antioxidants, polyphenols, pigments, flavors and etc. are among the most important bioactive plant-based compounds. Red beetroot is one of the unique plants that are rich in antioxidants, anthocyanins, and red pigmentation. The red pigment of the red beetroot is known as betacyanin, and betanin is the major betacyanin compound in red beetroot. Therefore, due to the red beetroot rich in natural pigments, especially betalains, this plant product has a high potential for use as a natural colorant in food, pharmaceutical, and cosmetic products. However, the restrictions on the use of natural and edible pigments are unstable during processing and preservation. The encapsulation process is one of the effective strategies in the food industry to resolve this problem and to protect bioactive compounds during production and storage. Different methods have been used for encapsulation of bioactive compounds, among which the most prominent ones are freeze-drying, emulsion, spray drying, liposomal, niosome, coacervation, and so on. Freeze drying and spray drying are two of the most widely used and industrial methods for the encapsulation of bioactive compounds, pigments, extracts, pharmaceuticals, and microorganisms. So, the aim of this study was to produce red beetroot pulp powder as a source of bioactive and colorant compounds using spray and freeze-drying processes.

    Materials and methods

    Whey protein isolate (WPI) and maltodextrin with a DE 18-20 in different ratios (100: 0, 75:25, 50:50, 25:70 and 0: 100) as wall materials were used to the beetroot extract encapsulation. The spray drying process of the extracts was carried out at an inlet air temperature of 140 °C and outlet air temperature of 65-70 °C with a pump power of 75%, a compressed air flow of 3.5 m3/h, and a feed flow rate of 5 mL/min. To dry the freeze-dried extracts, each sample was first kept at a temperature of -18°C for 3 h, and then the drying operation was performed in a freeze dryer for 24 h. In all treatments, the Brix feed solution was kept constant at 10%. The produced powders were evaluated in terms of encapsulation efficiency, moisture content, water solubility, and total phenol content.

    Results & discussion

    The results showed that by increasing the amount of WPI to 50% (50:50 ratio), encapsulation efficiency significantly increased (p<0.05). In the spray and freeze-dried samples, the lowest moisture content was observed in the sample treated with 100% maltodextrin. Increasing the maltodextrin ratio significantly (p<0.05) increased the solubility of the powders in water. The evaluation of total phenol content showed that the red beetroot extract powders prepared with freeze dryer had the total phenol content. Also, the powder samples obtained from the ratio of 50:50 maltodextrin to WPI had the highest total phenolic content. Based on the results obtained in this study, it was found that the use of the 50:50 ratio for maltodextrin and WPI resulted in desirable physicochemical properties in the powders obtained by both drying methods. Therefore, due to the high costs of freeze-drying and the results of the present study, it can be concluded that the spray drying method with the conditions applied during this study can be used as an effective and promising method for the production of natural pigments based on red beetroot extract for use in food, pharmaceutical, and cosmetic industries. Hence, using a 50:50 ratio for maltodextrin and WPI as wall materials and drying aid is recommended for the production of red beetroot pulp powder.

    Keywords: Freeze drying, Spray drying, Red beetroot, WPI, Maltodextrin
  • Haidar Naseri, Isa Hazbavi*, Feizollah Shahbazi Pages 323-330
    Introduction

    Among the foods consumed on a daily basis, milk has the most appropriate and balanced ingredients, that is the reason milk called whole food. Milk is the only known substance in nature that can provide the human body with complete and balanced nutrition. Recombined milk is a milk replacement product. Recombined milk components are more easily adjustable than milk components. The electrical conductivity is referred to as conductivity of specific material against the electric current, which is expressed in micro Siemens units per cm (mS/cm). Using electrical conductivity, valuable information is available about the quality of different materials, including food. In addition, by this method, as a simple and practical tool, the quality of many foods can be controlled. The aim of this study was to investigate the electrical conductivity of recombined milk affected by temperature, protein percentage, and lactose content.

    Materials and methods

    In order to investigate the effect of protein percentage (1, 2 and 3%) and percentage of lactose or sugar content (4, 6 and 8%) on the electrical conductivity of milk, pure dry milk powder without dietary supplementation was used. Lactose powder was used to increase the lactose content of dry milk powder. Sodium caseinate was used to increase the protein content of dry milk powder. Distilled water was used to increase the volume of samples. Total experiments were carried out at three temperature levels (50, 55 and 60 ºC). Data analysis was also done using SPSS 16 software.

    Results and discussion

    The results showed that temperature, protein percentage, and lactose percentage had a significant effect on the electrical conductivity of recombined milk. The electrical conductivity of the recombined milk ranged from 2.31 to 5.7 mS/cm at 50°C, 8% lactose, 1% protein, and 60°C, 4% lactose, 3% protein, respectively. The greatest and least effect on the electrical conductivity of recombined milk was related to the effect of protein percentage and lactose percentage, respectively. By increasing the temperature, the electrical conductivity of the reconstituted milk has increased significantly. The greatest changes in electrical conductivity (16%) of recombined milk occurred by the influence of temperature factor in protein 1% and lactose 4% and its value ranged from 2.44 to 2.83 mS/cm. In addition, the lowest changes in electrical conductivity (6%) of recombined milk were obtained by the temperature factor of 3% protein and 8% lactose, and it was increased from 4.68 to 4.95 mS/cm. By increasing protein content, the electrical conductivity of recombined milk has increased significantly. The most changes in electrical conductivity (107%) of recombined milk occurred by the influence of protein percentage at 55 °C and 6% lactose and its value ranged from 2.42 to 5.6 mS/cm. In addition, the lowest changes in the electrical conductivity (100%) of reconstituted milk occurred by the influence of protein percentage at 55 °C and 4% lactose, and its content increased from 2.5 to 5 mS/cm 5. These results indicate that the protein percentage factor has the most effect on the electrical conductivity of recombined milk (compared to two temperature factors and lactose percentage). By increasing lactose content, the electrical conductivity of recombined milk has decreased significantly. The greatest changes in electrical conductivity (13%) of recombined milk occurred by the influence of lactose percentage at 60 °C and protein 3% and its content decreased from 5.7 to 4.95 mS/cm. Also, the smallest changes in electrical conductivity (1.5%) of reconstituted milk occurred by the influence of lactose percentage at 55 °C and 2% protein, and its content decreased from 5.55 to 4.48 mS/cm. The maximum and minimum amount of electrical conductivity of reconstituted milk was 5.7 mS/cm at 60°C, 4% lactose and 3% protein, and 2.31 mS/cm at 50°C, 8% lactose and 1% protein, respectively.

    Keywords: Protein, Lactose, Reconstituted milk, Electrical conductivity
  • MohammadEbrahim Mohammadpour Mir, Sara Nanvakenari, Kamyar Movagharnejad* Pages 331-341
    Introduction

    Rice is one of the most important cereals and is the second-highest worldwide production after wheat and also is a good source of nutrients for humans. It plays an important role in the feeding of the many parts of the world including Iran. The harvested paddy rice has the high initial moisture content of nearly 25-28% (wet basis) that caused corruption. Therefore, in order to prevent corruption and safe storage, it must be dried to 10-13% moisture content. Drying is one of the oldest methods of preserving food and agricultural products that used to increase the food’s storage time. There are several methods for drying paddy rice that none of them are ideal and have several advantages and disadvantages that one of them that recently the use of it has been increased is microwave drying. Microwave drying uses electromagnetic radiations with the frequency range of 300 MHz to 300 GHz and the wavelengths of 1-0.01m. In microwave drying due to better energy concentration, moisture is removed more quickly so the drying time decreases. Due to the complex relationship between input and output variables in the drying process, the selection of the model that can estimate the drying behavior of the products is difficult. Hence, the use of intelligent modeling methods such as neural networks is the best choice.

    Materials and methods

    In this research, in order to investigate the effect of microwave power on kinetics of rice drying, head rice yield and effective diffusivity coefficient of moisture, a continuous type of domestic microwave dryer ( DEM-281 QOT-PW) were used. This dryer has a microwave radiation chamber where the samples are put on it on the tray that was placed on a digital balance. The experiments were performed at three microwave power levels designated as 270, 360 and 450 W. Also, Shirudi paddy rice was used as the raw material and the drying rice process from the initial moisture content of 21% to the final moisture content of 11% is examined. In this study, the neural network toolbox of MATLAB 2017R was used to model the kinetics of rice drying in the microwave dryers. RBF and MLP have 3 layers including input, hidden and output layers. The input layer has two neurons that show the number of input variables that were time and microwave power and the output layer has one neuron that shows the number of output variables that was MR in this study. 70% and 30% of the data was used for training and testing the network, respectively. To estimate the ANN performance, mean square error (MSE) and the coefficient of determination (R2) was used.

    Results and discussion

    The maximum and minimum drying time was 42 and 20 minutes in 270 and 450 watts, respectively. Also, the maximum and minimum effective diffusivity coefficient of moisture were 4.17 * 10^-9 and 1.82* 10^-9 in 450 and 270 watts, respectively. RBF network with Guassian transfer function and high neurons number and MLP network with Levenberg-Marquardt ( LM) learning algorithm and tan-sigmoid (tansig) transfer function with low neurons number were able to model the kinetics of drying as well as. In general, the drying time and head rice yield decreased but the effective diffusivity coefficient of moisture increased by increasing the microwave power. Also drying at different microwave power did not affect rice color and quality.  The results of the modeling of rice drying by using two different neural networks including MLP and RBF demonstrated that the MLP network with Levenberg-Mrrqurdt (LM) learning algorithm and tan-sigmoid (tansig) transfer function has the better performance than the RBF network with Gussian transfer function and the error and the correlation coefficient in MLP are less and higher than the RBF, respectively.

    Keywords: Microwave dryer, Head rice yield, Kinetics of rice drying, Neural network, ffective diffusivity coefficient of moisture, Rice quality