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پژوهشهای علوم و صنایع غذایی ایران - سال دوازدهم شماره 5 (پیاپی 41، آذر و دی 1395)

نشریه پژوهش های علوم و صنایع غذایی ایران
سال دوازدهم شماره 5 (پیاپی 41، آذر و دی 1395)

  • تاریخ انتشار: 1395/10/28
  • تعداد عناوین: 16
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  • مقاله پژوهشی فارسی
  • تاثیر ترکیبی بسته بندی تحت خلاء وعصاره چای سبز بر تغییرات کیفی ماهی قباد (Scomberomorus guttatus) طی نگهداری در یخچال
    فاطمه خدری، آی ناز خدانظری صفحات 533-542
    در پژوهش حاضر تاثیر بسته بندی تحت خلاء بر تغییرات کیفی ماهی قباد (Scomberomorus guttatus) نگهداری شده با و بدون عصاره چای سبز (1 گرم بر لیتر، عصاره چای سبز) در طی نگهداری در یخچال (oC 1±4) به مدت 10 روز مورد مطالعه قرار گرفت. آزمون های میکروبی (بار باکتریایی کل و سرمادوست) بیانگر تاثیر ضدمیکروبی عصاره چای سبز بود. آزمون های شاخص اکسیداسیون چربی (پراکسید، تیوباربیتوریک اسید) نیز حاکی از کمتر بودن میزان اکسیداسیون در نمونه های ماهی حاوی عصاره چای سبز و بسته بندی تحت خلاء نسبت به نمونه شاهد و ماهی نگهداری شده در بسته بندی تحت خلاء بود (05/0>P). میزان TVB-N و pH در تمام نمونه ها افزایش نشان داد که در نمونه های ماهی حاوی عصاره چای سبز و بسته بندی تحت خلاء نسبت به نمونه شاهد و ماهی نگهداری شده در بسته بندی تحت خلاء دارای مقدار اندکی می باشد (05/0>P). نتایج حاصل از ارزیابی حسی نشان داد که ویژگی بافت، بو، طعم، رنگ و پذیرش کلی تمامی تیمارها و نمونه شاهد با گذشت زمان کاسته شد. نمونه های دارای بسته بندی تحت خلاء بطور معنی دار بهتر از نمونه شاهد بود. عصاره چای سبز به همراه بسته بندی تحت خلاء می تواند تغییرات شیمیایی و میکروبی را کاهش دهد. بنابراین، ماهی های نگهداری شده با عصاره چای سبز پیش از بسته بندی تحت خلاء کمترین کاهش کیفیت را طی نگهداری در یخچال داشتند.
    کلیدواژگان: Scomberomorus guttatus، کیفیت، عصاره چای سبز، بسته بندی تحت خلاء
  • اورنگ خادمی، یونس نعمتی میرک صفحات 543-555
    گسی میوه در خرمالو یک صفت نامطلوب است که کاهش آن مستلزم برداشت میوه در زمان رسیدگی کامل و نرم شدن میوه می باشد. با این حال برداشت میوه در زمان بلوغ تجاری و رفع گسی با استفاده از ترکیبات مناسب می تواند در افزایش کیفیت میوه و بازاررسانی آن موثر باشد. در این پژوهش، رفع گسی میوه دو رقم خرمالو با نام های رایج رقم کرج و رقم ژاپنی با استفاده از دی اکسیدکربن جامد (یخ خشک) و اتانول بررسی شد. نتایج نشان داد تیمار یخ خشک به خصوص در غلظت بالا (7%)، در هر دو رقم موجب رفع گسی میوه و کاهش غلظت تانن محلول به زیر 1000 میلی گرم بر کیلوگرم شد ولی تیمار اتانول فقط در رقم کرج موثر بود. تیمارهای مورد استفاده سفتی بافت میوه را در هر دو رقم بطور معنی داری کاهش دادند ولی تیمار اتانول در مقایسه با تیمار یخ خشک سفتی بافت میوه را بیشتر کاهش داد. مقدار مواد جامد محلول در اثر تیمارهای رفع گسی در هر دو رقم به دلیل کاهش مقدار تانن محلول کاهش یافت ولی مقدار اسید آسکوربیک در این دو رقم تحت تاثیر تیمار رفع گسی قرار نگرفت. نتایج کلی نشان داد تیمار یخ خشک به عنوان تیماری موثر و ارزان قیمت، بصورت تجاری می تواند برای رفع گسی میوه خرمالو تولید شده در ایران مورد استفاده قرار گیرد.
    کلیدواژگان: آنتی اکسیدان، تانن محلول، خرمالو، سفتی، طعم گس
  • سیدعلی جعفرپور صفحات 556-564
    رنگ و ویژگی های ظاهری سطح یک ماده غذایی به عنوان اولین پارامترهایی هستند که توسط مصرف کننده مورد قضاوت قرار گرفته و مبنای رد یا قبول آن ماده می باشد. در این پژوهش کارآیی دستگاه IMG-Pardazesh در خصوص اندازه گیری رنگ در مقایسه با سیستم CIE L*ab، سیستم Hunter lab و سیستم استاندارد Patch Tool مورد ارزیابی قرار گرفت. بر این مبنا میزان عددی همبستگی (R2) موجود بین سه پارامتر L*، a* و b* بدست آمده از دستگاه IMG-Pardazesh در مقایسه باسیستم CIE L*ab به ترتیب معادل 996/0، 998/0، و 980/0 و در مقایسه با داده های Hunter lab معادل 983/0، 981/0، و 871/0 و با داده های نرم افزار Patch-color دارای میزان همبستگی (R2) معادل 935/0، 881/0 و 953/0 بود. در خصوص دستگاه اندازه گیری رنگ IMG-Pardazesh از بین ارزش عددی پارامترهای رنگ L*a*b*، و مقایسه آن با داده های سیستمCIE L*ab کاملا مشهود است که شاخص خطای جذر میانگین مربعاتRMSD در تمامی پارامترها با اختلاف جزئی کمتر بوده و در مقایسه با سیستم Hunter lab به جز پارامتر a در سایر پارامترها دارای ارزش عددی بسیار پایین تری بود. به علاوه محاسبه خطای نرمال شده ی میانگین ها نشان دهنده وجود خطای به مراتب بالاتر در تمامی پارامترها در سیستم CIE L*ab و خطای بسیار بالاتر در دو پارامتر L* و b* در سیستم Hunter lab می باشد. نتیجه اینکه بر مبنای این شاخص نیز می توان پی برد که دستگاه IMG-Pardazesh از میزان خطای کمتری در برآورد پارامترهای رنگ در مقایسه با سایر سیستم ها برخوردار می باشد.
    کلیدواژگان: عکس دیجیتالی، سنجش رنگ، RGB، L*a*b*
  • نجمه ملااحمدی بهراسمان، رضا فرهوش، علی شریف صفحات 565-571
    در پژوهش حاضر، ویژگی های فیزیکوشیمیایی، ساختار اسید چربی و پایدارسازی روغن ماهی کیلکا بررسی شد. اسید پاراهیدروکسی بنزوئیک، استر متیل آن و آلفا-توکوفرول به عنوان شاهد مثبت، با یکدیگر مقایسه شدند. 200 پی پی ام از آنتی اکسیدان های مذکور به روغن تخلیص شده اضافه شد و شرایط رژیم سینتیکی اکسایش در سه دمای 35، 45 و 55 درجه سانتی گراد مهیا گردید. پس از رصد مداوم اکسایش طی زمان توسط آزمون پراکسید، نمودار تغییرات پراکسید نسبت زمان ترسیم و دوره القاء و شاخص های سینتیکی F، ORR وA محاسبه شدند. به منظور بررسی عملکرد آنتی اکسیدان ها در محیط آبی، امولسیون ده درصد روغن در آب تهیه و 200 پی پی ام آنتی اکسیدان به آن اضافه شد و روند اکسایش آن در دمای 55 درجه سانتی گراد پایش گردید. نتایج آزمایش تعیین ساختار اسید چربی نشان داد ساختار اسیدچربی این روغن، حاوی انواع غیراشباع، اشباع و چند غیر اشباع (عمدتا اسیدهای لینولئیک، ایکوزاپنتانوئیک و دوکوزاهگزانوئیک) است. دما تاثیر معنی داری بر روند اکسایش روغن داشت. پاراهیدروکسی متیل بنزوات اندکی بیش از اسید پاراهیدروکسی بنزوئیک پایداری اکسایشی روغن را افزایش داد. آلفا-توکوفرول در مقایسه با سایر آنتی اکسیدان ها عملکرد بهتری داشت. عملکرد پاراهیدروکسی متیل بنزوات نسبت به شاهد، در امولسیون بهتر بود.
    کلیدواژگان: انتی اکسیدان، روغن ماهی، اسید بنزوئیک، امولسیون روغن در اب
  • آرش کوچکی، عبدالله همتیان سورکی، محمد الهی، سید محمدعلی رضوی صفحات 572-587
    در این پژوهش تاثیر شرایط استخراج شامل زمان، نسبت حلال به آرد جو و pH بر ویژگی های فیزیکوشیمایی، رفتار جریان، پایدارکنندگی کف و امولسیون و رنگ بتاگلوکان استخراج شده از دانه جو بدون پوشینه رقم لوت توسط طرح مرکب مرکزی و به روش سطح پاسخ تعیین گردید. نتایج تجزیه و تحلیل آماری و ضرایب مدل ها نشان داد که مدت زمان استخراج، نسبت حلال به آرد جو و pH اثر معنی داری بر بازدهی و خلوص بتاگلوکان، پایداری کف و امولسیون، ضریب قوام (k)، شاخص رفتار جریان (n) و مولفه های رنگیL*، a* و b* داشت. افزایش زمان استخراج و نسبت حلال به آرد جو اثر مطلوبی بر بازدهی و خلوص بتاگلوکان استخراج شده گذاشت که این امر خود موجب بهبود خاصیت قوام دهندگی و ویژگی های رفتار جریان آن شد. از طرفی با افزایش قدرت قوام دهندگی بتاگلوکان، توانایی پایدارکنندگی سیستم های کف و امولسیون نیز افزایش یافت. افزایش pH موجب کاهش بازدهی استخراج و افزایش خلوص بتاگلوکان گردید. بهترین شرایط استخراج زمانی حاصل شد که زمان استخراج 90 دقیقه، نسبت حلال به آرد جو 10 به 1 و pH، 33/7 بود. در این نقطه بهینه، بازدهی استخراج، 12/4 درصد؛ خلوص، 11/69 درصد؛ پایداری کف، 95/86 درصد؛ پایداری امولسیون، 77/88 درصد؛ ضریب قوام، Pa.sn 51/1؛ شاخص رفتار جریان، 62/0؛ L*، 42/73 ؛ a*، 81/0 و b*، 72/8 بود.
    کلیدواژگان: بتاگلوکان، جو بدون پوشینه، استخراج آبی، روش سطح پاسخ، رفتار جریان، پایداری کف و پایداری امولسیون
  • نجمه ملااحمدی بهراسمان، رضا فرهوش، سعید جانی، علی شریف صفحات 588-595
    پایداری اکسایشی روغن ماهی کیلکا در حضور دو مشتق اسید فنلی (وانیلیک و سیرینجیک) مورد بررسی قرارگرفت. آلفا- توکوفرول به عنوان شاهد مثبت در نظرگرفته شد. دو خصوصیت، مهارکنندگی رادیکال آزاد دی پی پی اچ و قطبیت نسبی آنتی اکسیدان های مذکور اندازه گیری شد. روغن به روش کروماتوگرافی جذبی تخلیص و 200 پی پی ام از آنتی اکسیدان های مورد مطالعه به آن اضافه شد و شرایط رژیم سینتیکی در دمای 55 درجه سانتی گراد برقرار گردید. در طول زمان گرمخانه گذاری در فواصل زمانی معین از روغن نمونه برداری و عدد پراکسید اندازه گیری شد. روند اکسایش امولسیون 10درصد نیز در همان دما بررسی شد. نتایج نشان داد اسید سیرینجیک با وجود قطبیت نسبی بالا و نیز قدرت مهارکنندگی بالایی که داشت، عملکرد آن در روغن تحت برهمکنش های درون مولکولی کاهش یافت و از فرضیه معروف «تناقض قطبی» تبعیت ننمود. کارایی آنتی-اکسیدانی اسید سیرینجیک در امولسیون نسبت به روغن افزایش قابل توجهی نشان داد و مشابه آلفا- توکوفرول بود. قدرت مهارکنندگی رادیکال و فعالیت آنتی اکسیدانی اسید وانیلیک مشابه هم بود. بطور کلی امولسیفایر و عملیات تهیه امولسیون نسبت به آنتی اکسیدان، نقش پررنگ تری در پایداری اکسایشی روغن امولسیون شده داشتند.
    کلیدواژگان: اسید فنلی، امولسیون، آنتی اکسیدان، تناقض قطبی، روغن ماهی
  • ندا نیری، محمدرضا عدالتیان دوم، محمد باقر حبیبی نجفی، معصومه بحرینی صفحات 596-608
    هدف این تحقیق، بررسی اثر ضدمخمری سویه های لاکتوباسیلوس پلانتاروم جدا شده از مراحل مختلف تولید پنیر لیقوان روی مخمر رودوتورولا موسیلوجینوسا واریته موسیلوجینوسا PTCC 5257)) به عنوان عامل فساد مخمری آبمیوه و بررسی تاثیر فاکتورهای تکنولوژیکی مانند تاثیر دما، pH و بررسی تاثیر آنزیم پروتیئناز K بر خواص ضدمخمری سویه های مزبور است. بدین منظور از 19 سویه،که 3 سویه از شیر خام و 8 سویه از دلمه و 8 سویه از پنیر تازه لیقوان، استفاده شد. طیف فعالیت ضدمخمری، سویه ها توسط روش نقطه گذاری و روش نفوذ در چاهک تعیین شد، و به دنبال آن تعیین تاثیر فاکتورهای تکنولوژیکی یا فیزیکوشیمیایی مختلف از جمله درجه حرارت های (80 درجه سانتی گراد به مدت 1 ساعت، 100 درجه سانتی گراد به مدت 10 و 30 دقیقه، 121 درجه سانتی گراد به مدت 15 دقیقه (شرایط اتوکلاو)، pHهای 2 تا 7 و اثر آنزیم پروتئیناز K . نتایج حاصل، نشان داد که سویه C28 دارای بالاترین خاصیت ضد مخمری در هر دو روش نقطه گذاری و نفوذ در چاهک بوده است، و با افزایش pH اثر ضدمخمری کاهش می یابد. در بررسی اثر دما، در شرایط اتوکلاو هیچ گونه هاله شفافی مشاهده نشد. تمامی جدایه های مورد بررسی درحضور آنزیم پروتئیناز K خاصیت ضدمخمری خود را از دست دادند. در نهایت، می توان اینطور فرض کرد که سویه های ایزوله شده از مراحل مختلف تولید پنیر لیقوان یا عصاره فاقد سلول آن ها، به عنوان نگهدارنده زیستی در سیستم های غذای بخصوص در سیستم های غذایی اسیدی مانند آبمیوه، بکار روند.
    کلیدواژگان: پنیر لیقوان، لاکتوباسیلوس پلانتاروم، رودوتورولا موسیلوجینوسا، ضد مخمری
  • بابک قنبرزاده، صحرا بشیری، حامد همیشه کار، جلال دهقان نیا صفحات 609-619
    ریزپوشانی مواد غذا- دارو در حامل های لیپیدی، از جمله لیپوزوم ها، منجر به افزایش قابلیت زیست فراهمی مواد فعال، رهایش کنترل شده و دقیق آن ها، حفظ پایداری آن ها در برابر شرایط مختلف محیطی و حلالیت مواد فعال آبگریز در محیط آبی می شود. از جمله ترکیبات مغذی آبگریز با خاصیت آنتی اکسیدانی و پروویتامینی مفید، بتاکاروتن می باشد که خاصیت آب گریزی این ماده و نیز حساسیت بالا در شرایط مختلف محیطی کاربرد آن را برای غنی سازی مواد غذایی محدود کرده است. هدف از انجام این پژوهش تولید و بررسی نانولیپوزوم های حامل بتاکاروتن به روش گرمایی اصلاح یافته (مظفری اصلاح شده) و بررسی ویژگی های مهم کاربردی آن بود. اندازه ذرات نانولیپوزوم های حامل بتاکاروتن در غلظت های مختلف لستین، کوچک تر از 500 نانومتر به دست آمد و برای غلظت های بهینه لستین، 84-64 نانومتر تعیین شد. استفاده از فیتواسترول (گامااوریزانول)، جهت حفظ پایداری غشای سیستم های لیپوزومی، موجب کاهش اندازه ذرات در غلظت های مختلف لستین گردید بطور مثال در غلظت 200 میلی گرم لستین اندازه ذرات از 88 نانومتر به 64 نانومتر کاهش یافت. همچنین گامااوریزانول مورد استفاده در لیپوزوم، روی کارایی ریزپوشانی بتاکاروتن موثر نبود و در هر دو سیستم کارایی حدود 89 درصد محاسبه شد. پایداری لیپوزوم های بدون گاما اوریزانول و حاوی آن، بر اساس پتانسیل زتا که معیاری برای دافعه الکترواستاتیک و پایداری است، مناسب بدست آمد.
    کلیدواژگان: نانولیپوزوم، بتاکاروتن، ویژگی های کلوئیدی
  • حمیده سپردار، ابراهیم رحیمی، ایمان شهابی قهفرخی، بهزاد آقابراری صفحات 620-629
    به دلیل آلودگی های زیست محیطی ناشی از مواد بسته بندی پلاستیکی و زیست تخریب ناپذیر تحقیقات زیادی برای تولید بسته بندی های زیست تخریب پذیر انجام شده است. فیلم تهیه شده از ایزوله پروتئین سویا (SPI) یک پلیمر زیست تخریب پذیر است، که دارای ارزش تغذیه ای بسیار بالایی است که اخیرا به عنوان یک ماده بسته بندی زیست سازگار مورد توجه قرار گرفته است. ازسوی دیگر کتیرا (TG) به عنوان یک صمغ گیاهی با خصوصیات مکانیکی خوب، مطرح است. در این تحقیق اثر افزودن کتیرا به عنوان بهبود دهنده خصوصیات کاربردی بیوپلیمر در سه سطح 1/0، 3/0، 5/0 (W/W) استفاده شد و تاثیر آن بر روی خصوصیات مکانیکی، حلالیت در آب، محتوای رطوبت، جذب آب، نفوذپذیری نسبت به بخار آب و رنگ فیلم ایزوله پروتئین سویا مورد بررسی قرار گرفت. نتایج نشان داد که با افزایش کتیرا و کاهش میزان ایزوله پروتئین سویا مقاومت کششی و میزان رطوبت فیلم افزایش، ولی ازدیاد طول تا نقطه شکست، حلالیت در آب فیلم، میزان جذب آب و نفوذپذیری نسبت به بخار آب فیلم کاهش یافت. در پارامترهای L، a و اندیس سفیدی بیشترین مقدار مربوط به نمونه کتیرا: ایزوله پروتئین سویا (5/0: 5/4 ) و در پارامترb ، تغییر رنگ واندیس زردی بیشترین مقدار مربوط به نمونه کتیرا: ایزوله پروتئین سویا (1/0: 9/4) بود.
    کلیدواژگان: ایزوله پروتئین سویا، کتیرا، زیست تخریب پذیر، مقاومت کششی، نفوذپذیری نسبت به بخار آب
  • آی ناز خدانظری، سارا گل گلی پور، کمال غانمی صفحات 630-638
    این پژوهش با هدف تاثیرروش های پخت (بخارپز، آب پز، مایکروویو، سرخ کردن تابه ای، سرخ کردن عمیق) بر تغییرات اسیدهای چرب آزاد، تیوباربیتوریک اسید، فلزات سنگین (کبالت، سرب، کادمیوم، کروم، نیکل) و خواص حسی ماهی آمور (Ctenopharyngodonidella) انجام شد. پخت ماهی آمور طبق تکنیک های معمول مصرف کننده تهیه شد: آب پز، بخارپز، سرخ کردن تابه ای (بدون افزودن روغن)، سرخ کردن عمیق (در روغن زیتون) و مایکروویو. روش های پخت بخارپز و سرخ کردن عمیق منجر به افزایش تیوباربیتوریک اسید شد، در حالی که در روش های پخت آب پز و سرخ کردن تابه ای میزان تیوباربیتوریک اسید تغییری نداشتند. میزان اسیدهای چرب آزاد فیله ها با روش های مختلف پخت بطور معنی داری کاهش یافت.نیکل در روش های پخت آب پز، سرخ کردن تابه ای و سرخ کردن عمیق شناسایی نشد. محتوی کروم در نمونه های پخته شده در مقایسه با سایر روش های پخت تفاوت معنی داری نداشت(05/0
    کلیدواژگان: Ctenopharyngodon idell، روش های پخت، تیوباربیتوریک اسید، اسیدهای چرب آزاد، فلزات سنگین، خواص حسی
  • ستاره حسین زاده، آرام بستان، محمدحسین حدادخداپرست، محبت محبی صفحات 639-651
    روغن برگ گیاه نعناع یکی از انواع طعم دهنده های طبیعی و غیر محلول در آب بوده که به علت دارا بودن ویژگی های آروماتیک خاص از اهمیت ویژه ای در صنایع غذایی برخوردار است. در این پژوهش ریزپوشانی روغن نعناع با هدف سهولت در مصرف، افزایش حلالیت و محافظت در برابر عوامل محیطی، به روش خشک کردن پاششی مورد بررسی قرار گرفت. به این منظور امولسیونی شامل 5/2% روغن نعناع و نشاسته اصلاح شده به عنوان ماده دیواره به نسبت 10%، 20% و 30% آماده، سپس در خشک کن پاششی با دمای 10±180 درجه سانتی گرادخشک شد. ویژگی های امولسیون اولیه از جمله اندازه ذرات، ساختار، پایداری و ویژگی های ریزکپسول ها از جمله اندازه ذرات، توزیع اندازه ذره، رطوبت، حلالیت، ساختار، راندمان درون پوشانی و نیمه عمر مورد بررسی قرار گرفت. اندازه ذرات امولسیون بین 8/1 تا 3/3 میکرومتر بود و غلظت ماده دیواره تاثیر معنی داری بر اندازه ذرات داشت. تاثیر غلظت ماده دیواره بر پایداری امولسیون نیز معنی دار بود و با افزایش غلظت، پایداری در برابر خامه ای شدن افزایش یافت. اندازه کپسول های حاوی روغن نعناع بین 2/1 تا 5/2 میکرومتر بود. راندمان درون پوشانی با افزایش غلظت دیواره به شکل معنی داری افزایش پیدا کرد. افزایش غلظت ماده دیواره و کاهش دما به شکل معنی داری سبب افزایش نیمه عمر ریزکپسول ها شد. کلیه ریزکپسول ها در آب به خوبی حل شده، محلولی شفاف ایجاد نمودند.
    کلیدواژگان: خشک کردن پاششی، نیمه عمر، منتول، لیمونن، ریزکپسول
  • محمودرضا گلزاریان، منصوره شمیلی، امید دوستی ایرانی، پیمان آذر کیش صفحات 652-662
    سیستم بینایی ماشین یکی از ابزارهای قدرتمند به منظور خودکار کردن روش های درجه بندی محصولات کشاورزی است. در این تحقیق با استفاده از پردازش تصاویر رنگی تهیه شده از میوه انبه به تشخیص خرابی های ظاهری ناشی از صدمات مکانیکی پرداخته شده است. برای این منظور از میان 80 عدد انبه با بازرسی چشمی تعداد 60 نمونه انبه که بر روی آن ها لکه های سیاه رنگ ناشی از آسیب های مکانیکی در حین برداشت و جابجایی به وجود آمده بود، تشخیص داده شدند و از هر میوه در شرایط نوردهی یکسان تصویربرداری شد. با استخراج ویژگی های رنگی در سه مدل رنگی RGB، HSI و L*a*b* و مقایسه آماری داده ها مشخص شد که ویژگی های رنگی G و 0.16G/0.5R در محیط رنگی RGB به ترتیب با دقت 90% و 6/91% و ویژگی های رنگیa* و 0.16L*-a*از فضای رنگی L*a*b* به ترتیب با دقت 33/93% و 100% قادر به تشخیص بافت آسیب دیده می باشند. درصد مساحت استخراج شده از هر نمونه به عنوان معیاری برای درجه بندی میوه انبه مورداستفاده قرار گرفت. با استفاده از روش خوشه بندی K میانگین نمونه ها به دودسته تقسیم بندی شدند و نقطه برش بین این دودسته با استفاده از منحنی راک برابر با 11/3 بدست آمد. مساحت منحنی راک برابر با 1 بدست آمد که نشان دهنده قدرت تفکیک بالای خوشه بندی است.
    کلیدواژگان: پردازش تصویر، آسیب های سطحی، صدمات مکانیکی، تصاویر رنگی، انبه
  • لیلا منجذب مرودشتی، مسعود یاورمنش، آرش کوچکی صفحات 663-677
    فیلم زیست تخریب پذیر ترکیبی با استفاده از پلی وینیل الکل- صمغ قدومه شیرازی با نسبت 60 به 40 با افزودن شش غلظت مختلف گلیسرول (%70-20) به روش قالب گیری ساخته شد. ویژگی های فیلم شامل ضخامت، دانسیته، میزان رطوبت، جذب رطوبت، حلالیت در آب، زاویه تماس قطره آب، رنگ، نرخ عبور بخار آب و خواص مکانیکی آنها مورد اندازه گیری قرار گرفت. در ضمن از آزمون های طیف سنج مادون قرمز و میکروسکوپ الکترونی نیز برای بررسی برهمکنش های شیمیایی و ویژگی های ریزساختار فیلم ها استفاده شد. افزایش غلظت گلیسرول بطور معنی داری (05/0 >P) باعث افزایش ضخامت، میزان رطوبت، جذب رطوبت، حلالیت در آب، دانسیته، شفافیت، کاهش زاویه تماس، نفوذپذیری به بخار آب و کدورت گردید. افزایش غلظت گلیسرول بر پارامترهای رنگ نیز اثر گذاشت، بطوری که میزان روشنایی و زردی فیلم را بترتیب از 90 به 4/94 و از 5/0 به 3/1 افزایش و میزان قرمزی را از 9/0 به 5/0 کاهش داد. بطور کلی فاکتورهای رنگی شامل اندیس سفیدی، اندیس زردی و میزان اشباعیت رنگ افزایش و اختلاف رنگ نمونه ها با پلیت سفید کاهش یافت. آزمون مکانیکی فیلم ها نشان داد که مقاومت کششی از 6/64 به 2/13 و مدول یانگ نیز از 892 به 85/156 مگاپاسکال کاهش و درصد کشیدگی از 1/2 به 47/15 درصد افزایش یافت. افزایش غلظت گلیسرول، نفوذپذیری به بخار آب را تا بیش از 7/4 برابر افزایش داد. با افزایش غلظت گلیسرول تغییر اندکی در ساختار فیلم ها مشاهده شد. فیلم ها با نسبت بالاتر گلیسرول تصاویر ریزساختار با سطوح یکنواخت و بدون منفذی را نشان دادند.
    کلیدواژگان: پلی وینیل الکل، صمغ قدومه شیرازی، گلیسرول، فیلم زیست تخریب پذیر
  • سید امیر اولیایی، بابک قنبرزاده، علی اکبر مویدی، فرهنگ عباسی صفحات 678-695
    در این پژوهش، فیلم های زیست نانو کامپوزیت نشاسته ی نرم شده (PS) حاوی نانولایه های دو بعدی سدیم مونت موریلونیت (MMT) و نانوذرات سه بعدی دی اکسید تیتانیم (TiO2) به روش قالب ریزی تهیه شدند. توپوگرافی سطح و ساختار شیمیایی فیلم ها توسط میکروسکوپ نیروی اتمی (AFM) و طیف سنجی فروسرخ (FT-IR) مطالعه گردید. در آمیزه ی دوجزئی PS-MMT، لایه های ورقه ای شده ی نانورس، به طور یکنواخت در ماتریس پلیمری پخش شده اند. تصاویر سه بعدی میکروسکوپ نیروی اتمی (AFM) توزیع یکنواخت تر نانورس و TiO2، زبری کمتر و سطح صاف تر ماتریس PS-3% MMT-TiO2 نسبت به فیلم های دوجزئی PS-3%MM را نشان داد. وجود پیوندهای هیدروژنی و برهمکنش های الکترواستاتیک بین نانورس و TiO2 با یکدیگر و با زنجیرهای نشاسته توسط پیک های مربوط به پیوند C-O-H در 1- cm1142 و1-cm 990 و افزایش پهنای باند و شدت جذب در ناحیه 1-cm800-500 در طیف سنجی فروسرخ (FT-IR) تایید گردید. نتایج آزمون گرماسنج پویشی تفاضلی (DSC) نشان داد، افزایش غلظت TiO2 فیلم های PS-3%MMT باعث افزایش دمای ذوب و دمای انتقال شیشه ای (Tg) به ترتیب از 1/295 تا 3/306 درجه سانتی گراد و از 1/199 تا 6/207 درجه سانتی گراد گردیده است. افزایش غلظت نانورس تاثیر معنی داری بر پارامترهای رنگی فیلم نداشت، اما با افزایش 1% محتوی TiO2 در فیلم حاوی 3% نانورس، اختلاف رنگ کلی (ΔE) و اندیس سفیدی (WI) فیلم ها به ترتیب %6/86 و 76% افزایش یافته و از میزان سرخی وزردی آنها کاسته شد. به منظور بررسی کدورت و رفتار جذب پرتوهای نوری از اسپکتروفتومتری UV-Vis در دامنه طول موج nm 200-800 استفاده شد. نتایج نشان داد که می توان فیلم نانوکامپوزیتی حاصل را به عنوان ماده بسته بندی جهت حفاظت از محتویات در برابر پرتوهای نور UV و مرئی بکار برد.
    کلیدواژگان: نشاسته، مونت موریلونیت، TiO2، AFM، FT-IR
  • سارا رهبران، اعظم اعرابی صفحات 696-705
    در این پژوهش استخراج فیبر از سبوس برنج در حضور هیدروکسیدسدیم به عنوان یک محیط قلیاییو در ظرف واکنش تحت فشار انجام گرفت. روش سطح پاسخ در قالب طرح مرکب مرکزی برای دستیابی یک مدل بر اساس سه متغیر شامل زمان X1))، دما X2)) و غلظت پراکسیدهیدروژن (X3) از نظر مقدار فیبر استخراج شده، ظرفیت اتصال باآب و ظرفیت اتصال با چربی فیبر تولیدی ارزیابیگردید. شرایط بهینه برای تولید حداکثر مقدار فیبر استخراج شده در زمان 35 دقیقه، دمای 6/99 درجه سلسیوس و غلظت پراکسید هیدروژن 4/13 درصد و تولید 83/13 درصدفیبر ازسبوس برنج حاصل گردید. نتایج نشان داد که دمای فرایند به عنوان فاکتور کلیدی بیشترین تاثیررا بر استخراج فیبر و ظرفیت اتصال با چربی فیبر داشت و هیچکدام از پارامترهابر ظرفیت اتصال با آب فیبر تاثیر معنی داری نداشت(p
    کلیدواژگان: سبوس برنج، فیبر، ظرفیت اتصال با آب، ظرفیت اتصال با چربی، سطح پاسخ
  • فاطمه حیدری دلفارد، مسعود تقی زاده، سید محمد علی رضوی صفحات 706-715
    تعیین خواص حرارتی- فیزیکی عصاره مالت جهت تخمین سرعت انتقال حرارت، تولید، حمل ونقل و نگهداری همچنین ارزیابی و مدل سازی فرایند هایی از قبیل خشک کردن و تغلیظ ضروری است. در این پژوهش خواص حرارتی– فیزیکی عصاره مالت شامل گرمای ویژه، ضریب هدایت حرارتی، ضریب انتشار حرارتی و جرم حجمی در سه سطح ماده جامد محلول 60،70 و 80 درصد و در محدوده دمایی 25 تا 90 درجه سانتی گراد بررسی و تعیین گردید. نتایج حاصل از تحلیل داده ها نشان می دهد که هم درصد ماده جامد وهم دما بر خواص حرارتی– فیزیکی عصاره مالت تاثیر معنی داری دارند. با افزایش درصد ماده جامد گرمای ویژه،ضریب هدایت حرارتی و ضریب انتشار حرارتی کاهش یافته ولی جرم حجمی افزایش می-یابد. همچنین با افزایش دما گرمای ویژه، ضریب هدایت حرارتی و ضریب انتشار حرارتی افزایش یافته ولی دانسیته کاهش می یابد. از سوی دیگر با تجزیه و تحلیل رگرسیون چندگانه، مدل های پیش بینی کننده خواص حرارتی– فیزیکی عصاره مالت بر مبنای متغیر های کاری تعیین گردید.
    کلیدواژگان: جرم حجمی، ضریب انتشار حرارتی، ضریب هدایت حرارتی، عصاره مالت
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  • Combined effect of green tea extract and vacuum packaging on quality changes Scomberomorus guttatus during refrigerated storage
    Fatemeh Khedri, Ainaz Khodanazary Pages 533-542
    Introduction
    The mackerel (Scomberomorus commerson; Scombridae) also known as "Sheer fish" in Persian, is the most popular fish in Iran with the highest economic value. This fish is mainly offered on the Iranian market as skinned and boneless fillets. Major changes occur in proximate, microbiological, chemical and sensory composition of fish fillets during storage in the refrigerator. To preserve the fish fillet, antioxidant additives prior to packaging is a common practice used in food market to extend the shelf life of aquatic products. Currently, synthetic antioxidants such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) frequently have been used prior to packaging. However, recently the consumers’ demand has ben changed to fillets with natural preservatives such as green tea extract (GTE), usually packaged in vacuum packaging (VP). Green tea is a good source of polyphenolic compounds such as catechina having strong antioxidant and antimicrobial properties. Incorporating GTE as a food additive due to its antioxidant activities is a growing interest in the seafood industry. GTE can improve the marketing potential of various seafood products and can effectively be used in the packaging food industry.
    Materials And Method
    Mackerel, Scomberomorus commerson was purchased from a local fish market in Abadan city, Khozestan province, Iran. Fish were freshly caught and completely free of additives. The fish samples were kept in ice with a fish/ ice ratio of 1:2 (w/w) and transported to the seafood processing laboratory within one hour. Upon arrival, fish samples were washed in cold water and each sample was carefully filleted by hand. Two fillets were obtained from each fish after removing the head and bone. Mackerel fillet were soaked with 1 g GTE/ L solution at a fillet/solution ratio of 1: 2 (w/v) for 15 min at 4 °C, followed by draining on the screen for 3 min at 4 °C. The trays of containing samples were then vacuum- packaged (VP).
    Results And Discussion
    The results indicated that the bacterial experiments (total count and pscychrotrophic bacteria) showed the antibacterial effect of green tea extract. Lipid oxidation value experiments (peroxide and thiobarbituric values) showed lower oxidation value in fillets treated with GTE, compared to fish kept under vacuum packaging without treatment and the control (P
    Keywords: Scomberomorus guttatus, Quality, Green tea extract, Vacuum packaging
  • Orang Khademi, Younes Nemati Pages 543-555
    Introduction
    There are two types of Japanese persimmon (Diospyros kaki Thunb.), astringent and non-astringent, based on the degree of astringent taste at maturity state. Fruits of either type are strongly astringent when small and immature, but non-astringent type loses its astringency during development on the tree, still with firm flesh. However, the astringent type keeps its astringency and is inedible even when fully colored. It loses its astringency when becomes over-ripe with extremely soft flesh. At this stage, the fruits are usually over ripe with poor quality. Astringency in persimmon is caused by soluble tannins present in the fruit flesh. One mechanism useful in artificial removal of astringency from persimmon fruit is condensation or polymerization of soluble tannins into insoluble non-astringent forms, by acetaldehyde, which is being produced in the fruit flesh during different treatments. Acetaldehyde accumulates in the fruit flesh during its exposure to ethanol vapor or high level of carbon dioxide (CO2) gas, Hence, constant temperature and short duration (CTSD) is the preferred method of CO2 treatment used to remove astringency of persimmon fruit. It involves holding the fruits in ≥95% carbon dioxide atmosphere for a short duration at constant temperature of 20-30°C then transferring to normal atmosphere. However using CO2 treatment as gas form is expensive and needs special equipment. However, solid CO2 (dry ice) is easily available in Iran with low price. It release CO2 gas and can be used for removing astringency in persimmon fruit. The response of persimmon to de-astringent treatment depends on the cultivar. In this study two persimmon cultivars namely: ”Karaj” and ”Japanese” were harvested at maturity (full coloring) stage and treated with dry ice and ethanol vapor to remove astringency and the quality of treated fruits were evaluated.
    Materials And Methods
    Astringent persimmon fruits cvs ‘Karaj’ and ‘Japanese’ were harvested at maturity stage and transported immediately to the Department of Horticulture Science, University of Shahed and treated with either ethanol or dry ice. Both ethanol and dry ice treatmenttreatments were applied in low-density polyethylene bags with 0.05 mm thickness and polyethylene container with 3 mm thickness. In the polyethylene container, dry ice was applied at amounts of 3, 5 and 7% per kilograms of fruit and in the polyethylene bags dry ice was applied at amount of 0.16, 0.25 and 0.33 per kilogerams of fruits. For ethanol treatment, in both polyethylene bag and polyethylene container, 10 ml of 36% ethanol per kilogram of fruit was sprayed. Thereafter, bags and containers were sealed completely and kept for 48 hours at 25°C and 80% RH. After removing from the closed bags and containers, fruits were held in air at 25°C, 80% RH for completing astringency removing. After astringency removal treatmenttreatments, soluble tannin contents, astringent taste degree, fruit firmness, total soluble solid and ascorbic acid content were measured. The content of soluble tannin was determined by Folin-Denis method and the degree of astringency was determined by panel test. The experiments were conducted in a completely randomized design (CRD) and analysis of variance (ANOVA) was performed and the means were compared using LSD Test.
    Results And Discussion
    After performing the astringency removal treatment, fruits containing less than 1000 ppm of soluble tannin on a fresh weight basis showed no astringency. Results presented here showed that, dry ice treatment, especially at higher concentrations such as 7% in both cultivars, causes removal of astringency and decreases soluble tannin contents below the threshold of 1000 ppm, but ethanol treatment was effective only in Karaj persimmon for the removal of astringency. Similarly, it was indicated that CO2 treatment removed the astringency more easily in some Chinese cultivars than the ethanol treatment. The response of persimmon cv. Karaj was similar to a leading cultivar Hiratanenashi in Japan, for astringency removal by both CO2 and ethanol treatments, while, according to this results, Japanese cultivar had not shown suitable response to ethanol, while it successfully responded to dry ice treatment.
    Treatments to remove astringency of persimmon fruit often cause fruit softening. Astringency removal treatment induced ethylene production in persimmon which causes to the fruits softening. In this study, the firmness of both cultivars decreased significantly after treatments, however, the average of flesh firmness was significantly higher after dry ice than after ethanol treatments.
    Total soluble solid contents under the astringency removal treatments in both cultivars reduced significantly. This reduction is due to the removing of soluble tannins responsible for fruit astringency, since they are included in SSC measurements when not polymerized. Moreover, the results showed that ascorbic acid content is not affected by astringency removal treatments.
    Conclusions
    The results presented here showed that removing astringency from persimmon cvs. Karaj and Japanese were achieved by postharvest application of dry ice in the poly ethylene container. Results also showed that dry ice was more effective than ethanol in astringency removal and retained higher quality of fruit. Dry ice is available treatment in Iran and it can be commercially used for removing astringency of Iranian persimmon.
    Keywords: Antioxidant, astringent taste, firmness, persimmon, soluble tannin
  • Seyed Ali Jafarpour Pages 556-564
    Introduction
    The use of computer vision technology has been highly successful in food classification in the past and it has continued this success in recent times. However, a number of opportunities to progress computer vision technology exist which are critically examined based on cost and feasibility. A range of hardware options are considered along with a range of software options. The economic cost of implementing new hardware continues to prove a major impediment. Thus future efforts need to be focused on maximizing the potential benefits of the existing hardware framework and instead concentrate on developing improved software. Of the improved software available the aspect that offers the greatest promise is more efficient analysis of food surface texture attributes which will lead to more powerful understanding of the relationships between quality factors and experimentally measured food quality.
    Materials And Methods
    In this study, the efficiency of IMG-Pardazesh instrument in color measurement in comparison with CIE L*ab, Hunterlab and Patch Tool color systems was evaluated. The IMG-Pardazesh instrument was designed and manufactured based on CIE 45/0 standard and all measurements were performed based on the ColorChecker® 24 Patch Classic target which is an array of 24 scientifically prepared natural, chromatic, primary and gray scale colored squares in a wide range of colors. Many of the squares represent natural objects, such as human skin, foliage and blue sky. Since they exemplify the color of their counterparts and reflect light the same way in all parts of the visible spectrum, the squares will match the colors of representative sample natural objects under any illumination, and with any color reproduction process.
    Results And Discussion
    According to the results, the regression value (R2) of L*a*b* resulted from IMG-Pardazesh compared to CIE L*ab recorded at 0.996, 0.998 and 0.980, respectively. In comparison withHunterlab, the values were equal to 0.983, 0.981, 0.871, and compared to Patch Tool system were 0.935, 0.881 and 0.953, respectively. However, to base an unbiased conclusion it is necessary to consider the numeric value of data that can be calculated in form of Root Mean Square Deviation (RMSD) rather than the similarity of color changes pattern.Therefore, as much as the RMSD value becomes smaller, the validity of color measuring instrument become greater compared to the standard system. RMSD was calculated following below formula:RMSDL= √((∑_(i=1)^n▒(L_i^*-L_(p )^* )^2 )/n)
    RMSDL= √((∑_(i=1)^n▒(a_i^*-a_(p )^* )^2 )/n)
    RMSDL= √((∑_(i=1)^n▒〖(b_i^*-b_(p )^*)〗^2 )/n)
    Which Li*,ai*,bi* are color parameter from Patch Tool system and Lp*,ap*,bp* are color parameters from other color systems.
    By calculating the RMSD index, it was revealed that numeric value of L*a*b* from IMG-Pardazesh was slightly lower than that of CIE L*ab. Compared to Hunterlab system, apart from a* value, the RMSD was remarkably lower in L* and b* values. By calculating the normalized error of means (e), the values of eL, eaandeb from IMP-Pardazeshwereequal to 0.776, 1.184 and 0.968, respectively, whereas, the same parameters for CIE L*ab were recorded as 0.882, 1.243 and 1.124, respectively, and for Hunterlab system were found to be 1.085, 0.933 and 1.423. Furthermore, computingthe average normalized error of means (e ̅) in CIE L*ab compared to L*a*b* from IMG-Pardazesh indicated that all color parameters had higher total average error and it terms of Hunterlab again L* and b* showed higher error. In a study conducted by Mendoza et al. (2006) on application of image analyzing for evaluation of food items color, the authors stated that that sRGB standard (linear signals) was efficient to define the mapping between R′G′B′ (no-linear signals) from the CCD camera and a device-independent system such as CIE XYZ. The CVS showed to be robust to changes in sample orientation, resolution, and zoom. However, the measured average color was shown to be significantly affected by the properties of the background and by the surface curvature and gloss. Thus all average color results should be interpreted with caution. L*a*b* system is suggested as the best color space for quantification in foods with curved surfaces. In another study on evaluation of L*a*b* units from RGB parameters, Leon et al. (2006) presented five conversion models as: linear, quadratic, gamma, direct, and neural network. Additionally, a method was suggested for estimating the parameters of the models based on a minimization of the mean absolute error between the color measurements obtained by the models and/or usinga commercial colorimeter for uniform and homogenous surfaces. In the evaluation of the performance of the models, the neural network model stands out with an error of only 0.93%. the same authors also stated that on the basis of the construction of these models, it is possible to find a L∗a∗b∗ color measuring system that is appropriate for an accurate, exacting and detailed characterization of a food item, thus improving quality control and providing a highly useful tool for the food industry based on a color digital camera.In conclusion, the IMG-Pardazesh instrument have lower error in determination of L*a*b* parameter from RGB of digital image compared to the other tested systems.
    Keywords: Digital Image, Color Measurment, RGB, L*a
  • Najme Molaahmadibahraseman, Reza Farhoosh, Ali Sharif Pages 565-571
    Introduction
    Medical benefits of Omega 3 fatty acids have appealeda lot of research to be done on of fish oil. Among marine fish, kilka has the most industrial application. Kilka oil contains significant amount of omega-3 fatty acids. In this study, physiochemical properties, fatty acid composition and stabilization of kilka oil were investigated. p- hydroxy benzoic asid, its methyl ester and alpha-tocopherol as control were compared to each other.
    Materials And Methods
    Crude Kilka fish oil was supplied by Khazarcompany (Babolsar, Iran). All chemicals and solvents used in this study were of analytical reagent grade and purchased from Merck (Darmstadt, Germany) and Sigma–Aldrich (St. Louis, MO). 200 ppm of the mentioned antioxidants was added to the purified oil and kinetic regime of oxidation at temperatures of 35, 45 and 55°C was prepared. After monitoring theoxidation over time using peroxide test, graph of peroxide changes over time was plotted and induction period and kinetic parameters (F, ORR and A) were calculated. In order to compare the performance of antioxidants in oil and water, 10% emulsion of Kilka oil-in-water was prepared and 200 ppm of antioxidant was added to it and its oxidation process was monitored at 55°C.
    Results And Discussion
    Results showed that the fatty acid composition of this oil contains a variety of unsaturated fatty acids, saturated and polyunsaturated (mainly linoleic, eicosapentaenoic and docosahexaenoic acids). Temperature had significant effect on oxidation. p-hydroxymethylbenzoate, a little more than p-hydroxybenzoic asid, could increase oxidative stability of oil. Alpha-tocopherol had better performance as compared with other antioxidants. Performance of methylp-hydroxybenzoatewas better in emulsion than oil. In general, the emulsifier and emulsion preparation as compared with antioxidant had a more prominent role in the oxidative stability of Kilka oil.
    Keywords: Antioxidant, fish oil, benzoic asid, O, W emulsion
  • Arash Koocheki, Abdollah Hematian Sourki, Mohammad Elahi, Seyed Mohammad Ali Razavi Pages 572-587
    Introduction
    β-glucan is the most important water soluble fiber found in cell wall of some cereals such as barley, oat, wheat and rye, that are composed of β-D-glucoseunits with (1→4) (70%) and (1→3) (30%)anomericbonds(Benito-Román, Alonso, & Cocero, 2013).β-glucan is regarded as a dietary fiber in functional foods. It can act as a hydrocolloid due to its thickening characteristic in aqueous phase and can be used as a stabilizer in some foods such as sauces, salad dressing and ice cream (Dawkins & Nnanna, 1995; Kontogiorgos, Biliaderis, Kiosseoglou, & Doxastakis, 2004; Temelli, 1997; Wood & Webster, 1986). Hull-less barley is a barley variety that has no hard coat around its’ seeds. The content of soluble fiber e.g. β-glucan in hull-less barley is higher than of ordinary barley varieties. Hull-lessbarley cv. Lut is the first commercial hull-less barley in Iran registered in 2013 by SPII(Seed and Plant Improvement Institute). Lut is a kind of spring barley cultivar which is precocious and resistant to lodging. It’s average yield is 6.425 t/ha and it is suitable to cultivation in temperate regions of Iran (SPII, 2013).This type of barley contains about 6% β-glucan and thus is a good source for β-glucan extraction.To date no research has been conducted on properties of β-glucan from this cultivar of barley.Considering high technological properties of β-glucan, the present study was carried out to determine the optimal condition for extraction of β-glucan from hull-lessbarley using hot watermethod to achieve the highest qualitative and best functional properties.
    Materials And Methods
    Barley flour was obtained by grinding whole kernels of cv. Lut in a laboratory mill and sieved through a 0.50 mm screen. Prior to the extraction procedure, 50 g of barley flour was suspended in 200 ml of aqueous ethanol (80%, v/v) and stirred under reflux for 3 h to remove most of the lipids and inactivate the endogenous β-glucanases. The liquid phase was separated by vacuum filtration and dried at 40 °C for 12 h. 50 g of dried defatted barley flour was suspended in specified amounts of distilled water (solven:flour ratio = 6:1, 8:1 and 10:1) in a 1000 ml beaker. pH was adjusted to the designed levels (5, 7, and 9) by 0.1 N HCl and 0.1 N NaOH solutions. Extraction procedure carried out at 50±1°C for 30, 60 and 90 minutes. Total β-glucan content was determined by the specific enzymatic method of McClear and Glennie-Holmes (1985) using the mixed linkage β-glucan assay kit (K-BGLU 07/11) supplied by Megazyme International (Wicklow, Ireland). The colour of β-glucan gums was measuredusing a Hunter-Lab Colour Flex 45 spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA, USA). The L*a*b* (CIELAB space) colour space measurement was used for colour analysis of β-glucan samples. Emulsion stability (ES) against high temperature was determined by heating emulsions in a water bath at 80 °C for 30 min followed by centrifuging at 1200 g for 10 min. For foam stability, ovalbumin was dissolved in distilled water and added to β-glucan solution and then whipped vigorously with a laboratory rotor-stator homogenizer at room temperature. Flow behaviour measurements were done by a Brookfield viscometer. The flow behavior index (n) and consistency coefficient (k) values were obtained by fitting the power law model. All chemicals, reagents and solvents were of analytical grade and obtained either from Sigma-Aldrich Co (Deisenhofen, Germany) or from Merck (Darmstadt, Germany).
    Results and Discussion
    Results showed that the extraction time, solvent: flour ratio and pH had significant effect on extraction yield, purity, foam and emulsion stability, consistency coefficient (k), flow behavior index (n) and colour. Increasing the extraction time had significant effects on β-glucan’s yield and purity and improved the emulsion and foam stabilizing effect of β-glucan. Increasing the pH from 5 to 9 significantly enhanced the purity, consistency coefficient (k), foam and emulsion stability. At higher pH levels, extraction yield, flow behavior index (n) and L* decreased. With increasing solvent:flour ratio, extraction yield, purity, consistency coefficient (k), foam and emulsion stability significantly increased. In contrast, the flow behavior index (n) decreased as a result of increase in solvent: flour ratio. However, solvent: flour ratio had no significant effect on L*, a* and b*. Models presented in this study were highly significant and the correlation coefficients could be used for optimization of ß-glucan extraction from hull-less barley. Considering the importance and desirability of the response variables, the best results were obtained when the extraction time, solvent: flour ratio and pH were 90 min, 10:1 and 7.33 respectively. At the optimal condition, extraction yield, purity, foam stability, emulsion stability, consistency coefficient (k), flow behavior index (n), L*, a* and b* were 4.12%, 69.11%, 86.95%, 88.77%, 1.51 Pa.sn, 0.62, 73.42, 0.81 and 8.72 respectively.
    Keywords: ß-glucan, hulless barley, water extraction, response surface method, flow behavior, foam, emulsion stability
  • Najmeh Molaahmadi Bahraseman, Reza Farhoosh, Saeid Johny, Ali Sharif Pages 588-595
    Introduction
    Medical benefits of omega-3 fatty acids have led to a lot of research on fish oil. Among marine fish, Kilka has the highest industrial applications. Kilka oil contains significant amounts of omega-3 fatty acids. In the present study, oxidative stability of Kilka fish oil based on the Schaal oven test and the use of two phenolic acid derivatives (syringic and vanillic acids) was investigated.
    Materials And Methods
    Crude Kilka fish oil was supplied by Khazar company (Babolsar, Iran). All chemicals and solvents used in this study were of analytical reagent grade and purchased from Merck (Darmstadt, Germany) and Sigma–Aldrich (St. Louis, MO). Free radical scavenging activities of phenolic compounds was measured by reading the absorbance of methanolic solutions of the antioxidants containing 1,1-diphenyl-2-picrylhdrazyl (DPPH)at 517 nm. The partition coefficient (log P) of the antioxidants was measured in terms of the maximal UV absorbance of aqueous (0.3 mM) and 50:50 aqueous/acetate buffer (0.1M, pH =5.5) solutions. In order to study the antioxidant activity in lipid systems, peroxide value of the chromatographically purified Kilka fish oil as well as its 10% oil-in-water emulsion containing 200 mg/kg of antioxidants was monitored at 55 °C.
    Results And Discussion
    Syringic acid with two methoxy groups showed higher scavenging activity (IC50) than vanillic acid with one methoxy group (54.2 vs. 418.2). Radical scavenging activity in phenolic acids had direct relationship with the type and number of electron donor groups on phenolic ring. Peroxide values changed exponentially. Despite the relatively high polarity (Log P = – 0.65) and high scavenging activity, the performance of syringic acid in Kilkafish oil was degraded as affected by inter-molecular interactions and was not in accordance with the "polar paradox" hypothesis. Antioxidant activity of syringic acid in emulsion increased significantly as compared with oil and it was similar to α-tocopherol. It was concluded that the type of emulsifier and also the way of emulsion preparation as compared with antioxidant had a more prominent role in the oxidative stability of Kilka fish oil.
    Keywords: Antioxidant, Fish oil, O, W Emulsion, Phenolic acid, Polar paradox
  • Neda Nayyeri, Mohammad Reza Edalatian Dovom, Mohammad Bagher Habibi Najafi, Masoomeh Bahreyni Pages 596-608
    Introduction
    Nowadays, attention to foods free from chemical preservatives is on the rise. Recently, consumers have concerned about foods containing these preservatives in their formulation .Therefore,the use of antimicrobial peptides produced by Lactic acid bacteria (LAB) are strongly highlighted. Ribosomally-synthesized peptides, which possess antimicrobial properties, are produced by a vast range of organisms including prokaryotes and Eukaryotes.
    Yeasts are the most important microorganisms which are responsible for fruit juice and soft drink spoilage. In case of growth and production of by-products like CO2, acid and other contaminants, the spoilage will be visible.
    Lactic acid bacteria isolated from natural, local sources such as dairy products have presented potentially antifungal features against food spoilage fungi. Among these, Rodotorula and Penicillium are regarded as the most critical genera in fruit juice spoilage.
    The main objective ofthis study was the evaluation of anti-yeast activity of Lactobacillus plantarum isolates from different stages of Lighvan production against Rodotorulamucilaginosa as fruit juice spoilage indicator. In the next step, technological parameters effects were analyzed on antimicrobial potential of cell-free supernatant of these isolates. Finally, we aimed at finding the most effective isolate on aforementioned yeast.
    Materials And Methods
    NineteenLb.plantarumisolates, which were identified previously, were subjected to antifungal assay. For this purpose, RodotorulamucilaginosaPTCC 5257 was selected. Agar spot and Well Diffusion Assay (WDA) were applied for antifungal assay in solid and liquid media, respectively.Determination of yeast colony: Following the cultivation of yeasts in Potato Dextrose Broth, it was determined using Spectrophotometer.
    Preparation of Lb.plantarum cell-free supernatant (CFS) was carried out. In agar spot method, clear zones of inhibition around the spotted colonies were evaluated after 24-48h incubation. In WDA, CFS of Lb.plantarum isolates were poured in wells and clear zones were evaluated around each well after 24-48 h incubation.
    Technological properties: The influence of different levels of pH (2, 3, 4, 5, 6, and 7) was analyzed on CFS of Lb.plantarum isolates. This assay was done according to Wang et al., 2011. Finally, results were reported using the measurement of clear zone diameter in mm. All experiments were performed in duplicates.
    The effects of various temperatures were applied on CFS and remaining the antifungal activity was evaluated according to Rouse et al., 2008. Finally, all CFS of Lb.plantarum isolates were subjected to Proteniase K and antifungal properties of CFS were assayed by WDA according to Ghrairi et al., 2005.
    Results And Discussion
    Agar spot results showed the highest and lowest clear zone of inhibition related to C28 and LF49 with 16 and 6 mm diameter, respectively. In this method, 11 out of 19 isolates (60%) presented anti-yeast activity with clear zone formation. In comparison between two incubation temperatures (25 and 30◦C), all isolates stronger clear zone in 30◦C than in 25◦C. This was due to enhancement of yeast growth in 25C rather than in 30C. Also, with respect to the mesophilic nature of Lb.plantarum isolates, the possibility of metabolite production are more likely in 30C. It was reported that antifungal activity of LAB is mostly due to synergistic effect of lactic acid and acetic acid. In agar spot, some colony-associated antimicrobial compounds are responsible for antifungal activity.
    In WDA, 8 out of 19 isolates (42%) were positive for their inhibitory effects. The highest anti-yeast activity was seen at pH=2. It seems that antimicrobial compounds are likely more stable at acidic conditions than at alkaline ones. Among isolates, C28 presented the highest stability at alkaline conditions. With pH increase, the antifungal activity decreased so that no anti-yeast activity was seen at pH=7. Regarding the different temperatures, we should mention that thermal resistance of isolate's CFSwitnessed declining trend with increasing of temperature. This fact implies the presence of low- molecular weight compounds in CFS. Finally, all isolate's CFS was subjected to proteinase K. All isolates have lost their anti-yeast activity after enzyme treatment showing their proteinaceous nature.
    Conclusion
    In WDA, the number of positive isolates showing anti-yeast activity declined in comparison with agar spot. Since some isolates retain their inhibitory activity toward food spoilage yeast at low pH, their CFS can be applied in acidic foods like fruit juice. Also, some isolates showed their antifungal activity at high temperatures (80C and 100C) which are applied for fruit juice pasteurization, so they can be applied in fruit juices as a bio-preservative.
    Keywords: Lighvan cheese, Lactobacillus plantarum, anti-yeast, Rodotorula mucilaginosa
  • Babak Ghanbarzadeh, Sahra Bashiri, Hamed Hamishekar, Jalal Dehgannya Pages 609-619
    Introduction
    The encapsulation of nutraceuticals in lipid based carriers, such as liposomes, can lead to increasing of bio-active ingredients bioavailability and controlled release, maintaining their stability in different environmental conditions and increasing solubility of hydrophobic active ingredients in aqueous conditions. Food grade liposomes are being increasingly used in food industry to delivery hydrophilic and hydrophobic components such as vitamin E and vitamin C, ascorbic asid, nutraceuticals, essential omega 3 fatty medium chain fatty acids-vitamine C, nisine, cartenoides, oleic acids, polyphenols include catechine, synamic acids.
    One of the hydrophobic nutrients with antioxidant and beneficial pro-vitamine property is beta-carotene, which its high hydrophobicity and sensitivity in different environmental conditions has limited using of it for foodstuff enrichment. In order to improve the characteristics of the lipid bilayer, cholesterol traditionally has been included in the lipid membrane. It is important in decreasing permeability and strengthening the membrane. People suffering from hyper-cholesterolaemia are encouraged to avoid foods containing cholesterol. Since the plant sterols are natural compounds found in plant cell membranes which help maintain the membrane integrity. Such as Gama oryzanol is combination of different of plant sterols that is used in the formulation of nanoliposomes in this study to improve the stability of bilayers. The principal aim of this study was to prepare beta-caroten encapsulated nano- liposome formulations as a mean to improve its aqueous dispensability and to study the effect of lecithin-phytosterol concentrations on the partical size, encapsulation efficiency (EE), zeta potential, turbibility of beta carotene loaded nano-liposomes to get the optimized formulation.
    Materials And Methods
    Preparing liposomes is being carried out using different methods one of which is a novel technique called is “Mozafari method” (based on heating method). This method is characterized by the absence of organic solvent for the solving of lipids.Non-toxicity of produced liposomes; rapid production and scalability are some of the advantages of Mozafari method over other methods of liposome production. In this study, the liposomal ingredients were added to a preheated (60 0C, 5 min) water, mixeture of beta-carotene, gamma oryzanol solution and glycerol (final concentration 3% v/v) were added. The mixtures volume increased by adding warm water until 50ml, the mixture was further heated 60 while stirring 1200 rpm for 50-60 min under nitrogen atmosphere.
    Results And Discussion
    Effect of different concentration of lecithin (20, 40, 75, 100, 150, 200 mg) on particle size and zeta potential of nano-liposomes with constant amount of beta carotene (4 mg) and gamma-oryzanol for different concentration of lecithin with ratio 1:14 w/w were evaluated. The Particle size of nano liposomes with different concentration of lecithin was obtained below 500nm andthe optimal concentration of lecithin was 100 mg that particle size was minimum (64-88 nm).The gamma-oryzanol is a natural phytostrol which is as stabilizer for liposome membrance and promoting agent of hardness of vesicles wall however, the particle size of liposomes were reduced especially in low concentration of lecithin. The using phytosterols (gamma oryzanol) for maintaining the stability of liposomal membranesystems caused to reducing of particle size from 88nm to 64nm in 200 mg concentration of lecithin.
    The entrapment efficiency increased by increasing concentration of lecithin for nano-liposomes. It is because increasing the lecithin concentration, more vesicles were produced which in turn increased the loading capacity of nano-liposomes. In the liposome structure, the aqueous core and bilayer are the hydrophilic and hydrophobic parts, respectively. Therefore, the phospholipid bilayers place for beta carotene, and other hydrophobic substances. The entrapment efficiency in different concentration of lecithin was between 27-98%. The entrapment efficiency of liposomes containing beta carotene that used gamma oryzanol was less than liposomes without gamma oryzanol probably because the position of capsulation of gamma oryzanol and beta carotene is same in the bilayer of liposome that’s hydrophobic source of liposomes. But Gamma oryzanol was not effective on encapsulation efficiency of beta-carotene.
    The zeta potential, the electric potential in the interface or particle surface charge, is used to predict the stability of colloidal systems. In general, higher zeta potential values, regardless of their positive or negativity, indicate a higher and longer-term stability of the particles. Zeta potential of liposomes, which is a measure for the electrostatic repulsion and stability, was -29 and -35 milivolt for samples with and with not containing gamma oryzanol, respectively.
    For turbidity of liposomes, encapsulation of bioactive compounds can change the optical appearance due to the fact that the refractive index at the interface between solvent and internal phase changes and the size of liposomes may be altered. Increasing significantly of turbidity of liposomes (16% -80%), the wave length increase from 0.116 to 0.585 cm-1 high concentration of lecithin maybe due to increasing visuals and hydrophobic interactions.
    Keywords: nano-liposom, beta-carotene, colloidal properties
  • Hamideh Separdar, Ebrahim Rahimi, Iman Shahabi, Behzad Aghabarari Pages 620-629
    Introduction
    One of the most important problems of synthetic packaging of materials had been the time consuming process of their decomposition. Therefore, they have the potential to contaminate the environment. During the recent years, the above-mentioned problem has paved the way for developing biodegradable biopolymers. One group of these polymers is films and edible coatings. Soy protein isolate is the purest type of soy protein which is available commercially and amount of its protein is more than 90% (based dry weight). These films have better nutritional value. In addition, they have better mechanical features and permeability than films made of carbohydrates and fats. Tragacanth gum is composed of two main ingredients under the name of Tragacantic acid or Basorin and Tragacantin. Basorin is in 60-70% of whole gum and is insoluble in the water. It can swell and make gel. Also, another ingredient or Tragacantin solves in the water and leads to make colloid solution. Hence, the main purpose of this work is studying effect of tragacanth gum as a supplementary and firmness-making material on physical and mechanical features of soy protein isolate film and are determining the best level of tragacanth gum and optimal film for using in food packaging.
    Materials And Methods
    A specified amount of soy protein isolate was solved in distilled water. Then, pH of solution was set on 10 by NaoH (0.1N). Solution of soy protein isolate was heated by bain-marie to 70˚c. Afterwards, solution of tragacanth gum with suitable amount of treatment which was solved separately in the water was added to solution of soy protein isolate slowly during agitating by magnetic mixer. Then, glycerol was added to the final solution as plasticizer. Final solution was agitated by magnetic mixer about 15 minutes to become smooth and pure. After degassing, the film forming solutions were casted by pouring the mixture onto polystyrene plate (10 cm diameter) and dried at 25±5˚c for 48 h in a laboratory oven and room relative humidity. Finally, the dried films were peeled off the casting surface. Film solutions were prepared from soy protein isolate with ratio of 0.5:4.5(A), 0.3:4.7(B) and 0.1:4.9(C), tragacanth gum: soy protein isolate and plasticizer of glycerol were prepared in 100gr water with ratio of 90% (w/w) dry weight. According to plasticizer effect of water, to uniform moisture before performing each test, all the films were conditioned inside desiccators containing saturated magnesium- nitrate solution to ensure a relative humidity 0f 50-55% at 25˚c ± 1 for 48 h.
    Tensile strength (TS) and elongation at break (EB) were conducted by using tensile evaluation machine (7010, Gotec of Taiwan) according to ASTM standard method D882-10 (ASTM, 2010).
    Films were cut in the dimension of 2×2 cm2 and dried to reach constant weight at 100 ˚C in a laboratory oven. Dried samples weighed to determine the initial dry weight (m1) and placed inside beaker including 50 ml of distilled water with periodic stirring for 24 h at 25˚C. Afterwards, the remained pieces of films were taken out and dried at 100˚C to reach constant weight (m2).
    After the films reached in moisture balance at 25˚C and a proportional humidity at %55. Their moisture was determined by measuring the loss amount of film weight during drying in a laboratory oven at 105˚c unti constant weight.
    The specimens of films was provided at 2×2cm2 dimensions and prepared by dried calcium chloride until reached to constant weight (m1). After the initial weight, they were conditioned in a desiccator containing saturated magnesium nitrate solution at 25˚c to provide reaching a relative humidity of %50-55. Then, the specimens were weighed in regular intervals until the equilibrium state was reached (m2).
    Water vapor permeability tests of films were performed according to ASTM- E95-96 standard (ASTM, 1995).The color of films was evaluated using a colorimeter device (LabscanXE, Hunterlab, USA).
    Statistical analysis was conducted in a completely randomized design with variance analysis (ANOVA) using SPSS software (Version 21; SPSS Inc., USA). Also, comparing the difference among mean values of film specimens was performed using Duncan,s multiple range tests at the confidence level of 95%.
    Results And Discussion
    The obtained results indicated that tensile test (TS) of film was increased by increasing tragacanth gum and decreasing soy protein isolate but elongation to break (ETB) decreased. This result was agreed with the results of Fazel et al (2013), Tian et al (2011), Chen and Lai (2008). The amount of film moisture increased by increasing tragacanth gum, while amount of solubility in water, water absorption decreased by increasing tragacanth gum. The highest of wvp was observed in SPI:TG (4.9:0.1) but the lowest value was related to the sample SPI:TG (4.7:0.3). In general, the amount of wvp decreased by increasing tragacanth gum. The free space between chains decreases by forming transversal connections between protein filaments. Also, filaments mobility decreases, while penetration and spread of vapor molecules from polymer will decrease and its prevention becomes more in the water. The highest L, a, and whiteness index was observed in SPI:TG (4.5:0.5). In contrary, the highest b, total color difference (ΔE), and yellowness index was observed in SPI:TG (4.9:0.1). Optical properties of films used in food packaging are very important for their effects on acceptance and food quality. Results of Sarmadizadeh et al. (2014) showed that increasing protein has changed films color. Therefore, adding tragacanth gum caused to improve the structure and to improve physicochemical properties of the samples. It could be concluded biodegradable film of SPI has desirable characteristics for the application in food packaging.
    Keywords: soy protein isolate, tragacanth gum, biodegradable, tensile strength, water vapor permeability
  • Ainaz Khodanazary, Sara Golgolipour, Kamal Ghanemi Pages 630-638
    Introduction
    Grass carp (Ctenopharyngodonidella, family Cyprinidae) is one of the main fresh water fish species and highly demanded aquaculture species in Iran. Among the cultivated fish, grass carp, also called farmed white fish, has received great attention because of its similarity to Caspian white fish in Iran. The muscle of fish contains important levels of nutrients which are beneficial to health. Most research has been done and published on raw flesh. Cooking can lead to a loss of the nutritional value of foods. In this case the preservation of the maximum nutritive value can be ensured by using correct methods of cooking. The aim of this research was the influence of five cooking methods (poaching, boiling, microwave pan- frying and deep- frying) on changes of free fatty acids, thiobarbitoric acid, heavy metal (Ni, Cr, Co, Cd, Pb) and sensory properties of grass carp (Ctenopharyngodonidella)fillets was evaluated.
    Materials And Method
    Grass carpsamples were purchased from a local market in Khorramshahr city, Khuzestan province, Iran. The fish were kept alive and transported to thelaboratory. On arrival,tsamples were washed and eviscerated. The samples were filleted and cut into slices (100 g each). The fish samples were cooked using AOAC 976.16 procedure (method for cooking seafood). Five common cooking procedures were selected: poaching in stainless steel pot of boiling water for 30 min and 30 s, steaming in stainless steel steamer for 5 min and 30 s, microwaving in microwave for 40 s, pan-frying (without oil) in frying pan for 6 min at 180 ºC and deep-frying in olive oil in a deep fryer for 5 min at 180 ºC. After the cooking process, the samples were cooled to room temperature and the skin and backbone of the samples were removed. All fish in each lot were homogenized using a kitchen blender and analyzed to determine free fatty acid, thiobarbitoric acid, heavy metal and sensory properties. All sample homogenates were assayed in triplicate.
    Results And Discussion
    The results indicated that the cooking methods of pouching, microwave and deep-frying increased thiobarbitoric acid (TBA), while cooking methods of boiling and pan- frying did not change TBA. The free fatty acid (FFA) content of the fillets was significantly reduced by the different cooking methods. The Ni in the cooking methods of boiling, pan- frying and deep- frying was not detected. The Cr in the cooking method of deep-fried samples was significantly decreased. The Co concentrations were below limits of detection in all samples. The Cd was only detected in microwave samples. The Pb content increased during cooking of fillets. The results of sensory properties were showed that the texture, odour, flavor, colour and overall likeness properties improve likeness score to some extent in deep-frying method and there were not significantly different between boiling, poaching and pan-frying.
    Keywords: Ctenopharyngodon idella, Cooking methods, TBA, FFA, Heavy metal, Sensory properties
  • Setareh Hosseinzadeh, Aram Bostan, Mohammad Hossein Haddad Khodaparast, Mohebbat Mohebbi Pages 639-651
    Introduction
    Flavors play an important role in consumer satisfaction and influence further consumption of foods. Most available aroma compounds are produced via chemical synthesis or extraction. Foodstuffs containing synthetic flavor in many cases are avoided, because the consumers suspect that these compounds are toxic or harmful to their health. Recently, the market of flavors is focused in using aromatic materials arriving from natural sources to replace the use of synthetic flavors gradually (Badee, et al., 2012).
    Flavorsare indispensable ingredients of food preparations, and usually they are in liquid form that makes their handling and incorporating into food more difficult. Furthemore, many flavorcomponents exhibit considerable sensitivity to oxygen, light, and heat. In response to these difficulties, dried flavors have been developed.
    The objective of this work was to study the influence of different wall material concentration on the emulsion and spray dried flavor powder characteristics.
    Materials and Methods
    Spearmint oil was obtained by clevenger distillation method and modified starch was obtained from National Starch&Chemical Limited company (England).
    Different concentration of modified starch solutions (10, 20 & 30% w/w) were prepared by dispersing the solids in deionized water and heating at 40 ⁰C over a steam bath to facilitate solubilization. Thesolutions were allowed to cool to room temperature before storing at 4°C overnight. The spearmint oil (2.5 % w/w) was added to the solution and was homogenized vigorously (15000 rpm for 10 min.) with an Ultra Turrax homogenizer (T25, IKA, Germany) at ambient temperature. The emulsions were then further emulsified using Ultrasounds (20kHz, 1 min) (Jafari, et al., 2007).
    The obtained emulsion was spray dried in a BUCHI 190 Spray Dryer (Swiss) with an evaporation rate of 600 lit/1 hour, equipped with a pressurized nozzle operating at 4bar pressure. Feed ismetered into the dryer by a peristaltic pump. Powder was collected at the bottom of dryer cyclone and kept inair tight containers at -18⁰C until analyzed.
    The particle size of emulsion droplets and spray dried powder were determined using dynamic laser light scattering (Analysette22, Fritsch company, Germany).
    Encapsulation Efficiency was defined as the percentage of Menthol ad d-limonene thatwere entrapped inside the microcapsules to the total loaded to the emulsion. . Theequations was as follows:Encapsulation Efficiency=(Menthol or Limonene in Microcapsul(ppm))/(Menthol or Limonene in Emulsion(ppm))×100%
    The powders were attached to SEM stubs using double adhesivetape, coated with 3–5 mA gold/palladium under vacuum,and examined with a scanning electron microscope (S360 model, Oxford , England).
    Results & disscussion: Emulsion particle size were found to be in the range of 1.8 to 3.3 μm and wall material concentration had significant effect on it ( p
    Keywords: spray drying, half life, Menthol Limonene Microcapsules
  • Mahmood Reza Golzarian, Mansore Shamili, Omid Doosti Irani, Payman Azarkish Pages 652-662
    Introduction
    Machine vision, which uses image processing techniques, is a branch of artificial intelligence that simulates human vision. These systems can be used for quality control, sorting and grading of agricultural products. Unlike engineering materials, agricultural fruits are living tissues that continue living even after they are harvested from trees or bushes. Therefore, the post-harvest process such as handling and packaging need to be done such that they make the least damage to these products (Barchi et al., 2002). Combination of suitable techniques and post-harvest management is required to bring down the waste loss in this supply chain. Fruits are susceptible to receive mechanical damages during harvesting (either manually or mechanized), or in transport or at the time of initial packaging. These damages may cause damage to the internal tissue of the fruit that subsequently causes the internal substances of the damaged cell leave spread out. While eradicating the fruit, the surrounding fruits are also affected negatively.Mangos are sensitive to mechanical and thermal sudden change (Xing & Baerdemaker, 2005). Today, surface defect detection and grading of many fruits including mangos are still performed in many cases with the help of trained workers which is time consuming and cost effective.. Image processing has been successfully used for measurement and calibration of products; it shows also a good potential to be used for assessing the quality of products (Mata et al, 2012). There has been no or very little research on the quality assessment of mangos based on the dark spots on the skin surface of mango fruits.The aim of this study was to detect and identify surface damage in mangoes of Kelk-e Sorkh cultivar using digital image processing as it has higher accuracy and processing speed as opposed to manual detection.
    Materials And Methods
    Mango fruits were picked from a garden in Minab in Hormozgan province, in Iran. Sixty samples were selected for imaging. These samples had black spots on the skin surface due to mechanical damages received during harvesting and handling. The imaging was performed in a homogenously controlled lighting condition(in an imaging box)against a blue sheet as background and at 24°C and 22% RH. The images were taken in visible range with a Nikon Coolpix P510 digital camera (Nikon Inc, Japan) of 4928 x 3264 dimensions (16.1 MP resolution). Considering the camera lens’s focal length, the samples were placed 20 cm under the camera’s lens to be in camera’s field of view. The taken images were read and analyzed in Matlab (Ver 2011a, Mathworks Inc, US). The quality of segmentation process, which is an important step in image processing project, affects the quality of information extracted from the objects or regions of interest (ROIs) in the next steps. The images of mangos were segmented from the background using thresholding of the high contrast images of red and blue difference. The optimum threshold value was obtained to be 0.3. Then, the affected and healthy regions of mangos were specified manually in each image. Then, the color features in two L*a*b* and RGB and HSI color models were extracted from each region on the sample surface.
    Results And Discussion
    The statistical analysis of these features showed that the accuracies for detecting the surface defects on mangos were 90% and 91.6% using the color factor of G and 0.16*G/0.5R in RGB color space, respectively. However, from the a* data, only 56 samples were correctly classified as damaged. This showed the classification accuracy of 93.33% using this color parameter. The accuracy reached to 100% when the two color parameters of a* and L* was used as an integrated color parameter of 0.16*L-a*. In L*a*b* color space, the influence of ambient light on the color of samples is trivial and much less than that on RGB. This can be the reason for higher classification error when R, G and B color components, which might be due to non-uniform lighting and the existence of highly bright or highly dark points on the surface of samples. According to USDA standard, the ratio of the size of defect region to the size of whole fruit can be used as an indicator for grading mangos (USDA, 2006). In this research, the k-means clustering was used to group the mangos based on their defect region size. The results showed that the mangos could be classified into three categories of grade 1, with the defect size of less than 5% of the total area, grade 2: when the defect region size was between 5 and 15% and grade 3: when the defect area size was more than 15% and less than 25%. By K-means clustering, the samples were grouped in two clusters. The cut-off point between two clusters was found from the ROC curve to be 3.11. The parameter of ROC area was equal to unity, which indicated the high discrimination capability of the clustering model.
    Conclusion
    In this research, after assessing several color factors and their combinations, four color components of a*, green (G), 2G/R and L*-0.16a* were selected and used for classifying mechanically defected mangos and the results were promising. The results of this research and similar ones can provide helpful recommendations in grading mangos considering the higher capability of Hormozgan province in Iran for producing mangos for fresh consumption, being used in high-quality domestic market, being exported to global markets.
    Keywords: Image processing, surface defects, mechanical damages, color images, mango
  • Leila Monjazeb Marvdashti, Masoud Yavarmanesh, Arash Koocheki Pages 663-677
    Introduction
    Packaging is an important factor in food industry and is dominated by petroleum-derived polymers. Therefore, the amount of research involving the production and characterization of biodegradable films has increased substantially, mainly due to interest in minimizing the ecological impact caused by the use of synthetic packaging materials. Several biopolymers have been exploited to develop eco-friendly food packaging materials. Usually, films based on biopolymers are highly sensitive to environmental conditions and generally present low mechanical resistance. As a result, several researchers have developed films based on mixtures of biopolymers and synthetic polymers. In order to increase the workability and flexibility of biodegradable films, various plasticizers, usually poly-ols, have been widely used, glycerol being one of the most preferred and most studied. Plasticizers reduce intermolecular forces, increase the mobility of the biopolymer chains and thereby improve the mechanical properties of the films. Therefore, the aim of the present study were to investigate the effect of different proportions (20e100% w/w) of plasticizer (glycerol) on physicochemical, mechanical, permeability, surface and thermal properties of biodegradable PVA-AHSG blend films.
    Polymer blending is one of the most effective methods to have new material with desired properties. Films formed by blending of polymers usually results in modified physical and mechanical properties compared to films made of individual components. Since synthetic polymers are easily obtained and have low production cost, blending of natural and synthetic polymers improves the cost performance ratio of the resulting films.
    Since Alyssum homolocarpumseed gum (AHSG) is environmentally friendly due to its biodegradability and has good film forming properties, it is considered as a very promising biopolymer.
    Some synthetic polymers from non-renewable sources are also biodegradable, such as polyvinyl alcohol (PVA). PVA is a synthetic, water soluble polymer with excellent film forming, emulsifying, and adhesive properties. It also imparts good tensile strength (TS) and biodegradability and hence has been used in many biomaterial applications. PVA has also been approved for use in packaging meat and poultry products by the USDA (DeMerlis&Schonek, 2003). AHSG contains free hydroxyl and amine groups, and is therefore miscible with PVA due to the formation of hydrogen bonds.
    Materials And Methods
    The aim of this study was to investigate the possibility of producing a novel biodegradable blend film from PVA-AHSG with glycerol as plasticizer in the different concentrations. Films were prepared by the casting method using PVA and AHSG (60:40 ratio). Glycerol was used ac plasticizer because it is compatible with PVA-AHSG blend improving film flexibility, facilitating its handling and preventing cracks. The PVA–AHSG blend film was prepared with different glycerol concentration (20–70%, w/w).The optical properties such as opacity and color were measured. Water vapor permeability, moisture content, water solubility and density of the films were also investigated. Films were evaluated for mechanical and antitoxin properties. The PVA–AHSG blend films were characterized using DSC, FTIR and scanning electron microscopy.
    Results And Discussion
    The results of this study showed that blend of PVA and AHSG could be used as a new film-forming material. However, it was not possible to make PVA-AHSG blend films without addition of glycerol as a plasticizer to the formula. Glycerols in 20-70% (w/w) concentration were used to prepare the blend films. At the level of 20% (W/W) of glycerol, PVA-AHSG blend films had the lowest thickness (0.065 mm), moisture sorption (118.76%), water vapor permeability (WVP) values (4.9 g mm m-2 kPa−1 d-1), elongation at break (EB)(2.1%), moisture content (22.5%) and water solubility (16.6%) and the highest values for tensile strength (TS)(64.6 MPa), young modulus (YM) (892 MPa),density (0.109 g cm-3),opacity (0.069 A/mm) and water contact angle (74.52◦). Increasing of glycerol concentration in PVA-AHSG blend films resulted in increase in water vapor permeability and percent of elongation while, decreased tensile strength and surface hydrophobicity.
    Increasing the glycerol concentration significantly (p
    Keywords: Polyvinyl Alcohol, Alyssum homolocarpum seeds gum, glycerol, biodegradable film
  • Seyed Amir Oleyaei, Babak Ghanbarzadeh, Ali Akbar Moayedi, Farhang Abbasi Pages 678-695
    Introduction
    Biodegradable films for food packaging applications have attracted an increasing amount of consideration over the last two decades, predominantly due to environmental pollution and the realization that our petroleum resources are not infinite. Starch, which is one of the natural biopolymers, has been considered as one of the best candidates primarily because of its processbility, availability and price. The main disadvantages of starch films are their pronounced hydrophilic character therefore; they are permeable to water vapor and have usually poor mechanical properties. However, these features can be significantly improved by blending with nanodimension materials such as Montmorillonite (MMT) and Titanium dioxide (TiO2). The main reason for this improvement in comparison with conventional composites is the large surface area which results in high interactions between the nanofillers and polymer when these nano-materials are well dispersed. The behavior of nanocomposite films has been depended to the dispersion of the nanoparticles in the polymer matrix. MMT as a one-dimensional (1D) material is the most commonly used layered silicates. TiO2 as three-dimensional (3D) nanoparticle has been investigated most widely because it is inert, inexpensive and, has a high refractive index with UV shielding potential. The study on films with different dimensions of nanofillers simultaneously is rarely reported. MMT and TiO2 as two inorganic nanofillers have different shapes and structures, so the combination of TiO2 and MMT apparently had a synergistic effect on the starch film properties. The aim of this study was to control particle agglomeration and investigate the synergistic effect of combination of TiO2 nanoparticles and MMT layers and on the surface topography, color, and thermal properties of plasticized starch-MMT-TiO2 nanocomposites.
    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 80ºC for 15 min. Different levels of MMT (3 and 5% w/w starch) and TiO2 (0.5, 1 and 2% w/w starch) were dissolved in distilled water and were added to the gelatinized starch after treatment with ultrasound for 30 min. Glycerol, as a plasticizer, with concentrations of 50% (w/w starch) were added to the filmogenic solution. The plasticized starch (PS) based filmogenic solutions were dried in an oven at 45 °C for 15 hours. The surface roughness and topography and thermal properties of the films were determined through atomic force microscopy (AFM) and differential scanning calorimetry (DSC) analysis, respectively. Fourier transforms infrared (FTIR) spectroscopy in the range of 4000 to 400 cm-1. UV-Vis spectroscopy was employed to evaluate the absorbance and opacity behavior of the PS-MMT-TiO2 nanocomposite films in the wavelength range of 200-800 nm. The color parameters of films were measured by a portable colorimeter. Statistical analysis was performed on a completely randomized design with the analysis of variance (ANOVA) and Duncan’s multiple range tests was used to detect differences among the mean values of the films properties
    Results And Discussion
    Atomic force microscopy’s images demonstrated an obviously uniform dispersion of MMT and TiO2 nanomaterials in the PS-3%MMT-TiO2matrix with smoother surfaces and a lower roughness parameters than that for the corresponding binary PS-MMT nanocomposites with the MMT filler content (3 wt%). Surface roughness of starch films was changed depending on the MMT and TiO2 content. The results of the roughness parameters and topographic images were confirmed by the high frequency distribution curves. In the PS-3 and 5% MMT films, most parts have height of about 400 and 600 nm, respectively; While the height of the PS-MMT-1% TiO2 bionanocomposites film were 200 and 800 nm. FTIR revealed the hydrogen bonds and electrostatic interactions between nanofillers with starch and themselves by the peaks associated with bond C-O-H at 1142 cm-1 and 990 cm-1 and wide and high intensity IR absorption in the 500-800 cm-1.Evanescence of 3626 and 3452 cm-1 peaks assigned to OH groups of MMT in the PS-3MMT spectrum affirmed the interaction between starch and MMT.Shift in melting temperature and glass transition (Tg) towards higher temperature respectively from 295.1C to 306.3 C and from 199.1 C to 207.6 C were illustrated by DSCresults due to addition of TiO2 in the PS-3%MMT matrix.Improvement of thermal stability might be attributed much jammed and conjugated 3D MMT-TiO2 network combined together, or powerful interaction between PS and nanofillers could also slowdown the polymer chains motion and melting point during heating. These results showed a significant effect of combination of 1D MMT layers and 3D TiO2 nanoparticles on the thermal properties of PS nanobiocomposite starch based films. Montmorillonite did not affect color of nanocomposite. The transparency of a nanobiocomposite film is not significantly varied when the clay layers with about one nm thick are excellent dispersed through the polymer matrix, since such MMT platelets are less than the of visible light wavelength and do not block lights transmission. Transmittance, redness and yellowness of new ternary films decreased when TiO2 was added to PS-3%MMT matrix at 1%. In this case, color difference (ΔE) and whiteness index (WI) are increased 86.6% and 76% respectively.Starch and PS-MMT films were colorless. The presence of TiO2 imparted whiteness to the nanocomposites due to its inherent whiteness. This phenomenon can be enucleated as the large specific surface area and high refractive index of nanosized TiO2 particles were accounted or diffuse reflection of light from the interface of the materials, and consequently, transparency loss of the composite films. UV-Vis spectroscopy was employed to evaluate the absorbance and opacity behavior of the PS-MMT-TiO2 nanocomposite films in the wavelength range of 200-800 nm. Incorporation of TiO2 nanoparticles into the starch film solution caused a significant decrease of transmittance in visible, UV-A (360 nm), UV-B (300 nm), and UVC (240 nm) regions. The results of UV-Vis spectroscopy showed that this type of films could be used as a packaging material to shield against UV and visible light.
    Keywords: Starch, Montemorillonite, TiO2, AFM, FT-IR
  • Sara Rrahbaran, Aazam Aarabi Pages 696-705
    Introduction
    The consumption of dietary fiber plays an important role in the prevention of illnesses such as diabetes type 2, hypercholesterolemia. Dietary fibers are not only desirable for their nutritional properties but also for their functional and technological properties. This study was undertaken to investigate the possibility of alkaline hydrolysis to remove fiber from rice bran.
    Material and
    Methods
    In this study, the extraction of fiber from rice bran was carried out in the presence of sodium hydroxide as an alkaline media and under autoclave condition. The Response Surface methodology was evaluated by the central composite design (CCD) to build a model based on three variables including the time (X1), temperature (X2) and the concentration of Hydrogen Peroxide (X3) for the extraction of fiber, and water binding and fat binding capacity of produced fiber.
    Results And Discussion
    Results showed that the optimum conditions for the maximum production of extracted fiber were 35min, 99.6 °C and 13.47% for time, temperature and the concentration of hydrogen peroxide, respectively. Results indicated that temperature was the most significant factor influencing considerably on fiber extraction and fiber fat binding capacity and none of the parameters had significant effect in the level of (0.05) on the water binding capacity of fiber
    Keywords: Rice Bran, Fiber, Water Binding Capacity, Fat Binding Capacity, Response Surface Method
  • Fatemeh Heidari Dalfard, Masoud Taghizadeh, S.M.A. Razavi Pages 706-715
    Introduction
    Malt extract is one of the malt products obtainedfrom concentrations of water soluble extract of grains such as barley and is a proper alternative to white sugar. It has a high diastasis properties andcontainshigh amount of different vitamins specially the group of vitamin B as well as high amount of fermentable sugars. Therefore, malt extract has high nutritional value and is recommended by nutritionist for children and people who are having growth problems. In addition, it has a high potential to be used as sweetening agent in different food products such as cookies, biscuits, ice cream, chocolates etc. Knowledge on the thermo-physical properties of malt extract such as density, specific heat, thermal conductivity as well as thermal diffusivity is highly necessary for the designing of processing equipments, formulation of derived products, heating and chilling processes, and other unit operations such as pasteurization, concentration, dehydration as well as final safety and quality of formulated products. Since, no research work has been reported on thermo-physical properties of malt extract, the aim of this study was to determine different thermal properties of malt extract as well as investigation of the effect of temperature and soluble solid contents (SSC) of the studied properties.
    Materials And Methods
    Barley malt was purchased from local market. 150 gr of malt was first grounded and added to 600ml water at 46°C and stored for 30 minutes. Then, its temperature was increased using a heater to reach 70°C. 300 ml water was then added to the mixture and stored at 70°C for 60 minutes. Then, the mixture was cooled at room temperature and filtered to gain a sweet solution. The obtained solution was concentrated to 60, 70 and 80 degree of Brix for further experiments.
    Specific heat and thermal conductivity of samples were determined using a differential scanning calorimeter (DSC). DSC is a powerful tool which is able to spontaneously measure different thermal propertiesof samples such as specific heat, thermal conductivity, glass transition temperature, melting point, crystallization point etc. as a function of time and temperature at the desired temperature levels. Density of samples was also measured using a 50ccvolumetric pycnometer. 25 grams of samples were first solved in hot water and then were placed in an isothermal bath to measure the density. Thermal diffusivity of samples was determined using the following equation:∝=k/〖pC〗_p
    Results And Discussion
    The obtained results on specific heat measurement showed that decreasing SSC from 80 to 60% and increasing the temperature from 25 to 90°C would increase cp from 2.074 to 3.063 kJ/kg°C in a linear manner. Following equations were obtained to predict specific heat as a function of temperature:C_p=2.756.004T R^2=0.893 ¡ X_s=60
    C_p =2.245 .005T 〖 R〗^2=0.868¡ X_s=70
    C_p=2.066 .001T R^2=0.75¡ X_s =80
    Thermal conductivity measurements were also showed that decreasing SSC from 80 to 60% and increasing temperature from 25 to 90°C would increase the K values from 0.1196 to 0.347 W/m°C in a linear manner. Increasing temperature would increase molecular movements and therefore it elevates the heat transfer velocity and K increases. Following equations were obtained to predict thermal conductivity as a function of temperature:K=0.152 .003T R^2=0.761¡ X_s=60
    K =0.097.002T R^2=0.851¡ X_s=70
    K=0.114.001T R^2=0.706¡X_s =80
    In order to develop a model to predict thermal conductivity of malt extract based on its soluble solid content and temperature, multiple regressions was used. The obtained model was a two-parameter linear model with R2 of 0.858. The results showed that 1% increase in soluble solid content percentage would cause an increase of 6% in K, while 1% increase in temperature would cause only 49% increase in thermal conductivity value.
    Density measurements were also showed that increasing density from 60 to 80% and temperature from 25 to 90°C would increase density of malt extract. Following equations were obtained to predict density as a function of temperature:P=1328.699-0.402T R^2=0.999¡ X_s=60
    P=1375.451-0.290T R^2=0.999¡ X_s=70
    P=1426.201-0.286T R^2=0.998¡X_s =80
    Thermal diffusivity of samples was also determined using indirect method for soluble solid content of 60 to 80 and in the temperature range of 25 to 90°C. It was found that thermal diffusivity would increase linearly by decreasing soluble solid content and increasing temperature. Following equations were obtained to predict thermal diffusivity as a function of temperature:∝=5.176〖×10〗^(-8).049×〖10〗^(-8) T R^2=0.783¡ X_s=60
    ∝=2.993×〖10〗^(-8).050×〖10〗^(-8) T R^2=0.929¡ X_s=70
    ∝=3.125×〖10〗^(-8).036×〖10〗^(-8) T R^2=0.94¡X_s =80
    The results of the present work were in agreement with the results reported by other researchers confirming that both SSC and temperature have significant effect on thermo-physical properties of malt extract.
    Keywords: malt extract, specific heat, thermal conductivity, thermal diffusivity, density