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پژوهشهای علوم و صنایع غذایی ایران - سال یازدهم شماره 4 (پیاپی 34، مهر و آبان 1394)
  • سال یازدهم شماره 4 (پیاپی 34، مهر و آبان 1394)
  • بهای روی جلد: 5,000ريال
  • تاریخ انتشار: 1394/08/13
  • تعداد عناوین: 17
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  • ام آرن، ی ی، رل ا، ی وری صفحات 285-295
    چای با نام علمی Camellia sinensis از دم نوش های رایج و معروف در دنیا محسوب می گردد. مهم ترین ترکیب شیمیایی چای پلی فنول ها(کاتچین ها) هستند که دارای خاصیت آنتی اکسیدانی و ضدسرطانی بوده و در جلوگیری از بروز بیماری های قلبی مفید می باشد. هدف از این پژوهش، بررسی اثر عوامل مختلف از جمله دما در چهار سطح(40، 60، 80 و 100 درجه سانتی گراد)، زمان(در چهار سطح 15،30، 45 و 60 دقیقه(، توان امواج مایکروویو(300، 600 و 900 درصد)و شدت امواج فراصوت (40، 60، 80 و 100 درصد) بر میزان استخراج پلی فنول ها از برگ چای سیز و فعالیت آنتی اکسیدانی عصاره در سه روش هیت رفلاکس، مایکروفر و فراصوت بوده است. نتایج نشان داد که با افزایش دما تا C°80، زمان تا 45 دقیقه، افزایش شدت امواج فراصوت از 40 تا 80 درصد و افزایش توان امواج مایکروویو از 300 تا 600 درصد، میزان پلی فنول های استخراج شده و فعالیت آنتی اکسیدانی عصاره در هر سه روش افزایش یافته و پس از آن تقریبا بدون تغییر بوده است. (0.05=α).
    کلیدواژگان: چای سبز، ترکیبات پلی فنولی، فعالیت آنتی اکسیدانی، هیت رفلاکس، فراصوت، مایکروویو
  • سیدعلی مرتضوی، فخری شهیدی، علیرضا صادقی، بلال صادقی صفحات 296-308
    در این پژوهش، تاثیر دماهای 28 و 32 درجه سانتی گراد و زمان های تخمیر 16و 24 ساعت دو نوع کشت آغازگر اختصاصی شامل لاکتوباسیلوس پلانتاروم و نسبت مساوی از مخلوط سویه مذکور با لاکتوباسیلوس برویس بر قوام خمیرترش و سپس تاثیر این شرایط تخمیری بر pH و اسیدیته قابل تیتر خمیرترش و همچنین حجم مخصوص پس از پخت، سفتی بافت، عطر و طعم نان های خمیرترشی حاصل از آرد مورد استفاده در تهیه نان های بربری، تافتون، سنگک و لواش مورد ارزیابی قرار گرفت. قوام این نمونه ها بر اساس روش قوام سنجی آدامز، بررسی و با نمونه شاهد مقایسه شد. این آزمایش ها در قالب طرح پایه کاملا تصادفی و با چهار تکرار صورت گرفته و مدل هایی به منظور ارزیابی شرایط تخمیر کشت آغازگر اختصاصی بر قوام خمیرترش حاصل از آردهای مذکور ارائه گردید. نتایج حاصل نشان داد که شرایط تخمیر بر قوام خمیرترش حاصل از آرد های مورد استفاده در مقایسه با نمونه شاهد، تاثیر معنی داری دارد (01/ 0≥ p). بر اساس این نتایج، نمونه های فرآوری شده با آغازگر لاکتوباسیلوس پلانتاروم در مقایسه با آغازگر دیگر و همچنین نمونه های فرآوری شده با آرد بربری در مقایسه با سایر آردها دارای مقادیر گسترش پذیری بیشتری بودند. علاوه بر این، در اکثر این تیمارها تفاوت معنی داری بین مقادیر اسیدیته قابل تیتر خمیرترش های حاصل از آردهای بربری و سنگک با یکدیگر و همچنین خمیرترش های حاصل از آردهای تافتون و لواش با یکدیگر مشاهده نشد. مقادیر گسترش پذیری خمیرترش-های حاصل از آردهای تافتون و لواش نیز تفاوت معنی داری با یکدیگر نداشتند اما این تفاوت بین خمیرترش های حاصل از آردهای بربری و سنگک کاملا معنی دار بود. بیشترین میزان حجم مخصوص نیز در نان فرآوری شده با خمیرترش دارای لاکتوباسیلوس پلانتاروم در مقادیر بیشینه دما و زمان تخمیر هنگام استفاده از آرد بربری بدست آمد اما روند تغییرات سفتی بافت، عطر و طعم نان های خمیرترشی از الگوی معینی پیروی نکرد.
    کلیدواژگان: کشت آغازگر اختصاصی، آرد های ایرانی، قوام خمیر، حجم مخصوص نان
  • عاطفه زمانی قلعه شاهی، رضا فرهوش، سید محمد علی رضوی صفحات 309-318
    در پژوهش حاضر، اثر پوشش دهی با هیدروکلوئید دانه ریحان (غلظتهای 5/ 0 و 1 درصد، وزنی/ وزنی) و مقایسه آن با هیدروکلوئیدهای رایج نظیر گزانتان و متیل سلولز (غلظتهای 5 /0 و 1 درصد، وزنی/ وزنی) بر میزان جذب روغن، خروج رطوبت، رنگ و بافت خلال سیب زمینی طی فرآیند سرخ کردن عمیق مورد مطالعه قرار گرفت. نتایج حاکی از آن بود که میزان جذب روغن در همه نمونه های پوشش دهی شده در مقایسه با نمونه شاهد کمتر بود. کمترین میزان جذب روغن در خلالهای سیب-زمینی تیمار شده با دانه ریحان 1 و 5 /0 درصد (به ترتیب 14 /0 و 16/ 0 گرم بر گرم ماده خشک) مشاهده شد. خلالهای سیب زمینی بدون پوشش (شاهد) و تیمار شده با متیل سلولز 5/ 0 درصد به ترتیب بیشترین میزان جذب روغن را دارا بودند. پوشش با مواد هیدروکلوئیدی به افزایش مقدار رطوبت خلالهای سرخ شده در مقایسه با تیمار شاهد منجر گردید. بیشترین میزان نگهداری رطوبت به ترتیب به نمونه های تیمار شده با هیدروکلوئید دانه ریحان در غلظتهای1 و 5/ 0 درصد مربوط بود. همچنین بیشترین تغییرات کلی رنگ و سفتی بافت به ترتیب به نمونه های تیمار شده با گزانتان و دانه ریحان در غلظت 1 درصد مربوط می شد.
    کلیدواژگان: پوشش های صمغی، جذب روغن، سرخ کردن عمیق، سیب زمینی
  • محمود یلمه، محمد باقر حبیبی نجفی، محمود نجف زاده صفحات 319-324
    اشریشیاکلی و باسیلوس سرئوس علاوه بر ایجاد فساد در مواد غذایی می توانند در مصرف کنندگان مواد غذایی حاوی مقدار کافی از این باکتری ها مسمومیت ایجاد کنند. به همین دلیل حذف یا کنترل این باکتری ها به شکلی ایمن اهمیت پیدا می کند. در این مطالعه اثر ضد باکتریایی پرتو فرا بنفش در مدت زمان های مختلف، بر رشد اشریشیا کلی و باسیلوس سرئوس مورد ارزیابی قرار گرفت. بدین منظور ابتدا اشریشیا کلی و باسیلوس سرئوس را به ترتیب از شیر خام و برنج جداسازی و سپس به ترتیب در محیط کشت های EMB وMYP به مدت 24 تا 48 ساعت کشت داده شدند؛ در مرحله ی بعد پس از انجام آزمایشات تاییدی مناسب، کشت خالص مربوط به هر یک از باکتری ها تهیه شد. بررسی ها نشان داد که بیشترین اثر پرتو فرابنفش بر باکتری ها در طول موج حدود 260 نانومتر است. مشاهده شد که باسیلوس سرئوس نسبت به اشریشیا کلی مقاومت بیشتری به پرتو فرابنفش نشان می دهد به شکلی که مقدار کلنی های اشریشیا کلی پس از 80 ثانیه قرار گرفتن در مجاورت با طول موج 254 نانومتر، به صفر نزدیک می شود اما در مورد باسیلوس سرئوس پس از این مدت به 1500 می رسد؛ و نیز با افزایش مدت زمان پرتو دهی و در غیاب نور مرئی تعداد میکروارگانیسم ها بیشتر کاهش می یابد.
    کلیدواژگان: اشریشیا کلی، باسیلوس سرئوس، شیر خام، برنج، پرتو فرابنفش
  • ساینا مویدزاده، اصغر خسروشاهی اصل، شهین زمردی صفحات 325-336
    در این تحقیق، تاثیر غلظت آنزیم ترانس گلوتامیناز میکروبی، میزان کازئینات سدیم و زمان نگهداری بر پروتئولیز، خواص رئولوژیکی و ظرفیت نگهداری آب در ماست همزده بدون چربی با استفاده از روش سطح پاسخ مورد بررسی قرار گرفت. غلظت آنزیم در محدوده 2-0 واحد در گرم پروتئین شیر، میزان کازئینات سدیم در دامنه 27/ 1-0 درصد و زمان نگهداری بین 19-1 روز بود. نتایج تجزیه آماری داده ها نشان داد که با افزایش غلظت آنزیم ویسکوزیته و ظرفیت نگهداری آب در نمونه ها به طور معنی داری افزایش و میزان پروتئولیز در آنها کاهش یافت (p≤0.05). با افزودن کازئینات سدیم نیز ویسکوزیته، ظرفیت نگهداری آب نمونه ها افزایش پیدا کرد. همچنین در طی نگهداری، ظرفیت نگهداری آب کاهش و میزان پروتئولیز افزایش معنی داری نشان داد (p≤0.05). در شرایط بهینه، غلظت آنزیم 42/ 1 واحد در گرم پروتئین شیر، میزان کازئینات سدیم 47/ 0 درصد و زمان نگهداری 15 روز تعیین گردید. مقدار مطلوبیت کلی برابر 83/ 0 بود. در شرایط مزبور درصد ظرفیت نگهداری آب، ویسکوزیته و پروتئولیز به ترتیب 51 /27 درصد، 5220 سانتی پوآز و میزان جذب آن در طول موج 340 نانومتر به عنوان شاخص پروتئولیز 349/ 0 بود.
    کلیدواژگان: آنزیم ترانس گلوتامیناز، پروتئولیز، پیوندهای عرضی، ماست بدون چربی
  • حبیب جهاندیده، مسعود تقی زاده، محمدحسین حداد خداپرست، آرش کوچکی صفحات 337-350
    کنجاله ارده نقش تغذیه ای مناسبی از نظر پروتئین با کیفیت بالا و مواد معدنی نظیر کلسیم و فسفر ایفا می کند. جایگزینی بخشی از آرد گندم با کنجاله ارده اثرات نامطلوبی بر خواص فیزیکی و بافتی نان دارد. در مطالعه حاضر، اثرات صمغ زانتان (0، 25/ 0 و %5/ 0) بر خواص فیزیکی نان باگت دارای کنجاله ارده (0، 37/ 4، 45/ 9 و %53/ 14) شامل حجم مخصوص، تخلخل، رنگ مغز و پوسته نان و خواص بافتی شامل سختی، صمغیت و پیوستگی بررسی شد. آزمون های فوق با آرایش فاکتوریل و در قالب طرح تصادفی کامل انجام شد. خواص بافتی پس از 3، 24 و 48 ساعت نگهداری تعیین شد. نتایج نشان داد کنجاله ارده در غلظت بالاتر از %37/ 4 باعث کاهش معنی دار تخلخل، افزایش معنی دار سختی و صمغیت، کاهش معنی دار حجم مخصوص درسطح %53/ 14 می شود (01/ 0>P). با افزایش کنجاله ارده، مولفه L* مغز و پوسته کاهش و مولفه های a* و b* مغز افزایش معنی دار نشان داد. %25/ 0 صمغ زانتان تخلخل را افزایش داد ولی %5/ 0 صمغ باعث افت معنی دار تخلخل و حجم مخصوص در مقایسه با شاهد شد (01/ 0>P). با افزایش صمغ زانتان، افزایش مولفه L* مغز و پوسته و کاهش معنی دار مولفه b* مغز مشاهده شد. افزایش معنی دار سختی و صمغیت با افزایش صمغ زانتان از %25/ 0 و افزایش زمان نگهداری مشاهده شد (01/ 0>P). افزایش کنجاله ارده، صمغ زانتان و زمان نگهداری کاهش معنی دار پیوستگی را نشان داد (01/ 0>P). با افزودن %25/ 0 صمغ زانتان اثرات نامطلوب کنجاله ارده بر خواص فیزیکی، بافتی نان باگت تا حدودی جبران شد.
    کلیدواژگان: باگت، شاخص های رنگ، صمغ، کنجاله ارده
  • حمیدرضا صمدلویی، روشنک احمد مخبری صفحات 351-360
    تولید توده زیستی، روغن، آراشیدونیک اسید و همچنین بیان ‍ژ‍ن های طویل ساز موثر در تولید آراشیدونیک اسید در گونه قارچی Mortierella alpina CBS 754.68 مورد بررسی قرار گرفت. نتایج نشان داد غلظت بالای گلوکز (70 گرم در لیتر) اثر بازدارندگی در تولید روغن داشته درحالیکه باعث افزایش تولید توده زیستی شد. در سطح پایین گلوکز (50 گرم در لیتر) و پودر سویا (10 گرم در لیتر) میزان تولید روغن حداکثری (47% توده زیستی) می باشد در حالیکه در این شرایط میزان تولید آراشیدونیک اسید نسبت به بقیه تیمارها کمتر می باشد. سطوح پایین گلوکز و بالای سویا باعث افزایش آراشیدونیک اسید (56%) نسبت به بقیه تیمارها شد. نتایج نشان داد که میزان بیان ژن GLELO وقتی میزان کربن به زیر 5 گرم در لیتر در روز ششم رسید کاهش یافت. با بررسی میزان بیان ژن MALC1 و GLELO چنین مشخص شد که GLELO ژن محدود کننده تولید آراشیدونیک اسید می باشد.
    کلیدواژگان: Mortierella alpina، چربی، آراشیدونیک اسید، بیان ژن، ~ژن طویل ساز
  • مسعود تقی زاده، امیر جاجرمی صفحات 361-371
    مدل سازی ریاضی به منظور تخمین جرم لیموترش با استفاده از خصوصیات هندسی (ایعاد، حجم) و سطح تصویری صورت پذیرفت. مدل ها به صورت تک و چند پارامتری ایجاد شدند. همچنین خصوصیات فیزیکی لیموترش شامل ایعاد هندسی، جرم، حجم، دانسیته میوه و توده، ضریب اصطکاک و سطح تصویری میوه اندازه گیری شدند. سطح تصویری لیموترش با استفاده از تکنیک پردازش تصویر و در 3 بعد محاسبه گردید. در میان مدل های ساخته شده، مدلی بر مبنای3 بعد میوه، حجم محاسبه شده با استفاده از فرمول محاسبه حجم کره دوکی شکل و سطح سوم تصویری لیموترش با ضریب تبیین 909/.، 958/.، 942/. و خطای استاندارد تخمین 52/ 1، 19/ 1، 14/ 1 به ترتیب به عنوان مدلهایی مناسب جهت پیشگویی جرم لیموترش و مدلی بر مبنای 3 بعد میوه و سطح تصویری سوم لیمو ترش با ضریب تبیین 951/ 0 و 942/ 0 و خطای استاندارد 32/ 1 و 41/ 1 به ترتیب به عنوان مدلهای مناسب جهت تخمین حجم لیموترش پیشنهاد گردید. به منظور بررسی خصوصیات فیزیکی لیموترش و روابط بین آنها از روش تحلیل مولفه اصلی استفاده گردید. نتایج نشان دهنده وجود رابطه نزدیک میان سطوح اصطکاکی با یکدیگر و پارامتر های رنگی لیموترش می باشد.
    کلیدواژگان: لیمو ترش، خصوصیات فیزیکی، پردازش تصویر، مدل سازی ریاضی
  • فرهاد سلمانی زاده جوپاری، علی اصغر زمردیان، حسین رحمانیان، حسن صفی یاری صفحات 372-381
    میوه های خرمالو از زمان برداشت تا مصرف در معرض شرایط محیطی مختلف قرار می گیرند. از آنجاییکه ویژگی های رئولوژی میوه ها برای هر عملیات فرآوری مهم می باشد، رفتار لزج-کشسان میوه های خرمالو در طی نگه داری در شرایط محیطی بوسیله ی تخمین پارامترهای آسایش آن از طریق داده های تجربی آسایش تنش بررسی شد. رفتار رئولوژی میوه های خرمالو تحت آزمون فشاری تک محوری برای رهایی تنش به مدت 480 ثانیه ارزیابی شد. سه مدل معروف آسایش تنش به نام های مدل سه جزئی ماکسول عمومی، ناسینوویچ و پلگ بر داده های تجربی برازش شدند و برای ارزیابی مدل ها از شاخص های ضریب تبیین (R2)، خطای استاندارد تخمین (SEE) و درصد خطای نسبی متوسط (ARE%) استفاده گردید. نتایج نشان داد که در طی نگه داری میوه خرمالو در شرایط محیطی مقدار تنش اولیه لازم برای ایجاد یک کرنش ثابت در میوه کامل به طور معنی داری به میزان 80% کاهش یافت، ولی زمان آسایش تنش در گستره ی 10/ 312 تا 90/ 353 ثانیه افزایش یافت. طبق نتایج بدست آمده در طی نگه داری میوه، رفتار کشسان میوه خرمالو تشدید و سفتی آن کاهش یافت. هرسه مدل رفتار لزج-کشسان میوه های خرمالو را تایید کردند، با این وجود مدل های سه جزئی ماکسول عمومی (با R2=0.999، SEE=0.017 و ARE=0.19%) و ناسینوویچ (با R2=0.996، SEE=0.057 و ARE=0.36%) بهترین مدل ها در پیش بینی داده های تجربی بودند.
    کلیدواژگان: مدل سه جزئی ماکسول، مدل ناسینوویچ، مدل پلگ، آسایش تنش، شاخص های لزج، کشسان
  • حامد سیگاری، محمد طبسی زاده، محمدحسین عباسپورفرد، محمودرضا گلزاریان صفحات 382-391
    با توجه به این که امکان اندازه گیری پیوسته جرم محصول در خشک کن های تحت خلا وجود ندارد، روش های تخمین رطوبت محصول درون محفظه خلا کاربرد پیدا می کند. در این پژوهش از مدل سازی ریاضی برای تخمین رطوبت میوه کیوی در شرایط خلا استفاده شده است.
    ورقه های میوه کیوی درون خشک کن تحت خلا در فشار 10 کیلوپاسکال و دمای 70 درجه سلسیوس خشک گردیدند. ضمن انجام آزمایش، محصول با فواصل 30 دقیقه توزین و نمودار های رطوبت نهایی محصول در یک فشار، دما و ضخامت مشخص بر حسب زمان رسم شد. از توابع چندجمله ای، تابع نمایی درجه یک، توابع کسری و توابع گاوسی برای مدل سازی فرآیند خشک شدن با استفاده از نرم افزار متلب استفاده گردید. برای مقایسه نتایج توابع پیش بینی کننده، مقادیر ضریب همبستگی و مربع میانگین خطای نسبی مورد مقایسه قرار گرفت. بهترین منحنی گذرا از نمودار رطوبت نسبی محصول بر حسب زمان، با استفاده نرم افزار متلب ترسیم گردید و تابع کسری با درجه صورت و مخرج یک و سپس تابع چند جمله ای درجه 3 با بیشترین ضریب همبستگی R2، به ترتیب 9991 /0 و 9977/ 0 و کمترین مربع میانگین خطای نسبی RMSE، به ترتیب 01267/ 0 و 02412/ 0 برای پیش بینی فرآیند خشک شدن در خشک کن خلا تعیین گردید. ضریب انتشار حرارتی برای ضخامت های مختلف کیوی از روی نمودار (Ln(MR بر حسب زمان بدست آمد و نشان داده شد که با افزایش ضخامت مقدار این ضریب نیز افزایش پیدا می کند.
    کلیدواژگان: خشک کن خلا، مدل سازی ریاضی، محتوای رطوبت
  • مرضیه رمزی، مهدی کاشانی نژاد، علیرضا صادقی ماهونک، سید محمد علی رضوی صفحات 392-392
    در این تحقیق خصوصیات فیزیکوشیمیایی و رفتار رئولوژیکی چهار نمونه از عسل های طبیعی استان گلستان با منشا گل های مختلف شامل دو نمونه عسل تک گل (آفتابگردان و عشقه) و دو نمونه عسل چند گل (جنگل و کوهستان) با یک نمونه عسل شکری و یک نمونه عسل تقلبی مورد مقایسه قرار گرفت. مقادیر به دست آمده مربوط به خصوصیات فیزیکو شیمیایی در تمام نمونه هابا هم متفاوت بود. در عسل های طبیعی این تفاوت می تواند به علت تفاوت در نوع گل و گیاه موجود در منطقه و فصل برداشت عسل مربوط باشد. تمام مقادیر به دست آمده در عسل های طبیعی مطابق با مقادیر تعیین شده توسط استاندارد و کدکس بود. درصد ساکارز و نسبت فروکتوز به گلوکز عسل شکری و درصد ساکارز، نسبت فروکتوز به گلوکز، pH، هیدروکسی متیل فورفورال و فعالیت دیاستاز عسل تقلبی با مقادیر تعیین شده توسط استاندارد عسل مطابقت نداشت. ویژگی های رئولوژیکی نمونه های عسل در دما های مختلف (10، 15، 20، 25 و 30 درجه سانتی گراد) مورد ارزیابی قرار گرفت. در محدوده سرعت برشی مورد مطالعه (1s-41/8-1/045) تمامی نمونه ها رفتار نیوتنی از خود نشان دادند. مقادیر ویسکوزیته با توجه به نوع عسل و دمای اندازه گیری در محدوده 7/ 1 تا 48 /270 به دست آمد. نمونه ی عسل تقلبی در مقایسه با نمونه ی عسل طبیعی با همان مقدار رطوبت از ویسکوزیته بیشتری برخوردار بود. در توصیف وابستگی دمایی ویسکوزیته دو مدل آرنیوس و (Vogel–Taumman–Fulcher) VTF و در توصیف وابستگی ویسکوزیته به رطوبت و غلظت (درجه بریکس)، مدل های قانون توان و نمایی برازش خوبی را با داده ها نشان دادند.
    کلیدواژگان: عسل، تقلب، خصوصیات فیزیکو شیمیایی، رئولوژی، مدل آرنیوس، مدلVTF
  • سید حمید مرتضوی، صدیف آزادمرد دمیرچی، رزاق محمودی، محمود صوتی، مجید شیرمحمدی صفحات 408-419
    هدف از این پژوهش، مطالعه و بررسی ترکیبات شیمیایی و تغذیه ای پوسته و مغز هسته میوه پسته وحشی گونه خینجوک (Khinjuk) بود. برای این منظور، از پوسته و مغز هسته میوه به روش سرد با هگزان روغن گیری شد و پروفایل اسیدهای چرب با روش کروماتوگرافی گازی بررسی گردید. همچنین از روغن های استخراجی نگهداری شده به مدت 3 ماه در دمای اتاق، هر 30 روز آزمون های عدد پراکسید، عدد اسیدی و مقدار کلروفیل اندازه گیری شدند. از پوسته و مغز هسته خشک شده میوه به روش پرکولاسیون با اتانول عصاره گیری شد و میزان ترکیبات فنلی و قدرت مهار رادیکال های آزاد DPPH عصاره ها مورد ارزیابی قرار گرفت. همچنین عصاره ها در درصدهای 1، 2 و 3 درصد به روغن کلزا اضافه شدند و پایداری اکسیداتیو آن ها با دستگاه رنسیمت بررسی گردید. نتایج نشان داد نوع و درصد اسیدهای چرب غالب در پوسته و مغز هسته میوه به ترتیب اولئیک اسید 33 و 2/ 41، لینولئیک اسید 6/ 10 و 5 /21، آلفالینولنیک اسید 6 و 1/ 3، پالمیتیک اسید 2/ 17 و 11، پالمیتولئیک اسید 1/ 13 و 1/ 3 بودند. میزان ترکیبات فنلی در پوسته و مغز هسته به ترتیب 6/ 25 و 3 /6 میلی گرم اسید گالیک درگرم نمونه خشک بدست آمد. عدد پراکسید و عدد اسیدی در طول 4 ماه نگهداری به طور معنی داری افزایش پیدا کرداما مقدار کلروفیل در طول زمان به طور معنی داری کاهش پیدا کرد (01/ 0≥p). بیشترین پایداری اکسیداتیو روغن کلزا مربوط به تیمار 3 درصد عصاره پوسته بود (05/ 0≥p). عصاره پوسته تاثیر بیشتری بر مهار رادیکال های آزاد (88 درصد) نسبت به مغز هسته (75درصد) داشت که این دو می توانند ناشی از مقادیر بالاتر ترکیبات فنولیک پوسته باشد.
    کلیدواژگان: پسته وحشی، ترکیبات شیمیایی، خینجوک، ویژگی آنتی اکسیدانی
  • روناک غلامی، جلال دهقان نیا، بابک قنبرزاده صفحات 420-434
    هدف از این تحقیق، بررسی انتقال جرم در فیلم های نانوکامپوزیت نشاسته-نانوکریستال سلولز (NNC) بود. تاثیر افزودن درصدهای مختلف NCC، بر میزان جذب رطوبت و نفوذپذیری نسبت به بخار آب و سینیتیک جذب رطوبت در نمونه های نانوکامپوزیت مورد بررسی قرار گرفت. از قانون دوم فیک و چهار معادله تجربی برای مدل سازی جذب رطوبت استفاده شد. همچنین، تاثیر غلظت گلیسرول بر میزان نفوذپذیری نسبت به بخار آب بررسی و داده های تجربی با یک مدل نمایی برازش شدند. نتایج نشان داد که روند تغییرات نفوذپذیری نسبت به بخار آب، به صورت تابعی از غلظت پلاستی سایزر از یک نمایی تبعییت می کند و مقاومت رطوبتی فیلم ها با افزیش غلظت NCC و گلیسرول به ترتیب افزایش و کاهش می یابد. همچنین، مراحل ابتدایی جذب رطوبت به خوبی توسط قانون فیک توصیف شد.
    کلیدواژگان: مدل سازی، انتقال جرم، نشاسته، نانوکامپوزیت
  • محسن زندی، محبت محبی، مهدی وریدی، نوید رمضانیان صفحات 435-444
    در این پژوهش میکروکپسول جدیدی تحت عنوان میکروکپسول آلژینات- پروتئین آب پنیر حامل دی استیل تهیه و خصوصیات آن تعیین گردید. رهایش دی استیل در شرایط شبیه سازی شده دهانی در سطوح مختلف بزاق به میکروکپسول (0:1، 1:4 و 1:8) و نیروهای برشی متفاوت (0، 50 و 100 معکوس ثانیه) مورد بررسی قرار گرفت و ضریب نفوذ با کمک معادله فیک تخمین زده شد. هدف اصلی این پژوهش توسعه مدلی به منظور پیش بینی فرآیند رهایش و نیز تخمین ضریب نفوذ از میکروکپسول جدید ابداعی بوده تا بتوان به کمک آن رهایش کنترل شده عطر و طعم در شرایط دهانی ایجاد نمود. نتایج این تحقیق نشان داد که مدل حاصله می تواند با ضریب همبستگی بالای 95 درصد رفتار رهایش را پیش بینی نموده و علاوه بر این مدل مذکور به خوبی قادر به تخمین میزان ضریب نفوذ می باشد. نتایج همچنین نشان داد که اعمال نیروی برشی بطور معناداری سبب افزایش ضریب نفوذ شده درحالیکه تغییر میزان بزاق تاثیر معناداری بر آن ندارد.
    کلیدواژگان: ضریب دیفوزیون، قانون فیک، میکروکپسول آلژینات، پروتئین آب پنیر، دی استیل، رهایش کنترل شده
  • فروغ محترمی، محسن اسمعیلی، محمد علیزاده خالدآباد، سید مهدی سیدین اردبیلی صفحات 445-457
    اثر افزودنی های مختلف (اینولین به عنوان پری بیوتیک، پودر آب پنیر، آنزیم آسپاراژیناز و ترانس گلوتامیناز) بر ویژگی های فارینوگرافی و اکستنسوگرافی دو نوع آرد (قوی و ضعیف) گندم با استفاده از طرح مورد مطالعه قرار گرفت. ویژگی های فارینوگرافی مانند درصد جذب آب، زمان گسترش، پایداری خمیر، درجه نرم شدگی خمیر، عدد کیفیت فارینوگراف و ویژگی های اکستنسوگرافی مانند مقدار انرژی، قابلیت کششی، مقاومت کششی و نسبت مقاومت کششی به قابلیت کششی تعیین شدند. تمام مدل های رگرسیون در سطح 01/ 0 و با ضریب تبیین R2: 81/70 تا %67/ 98 معنی دار و قادر به پیش بینی ویژگی های خمیر فرموله شده بودند. نوع آرد و سطح اینولین اثر منفی زیادی بر درجه نرم شدگی خمیر و اثر مثبت بر زمان گسترش، پایداری، عدد کیفیت فارینوگراف، قابلیت کششی و مقاومت کششی نشان داد. درصد جذب آب با افزایش سطح اینولین، کاهش و با کاربرد آرد قوی، افزایش یافت. پودر آب پنیر اثر مشابه با اینولین بر پارامترهای فارینوگرافی و اکستنسوگرافی داشت. آنزیم آسپاراژیناز و ترانس گلوتامیناز به تنهایی اثر معنی دار بر ویژگی های فارینوگرافی نداشتند ولی اثر بر همکنش آنها بر کاهش درجه نرم شدگی خمیر معنی دار بود. تمام پارامترهای اکستنسوگراف به جز قابلیت کششی به طور قابل توجهی تحت تاثیر ترانس گلوتامیناز قرار گرفت. درمیان برهمکنش ها، برهمکنش بین آنزیم ترانس گلوتامیناز و نوع آرد مصرفی اثر مثبت قابل توجهی بر مقاومت کششی خمیر داشت.
    کلیدواژگان: فارینوگراف، اکستنسوگراف، پری بیوتیک، خمیر آرد گندم
  • حسن صباغی امان، محمد ضیایی فر، علیرضا صادقی ماهونک، مهدی کاشانی نژاد، حبیب الله میرزایی صفحات 473-484
    در این پژوهش ضریب انتقال حرارت جابجایی به عنوان تابعی از نرخ کاهش آب با توجه به اثرات تبخیر آب و جوشش روی این پارامتر طی سرخ کردن بیان شد. کنترل حرارتی فرآیند سرخ کردن برای دستیابی به محصولی باکیفیت مطلوب بسیار اهمیت دارد. بدین منظور خلال های سیب زمینی در اندازه مشخص در روغن آفتابگردان در دمای 145، 160 و °C 175 به مدت 60، 120، 180و 240 ثانیه سرخ شدند. دمای مرکزی و سطحی خلال سیب زمینی با استفاده از ترموکوپل نوع T و دیتالاگر با فاصله زمانی 2 ثانیه ثبت شد. رطوبت خلال های سیب زمینی نیز با خشک کردن آن ها در آون اندازه گیری شد. با فرض اینکه کل حرارت منتقل شده از روغن به سطح خلال سیب زمینی برای حرارت دهی سیب زمینی و برای تبخیر آب استفاده می شود، ضریب انتقال حرارت جابجایی تخمین زده شد و تغییرات آن طی فرآیند بررسی شد. همچنین تغییرات جزء حرارتی مصرف شده برای تبخیر آب به صورت یک مدل تجربی نمایی بیان شد. نتایج نشان داد که ضریب انتقال حرارت در دماهای بالا به دلیل نرخ خروج رطوبت بیشتر و در نتیجه تلاطم زیاد روغن بیشتر است. حداکثر ضریب انتقال حرارت برای دمای 175، 160 و °C145 به ترتیب 68/ 943، 81/ 847 و°C2W/m 64/ 682 برآورد شد. برای دماهای کمتر جزء حرارتی مورد نیاز برای تکمیل فرآیند تبخیر بیشتر می باشد که این امر نیز نشان دهنده کمتر بودن ضریب انتقال حرارت جابجایی با کاهش دمای روغن می باشد.
    کلیدواژگان: انتقال حرارت، سرخ کردن، خلال سیب زمینی، تبخیر، مدل تجربی
  • رضا صفری، زهرا یعقوب زاده صفحات 485-495
    پنیر ماهی یاfish cheese محصولی است که با استفاده از انعقاد پروتئینهای محلول آبزیان تولید میشود. هدف از انجام این بررسی استحصال و رسوب پروتئینهای سارکوپلاسمیک ماهی فیتوفاگ و استفاده از آن در فرمولاسیون فرآورده ایی شبیه پنیر بوده است. پس از آماده سازی اولیه ماهی، ماهی چرخ شده و عمل شستشو با آب نمک انجام شده و پروتئینهای سارکوپلاسمیک جدا گردید. برای رسوب و جمع آوری این پروتئینها از اسید استیک 5% و سانتریفوژ استفاده گردید. گوشت چرخ شده، خمیر پروتئینی و پنیر ماهی از نظر پارامترهای غذایی و شاخصهای شیمیایی و میکروبی مورد آزمایش قرار گرفتند.
    نتایج نشان داد که میانگین درصد چربی، رطوبت، خاکستر و پروتئین در گوشت چرخ شده ماهی کپور نقره ای، پروتئین سارکوپلاسمیک تغلیظ شده و پنیر ماهی تولید شده به ترتیب 71/ 2%، 44/ 79%، 91/ 0%، 90/ 16% و 16/ 1%، 97/ 81%، 42/ 0% و 41/ 16% و 30/ 28%، 41/ 48%، 46 /3%، 50/ 17%، 21/ 2% بوده است. بهترین فرمول تهیه شده از پنیر ماهی دارای 26 /22% پروتئین بوده است. میانگین تغییرات TVN و PV در گوشت چرخ شده ماهی کپور نقره ای، پروتئین سارکوپلاسمیک تغلیظ شده و پنیر ماهی به ترتیب 32/ 11، 51/ 1 و 63/ 13، 65/ 3 و03/ 15،38/ 5 بوده است.
    این محصول را میتوان بعنوان فرآورده جانبی در کارخانجات فرآوری ماهی تولید کرده و بعنوان فرآورده جدید شیلاتی به مردم معرفی نمود.
    کلیدواژگان: پنیر ماهی: ماهی کپور نقره ای: انعقاد اسیدی: پروتئینهای سارکوپلاسمیک
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  • Akram Arianfar, Fakhri Shahidi, Rasoul Kadkhodayi, Mahdi Varidi Pages 285-295
    Introduction
    Tea (Camellia sinensis), is the most widely beverage after water across the world. The most important chemical composition in tea is phenolic compounds (catechins) that have antioxidant and anticarcinogenic properties and are benefited for cardiovascular disease. There are two major kinds of tea, black tea and green tea. Green Tea, is originated in China and dates back to several thousand years ago. In the production of green tea, young leaves are rolled and oxidized to decreasing oxidation but in production of black tea, tea leaves are oxidized (fermented) for 90-120 min after rolling and then catechins are converted to complexe compounds (theaflavins and thearubigins). The conventional method for extraction of green tea polyphenols compounds are heating, boiling, cold and heathing refluxe extraction, with long extraction periods and low extraction efficiency. In this study 3 techniques for extraction of polyphenol compounds from Green tea leaves were investigated and compored together.The main objective of this study was to determine the effects of differrent extraction conditions, temperature (40, 60, 80 and 100° C), different time (15, 30, 45 and 60 min), microwave power (300, 600 and 900 %) and ultrasound amplitude (40, 60, 80 and 100 W) on Green tea polyphenol content and antioxidant activity in three methods including Heat Reflux Extraction(HRE), Microwave Assisted Extraction(MAE) and Ultasound Assisted Extraction(UAE).
    Materials And Methods
    Dried green tea leaves (supplied from Lahijan (Iran))were grinded for increasing the contact surface area between the solvent and solute. 1 g of green tea was extracted with 100 mL of water at various methods, Heathing Reflux Extraction(HRE), Microwave Assisted Extraction(MAE), by microsynth laboratory system (Milestone-ACT-36-Rev01) at 50 Hz and output 2450 MHz with adjustable power output (100-1000 W), temperature 180° C and Ultrasound Assisted Extraction (UAE) in double jacket vessel by using a 25 kHz ultrasonic system (model VCX 750, Sonics & Materials, Inc., USA), at a maximum nominal power output of 750W. All measurements were carried out in triplicate. The results were analysed statistically using the minitab 16 Program to determine the average value and standard error. Variance analysis, with a significant level of α= 0.05% was performed to determine the effect of time, temperature, microwave power and ultrasound amplitude on polyphenols content and antioxidant activity. Total phenol were determined spectrophotometerically by Folin-Ciocalteu method at 765 nm)Hewlett- Packard spectrophotometer model 8452A, Rockville). The antioxidant activity evaluated with the DPPH test spectrophotometrically at 517 nm.
    Results And Discussion
    These results showed that polyphenol content is increased with increasing the time, temperature, ultrasound amplitude and microwave power of extraction. By increasing temperature to 80°C, time to 45 min, ultrasound amplitude from 40 to 80 and microwave power from 300 to 600, polyphenol content and antioxidant activity was increased and after that was constant. These results showed that, H.R.E require long extraction time and have low efficiency. Polyphenol compounds are thermally unstable and maybe degredate in thermal processing. Also, the best method for extraction was MAE, because of higher yield, higher contents of pol-yphenol and shortend time and this method was very efficient in the extraction of polyphenl compounds. The efficiency of extraction by UAE method is higher than HRE and lower than MAE method.
    Conclusion
    UAE method compared to HRE method is enhanced the extraction of polyphenol, facilating solvent peneteration and increase the product releasing from intracellular. This method agitated the solvent to material and increased the contact surface between material and solven, and peneteration of solvent in to the green tea leaves. UAE canbe carried out at a lower temperature than HRE and decreased thermal damage.
    Keywords: Antioxidant Activity, Green tea, Heat Reflux Extraction(HRE), Microwave Assisted Extraction(MAE), Polyphenol compounds, Ultasound Assisted Extraction(UAE)
  • S. Ali Mortazavi, Fakhri Shahidi, Alireza Sadeghi, Belal Sadeghi Pages 296-308
    Introduction
    Sourdough has been used since ancient times and sourdough fermentation has been studied for its effect on the sensory, structural, nutritional and shelf life properties of bread. During fermentation, biochemical changes occur in the carbohydrate and protein components of the flour due to the action of microbial and indigenous enzymes. The rate and extent of these changes greatly influence the properties of the sourdough and ultimately the quality of the final baked product. From a rheological point of view, it is well established that as fermentation progresses, there is a change in nature of the elements contributing to dough structure such as the decrease in the viscosity. During sourdough fermentation, lactic acid bacteria produce a number of metabolites which have been shown to have a positive effect on the texture of bread. In addition to the direct impact of decreasing pH values on dough characteristics, secondary effects of acidification and fermentation time may include changes in the activity of cereal or bacterial enzymes associated with changes in the pH of the environment during the fermentation period. Further to the impact of sourdough on the structure and rheology of the constituent gluten proteins making up the framework of the dough, its effect on gas formation must also be considered in view of the fact that gas formation by microorganisms is necessary in order to obtain leavened bread. The application of sourdough to wheat breads has also a positive impact on bread volume. The rate of application is important, however, because optimum levels of sourdough must be applied to achieve optimal bread quality. The nature of the acidification process may also be a key. The present study was undertaken to evaluate the effects of different fermentation conditions on sourdough consistency and properties of Iranian main breads.
    Materials And Method
    In this research the fermentation temperatures (28 and 32 ºC) and fermentation times (16 and 24 hours) effects of two specific starter cultures including Lactobacillus plantarum (ATCC 43332) and a mixture of this starter with Lactobacillus brevis (ATCC 14917) on consistency of sourdoughs produced from flours of Iranian main breads (Barbari, Taftoon, Sangak and lavash), were investigated. An inoculum of mentioned strains was added to the mixture of water and wheat flour. The mixture was allowed to ferment at different fermentation temperatures and times without agitation for sourdough preparation. Then an amount of 0.5% active dry yeast extract, containing Saccharomyces cerevisiae and 25% sourdough samples (w/w) were added to each 100 g flour and mixed. The dough was left for bulk fermentation and at the end of the fermentation time; each piece was rounded before moulded by hand. The moulded dough pieces were proofed for 1.5 h at 30 ± 1 ºC and 85% relative humidity before baking at 220 ± 5 ºC for 15–16 min in a heated oven and then cooled in aseptic conditions for 1 h. The effect of fermentation conditions on pH and total titerable acidity of sourdough and also specific volume (rapeseed displacement method), firmness, aroma and flavour (based on organoleptic analysis) of sourdough breads prepared from the mentioned flours, were evaluated. Sourdoughs consistency were also estimated by Adams consistometer and compared with control samples. In these experiments a completely randomized design with four replications were conducted.
    Results And Discussion
    Based on the results, some models were developed. These results showed that, fermentation conditions had significant effect (p≤0.01) on sourdough consistency prepared from flours of main Iranian breads in comparison with control samples. Moreover the produced samples with L. plantarum compared to other starter culture and the samples processed with Barbari flour in comparison with other flours had higher extensibility values. In most treatments, total titerable acidity in Barbari and Sangak sourdoughs and also Taftoon and Lavash sourdoughs were the same. The consistency of Taftoon and Lavash sourdoughs were also similar, but consistency of Barbari and Sangak sourdoughs were completely different. The maximum amount of specific volume was observed in sourdough bread, produced with L. plantarum in highest amounts of fermentation temperature and time and using of Barbari flour, but the changes in firmness, aroma and flavour of sourdough breads did not follow a specific pattern. There exist a myriad of microbial, technological and processing dimensions that must be considered in order to produce cereal products of optimum quality. Significant advances have been made in understanding the contributions made by the presence of acids, the fermentation period and the role played by cereal and bacterial enzymes in terms of sourdough and bread characteristics.
    Conclusion
    process requirements for optimum quality were strain-specific and different for textural improvement which should be taken in to account in designing future sourdough baking processes.
    Keywords: Specific starter culture, Iranian flours, Dough consistency, Bread specific volume
  • Atefeh Zamani, Reza Farhoosh, Seyed M.A. Razavi Pages 309-318
    Introduction
    In this research, the effects of coating by Basil seed gum (BSG) (0.5 and 1%, w/w) compared to that by common gums such as xanthan and methylcellulose (MC) on the oil uptake, moisture removal, color, and texture in deep-fat fried potato strips were investigated. Today, numerous processed foods are prepared by deep-fat frying all over the world, since in addition to cooking, frying provides unique flavours and textures that improve the overall palatability. In fact, the desirable characteristics of most fried foods are derived from the formation of a composite structure: a crispy, porous, and oily outer layer or crust, and a moist cooked interior or core, whose microstructures have been formed during the process. In addition, the high oil content is costly to the processor and results in an oily and tasteless product. Also, Excess consumption of fat is considered as the key dietary contributor to coronary heart disease and perhaps cancer of the breast, colon, and prostate. The concern to develop healthier products that contain less fat, absorbed during industrial pre-frying and frying processes, is one of the prevailing factors in the latest research trends in this area, prompting studies of ways to lower the oil content of fried food. An edible coating (EC) is a thin layer of edible material formed as a coating on a food product, the EC are applied in liquid form on the food, usually by immersing the product in a solution generating substance formed by the structural matrix (carbohydrate, protein, lipid or multicomponent mixture), When frying coated food pieces, the film hinders absorption of the oil, improving its nutritional qualities and reducing the fat content and calories of the final product. Basil (Ocimum basilicum L.) is one of the domestic plants in Iran that is produced and used as a pharmaceutical plant in high quantity. When the seed of the O. basilicum L. is soaked in water, the outer pericarp swells into a gelatinous mass due to the presence of a polysaccharide layer. the present study aimed to expands the scope of previous works and focus on the effect of basil seed gum (as a novel hydrocolloid) on oil uptake and product quality (texture and color) during deep-fat frying of potato strips. In the first part of the study, investigate and compare the effects of endemic hydrocolloid, basil seed gum with xanthan(xan) gum and methyl cellulose(MC) for use as commercial hydrocolloids for coating edible.
    Materials And Methods
    Aqueous suspensions of 0.5 and 1% (w/w) were provided and used for coating formulations. blanched samples of potato were dipped in the coating suspensions for 2 min and rinsed to removal excessive gum then dipped samples dryed in oven 150 ºC for 3 minute. Frying was carried out in a controlled temperature deep fat fryer (Moulinex, Toucan Automatic). For each stage, nine samples were fried in 3 L of blended oil of canola: palm olein: olive oil (75:15:10, respectively). The uncoated and coated potato strips were fried 6 min at three temperatures (160 °C, 180 °C, and 190 °C).Rheological characterization of gum dispersions were measured using a rotational viscometer (Bohlin Model Visco 88; Bohlin Instruments, Worcestershire, UK) equipped with a heating circulator (Julabo, Model F12-MC; Julabo Labortechnik, GmbH D-77960, Seelbach, Germany). According to the viscosity of dispersions, appropriate measuring spindles (C25 and C30) were selected during viscosity measurements. Moisture and fat contents were determined according to the method of AOAC (1996). The color Color of crust models was measured using an image processing technique. Crispiness of potato strips was evaluated in term of hardness by a penetration test performed in a Texture Analyser (QTS25 CNS Farnell, UK). The Conical prob diameter and the cross-head speed was 3 mm and 60 mm/min, respectively. Statistical analysis was performed using factor completely randomized design in Mstat version 1.42 software. The level of statistical significance was determined at 95%. If significant difference was found, the treatments were compared by using Duncan’s multiple comparison test.
    Results And Discussion
    Solutions of BSG and XAN exhibited interesting pseudoplastic behavior with the viscosity decreasing with increasing shear rate(from 10 – 1001/s). No Newtonian region was detected at low shear rates suggesting that the zero-shear viscosity could exist at very low shear rates. The presence of high yield stress in BSG solution was comparable to xanthan gum. The apparent viscosity of Xanthan was markedly higher but methylcellose at both concentrations had Newtonian behaivear during shear rate. with regard to the controlling role of water in oil uptake, the oil content in all coated samples was less than that of the control (uncoated potato strips). The potato strips treated with BSG 1% and 0.5% had the lowest oil uptake (0.14 and 0.16 % d.b., respectively). The highest amounts of the oil uptake were found for the control and potatoes coated with methylcellulose 0.5%, respectively. The potatoes treated with the hydrocolloids experimented showed that the moisture content in all coated samples was higher than that of the control. The samples treated with the BSG 1% and 0.5% had the highest amounts of the reduced moisture loss. Also, the samples treated with xanthan and BSG 1% had the highest total color change (∆E) and hardness.
    Conclusion
    Results of this study showed that basil seed gum (as a novel hydrocolloid) can be suggested for coating and usage in industrial French fries production.
    Keywords: Coating, Deep, fat frying, Potato strips, Oil uptake, Moisture removal
  • Mahmoud Yolmeh, Mohammad Bagher Habibi Najafi, Mahmoud Najafzadeh Pages 319-324
    Introduction
    One of the most important aspects of food preservation is controlling the growth of microorganisms, which if overlooked it leads to uncontrolled growth of microorganisms associated with food spoilage and food poisoning. Microbial contamination of foods is important because of pathogens are capable to transfer to foods during the processing, distribution, and storage. Escherichia coli and Bacillus cereus can cause spoilage in food; intake food contains plenty of bacteria and toxic. Therefore it is important to eliminate or control these bacteria safely. Ultraviolet (UV) radiation is considered as non-ionizing radiation and the first time in 1940 was used as a method for infection elimination in air. This approach nowadays is widely used for controlling microbial growth and as disinfection in food industry. Wavelength range of ultraviolet radiation is approximately 328-210 nm. The beam is naturally present in the sunlight. The bactericidal effect of UV irradiation depends on the type of bacteria, the distance, and dose of radiation. The most cytotoxic effect of UV irradiation is obtained at the wavelength of 260 nm, which corresponds to the intense absorption of energy by organic bases in the nucleic acid. UV irradiation causes radicals generation, which subsequently attack the nucleic acid and develop mutations in their genomes and gene transcription and translation processes. In this study, the antibacterial effect of different exposure times of ultraviolet radiation on the growth of E. coli and B. cereus was evaluated.
    Materials And Methods
    All media used in this study was procured from Merck Company. Ultraviolet device (Camag, USA) was used at wavelength of 254 nm, Nr= 29000, Amp= 0.25. B. cereus isolation: 1 mL of different dilutions of rice (0.1, 0.01, and 0.001) was transferred to Brain-heart infusion (BHI) and it was incubated at 32 °C for 24 h. A loop containing the bacteria was then transferred to Mannitol Egg Yolk Polymyxin (MYP) agar and it was incubated at 35 °C for 24 h. B. cereus produce big and round colonies, with a halo around the colonies. Starch test was carried out as confirming test for B. cereus colonies. Briefly, some colonies of B. cereus were added to test tube with sterile distilled water containing starch and a few drops of lugol. Development of blue color indicates the presence of B. cereus due to starch hydrolysis. E. coli isolation: E. coli was isolated from raw milk following the method described by Kargar et al. (2005). Briefly, raw milk was first homogenized; 0.1 ml of each dilution of homogenized raw milk was inoculated on Escherichia coli broth medium containing 20 mg novobiocin. E. coli was then isolated after transferring the former media on EMB specific culture and incubation at 36 °C for 24 h. After confirming colonies by Durham tube and complementary tests, pure cultures were obtained from them by streak-plate method. UV irradiation: A loop of E. coli colonies was transferred to nutrient broth and it was treated with UV beam (254 nm) at three times (40, 60, and 80 s). After preparing dilution of 0.0001 for each of the treatments and incubating for 24 h, survival curve was plotted. These operations were also carried out on B. ceruse colonies. A control sample also was considered for each examined bacterium.
    Results And Discussion
    Rate of Bacillus cereus growth was reduced under UV radiation. As it is shown, Death curve of E. coli, E. coli count was decreased by increasing the time of UV radiation, so that count of this bacteria reached to about zero after UV radiation for 80 s. However, reduction of B. cereus count was less than E. coli count at same wavelength (254 nm) and time of irradiation. This revealed that B. cereus have more resistance to UV radiation compared to E. coli. These results were consistent to observation of Sharp (1940) who evaluate the effects of UV light on bacteria suspended in air and reported that required energy for air sterilization containing B. cereus is more than twice the energy is needed to eliminate E. coli. UV light more penetrates to cell wall of Gram-negative bacteria compared to Gram-positive bacteria due to having a small amount of peptidoglycan in the cell wall and caused mutations in regulating genes of transcription and translation.
    Conclusion
    The efficiency of the two main processes of cell is reduced in the presence of UV irradiation and leads to growth reduction and death. The more resistance of B. cereus can be for several reasons, such as having a thicker cell wall compared to E. coli, and the capability to produce spore, and the capability to proofing mutations.
    Keywords: Escherichia coli, Bacillus cereus, Raw milk, Rice, Ultraviolet
  • Saina Moayedzadeh, Asghar Khosrowshahi, Shahin Zomorodi Pages 325-336
    Introduction
    Microbil transglutaminase (MTG, E.C. 2.3.2.13) is a transferase enzyme that catalyses the acyl transfer reaction between -carboxyamide groups of peptide-bound glutamine residues and the primary amino groups including -amino groups of lysine residues. This will lead to the formation of new intra- and intermolecular crosslinks between proteins in order to formation of polymers with high molecular weight. Such crosslinks can modify the structure and functionality of proteins. Actually, crosslinking of milk proteins caused by enzyme leads to improvement in functional characteristics of proteins and formation of products with desirable sensory and rheological properties. Nowadays enzymatic cross-linking is widely used to improve the functional properties of proteins. Because undesirable side reactions that could lead to produce of toxic co-products by chemical modification may be minimized by enzyme catalysis. In last twenty years, consumer trends towards low or non-fat dairy products especially nonfat yoghurt have increased because of harmful effects of excess fat on human health. However, many consumers prefer low-fat products with a similar sensory quality to full-fat ones. The traditional methods used to improve yoghurt texture and decrease syneresis include the enrichment of dry matter (total solids) and/or protein content, as well as the addition of natural or synthetic gums. The polymerization of milk protein chains by transglutaminase for three-dimensional net stabilization in yoghurt provides new technology to prevent common problems in dairy product processing. In this study, the effect of microbial transglutaminase concentration, incorporation amount of sodium caseinate into milk and storage time on proteolysis, rheological properties and water holding capacity of nonfat stirred yoghurt was investigated using response surface method (RSM).
    Materials And Methods
    Twenty treatments were carried out according to a face-central composite design with three factors and three levels for each variable. The independent variables of the design were Enzyme concentration, amount of sodium caseinate and storage time. They were in the range of 0-2 Unit per gram of milk protein, 0-1.27 percent and 1-19 days, respectively. For preparation of samples, first of all the SNF and protein content of milk were fortified by addition of skim milk powder and sodium caseinate. The milk was tempered to 50°C in a water bath and subsequently transglutaminase was added at different concentration. It was incubated for 1 hour at 50°C in the water bath. Then it was pasteurized at 85°C for 15 min to inactive the enzymatic reaction and cooled to 45°C. After inoculation with the appropriate inoculum type according to the commercial recommendation, incubated at 42°C until the pH value of 4.6 was obtained. The yogurt samples were cooled in ice-water bath and stirred for 60 second using manual stirrer. Samples were distributed into sterilized plastic containers; they were sealed and stored at 4°C until examined. Characteristics of all yoghurt samples were evaluated, such as: proteolysis by using o-pthaldialdehyde (OPA) assay, apparent viscosity by Brookfield viscometer and water holding capacity. Proteolysis was carried on 3 steps including preparation of yoghurt water extracts, preparation of OPA reagent and absorbance measurements. Briefly, 150 µl of yogurt serum was added directly to 3 ml of OPA reagent in a 5 mL quartz cuvette and the solutions were mixed briefly by inversion prior to 2 min incubation at room temperature followed by absorbance measurement at 340 nm.
    Results And Discussion
    The statistical analysis of results showed that increase in enzyme concentration increased viscosity and water holding capacity of samples and decreased the proteolysis (p≤0.05). The presence of transglutaminase contributed to an increase in the viscosity due to its ability to form high molecular weight polymers from protein monomers. Crosslinking of protein chains stabilized the three-dimensional network of yoghurt gel and prevented yoghurt whey expulsion as a result of a decrease in gel permeability; thus, increasing water holding capacity. The lesser proteolytic activity with using transglutaminase may be explained by a combination of these two factors: 1) transglutaminase-induced cross-linked milk proteins were less suitable substrates for proteolytic enzymes in starter culture than native milk proteins and, 2) Proteolytic products such as peptides were crosslinked into the milk proteins by transglutaminase. It is known that the yoghurt may become too acidic and bitter due to excessive acidification and proteolysis even at refrigerator temperatures. The development of these defects generally determines the shelf life. Our results indicate that it may be possible to produce yoghurts with longer shelf life when using transglutaminase. Addition of sodium caseinate resulted in the increased viscosity and water holding capacity of samples. Also, during the storage period, water holding capacity was decreased and proteolysis of samples was significantly increased (p≤0.05).
    Conclusion
    The optimum conditions for the production of yoghurt was obtained using 1.42 Unit enzyme per gram of milk protein, 0.47 percent sodium caseinate with a storage period of 15 days. The overall desirability value was equal to 0.83. Under these conditions the predicted percentage of water holding capacity, viscosity and proteolysis being 27.51, 5220 cp and the absorbance at 340nm was 0.349 nm (as proteolysis index), respectively
    Keywords: Transglutaminase, Proteolysis, Cross linking, Nonfat yoghurt
  • Habib Jahandideh, Masoud Taghizadeh, Mohammad Hossein Haddad Khodaparast, Arash Koocheki Pages 337-350
    Introduction
    Nowadays, one of the most important nutritional problems in different societies is the protein mal-nutrition. Since bread is the main food material being consumed in all over the world, bread enrichment using the grains rich in protein such as sesame seeds would be an appropriate alternative. However, addition of sesame products such as Tahini meal would cause some technical difficulties such as dough stability, water absorption, dough extension time, etc. in bread manufacturing processes.In this study the effect of addition of xanthan gum to on physical and textural properties of Baguette bread containing tahini meal was investigated.
    Materials And Methods
    Wheat flour and tahini meal were supplied from Damghan and Ardakan cities, respectively. They were then refrigerated prior to baking process and different chemical tests were carried out according to standard methods. Protein was measured based on Kejeldahl method. Moisture content as well as ash content were determined using oven method.Raw fat was calculated according to AACC-No. 30-10 and raw fiber was measured using appropriate instrument (Scientific velp-FIWE6 F30530201). Starch determination was carried out using Small universal polarimeter (SUP-Germany). Xanthan gum was purchased from Provisco Ltd. (Switzerland) in food grade quality. Bread yeast (Saccharomyces cerevisiae) was also supplied in dried form. All other chemical enhancers were purchased from Merck Ltd. (Germany). Baguette dough was produced from mixture of wheat and Tahini meal flour based on protein content and the amount of protein in final dough was increased from 10.28% in flour free of tahini meal to 12, 14 and 16% in different treatments. The rest time for all flour samples was fixed at 15 min and the baking process was carried out for 15 min at 300°C. Baked breads were exposed to room temperature for two hours and then were packed using poly-ethylene (PE) film for further tests. Specific volume of bread samples was measured using rapeseed displacement method (AACC, No. 54-30, 2000). Samples porosity was determined using image processing techniques. Samples were cut to 2cm×2cmcubes and an appropriate scanner (Canoscan 8800F, Japan) with 300 pixel resolution was used to acquire the images for further process using Image J(1.6r, 2010). Apparent color for the baguette samples (in terms of CIE ‘L*’- lightness,“a*” - redness and greenness, and “b*”- yellowness and blueness) were also measured using image processing techniques (Image J, 1.6r, 2010).Texture profile analysis (TPA) test was carried out using a texture analyzer (QTS Texture Analyzer, CNS Farnell, Hertfordshire, UK) to study the effect of xanthan gum and tahini meal on parameters such as hardness, gumminess and cohesiveness in all baguette samples.
    Results And Discussion
    ANOVA test showed the significant effect of xanthan gum and tahini meal on the porosity of samples. The porosity of samples containing less than 0.5% xanthan gum at all tahini meal levels, was significantly less than control sample.Similar results were obtained in the case of specific volume meaning that the employed treatments have significant effect on bread’s specific volume. Increasing tahini meal from 9.45% to 14.53% caused significant decrease in specific volume. This could be due to the weakness of dough gluten matrix. These results are in agreement with other works reported by other researchers (Paraskevopoulouet al., 2010; Mohammad Idrisset al., 2012; and Guardaet al., 2004). The results obtained for apparent color of bread core also showed the effect of xanthan and tahini meal. The only exception was found in case of a* value when studying the effect of xanthan gum, meaning that xanthan gum has no significant effect of this parameter. In the case of apparent color in bread crust, the studied treatments (xanthan gum and tahini meal) showed significant effect on all color parameters. Different textural properties of baguette samples including hardness, gumminess and cohesiveness were also measured.
    Conclusion
    The results indicated obvious effect of xanthan gum and tahini meal levels on these mentioned parameters. Increasing tahini meal and xanthan gum levels would increase hardness as well as gumminess. However, addition of xanthan gum and tahini meal cause significant decrease in cohesiveness. This could be due to dilution effect of these substances which decrease the concentration of protein matrix existed in flour’s gluten.
    Keywords: Tahini Meal, Baguette, Xanthan Gum, Physical, Textural Properties
  • Hamid Reza Samadlouie, Roshanak Mokhberi Pages 351-360
    Introduction
    Arachidonic acid (5, 8, 11, 14-eicosatetraenoic acid, ARA), a long chain polyunsaturated fatty acid (PUFA) of the n-6 class, plays an important roles in the structure and function of biological membranes. ARA has also attracted attention as a precursor of prostaglandins, thromboxane, prostacyclin, and leucotrienes, which have potent and various physiological actions including uterine muscle contraction, relaxation, vasodilatation, and antihypertensive action. Lower fungi of Zygomycetes especially Mortierella alpina were served as rich sources of ARA. In this research the time courses for biomass, lipid and arachidonic acid production by Mortierella alpina CBS 754.68 with different levels of glucose and soybean concentrations were examined. Afterward the effect of substrates levels on expression of the elangase genes involved in biosynthesis of ARA was studied in a shaker flask scale.
    Materials And Methods
    Mortierella alpina CBS 754.68 was purchased from Centraal Bureau Schimmel cultures (CBS, the Netherlands). The seed culture medium contained (g/L): glucose 30 and yeast extract 7. The seed culture of 100 mL was incubated at 25 °C for two days in a gyratory shaker at 185 rpm. The fermentation medium was inoculated of with 5% (v/v) of the mycelium suspension of the seed culture. Fermentation was carried out at 21 °C; pH 6 for ten days with glucose (70 and 50 g/L) and soy bean meal (20 and 10 g/L) as carbon and nitrogen resources, respectively. The dinitrosalicylic acid (DNS) method was used to determine the reducing sugar concentration. Protein concentration was assayed using the Lowry’s method. Total RNA was extracted using the RNA Kit according to the manufacturer’s instructions (Invitrogen) The NCBI database was scanned for genes encoding for elongases. The hints were aligned and the conserved regions were used for primer designing. PCR primers for mentioned genes and the Housekeeping Gene (actin) were designed using the Gene Runner Design software. cDNA was synthesized using the cDNA synthesis kit (Invitrogen) using oligo (dT) as primers according to the manufacturer’s instructions. Expression analysis of genes involving in ARA biosynthesis was carried out using Real-time PCR. The Real-time PCR mixtures containing cDNA and each primer were heated at 95 °C for 15 min and then subjected to 40 cycles consisting of denaturation at 95 °C for 5 s, annealing at 60 °C for 20s, and extension at 72 °C for 20 s, and finally for an extension of 10 min at 72 °C. The expression levels of target genes were normalized based on actin encoding gene (ΔCt = Ct target gene − Ct reference gene). Since the total number of cycles in the Real-Time PCR was 40, for easier interpretation, the ΔCt was converted into 40-ΔCt.
    Results And Discussion
    Biomass growth was declined with increasing carbon content in the early days of cultivation and subsequently increased. Growth has great effect on reduction of the amount of glucose in the medium; thereby osmotic pressure had been reduced and biomass production was boosted. Protein content of media had a significant impact on biomass production. The results indicate that the protein was depleted in 2 day of fermentation. In all three media the destruction of biomass was started when the carbon source was reached the lowest level. In media with high content of protein, oil accumulation was lower than the two other media, which indicated the negative impact of protein on the lipid accumulation. In this media although the protein source along with the other medium to be depleted on day 2, In following fermentation, the biomass growth and lipid accumulation was higher and lower respectively than other medium. High concentrations of glucose had inhibitory effect on oil production while had positive effect on biomass production. Results indicated that oil accumulation significantly increased until day 6 and then the trend was slow. Reduced glucose medium can have a significant effect in this phenomenon. Initial concentrations of glucose (50 g/l) and soybean (10 g/l) have good effect on lipid production (47% of biomasss) while in this condition; the production of arachidonic acid was lower than the other media. ARA content of lipid was increased during the whole fermentation process in all treatment. It was observed that an improvement in arachidonic acid (56% of lipid) in lipid was achieved at lowest and highest levels of glucose (50 g/l) and soy bean (20 g/l) respectively. The results of this study showed that the expression of our target genes depends on culture conditions. Expression of MALC1 was influenced by culture condition. Low and high levels of carbon and nitrogen content respectively also biomass growth had great impact on MALC1 expression. A significant decrease of biomass from 6 to 8 had a significant impact in reducing MALC1 expression. the expression of GLELO gene was lowest at day 6 and increased again at day 8.
    Conclusion
    The results showed that the expression of GLELO gene was decreased coincided with reduced levels of carbon content less than 5 grams per liter on the sixth day. With comparison of expression of MALC1and GLELO encoding genes in optimal media for ARA production can be concluded that the GLELO gene is a rate-limiting step in the ARA biosynthesis.
    Keywords: Mortierella alpine, Lipid, Arachidonic acid, Gene Experssion, Elangase Gene
  • Masoud Taghizadeh, Amir Jajarmi Pages 361-371
    Introduction
    Lime (Citrus aurantifolia L) is belonged to citrus family and has two varieties on the basis of sweet or sour taste; two well known varieties of sour lime are Persian and Key that are cultivated in the southern of Iran. Based on FAO statistics, Iran produced about 615,000 tons of lime in 2010, and is ranked among 10 lime producersinworld wide. Physical properties of fruits are essential information in designing equipments and processes being used in different manufacturing stages such as harvesting, cleaning, sorting and grading, transporting, packaging, as well as estimating of cooling and heating loads during heat transfer processes. Moreover, physical properties affect products acceptability since consumers usually prefer fruits and vegetables with brighter color, appropriate size and uniform shape. Among physical properties, weight, volume and projected area are important parameters for designing sorting equipment.
    Materials And Methods
    In this study, lime samples were selected from Key variety which is cultivated in southern of Iran. From the whole, physical properties of about 300 limes were investigated and regression model were developedto estimate weight and volume on the basis of length, width, thickness and projected area.In order to determine the initial moisture, tenlime samples were randomly selected and taken in to hot air oven at 80C for 24 h. The average values of three replicateswerereported.The major dimensions (Length (L), width (W), thickness (T)) were measured using a micrometer with an accuracy of 0.01 mm.Projected area of limes was calculated in three dimensions using image processing technique. Apparent color for the lime samples was also measured in terms of CIE ‘L*’ (lightness), “a*” (redness and greenness) and “b*” (yellowness and blueness), using image processing techniques. Step wise regression was used to develop multivariate models. In this method, the independent variables would enter the equation successively based upon their degree of dependency. In order to estimate weight and volume of lime samples,three category modelswere developed as follow. 1- Regression models based on length, width and thickness. 2-Regression models for predicting weight of lime based on calculated volume. 3- Regression models based on projected area. When there are a large number of variables in the database, it is very likely that subsets of variables are highly correlated with each other.In this study, principle component analysis (PCA)was applied in order to have an accurate and reliable evaluation from existed correlation between physical properties of lime.
    Result And Discussion
    The initialmoisture content of limeswas found to be 84.34%.The averaged values of length, width and thickness of limes were35.84, 32.92 and 32.56, respectively. The static coefficient of friction for limes was determined on fourdifferent surfaces namely plywood, galvanized iron sheet, rubber and glass. The glass and plywood showedmaximum and minimum static coefficient of friction respectively. In addition, the sphericity and aspect ratio of lime were found to be 94.32% and 92.18%, respectively. The obtained sphericityvalues were similar to values reported by Sharifi et al., (2007) for orange variety of Tamson and lower than orange varieties of Navel reported by Topuz et al., (2006). The obtained results showed high correlation between three major dimensions and lime’s weight. The predictive models for lime have lower coefficient in comparison with LorestaniandTabatabaeefar(2006) research report forheterogeneous shape of limes. Among regression models for weight prediction of limes, the best model was obtained on the basis of the third projected area with R2of 0.921. The regression models on the basis of calculated volume showed appropriate performance for prediction of lime’s weight. Among regression models on the basis of dimensions, the single parameter model based on lime’s width found to bethe highest coefficient for prediction of volume. Similar toweight prediction, single parameter model on the basis of the third projected area showed the best performance for volume prediction.
    Conclusion
    The results obtained from principle component analysis confirmed the regression models and showed high correlation between physical properties such as projected area, dimension, weight and volume with each other as well as positive correlation with coefficient of friction on the rubber surface and negative correlation on theglass surface.
    Keywords: sour lemon, physical properties, image processing, mathematical properties
  • Farhad Salmanizade Joopari, Ali Askhar Zomorodiian, Hossein Rahmaniian, Hasan Safiyari Pages 372-381
    Introduction
    Persimmon fruits are subjected to different environmental conditions from harvest to consumption. Foods, those are exhibiting characteristics of both liquid and solid, are described as viscoelastic where stress relaxation and strength properties are time dependant. Knowledge of viscoelastic properties of foods and agricultural materials are important when considering harvesting, handling, transportation, processing, and storage. Also the data on viscoelastic properties are required as an input for mathematical models, which describe and predict internal stress and cracking during different handling and processing procedures. The mechanical properties are considered one of the most important four parameters, which reflect the quality of food material. Those parameters include texture, firmness and chewability. Viscoelastic material exhibit stress relaxation phenomena, which is one of the most important factors in characterizing agricultural materials. The objectives of the current study were: (1) to obtain data to describe the stress relaxation characteristic of Persimmon fruits during Storage, (2) to investigate the effect of storage time on stress relaxation properties, and (3) to find the best model to describe the obtained stress relaxation data.
    Materials And Methods
    The persimmon fruits were manually picked up at maturity stage from persimmon trees in a garden, in Fars province, Iran. They were handled to Biophysics laboratory in Agricultural Engineering department, at Shiraz University, on the foam sheets in one layer array for minimizing any likely compaction. Initial moisture content was determined by gravimetric method in an oven at 70C till obtaining constant successive weight loss of 0.001 g. The initial moisture content was 44.26% (d.b). Since the rheological characteristics of fruits are important for any processing operation, viscoelastic behavior of persimmon fruits during storage in environmental conditions was investigated using estimating its relaxation parameters from experimental stress relaxation data. The rheological behavior of persimmon fruits was evaluated to uniaxial compression test for relaxing the stress during 480 s. Texture Profile Analyser (TPA) (TA.XT2 plus model, Stable Microsystems, England) with Exponent Lite (Version 4,0,8,0, UK) software was used to compress whole date samples and export data into Excel worksheets. TPA was equipped with a 30 kgf load cell. The cross head speed was adjusted on 1 mm/s, and samples compressed with 30% strain. The cross head then kept at 30% of strain for relaxing the stress in 480 s duration. A chamber with temperature control circuit was fabricated around the TPA cross head to prepare constant temperature identical to sample temperature with an accuracy of ±0.1C during the stress relaxation tests. All tests were performed with ten replications. Three popular stress relaxation models, namely the generalized Maxwell with three elements, Nussinovitch, and Peleg were fitted to experimental data and was used from R-square, standard error of estimation (SEE) and percent of average relative error (ARE%) indexes for evalution of models.
    Results And Discussion
    The force–time curves were converted to stress–time curves by dividing the true compression force values to the corresponding true values of contact surface area. Analysis of variance showed that storage time had significant effect on initial stress relaxation. The results showed that the magnitude of initial stress (stress at time zero) required to create a fixed strain on whole fruit was significantly decreased up to 80% during storage in environmental conditions, but the relaxation time was increased at the range of 312.10 to 353.90 s. Based on the results, elastic behavior of persimmon fruit was enhanced and its firmness decreased during fruit storage. Persimmon is sugar rich fruit that its behavior is principally partly controlled by physico-chemical properties of sugar. Changes in sugar type as a result of enzymatic action are taken place during the storage process. However, in the present study all samples were in the time of maturation, and therefore the physical state of sugar was influenced by free water which is resulted in increasing in fruit moisture content. Stress relaxation curves were plotted at different storage time. Some variations were apparently observed among the curves. Sucrose decreased initial stress decay rate and increased proportion of un-relaxed force. Variations in stress decay rate might refer to the amount of initial stress which was affected by physic-chemical properties of the sugar. Recall that nonlinear regression method with non-negative constraint was used to derive the models constant.
    Conclusion
    All three models were valid for quantifying the viscoelastic behavior of persimmons; however the generalized Maxwell with three elements (with R2=0.999, SEE=0.017 and ARE=0.19%) and Nussinovitch (with R2=0.996, SEE=0.057, ARE=0.36%) were the best models in predicting experimental data.
    Keywords: Generalized Maxwell model, Nussinovitch model, Peleg model, Stress relaxation, Viscoelastic characteristics
  • Hamed Sigari, Mohammad Tabasizadeh, Mohammad Hosein Abaspourfard, Mahmood Reza Golzarian Pages 382-391
    Introduction
    Harvesting of Kiwifruit (Actinidiadeliciosa, family: Actinidiaceae) is usually performed in mid-October in Iran. The average weight of this fruit is about 70 g. Hayward is the most popular kiwifruit variety in the world mainly due to its large size, oval shape and high shelf life. Drying fresh products is a long-standing method for conservation of food products. This method reduces water-borne and microbiological activities in fresh products while only minor physical and chemical changes occur in these products. Drying, therefore, is regarded as a common method used for food product conversation. There have been several researches on modeling drying of food products. Wang et al. (2007) worked on a mathematical modeling for drying apple slices in a hot air drying process and determining the effective thermal diffusivity. These researchers stated that Midili model was found to be the best for predicting the moisture content changes during drying. Torgul (2005) confirmed this finding in modeling the drying of apple slices in an infrared drying system. How ever not much research has been carned out on drying kiwifruit slices. Therefore, in this research, the drying process of kiwi slices in a vacuum dryer was examined in order to understand their behavior during the process and to determine a best predictive model for drying and also study the diffusivity coefficient for this product.
    Materials And Methods
    In thes research Hayward variety of kiwifruit for was used Sinco this variety is commonly grown in Iran. The fruits were purchased from local market in mid-October and transferred to a cool storage (50 C) in a lab at the Department of Biosystems Engineering at the Ferdowsi University of Mashhad. The samples used in this study were of medium size and suitable for cutting in a cylinder-shape cutter. The initial moisture content was determined by so-called oven-drying method on wet basis according to the following equation (Mohesnin, 1986):〖%MC〗_wb=(Initial weight-Final weight (after drying in oven))/(Initial weight) 100 (1) The moisture content was determined as 80.23% on a wet basis. The kiwifruits were sliced at 3 mm thickness using a 35 mm-diameter cylinder and weighed with a digital scale. The slices were moved out of the dryer and weighed every 30 min to monitor their moisture content. Weighing continued until the sample’s moisture content reached to 15-20% on a wet basis. Moisture ratio of kiwifruit slices during drying process was determined according to the follow equation:……………… ……….(2) where MR is moisture ratio (dimensionless), Mt is moisture content at any desirable time, Me equilibrium moisture content, percent, dry basis, and M0 is the initial moisture content (kg H2O/kg of dry matter). The value of Me is very small compared with Mt and M0, hence, the error involved in the simplification of above equation by omitting Me is negligible. The experimental drying data were fitted in various drying models commonly used for monitoring the trend of being-dried products. A few of which models are as follows: MR=exp (-kt): Newton model MR = exp (_ktn): Page model MR = 1 + a.t + bt2: Wang and Singh model MR = a.exp (_ktn) + b.t: Midilli model In this research, two statistical proameters were used to evaluate the goodness of fit of the tested models to the experimental data: the coefficient of determination (R2) and root mean square error (RMSE) between the experimental and the predicted moisture ratio values. Diffusivity coefficient for each slice was determined from the following equation: MR=8/π^2 ∑_(n=0)^∞▒〖1/(2n+1)^2 exp⁡[-(π^2 (2n+1)^2)/4 (D_eff t)/a^2] 〗 (3) where a is sample thickness (in meter), t drying time (in seconds), n is the number of observations and Deff is effective diffusivity coefficient (in m2.s-1). In long drying process, the following simplified equation is used: MR=8/π^2 exp⁡[-(〖π^2 D〗_eff t)/(4a^2)] (4) The diffusivity coefficient is the slope of the straight line when experimental drying data in terms of Ln (MR) is plotted versus drying time (t).
    Results And Discussion
    The results of this research revealed that the best prediction curve of moisture content against time was drawn using of MTLAB software. In this regards the rational function with first degree in both numerator and denominator and the third degree polynomial function with maximum coefficient of determination (R2) of 0.9991 and 0.9977 and minimum root mean square error (RMSE) of 0.01267 and 0.02412 were the best prediction models, respectively (Table 2). Furthermore, the drying time becomes shorter as the thickness of kiwifruit slices becomes thinner. This is mainly due to the higher thermal gradient within the thinner slices and hence faster moisture removal due evaporation. The heat diffusivity coefficient was also determined from “Ln (MR) – Time” curves (Figure 3). It was observed that with increase of fruit’s thickness, the heat diffusivity coefficient increases. This phenomenon may be related to the molecular dynamics and the surface tension of materials being dried. In other words the minimum and maximum values of the diffusivity coefficient were observed as 2.0904E-6 and 7.1303E-6 m2.s-1 for fruit thicknesses of 3 and 9 mm, respectively (table 3).
    Conclusion
    The trend of moisture content evolution against drying time during vacuum drying of kiwifruit was investigated using MTLAB software. Different prediction models were examined for the prediction of moisture removal during vacuum drying of kiwifruit. The rational and polynomial functions were determined as the most accurate prediction models with the coefficient of determination (R2) of higher than 0.99 and RMSE of about 0.02. Furthermore, the heat diffusivity coefficient of kiwifruit slices was investigated as a function of slice thickness. A general increasing trend observed for this coefficient as the thickness of the slices increased.
    Keywords: Vacuum Dryer, Mathematical Modeling, Moisture Content
  • Marziyeh Ramzi, Mahdi Kashaninejad, Ali Reza Sadeghi Mahoonak, Seyed Mohammad Ali Razavi Pages 392-392
    Introduction
    Honey is a natural food product having a high nutritional and medicinal value. It is a sweet, viscous substance produced by the honeybees from the nectar of plants. Sensory and physical properties and chemical composition of honey depend on the botanical origin and the regional and climatic conditions of the area in which it is produced.The knowledge of honey rheology is very important for its processing, quality control, process control, and selection of proper process equipment, storage, handling, and transportation and plays an important role in fluid heat transfer. Rheological properties of honeys depend on many factors including composition, temperature, and amount and size of crystals. Different kinds of honeys with various floral origins (such as Rosa, Thyme, Astragalus, Trifolium, sunflower, Medicago, alfalfa and etc.) are produced in different regions of Iran. In this study, some physicochemical and rheological properties of four Iranian honeys from Golestanprovienceobtained from various floral sources, two poly floral (Mountain, Forest) and two mono floral (Sunflower, Ivy) were compared with adulteratedand sugar honeys.
    Materials And Methods
    Sixhoney samples were collected directly from beekeepers in Golestan Province,two monofloral (Sunflower, Ivy) and two polyfloral(Mountain, Forest), adulterated and sugar honeys. Some physico–chemical characteristics of samples including water content, Hydroxymethylfurfural content (HMF), diastase activity, pH, ash, free acidity, reducing sugars (fructose and glucose), sucrose contentand electrical conductivity were determined by the harmonized methods of the International Honey Commission. The rheological measurements were also carried out on the honey samples at eighteen rotations, ranging from 5-200 rpm and at five temperatures, ranging from 10-30ºC, using a viscosimeter Brookfield.
    Results And Discussion
    The samples were found to be different from each other in terms of physico-chemical properties. In the natural honey samples, this discrepancy can be due to diversity in original plant and harvesting season. All the values obtained in the natural honey samples were agreement with those reported by Codex Alimentarius and ISIRI. The values of sucrose and fructose/glucose ratio the sugar honey sample and sucrose, fructose/glucose ratio, pH, HMF, diastase activity of adulterated honey were not in the range suggested by Codex Alimentarius and ISIRI.
    Conclusion
    Rheological characteristics of honeys were evaluated at different temperatures (10, 15, 20, 25 and 30ºC). All the honeys exhibited Newtonian behavior for shear rate in range of 1.045- 41.8 s-1.The temperature dependence of viscosity was described using the Arrhenius and the Vogel–Taumman–Fulcher (VTF) equations.Two models (Power Law and Exponential models) were also investigated to describe the concentration (ºBrix) dependence of viscosity.
    Keywords: Honey, Adulteration, physico, chemical properties, Rheology, Arrhenius model, VTF model
  • Seyyed Hamid Mortazavi, Sodeif Azadmard Damirchi, Razagh Mahmodi, Mahmod Sowti, Majid Shirmohammadi Pages 408-419
    Introduction
    Pistacia is a genus of the family Anacardiaceae. Among the 15 known species of pistachios, only 3 species grow in Iran, including Pistacia vera, Pistacia Khinjuk and Pistacia atlantica. P. Khinjuk is a native plant in Iran. The plant is known as Khenjuk or Kelkhong in Persian. Resin of this plant has been used as an indigestion, tonic, toothache and astringent. In addition, fruits of P. Khinjukare used as edible wild fruits in form of roasted or salted nuts. There are reports on extract obtained from wild pistachio. It has been shown that the extract is rich source of phenolic compounds and other antioxidant compounds. Oil obtained from wild pistachio also has high content of essential fatty acids which can reduce and prevent from different diseases. Extracts obtained from the wild pistachio tree has also been used in pharmaceutical and cosmetic industries. However, there is no scientific report on qualitative properties of wild pistacia species khinjuk. Therefore, the aim of this research was to study the chemical and nutritional composition hull and core of wild pistacia species khinjuk.
    Materials And Methods
    The Pistacia Khinjuk was collected during flowering stage from Southwest of Iran (KouhgiloyeBoyerahmad province) and identified by the Herbarium. Separate tests were performed on the hull and core of wild pistachio. First, the fruit hull was isolated from its core and then they were crashed and their core was separated. Moisture, oil, protein and ash content and pH of the hull and core of the fruit were determined. The hull and core of fruit were used for oil extraction. The hull and core were powdered and their oil was extracted by hexane. For fatty acids profile, extracted oil samples were methylated and obtained fatty acid methyl esters were analyzed by gas chromatography. Also, the extracted oil stored for three month at room temperature, and every thirty day peroxide value (PV), acid value (AV) and chlorophyll content were determined. PV and AV were determined by titration methods. Chlorophyll content was determined by spectrophotometer. Extract of the dried hull and core of fruit were obtained with percolation in ethanol and its total phenol content and DPPH free radical scavenging activity were determined. Phenolic content was determined using folinciocalteu method. Also, the extracts were added at percentages of 1, 2 and 3% to the rapeseed oil and extracts antioxidant properties were evaluated by rancimat.
    Result And Discussion
    Analysis showed that hull has more oil and ash content and lower protein content than core. Hull oil content (84%) was two times more compared to the core of the fruit (47%), but core protein content (7%) was almost twice compared to hull protein content (3%). The results showed that the percentage of major fatty acids in hull and core of fruit was oleic acid 33% and 41.2%, linoleic acid 10.6% and 21.5%, alpha-linolenic acid 6% and 3.1%, palmitic acid 17.2% and 11% and palmitoleic acid 13.1% and 3.1%, respectively. Results showed that oil extracted from hull and corehave high content ofmonounsaturatedand polyunsaturated fatty acids with relatively high amount of essential fatty acids. Total phenolic content of hull and core of the fruit were 25.6 and 6.3 mg gallic acid per 1 gram of dried sample, respectively. This results show that hull is a rich source of phenolic compound which can be important from nutritional point of view. Peroxide value and acid value increased during 4 month storage significantly. Increase in PV was higher in oil obtained from hull than core oil. Increase in PV can be result of fatty acid oxidation which is affected by several factors such as fatty acid composition, antioxidant content, peroxidant content and storage condition. AV of oil extracted from hull was higher than oil obtained from core. AV was increased in oils obtained from core and hull, but increases in hull were higher. Increase of AV can be result of hydrolyses of triacylglycerols which produce free fatty acids.Chlorophyll content was higher (7 times) in oil obtained from core compared with oil obtained from hull. Oil obtained from core had green color because of high chlorophyll content. Chlorophyll content reduced significantly (P≤0.01) during storage. It should be mentioned that chlorophyll content is an important factor in oil oxidative stability because chlorophyll act. as a sensitizer and enhance oil photoxidation.Evaluation of oil stability by rancimat showed that highest rapeseed oiloxidative stability was obtained by addition 3% of hull extract. Hullextract was more effective onfree radicalscavenging(88%) than core(75%).Hull of wild pistachio in comparison to its core has more phenolic content, therefore more antioxidant activity is also is expected. Phenolic compounds can act as antioxidant and make oils more stable against oxidation.
    Conclusion
    According to suitable fatty acid composition and total phenol content, wild pistachio need more attention in people’s diets as a cheap and useful nut.
    Keywords: wild pistacia, Khinjuk, chemical composition, antioxidant properties, fatty acid composition
  • Ronak Gholami, Jalal Dehghannya, Babak Ghanbarzadeh Pages 420-434
    Introduction
    In recent years, demand for edible and biodegradable films has increased. One reason for this increase is the pollution caused by synthetic polymers. Edible films are produced from different biopolymers such as lipids, polysaccharides and proteins. Starch is a common polysaccharide in the preparation of edible films which is taken into consideration because of its low price and easy access. Structure and composition of starch-based films affects the resulting film properties such as moisture sorption, gas permeability, plasticizer crystallization, glass transition temperature and its mechanical properties. Starch films have usually poor mechanical properties and are permeable to water vapor. The use of nanofillers such as cellulose nanocrystal (CNC) in the structure of starch films and production of nanocomposite films is one way to modify properties of the films. The most important purpose of the application of edible films is to prevent moisture or other compounds such as carbon dioxide or volatile components transfer between the product and the environment or between different layers of the product. Modeling mass transfer and moisture permeability of edible films can be effective in predicting film properties and packaged product during storage. For example, it can be predicted that at a certain temperature, relative humidity and time, how much moisture packaging material will absorb. Therefore, before using edible film as a protective coating for food, calculation of the amount of moisture sorption and permeability to water vapor is essential. The purpose of this study was to investigate mass transfer in starch - CNC nanocomposite films. The effect of adding different percentages of CNC on the water vapor permeability and moisture sorption kinetics of nanocomposite films was studied
    Materials And Methods
    First, 100 ml of potato starch solution with a concentration of 4% (w/v) was prepared by dispersion of the starch in distilled water and was gelatinized at 90ºC for 5 min. Different levels of CNC (0, 3, 5, 7 and 9% w/w) were dissolved in distilled water and were added to the gelatinized starch after treatment with ultrasound for 10 min. Then, glycerol, as a plasticizer, with concentrations of 0.2, 0.3 and 0.4% (w/w) were added to the solution. The film solutions were distributed on polystyrene surfaces and the resulting films were dried in an oven at 40°C for 24 hours. The Fickʹs second law and four empirical equations were used for moisture sorption modeling of samples. The effect of glycerol concentration on water vapor permeability was investigated and the experimental data were fitted with an exponential model.
    Results And Discussion
    By increasing the concentration of CNC, moisture content of the nanocomposite films declined. Effective moisture diffusion coefficient values for nanocomposite samples were higher than the pure starch film. The coefficient increased from 0.293×10-13 to 0.547×10-13 m2/s by increasing CNC concentration from 0 to 9%. This result can be attributed to the influence of cellulose nanofibers on the polymer matrix and gaps creation in the polymer amorphous regions. This, in turn, would facilitate moisture diffusivity into the polymer structure. It should be noted that plasticizer presence in the nanocomposite structure can be an important factor. Regarding that plasticizer lead to increase in polymer chain mobility, simultaneous presence of CNC and plasticizer could lead to create gaps in the structure of nonocompositefim. As expected, in the absence of plasticizer, the effective moisture diffusion coefficient in nanocomposite samples decreased by increasing the concentration of nanoparticles due to high immobility of polymer chains. In addition, the initial stages of moisture sorption were well described by the Fickʹs law but due to the polymer relaxation between 2.5 - 9 h interval, its behavior was deviated from this law. Finally, after about 9 hours, it was observed that the equilibrium moisture content of the nanocomposite samples were consistent with the values predicted by the Fickʹs model. Equilibrium moisture content depends on the hydrophilic locations of the nanocomposite structure. These locations have the ability to absorb moisture and this ability is not influenced by changes in the structure of the polymer during the moisture sorption process. Despite higher levels of effective moisture diffusion coefficients in starch-nanocrystalline cellulose nanocomposites compared to pure starch film, moisture content was lower in nanocomposite films. These results are probably due to the nature of nanocrystalline cellulose which is resistant to water and is compatible with the starch polymer. Nanocrystalline cellulose has the ability to make many hydrogen bonds with the hydrophilic polymer matrix. This results in decreasing hydrophilic property of starch. On the other hand, in all samples, the permeability to water vapor reduced with increasing nanoparticles concentration. For example, in the starch film which contained 0.4% glycerol, water vapor permeability was 2.62×10-7g.m/m2.h.Pa; with the addition of nanocrystalline cellulose to 9%, its value was decreased to 1.8×10-7g.m/m2.h.Pa. Moreover, the permeability to water vapor in all cases increased by increasing the concentration of plasticizer. Results also showed that there is an exponential relationship between the water vapor permeability and plasticizer content.
    Conclusion
    By increasing the concentration of CNC, moisture content of the nanocomposite films declined. Effective moisture diffusion coefficient values for nanocomposite samples were higher than the pure starch film. The coefficient increased by increasing CNC concentration. The initial stages of moisture sorption were well described by the Fickʹs law but due to the polymer relaxation, its behavior was deviated from this law. Finally, after about 9 hours, it was observed that the equilibrium moisture content of the nanocomposite samples were consistent with the values predicted by the Fickʹs model. In addition, in all samples, the permeability to water vapor reduced with increasing nanoparticles concentration. However, the permeability to water vapor increased by increasing the concentration of plasticizer. Results also showed that there is an exponential relationship between the water vapor permeability and plasticizer content
    Keywords: Kinetic, Moisture Sorption, Permeability, Water Vapor, Nanocomposite, Starch, Cellulose Nanocrystal
  • Mohsen Zandi, Mohebbat Mohebbi, Mahdi Varidi, Navid Ramezanian Pages 435-444
    Introduction
    Flavor release from food during consumption in the mouth plays an important role in flavor perception and influenced by the food matrix. Since, food matrix changes biochemically and physically during eating, therefore, food flavor microencapsulation results in controlled release at specific situations. On the other hand, stability and availability of flavors are affected by food processing and storage. To control the flavor release at specific condition during consumption or stability and availability during food processing and storage; it is essential to encapsulate flavor components before use in food complex. Encapsulation is the term for a collection of technique that used as delivery of active and bioactive parts. This novel technology enables isolated of gases, liquid droplets, or solid particles in the core of microscopic vesicular system with porous or non porous semi permeable shell that release occurs in response to the specific situations. Controling release of active compound depends on microcapsule characteristics such as pore size, mechanical stability of the colloidal shell, shell thickness and shell permeability; molecular size and solubility of active parts in the shell and properties of the release media including shear force, temperature, pH, ionic strength, etc. This paper presents the formation and characterization of novel diacetyl encapsulated alginate-whey protein concentrate (AL-WPC) microcapsules. Diacetyl release was investigated at simulated mouth condition in different ratios of artificial saliva (0, 1:4 and 1:8) and three various oral shear rates (0, 50 and 100 s-1) and the diffusion coefficient was estimated using Fick’s law. The main aim of this work was to develop a prediction model to study the flavor release from microcapsules. Materials and Methodes: Aiming to show the applicability of our agent-based model platforms, the release of 2,3-butanedione (diacetyl) from alginate-whey protein concentrate (AL-WPC) microcapsules was used as a case study to validate our simulation model based on NetLogo platforms. For this purpose, our previous work on evaluation of diacetyl encapsulated alginate-whey protein microspheres release kinetics and mechanism at simulated mouth conditions was used (Zandi, M., Mohebbi, M., Varidi, M., Ramezanian, N., 2014). In previous our work, encapsulated diacetyl release was measured at three oral shear rates (0, 50 and100 s-1) and various ratios of saliva to microcapsule (0, 1:4 and 1:8) simulating mouth conditions. Then, experimental release data were fitted using different kinetic models. It was found that release from these microcapsules followed a classical Fickian diffusion. We use release data for calculating release rate. For model validating, diffusion equation was fitted to the experimental data, and diffusion coefficient was obtained for diacetyl release at various mouth conditions. To this purpose, the following model was obtained by solving unsteady diffusion equation in spherical coordinate: (M(t))/M_0 =100-exp⁡(-(3×D×(R+b))/(R^2×b)×t) (1) where M (t) and M0 are the diacetyl release at time t and 0 respectively, R is a microcapsules radius (m), t is time, D is the diffusion coefficient and b is the shell thickness (m). We also use diffusion coefficient to calculate permeability for each specific condition by equation (2): P=(D×K)/b (2) Where P is the permeability coefficient, D is the diffusion coefficient and K is the partition coefficient. Finally, the model and experimental data were analyzed using Matlab software (R2007).
    Result And Discussion
    In our study, AL-WPC microcapsule was fabricated by emulsification/internal gelation method, and diacetyl was loaded into microcapsule. Most of microspheres had a completely spherical shape with smooth surface, and range in size from 20-150 μm. The diacetyl encapsulated microsphere had a porous and smooth shell with some holes that caused the quicker diacetyl release initially. The mean hydrodynamic diameter 112.8 ± 0.9 μm (mean value ± SD for n= 2) was measured via particle size analyzer (DLS). the high efficiency of 79.34% was obtained for diacetyl encapsulated AL-WPC microcapsule. About 20% of diacetyl was loosed because of the solubility and volatility of the diacetyl molecule (diacetyl is a low molecular weight and water soluble component)..
    Conclusion
    It was showed that the shear rate of release media had a significant (p<0.05) effect on the release of diacetyl from AL-WPC microspheres, but saliva ratio had not any significant effect. The diacetyl release data fit well to developed model with R2 values greater than 0.95
    Keywords: Diffusion coefficient, Fick law, alginate, whey protein concentrate microcapsule, Diacetyl, controlled released
  • Forough Mohtarami, Mohsen Esmaiili, Mohammad Alizadeh Khaledabad, Seyed Mahdi Seyedain Ardabili Pages 445-457
    Introduction
    A mixture of wheat flour, water, salt, yeast and other optional ingredients such as preservatives, enzymes, whey powder, surfactants, sugar, fibres and improvers form bread dough. Enrichment of dough and bakery products by dietary fibres such as wheat bran and resistant starch, beta-glucans and inulin has been reported (Peressini, & Sensidoni, 2009; Hager, Ryan, Schwab, Gänzle, O’Doherty, &Arendt, 2011; Wang, Rosell, Barber, 2002; Angioloni, Collar, 2008). Whey has many applications in food and dairy industries due to its high quality of nutrients and functional properties. It possesses essential amino acids (Mann, 1998; Sharma, & Bhatia, 1999). There are other alternatives such as transglutaminase and asparaginase enzymes as innovative ingredients, which are recognized as safe in the food technology. The microbial transglutaminase enzyme (MTG) catalyzes the reaction between a ε-amino group of lysine residues and a β-carboxyamide group of glutamine residues, which causes to make covalent cross-linking of proteins (Yokoyama, Nio, & Kikuchi, 2004). Asparaginase (ASP) can catalyze the hydrolysis of asparagines, as a key factor for acrylamide formation, into aspartic acid and ammonia (Ciesarova, Kukurova, &Benesova, 2010). The present work was undertaken to study the influence of whey powder, inulin, asparaginase and transglutaminase enzymes on farinograph and extensograph properties of wheat flour dough using a D-optimal design.
    Materials And Methods
    Two types of wheat as insect damaged (50% insected) and sound hard red wheat (imported variety), milled into two types of flour by traditional mill. The characteristics of the flours such as moisture, ash, protein, falling number, wet gluten and Zeleny-value were determined using AACC methods (2000) in three replicates. Enzymes included MTG and ASP and other applied additives such as inulin (Frutafit-HD) and whey powder used at different levels based on flour weight in dough formulation. Effect of enzymes, additives and wheat flour types (WFT) on farinograph and extensograph characteristics were conducted according to the constant flour weight procedure of AACC (2000). D-optimal design was used to determine the effects of five independent variables including MTG, ASP, whey powder, inulin, and flour type on farinograph and extensograph properties. Response data were used to fit the second-order polynomial equation. Normal probability was used for separation of significant effects from noise or random effects. The significance of each coefficient in the regression model was determined using p-value lower than 0.05. Adequacy of models for regression were estimated using coefficient of determination (R2) and adjust R2 (adj-R2).
    Results And Discussion
    According to chemical and physical analysis of flour, it is obvious that in spite of having nearly the same amount of protein and wet gluten, the two types of flour had prominent difference in dough and gluten quality as indicated by gluten index and farino-extensograph tests. Due to this fact, the wheat flours with gluten index of 5.43±4.31 and 76.93±5.87 were named as weak and strong flours, respectively. Analytical data of farinograph properties were fitted to regression models. Analysis of variance of lack-of-fit test showed that the water absorption model is adequate with a non-significant lack of fit (p=0.267) and a satisfactory adj-R2 (97.53%). Among the different additives, strong wheat flour had positive effect and inulin and whey powder had negative effect on water absorption. According to half-normal plot and regression model coefficients, wheat flour type, inulin and whey powder significantly affected dough development time (DT) and stability (S). The models of DT and S had R2 values of 88.58%, 98.45% and non-significant lack of fits p=0.087 and p=0.018, respectively. DT and S increased with an increase in inulin and whey powder level using strong wheat flour. The regression model for degree of softening as a function of different ingredients was significant at a p-value less than 0.0001. Based on analysis of variance, the model appeared to be adequate with a non-significant lack of fit p=0.017 and a R2 value of 97.57%. Among the investigated factors, wheat flour showed the greatest positive effect on the degree of softening followed by inulin. The degree of softening was decreased by addition of inulin and whey powder. Among the interaction terms, a negative interaction effect on degree of softening was found between MTG and ASP (p<0.05). The regression model for farinograph quality number (f.q.n) possessed a good fitness with experimental data, with a high R2 value (98.59%) and non-significant lack of fit. Interaction effect between wheat flour type and inulin on the f.q.n was significant at a p-value less than 0.0001. Usage of inulin, whey powder and strong wheat flour improved and elevated f.q.n. The regression model for energy value as a function of different ingredients was significant at a p-value less than 0.0001 with an R2 value of 94.22%. Among the investigated factors, inulin and MTG had significant single positive effect on energy value. The energy value increased with the addition of whey powder to dough formula. This increase was more evident in the strong flour samples. Regression analysis revealed that interaction between wheat flour type and MTG had the most pronounced effect on dough resistance to extension (R) followed by inulin. A progressive increase in this parameter was observed with increasing MTG dosage especially along with strong wheat flour. Inulin and whey powder had also positive effect on it.
    Conclusion
    The model for extensibility (Ex.) had an R2 value of 86.29% and non significant lack of fit (p=0.124). Among the investigated factors, flour type showed the most pronounced positive effect followed by inulin on extensibility. Dough extensibility was increased by adding whey powder. The regression model for R/Ex. ratio as a functional of different ingredients was significant at a p-value of < 0.0001 with an R2 value of 81.73%. Among the applied factors, the flour type and MTG had pronounced influence on R/Ex. ratio.
    Keywords: Farinograph, Extensograph, Prebiotic, Wheat flour dough
  • Reza Safari, Zahra Yaghoubzadeh Pages 485-495
    Introduction
    Evaluation of fish and seafood markets in Iran show that people have little interest to consume fish, despite the fact that fish consumption in developed countries is the rapid growth. However, despite the significant sources of demand for fish consumption of fish is generally seasonal. One of the problems consumers clean and ready to cook the fish, which need to experience and time, although it is common for all the fish, but the warm water cultured fish is more important, therefore, must be programmed in such a way that the fish are supplied all year. The fish processing provides the possibility that fish that are produced in a limited time and gradually throughout the year are marketed. Due to high production of warm water fish and using of small-scale and traditional methods for processing of fish such as salting and smoking, is necessary to use from modern processing methods for production of high quality of fishery products from fish particularly warm water fish such carp, silver carp, grass carp and big head. In 2004, a joint project with title "improvement of silver carp processing and production of different products from fish" was signed between Iranian Fisheries Science Research Institute and Rivo Institute and Wageningen university of Netherlands. According to the project 7 sub projects were defined that including: quality of fish sausage, fish cheese, fish snake, fish ball, fish ice cream, trimming machines for production of fish fillet and pin bone machines for production of deboned fillet. Two main objectives of the project were production of high quality of fish fillet with low fat and bone and development of various products from silver carp for introduce to market. Fish Cheese is produced from coagulation of soluble proteins (sarcoplasmic proteins) of fish. The aim of this study was to extraction and precipitatation of sarcoplasmic proteins of silver carp (Hypophthalmichthys molitrix) and its use in fish cheese formulations.
    Materials And Methods
    After washing, the fish was beheaded, gutted, and again washed and bones were manually separated. Fish fillets were grained and prepared for surimi production. Minced fish were washed three times in 10 ° C water (1 to 4 w/v) for 15 minutes, and the third stage was rinsed in the brine (0.3%). For coagulation and concentration of sarcoplasmic proteins were used from acetic acid (5%) and centrifuge in 5000 rpm for 15 minutes respectively. At the end of the process the sugar and sorbitol, (each in the amount of 4%) and tri sodium polyphosphate was used in the amount of 0.3%. Proximate composition (total protein, total fat, moisture and ash) and chemical parameters (peroxide value (PV) and total volatile base nitrogenTVB-N) and microbial analysis (total viable counts) were examined for three forms of fish (minced fillets, concentrated protein and fish cheese). All examinations were done as standard methods for food analysis.
    Results And Discussion
    The results indicated that mean of lipid, ash, moisture and protein in minced silver carp were %2.71, %79.44,, %0.91, %16.90 and in sarcoplasmic protein concentrated were %16.90, %1.16, %81.97, %0.42 and in fish cheese were %16.41, %28.01, %48.41, %3.46, %17/50 respectively. The best formula was treatment of 15 with %22/26 of protein. Mean of TVN and PV in minced fish, primary protein paste and fish cheese were, 11.32 mg/100, 1.51 meqo/kg and 13.63 mg/100, 3.65 meqo/kg and 15.03 mg/100, 5.38 meqo/kg respectively. The results indicated that mean total bacteria count was in minced meat 7.2 × 104per grams was the lowest (1.1×103) and highest (5.4 ×104), respectively. The mean total count of bacteria in fish protein concentrated sarcoplasmic 3.1 × 104 g, which is the lowest number (1.8×103), and the highest number (5.2 ×104), respectively. The mean total count of bacteria in cheese, fish 8/1 × 103 per gram was the lowest number (5.8×103), and the highest number of (4×104). Total count of bacteria in three of the treatments showed that the number of bacteria in the range of 4 logs, and the final product slightly decreased (in some treatments). Changes in the number of microbes in the products depend on two factors such as time - temperature and the temperature are lower and therefore faster processing time will count as standard.
    Conclusion
    According to the results, the product production of sarcoplasmic proteins silver carp namely fish cheese the quality parameters, indicators of chemical and microbial spoilage in a range of reference standards can be used as a new product made silver fish with different formulations, in the diet However supplemental tests including organoleptic criteria for the evaluation of the physical properties of the product is necessary.
    Keywords: fish cheese, silver carp, acid coagulation, sarcoplasmic protein