فهرست مطالب

پژوهش های صنایع غذایی - سال بیست و نهم شماره 2 (تابستان 1398)
  • سال بیست و نهم شماره 2 (تابستان 1398)
  • تاریخ انتشار: 1398/05/01
  • تعداد عناوین: 10
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  • اعظم ایوبی*، مهدا پورابوالقاسم صفحات 1-16
    زمینه مطالعاتی
     شهد خرما کنسانتره شیره خرماست که پس از مراحل استخراج و خالص سازی عصاره خرما با حذف ترکیبات پکتینی، پروتئین، فیبر و رنگ تولید می شود.
    هدف
    هدف از این پژوهش بررسی امکان تولید کیک کم شکر با استفاده از شهد خرما بوده است.
    روش کار
    در این تحقیق، اثرات شهد خرما به عنوان جایگزین شکر (در چهار سطح 25، 50، 75 و 100 درصد) بر ویژگی های فیزیکی شیمیایی (افت وزنی، pH، تخلخل، دانسیته، رطوبت، سفتی بافت، رنگ پوسته و رنگ بافت) و حسی (رنگ پوسته، بافت، طعم و پذیرش کلی) کیک فنجانی مورد بررسی قرار گرفت. به منظور ارزیابی میزان تخلخل مغز کیک، از تکنیک پردازش تصویر استفاده شد. بافت کیک در دو روز متفاوت یعنی 4 و 8 روز پس از تولید و با استفاده از دستگاه بافت سنج و رنگ پوسته و بافت  کیک  توسط سیستم رنگ سنجی هانترلب مورد ارزیابی قرار گرفت.
    نتایج
    نتایج آنالیز داده ها نشان داد که تاثیر شهد خرما بر خصوصیات فیزیکی شیمیایی و حسی کیک معنی دار بوده است. مشاهدات نشان داد که با افزایش درصد شهد خرما در فرمولاسیون کیک، افت وزنی، pH، تخلخل، روشنی پوسته و بافت، زردی پوسته و امتیازات حسی کاهش  و دانسیته، رطوبت، سفتی بافت و قرمزی پوسته و بافت کیک افزایش یافت. کمترین افت وزنی (2/18 درصد)، pH (59/6)، تخلخل (6/13 درصد) و بیشترین مقدار دانسیته (5/0 گرم بر سانتی مترمکعب) و تیرگی رنگ پوسته و بافت کیک (به ترتیب 21/33 و 62/43) مربوط به سطح جایگزینی 100 درصد بود. نتیجه گیری نهایی: نتایج پژوهش حاضر نشان داد که استفاده از شهد خرما به عنوان جایگزین شکر در کیک فنجانی تا سطح 50 درصد تاثیر نامطلوب چندانی بر خصوصیات فیزیکی شیمیایی این نوع کیک نداشته و خواص حسی محصول را نیز حفظ می کند.
    کلیدواژگان: تخلخل، رنگ، سفتی، شهد خرما، کیک فنجانی
  • شلاله زاهدی نیا، شهرام حنیفیان صفحات 16-28
    زمینه مطالعاتی
     کلی فرم ها گروه مهمی از خانواده انتروباکتریاسه هستند که 10% از جمعیت میکروبی روده را تشکیل می دهند و اکثرا بیماری زا نیستند. آزمون های میکروبی مرتبط با جستجو و شمارش کلی فرم به صورت وسیع در صنایع شیر به عنوان میکروارگانیسم های شاخص جهت نشان دادن خطای فرآیند، بهداشت محیط و آلودگی ثانویه در محصول استفاده می شوند.
    هدف
    این مطالعه با هدف بررسی میزان آلودگی و تنوع گونه ای کلی فرم ها در بیوفیلم مخازن حمل و نگهداری شیر خام و تجهیزات فرآوری محصولات شیر انجام گرفت. هم چنین قابلیت تولید بیوفیلم هر یک از جدایه های کلی فرمی ارزیابی گردید.
    روش کار
    برای این منظور تعداد 80 نمونه شامل 30 نمونه از مخازن حمل و نگه داری شیر خام، 30 نمونه از تجهیزات فرآوری محصولات لبنی و 20 نمونه از سطوح مختلف سالن تولید نمونه گیری شد.
    نتایج
    با توجه به نتایج حاصل مشخص گردید که 75/8% کل نمونه ها آلوده به کلی فرم ها بودند. بالاترین میزان فراوانی مربوط به جنس های انتروباکتر و کلبسیلا با 25/31% و کم ترین میزان فراوانی مربوط به سیتروباکتر با 5/12% به دست آمد. نتایج الایزا نشان داد از 16 جدایه شناسایی شده، 5/87% قابلیت تولید بیوفیلم دارند و فقط 2 (5/12%) جدایه اشریشیا کولای فاقد این توانایی بودند. نتیجه گیری نهایی: در مجموع می توان گفت وجود آلودگی بالای کلی فرمی در کف سالن و تسمه نقاله ها، نشان دهنده پتانسیل بالای این مکان ها برای آلوده کردن فرآورده های شیر است و نیاز به استفاده از رویکردی جدید برای رفع این مشکل وجود دارد.
    کلیدواژگان: کلی فرم ها، بیوفیلم، مخازن شیر خام، تجهیزات فرآوری شیر
  • علی گنجلو*، ماندانا بی مکر، مسعود قربانی صفحات 29-45
    زمینه مطالعاتی
     استخراج ترکیبات فنولی از منابع ارزان قیمت خصوصا محصولات جانبی و ضایعات صنایع فرآوری مواد غذایی از اهمیت بالایی برخوردار است.
    هدف
    این پژوهش به منظور بررسی تاثیر روش های مختلف خشک کردن و نوع حلال بر سینتیک استخراج ترکیبات فنولی از غلاف نخود فرنگی انجام شد.
    روش کار
    غلاف نخود فرنگی به روش های خشک کردن در سایه، هوای داغ (ºC50 و70) و انجمادی خشک شد و ترکیبات فنولی به روش غرقابی با استفاده از حلال های آب، استون، اتانول و هگزان استخراج گردید. از شناساگر فولین - سیکالتیو برای اندازه گیری محتوای ترکیبات فنولی کل و از روش های مهار رادیکال های آزاد 1،1- دی فنیل- 2- پیکریل هیدرازیل (DPPH) و هیدروژن پراکسید برای ارزیابی فعالیت ضد رادیکالی استفاده شد. سینتیک استخراج ترکیبات فنولی غلاف نخود فرنگی با استفاده از مدل های سینتیکی قابل برازش مورد مطالعه قرار گرفت.
    نتایج
    روش خشک کردن و نوع حلال تاثیر بسزایی بر میزان استخراج ترکیبات فنولی داشت. داده های آزمایشگاهی با در نظر گرفتن حداکثر ضریب همبستگی، حداقل ریشه میانگین مربعات خطا و مدول میانگین انحراف نسبی به خوبی با مدل پلگ برازش شدند. مقدار ترکیبات فنولی در دامنه 44/14-22/0 میلی گرم معادل اسید گالیک بر گرم عصاره به دست آمد. بر اساس مدل پلگ، کمترین مقدار ثابت سرعت پلگ برای نمونه های خشک شده به روش انجمادی و استفاده از اتانول به دست آمد که نشان گر سرعت بالاتر انتقال جرم است. حداکثر فعالیت ضد رادیکالی عصاره های فنولی غلاف نخود فرنگی معادل 48/85% برای مهار رادیکال های آزاد DPPH و 51/14% برای هیدروژن پراکسید بود. رابطه خطی با ضریب همبستگی بالا (80/0-70/0) بین محتوای فنولی کل و فعالیت مهار کنندگی رادیکال های آزاد به دست آمد. نتیجه گیری نهایی: غلاف نخود فرنگی را می توان به عنوان یک منبع ارزان قیمت برای استحصال ترکیبات فنولی به منظور استفاده در صنایع غذایی و دارویی معرفی نمود. روش آماده سازی و نوع حلال تاثیر چشمگیری بر استخراج ترکیبات فنولی غلاف نخود فرنگی دارند. از مدل پلگ می توان برای بررسی سینتیک انتقال جرم حین فرایند استخراج ترکیبات فنولی استفاده نمود.
    کلیدواژگان: استخراج، ترکیبات فنولی، سینتیک انتقال جرم، غلاف نخود فرنگی، فعالیت ضد رادیکالی
  • آیمن سرداری فر، هادی الماسی*، لیلا روفه گری نژاد صفحات 47-63
    زمینه مطالعاتی
     غنی سازی مواد غذایی یکی از روش های تامین کمبود ریزمغذی ها برای اقشار مختلف مردم محسوب می شود.
    هدف
    هدف از این پژوهش، تولید آب سیب غنی شده با روی به عنوان یک محصول فراسودمند و غنی شده ی جدید بود.
    روش کار
    برای این منظور، سولفات روی با پکتین و صمغ عربی به نسبت 1 به 10 و با استفاده از روش خشک کردن پاششی درون پوشانی شد و آزمون های تعیین اندازه ذرات و پتانسیل زتا و میکروسکوپ SEM بر روی نمونه های پودر انجام شد. در مرحله دوم، میکروکپسول های تولید شده و همچنین سولفات روی به شکل آزاد، به میزان 5/2 میلی گرم بر لیتر به فرمولاسیون آب سیب اضافه شدند و در طی مدت 60 روز نگهداری در دمای یخچال، تاثیر آنها بر روی خواص فیزیکوشیمیایی و حسی آب میوه مطالعه شد.
    نتایج
    بررسی خواص میکروکپسول ها نشان داد که اندازه ذرات کپسول های پایدار شده با پکتین (nm 430) کمتر از صمغ عربی (nm 760) و می باشد. تصاویر میکروسکوپ SEM توزیع یکنواخت اندازه ذرات در هر دو نوع میکروکپسول را نشان داد. افزودن میکروکپسول یا روی آزاد، تاثیر قابل توجهی بر روی pH، اسیدیته و اندیس فرمالین آب سیب ندارد. با افزودن میکروکپسول ها، کدورت آب سیب افزایش یافت. تاثیر میکروکپسول پایدار شده با صمغ عربی بر روی کدورت بیشتر از پکتین بود. میکروکپسول صمغ عربی - روی، باعث بهبود شاخص رنگ آب سیب شد. افزودن میکروکپسول ها همچنین ویسکوزیته آبمیوه را افزایش داد که تاثیر صمغ عربی در روی این ویژگی نیز بیشتر از پکتین بود. غنی سازی آبمیوه با میکروکپسول ها، شمارش باکتری های سرمادوست را در طول نگهداری اندکی افزایش داد. همچنین میزان پذیرش کلی نمونه های آب سیب در حالت استفاده از میکروکپسول ها، تفاوت معنی داری با نمونه شاهد نداشت. نتیجه گیری نهایی: در کل نتایج نشان داد که با افزودن میکروکپسول های حاوی سولفات روی به آب سیب می توان یک محصول غنی شده جدید تولید نمود بدون اینکه در خواص فیزیکوشیمیایی آن تغییر قابل توجهی ایجاد شود.
    کلیدواژگان: آب سیب، غنی سازی، روی، درون پوشانی، خواص فیزیکی شیمیایی
  • فاروق خلیفه زاده، ایمان شهابی قهفرخی* صفحات 65-79
    زمینه مطالعاتی
     به نظر می رسد تا سال 2050 جمعیت جهان حدود 50 درصد افزایش می یابد. از این رو به منظور مقابله با افزایش ناگهانی جمعیت و تامین نیازهای اولیه غذایی، بشر به دنبال راه هایی برای افزایش بهره وری، کاهش ضایعات مواد غذایی و کاهش مصرف انرژی است. اکسیژن به عنوان یکی از مهم ترین علل فساد موادغذایی و کشاورزی موجب تخریب عطر، طعم، رنگ و خصوصیات تغذیه ای آنها می شود. بنابراین به منظور حذف اکسیژن و افزایش عمر مفید مواد غذایی در بسته بندی آنها، از روش هایی مانند پر کردن تحت خلاء، پر کردن داغ، تزریق گاز خنثی و بسته بندی با اتمسفر اصلاح شده استفاده می شود. یکی از بهترین روش های کاهش اثرات نامطلوب اکسیژن، توسعه جاذب های اکسیژن در بسته بندی مواد غذایی است.
    هدف
    در این پژوهش به دنبال توسعه نانو جاذب اکسیژن مبتنی بر فعالیت فتوکاتالیستی نانو دی اکسیدتیتانیوم بر روی بستر الکتروریسی شده پلی کاپرولاکتون به عنوان جاذب اکسیژن در بسته بندی مواد غذایی بودیم.
    روش کار
    در این پژوهش با استفاده از روش الکتروریسی محلولی از پلی کاپرولاکتون و مقادیر مختلف نانو دی اکسید تیتانیوم (1%، 3% و 5%) در حلالی متشکل از کلروفورم-متانول، نانو جاذب اکسیژن تهیه شد. پس از ارزیابی نانوالیاف ها از لحاظ ریزساختار، محتوای مواد فرار و تخلخل، هر یک از این نانو الیاف در یک محفظه مناسب در معرض پرتوی فرابنفش C قرار داده شدند. تغییرات میزان اکسیژن درون محفظه در طی مدت 72 ساعت اندازه گیری شد.
    نتایج
    با افزایش میزان نانوذرات دی اکسید تیتانیوم درون نانوالیاف، قابلیت جذب اکسیژن، تخلخل و میانگین قطر نانوالیاف افزایش یافت. از سوی دیگر با افزایش میزان نانوذرات دی اکسید تیتانیوم میزان ترکیبات فرار در نانوالیاف کاهش یافت.
     نتیجه گیری نهایی: نانوالیاف حاوی نانو ذرات دی اکسید تیتانیوم در معرض تابش پرتوی فرابنفش C، می تواند به عنوان یک جاذب اکسیژن در بسته بندی موادغذایی حساس به اکسیژن به کار گرفته شود.
    کلیدواژگان: پلی کاپرولاکتون، نانوالیاف، نانودی اکسید تیتانیوم، الکتروریسی، جاذب اکسیژن، پرتو فرابنفش
  • علیرضا صادقی ماهونک، روح الله حیدری، اصغر سپه وند، منصوره سلیمانی فرد * صفحات 81-96
    زمینه مطالعاتی
    اولئوروپین فراوان ترین نوع از ترکیبات فنولی برگ زیتون است و اثرات درمانی آن به عنوان یک آنتی اکسیدان قوی به خوبی شناخته شده است. استخراج اولئوروپین از برگ زیتون به عنوان یک منبع غنی از این ترکیب، بسیار ارزشمند است. از طرفی درون پوشانی این ترکیب روشی موثر جهت حفظ ویژگی های آن طی نگهداری است.
    روش کار
    در مطالعه ای عصاره حاوی اولئوروپین، مستخرج از برگ های زیتون، به شکل نانوحامل های لیپیدی تهیه گردید. استخراج عصاره با ترکیب حلال های اتانول: آب (70:30) در حمام آب گرم (دمای 40 درجه سانتی گراد به مدت 30 دقیقه) با استفاده ازدستگاه HPLC انجامشد. با طراحی 15 فرمول برای نانوحامل لیپیدی، اندازه ذرات و کارایی درون پوشانی به ترتیب توسط دستگاه زتاسایزر و اسپکتروفوتومتر تعیین شد. بعد از تشخیص فرمولاسیون بهینه، پتانسیل زتا نیز با استفاده از دستگاه زتاسایزر ارزیابی شد.
    نتایج
    نتایج حاصل نشان داد که روش استخراج اولئوروپین از برگ زیتون با حلال های اتانول و آب (70:30) حاوی 37/221میلی گرم بر گرم اولئوروپین با درصد خلوص اولئوروپین 137/22 می باشد. همچنین نتایج حاصل از آزمون پراکندگی دینامیکی نور نشان داد که فرمول بهینه دارای میانگین اندازه ذرات 9/121 نانومتر، شاخص پراکندگی 153/0، پتانسیل زتای 3/43-میلی ولت می باشد. همچنین نتایج حاصل از بازدهی درون پوشانی نشان داد نانوحامل دارای دارای 82 درصد اولئوروپین درون پوشانی شده می باشد. در نهایت این که نانوحامل با کم ترین پودر عصاره برگ زیتون، دارای بالاترین کارایی درون پوشانی اولئوروپین، کم ترین شاخص پراکندگی و اندازه ذره ای مناسب بود.
    کلیدواژگان: حامل لیپیدی نانوساختار، اولئوروپین، کروماتوگرافی مایع با کارایی بالا، کارایی درون پوشانی
  • فوژان بدیعی*، ندا مفتون آزاد، صغری معدنی، مریم شاه امیریان صفحات 97-108
    زمینه مطالعاتی
     قهوه ای شدگی انجیر از جمله تغییرات بیوشیمیایی وابسته به دمای انتقال شیشه ای است.
    هدف
    هدف از انجام این مطالعه بررسی امکان تولید انجیر نیمه مرطوب با افزودن پلاستی سایزرها و تاثیر آن بر سرعت قهوه ای شدگی و پایداری آن بوده است.
    روش کار
    برای این منظور انجیرهای نیمه مرطوب توسط پلاستی سایزرهای شربت ساکارز، شربت گلوکز و گلیسرول در غلظت های 25 و 50 درصد آماده و پس از خروج نمونه ها از محلول، در ظروف پلاستیکی غیرقابل نفوذ به هوا بسته بندی شده و در سه سطح دمایی 5، 25 و 35 درجه سانتی گراد نگهداری شدند. خواص حرارتی نمونه ها با استفاده از دستگاه گرماسنج پویشی تفاضلی (DSC) اندازه گیری شد. 
    نتایج
    نتایج اندازه گیری دمای انتقال شیشه ای (Tg) نشان داد که نمونه انجیر آبدارشده (شاهد) دمای انتقال شیشه ای کمتری نسبت به سایر نمونه ها دارد. در ادامه پس از سه ماه، میزان قهوه ای شدگی نمونه ها مطالعه شد. شاخص قهوه ای شدگی انجیر در این مدت در تمام نمونه ها و شاهد به تدریج افزایش یافت. افزایش دمای نگهداری نیز در تمام تیمارها باعث افزایش روند قهوه ای شدگی نمونه ها شد. شاخص قهوه ای شدگی انجیر شاهد افزایش معنی داری نسبت به سایر نمونه ها نشان داد و رنگ تیره تری نسبت به نمونه های تیمارشده با پلاستی سایزرها داشت. در پایان با استفاده از پارامتر دمای جابه جایی (T-Tg) تغییرات شاخص قهوه ای شدگی انجیر بررسی شد، صرفنظر از اینکه دمای نگهداری (T) یا پلاستی سایزر (که روی Tg اثر می گذارد) تغییرکند. نتیجه گیری نهایی: به طور کلی نتایج حاصل از این پژوهش نشان داد که شربت گلوکز 50 درصد و شربت ساکارز 50 درصد در کنترل تیرگی و قهوه ای شدگی انجیر موثرتر از سایر تیمارها هستند.
    کلیدواژگان: انجیر، پلاستی سایزر، دمای انتقال شیشه ای، دمای جابه جایی، شاخص قهوه ای شدگی
  • محمد رزم پور، جمشید فرمانی*، رضا اسماعیل زاده کناری صفحات 109-119
    زمینه مطالعاتی
    چربی مرغ  با دمای ذوب حدود 0C 25، در دمای اتاق حالتی نیمه جامد و سیال دارد. با این حال، در فصل های سرد جامد شده و مشکلاتی را در هنگام تخلیه کردن آن از بسته بندی یا تانکر حمل آن ایجاد می کند.
    هدف
    هدف از هدف این پژوهش تولید چربی مرغ پایدار در برابر سرما بود.
    روش کار
    در این مطالعه اثر دما و زمان زمستانه کردن بر ویژگی های فیزیکی شیمیایی چربی مرغ (بازده، پایداری سرمایی، نقطه کدورت، اندیس یدی، نقطه ذوب لغزشی، پایداری اکسیداتیو، ترکیب اسید چرب و کلسترول) بررسی شد.
    نتایج
    نتایج نشان داد که با افزایش دمای زمستانه کردن از 10 به 0C 30، پایداری سرمایی روغن زمستانه شده کاهش (از 25/4 به 45/0 ساعت)، اما نقطه کدورت آن افزایش (از 0/1 به 0C 5/8) و بازده روغن زمستانه شده افزایش (از 4/74 به 1/98 درصد) می یابد (05/0>P). از طرفی با افزایش دمای زمستانه کردن میزان اسیدهای چرب استئاریک و لینولئیک به طور جزئی کاهش یافت (05/0>P). همچنین، مقدار اسید استئاریک نمونه های زمستانه شده اندکی کمتر از چربی مرغ بود (05/0>P). زمستانه کردن در دماهای 10 تا 0C 20 تاثیری بر میزان کلسترول چربی مرغ زمستانه شده نداشت (05/0<P)، با این حال، زمستانه کردن در دماهای 25 و 30 درجه مقدار کلسترول چربی مرغ را کاهش داد (05/0>P). زمستانه کردن اثری بر عدد یدی و اندیس پایداری اکسیداتیو نداشت (05/0<P). با این حال، عدد یدی استئارین های حاصل از زمستانه کردن از چربی مرغ و روغن زمستانه شده کمتر و نقطه ذوب آن بالاتر (در محدوده 0C 50-42) بود (05/0>P). نتیجه گیری نهایی: اگرچه هیچ کدام از نمونه های زمستانه شده از نظر پایداری سرمایی مطابق با استاندارد روغن مایع نبودند، اما زمستانه کردن می تواند مقاومت چربی مرغ در برابر جامد شدن را تا حد زیادی بهبود دهد. از دیدگاه تولید چربی مرغ با بیشترین پایداری سرمایی، زمستانه کردن در دمای 0C 10 توصیه می شود.
    کلیدواژگان: زمستانه کردن، چربی پوست مرغ، استئارین، ویژگی های کیفی
  • مژگان حاج حسینی، سید پژمان حسینی شکرابی*، سید ابراهیم حسینی صفحات 121-136
    زمینه مطالعاتی
     زائدات ماهیان به دلیل ارزش تغذیه ای بالا می توانند به عنوان یک ماده غذایی با ارزش افزوده در تهیه سوپ استفاده شوند.
    هدف
    این پژوهش از منابع دور ریز فیل ماهی پرورشی در تهیه سوپ استفاده و ویژگی های فیزیکی شیمیایی و حسی آن طی 120 روز نگهداری در دمای محیط ارزیابی شد.
    روش کار
    ابتدا زائدات تازه پس از آماده سازی در خشک کن تا رسیدن به رطوبت کمتر از 10 درصد خشک شدند. سپس سوپ آماده مصرف در چهار فرمول مختلف حاوی 20، 35، 50 و 65 درصد گوشت فیل ماهی در مقایسه با سوپ سبزیجات فاقد گوشت فیل ماهی (شاهد)، برای ارزیابی حسی و انتخاب فرمول برتر تهیه شد.
    نتایج
    ارزیابی حسی نشان داد سوپ حاوی 50 درصد گوشت فیل ماهی به طور معنی داری (05/0P<) واجد قابلیت پذیرش کلی (70/4) بالاتری نسبت به سایر فرمول ها بوده و به عنوان فرمول برتر انتخاب شد. پس از چهار ماه نگهداری سوپ ماهی برتر، مقدار اسیدهای چرب آزاد (87/8 درصد)، مقدار پراکسید (30/7 میلی اکی والان اکسیژن در کیلوگرم)، عدد تیوباربیتوریک (1/0 میلی گرم مالون آلدئید در کیلوگرم) و مجموع ترکیبات ازته فرار (78/2 میلی گرم در 100 گرم گوشت) در حد مجاز بود. مقدار فعالیت آبی در هر دو نوع سوپ در تمام زمان های نگهداری، کمتر از 5/0 بود. مقدار DE سوپ ماهی از 21/1 در زمان شروع به 83/2 در پایان چهار ماه نگهداری رسید. سوپ ماهی منبع خوبی از اسیدهای چرب غیراشباع بلند زنجیر بوده و میزان آنها بخصوص انوع ایکوزاپنتاانوئیک اسید و دیکوزا هگزاانوئیک اسید آن با گذشت زمان به ترتیب به 01/2 و 41/4 درصد کاهش یافت. نتیجه گیری نهایی: استفاده از 50 درصد گوشت خشک ماهی در فرمول سوپ آماده مصرف می تواند محصولی غنی شده با ارزش تغذیه ای بالا و زمان ماندگاری مناسب تا چهار ماه تولید کرد.
    کلیدواژگان: زمان ماندگاری، سوپ، فیل ماهی، ویژگی های فیزیکی شیمیایی
  • فخرالدین صالحی* صفحات 137-149
    زمینه مطالعاتی
     محصولات غذایی سرخ شده به دلیل دارا بودن ویژگی های بافتی منحصربه فرد از محبوبیت بالایی در میان مصرف کنندگان برخوردارند. تغییر رنگ سطح محصولات کشاورزی طی سرخ کردن یک پدیده وابسته به دما و زمان فرآیند است و از نظر سلامتی اهمیت دارد.
    هدف
    در این پژوهش سینتیک انتقال حرارت و تغییر رنگ برش های بادمجان حین فرآیند سرخ کردن به صورت یک مدل ریاضی در دماهای مختلف بررسی شده است.
    روش کار
    برش های بادمجان با ضخامت 1 سانتی متر در دماهای 150، 175 و 200 درجه سلسیوس سرخ و تغییرات دمای مرکز آن ها با ترموکوپل دمایی نوع K با ضخامت یک میلی متر هر 5 ثانیه ثبت شد. دمای سطحی محصول، با استفاده از دمانگار لیزری (مادون قرمز) ثبت شد. پارامترهای رنگی شامل روشنایی (L*)، قرمزی (a*)، زردی (b*) و تغییرات رنگ (EΔ) در طی زمان سرخ کردن ثبت و تغییرات آن ها در برابر زمان روی مدل سینتیکی برازش و ضرایب مدل گزارش شد.
    نتایج
    نتایج این آزمایش نشان داد که بخش عمده تغییرات رنگ در مراحل ابتدایی فرآیند رخ می دهد. نرخ تغییر رنگ طی سرخ کردن وابسته به دما و زمان فرآیند بود. دماهای بالاتر موجب روشنایی و زردی کمتر، اما قرمزی بیشتر می شود. در مجموع، فرآیند دمای بالا و زمان کوتاه می تواند نتیجه گیری نهایی: جهت کنترل کیفیت رنگ و در نتیجه ایمنی محصول مناسب می باشد. سینتیک تغییرات رنگ سطح بادمجان از یک تابع نمایی افزایشی تبعیت نمود. نمونه های سرخ شده در دمای 200 درجه سلسیوس افت بیشتری از نظر اندازه سطح داشته و اندازه کوچک تری داشتند.
    کلیدواژگان: انتقال حرارت، بادمجان، رنگ، سرخ کردن، سینتیک
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  • A Ayoubi *, M Pourabolghasem Pages 1-16
    Introduction
    The cake is a very diverse variety of flour products that are popular among people, especially children and adolescents. This product is a sweet with a special soft tissue that flour, oil, sugar and eggs are the main its ingredients (Institute of Standards and Industrial Research of Iran 2006). Despite the benefits of sucrose as a natural sweetener with desirable performance characteristics, due to problems with blood pressure, heart disease, tooth decay, obesity and increased blood glucose and insulin levels, especially for harmful diabetics in addition, due to economic and technological issues, increasing research are under way to replace sugar with other sweeteners. One of the important issues regarding the replacement of sugar in food products is the choice of the type of sweetener to replace and how to preserve the quality of the product during the storage period (Gohari Ardabili et al 2005). Sugar is an essential ingredient in the preparation of various types of cakes, which in addition to the role of sweetening has a great effect on the physical and chemical properties of the product (Specter and Setser 1994). There are many substitutes for sugar for use in baking products. For example, raw honey, maple syrup, molasses, stevia, xylitol, brown rice syrup, sugarcane condensate extract, glucose syrup, brown sugar, dextrose, corn syrup, invert sugar, malt extract and date sugar are the natural substitutes for sugar in the baked goods (Asghar et al 2006, Obiegbuna et al 2013). Considering the nutritional properties and high sugar content, date palms are used as a desirable substitute to sugar in food formulations to increase nutritional value and avoid sucrose complications. One of the products produced from dates is honey or date liquid sugar, which contains compounds such as glucose, fructose, sodium, potassium, calcium and magnesium, and because of the solid particles being separated from the liquid portion of the product, it can be used to prepare the syrup and clear beverages (Kordi et al 2010). Date liquid sugar is concentrate of clear and bleached date syrup that is produced after extraction date juice with removing pectin compound, protein, fiber and its color is brown to yellow. Its properties are similar to honey bee honey, and this product has high functional and nutritional value. In this study, date liquid sugar was used as a replacement for sugar in cake production with the aim of evaluating the physicochemical and sensory properties of the cake.
    Materials and methods
    The date liquid sugar used in this work was purchased from Dambaz Company and wheat flour was purchased from Tavakkol factory of Kerman. Other materials including sugar, oil, egg and baking powder purchased from local market of Kerman. Sugar substitution with date liquid sugar in this research was 25, 50, 75 and 100 percent After cooking, cakes were cooled at room temperature for about one hour and then packaged in zip-kip polyethylene bags and stored at refrigerator (4-6 °C) until performing tests. The cake was evaluated in terms of physicochemical (including weight loss, pH, porosity, density, moisture, hardness of texture and color of crust and crumb) and sensory (texture, crust color, taste and total acceptance) properties. The weight loss calculated by measuring the difference of weight before and after baking. PH was measured by a digital pH meter. Cake moisture content was determined by drying samples at 105±2°C in a hot air oven. The volumes of the cake samples were measured by the seed replacement method and then density was calculated by dividing the volume by the weight (Sahin and Sumnu 2006). For determining of porosity of cake crumb, image processing technique used.Cross sectional image of cake was documented by a table top scanner (HP Scanjet 2400, China) with 300 ppi. The images were analyzed by ImageJ software and percentage of porosity was calculated (Turabi et al 2010). The hardness of the cake was evaluated in two different days, 4 and 8 days after production, using a texture analyzer machine. The first, the cake samples were cut into cubes of 25 × 25 × 20 mm then compressed by a plate probe (50 × 100 mm) at 50 mm/min speed for 10 mm (Aghamohammadi et al 2012). Color measurements were done using a Hunterlab Colorimeter (Celik et al 2007). Sensory evaluation was carried out by 5-point Hedonic Scale. The cakes were estimated for the sensory attributes by selected semi-trained panelists. The panelists were asked to evaluate the samples and score them between 1 (most disliked) to 5 (most liked). Analysis of variance (ANOVA) was conducted for data using MSTAT-C software. Differences between the mean values were also determined using Duncan’s Multiple Range test (P<0.05).
    Results and discussion
    The results of this research showed that date liquid sugar had a significant effect on physicochemical characteristics and sensory properties of samples. By increasing of date liquid sugar in cake formulation weight loss, pH, porosity, lightness of crust and crumb, yellowness of crust decreased and density, moisture, hardness of product texture, and redness of crust and crumb increased. The least value of weight loss (18.2%), pH (6.59), porosity (13.6%) and most value of density (0.5 g/cm3), darkness of crust and crumb of cake (respectively 33.21 and 43.62) were related to substitution level of 100%. The sensory evaluation results indicated that all sensory scores of cake decreased with increasing level of date liquid sugar. However, no significant difference was found between the crust color, texture and total acceptance scores of the low sugar cake and the control in the replacement levels of 25 and 50. Also, based on the mean comparison results, the taste score of the cake has been significant with the control just at the level of 100% replacement.
    Conclusion
    Between different levels of date liquid sugar, the Levels of 25 and 50% had less negative effects on physicochemical properties of the cake. On the other hand, the low sugar cakes with 25 and 5o% date liquid sugar showed sensorial attributes similar to the control cake. It can be concluded that date liquid sugar can be replaced with sugar up to 50% to the cupcake formulation without adverse effects on the quality of cakes.
    Keywords: Color, Cupcake, Date liquid sugar, Hardness, Porosity
  • Sh Zahedinia, Sh Hanifiyan * Pages 16-28
    Introduction
    Coliforms are an important broad class of Enterobacteriaceae that make 10% of the intestinal microbial population and they are not basically pathogen. Microbial evaluations dealing with the detection and enumeration of coliforms as indicator microorganisms are extensively used in dairy industries to show process error, environmental health and secondary contamination of the products (Eden, 2014; Cowan et al., 2004). A biofilm is microbial cells that enclosed in an EPS (extracellular polymeric substance) matrix and attached to surfaces (Srey et al., 2013). The biofilm structure is such that it protects the bacteria against environmental stresses so that biofilm cells are more resistant to antimicrobial agents than planktonic (individualized) bacteria (Rendueles et al. 2013). As a result, biofilms have become a major problem in the milk industry, the processing of fish, poultry, meat and prepared foods (McDonogh 1994). The formation of biofilms, in addition to having health effects, by blocking pipes in heat exchangers and cooling towers in milk processing plants, significantly reduces the amount of heat transfer, and also decomposes and decays the UF membranes used in the production of cheese and reverse osmosis (Kumar et al. 1998). This study aimed to evaluate the contamination rate and biodiversity of coliform bacteria in raw milk tanks and dairy processing equipment as well as to assess the ability of the isolates to produce biofilm.
    Material and methods
    A total of 80 samples, consisting of 30 samples of raw milk tanks, 30 samples of dairy processing, storage and packaging equipment (processing lines of pasteurized milk, sterilized milk, buttermilk, and yogurt) and 20 samples from different surfaces (such as production floor, equipment surface, conveyor belts) were sampled. For this purpose, after cleaning in place (CIP), the specimens were obtained by sterilized wire brush and mechanically removed from the surfaces and transferred to the sterile ringer serum (Percival et al. 2014). The samples were centrifuged for 4 minutes at 4000 g for 5 minutes and the precipitate was cultured on VRBA agar and incubated at 37°C for 24-48 h. The colonies were subjected to screening and confirmation tests (Razavilar 2002). To determine the amount of biofilm produced by the coliform isolates, the quantitative microplate technique was conducted (Srey et al., 2013).
    Results and discussion
    According to the results, 8.75% of the samples were contaminated with coliforms. Amongst Enterobacter and Klebsiella had the highest contamination rate of 31.25%; meanwhile Citrobacter showed the lowest contamination rate of 12.5%. The results of ELISA assay showed that among the 16 isolates, 87.5% had the biofilm-forming capability, however 2 (5.12%) Escherichia coli isolates were found biofilm-negative. According to the findings of the study, 87.5% of the isolates (except for the two E. coli isolates) were biofilm producers and produced different biofilm values. Meanwhile, the largest production of biofilms was measured by Citrobacter freundii. Biofilm producing isolates produced different biofilm values. So that E. coli, Enterobacter cloacae, and E. sakazakii produced a low amount of biofilm; meanwhile, medium amounts of biofilm were formed by Klebsiella pneumoniae and K. aerogenes. The ability to form biofilms was not only widely differentiated among different species, but could also be significantly different among isolates of a specific species.
    Conclusion
    Presence of high contaminated specimens (43.75%) on the floor and surfaces of processing plants indicates the high potential of these places for contamination of milk products. The existence of cracks, the presence of residual organic matter –as the sources of the microbes- and the lack of insufficient washing and disinfection of the floor can be the main reasons for the presence of contamination in these areas. In addition to the floors, conveyor belt (37.5%) and raw milk tank drain valve (18.75%) had a high contamination rate. During washing and CIP of tank trucks, it is not possible to have full access to all surfaces of the tanker and consequently is not effectively disinfected; so as biofilm was clearly visible in some of the tankers. To eliminate such biofilms along with the CIP, mechanical methods should be used (Simões et al., 2006). The use of supplemental washing and disinfection techniques, staff training for personal hygiene, more supervision over floor cleaning, replacement of damaged materials, monitoring of CIP and the use of efficient methods for raw milk tankers can greatly reduce coliform contamination.
    Keywords: Coliform, Biofilm, raw milk tanks, Dairy processing equipment
  • A Ganjloo *, M Bimakr, M Ghorbani Pages 29-45
    Introduction
    Agriculture is regarded as one of the most important fields of human industry, due to its role in ensuring global food security for people around the world and supporting other industries. Agricultural processing industries create a great amount of residues/byproducts, which are considered as “wastes”. The green pea (Pisum sativum L.) is one of the most important legumes in the world which its pod is considered a biological waste and discarded (Amarowicz and Troszyñska 2003). Interestingly, agricultural wastes contain many valuable bioactive compounds, possessing a wide range of potential pharmacological properties, which have great contributions to make in related industries, such as nutraceuticals or functional foods, medicines, pharmaceuticals and cosmetics. However, they are still underutilized as abundant, inexpensive, renewable and sustainable sources of natural bioactive compounds. Phenolic compounds are a large class of plant secondary metabolites that exhibit multiple biological activities (Diouf et al. 2009). Thus, phenolic compounds recovery from the low-cost resources has become increasingly important in recent years. Extraction is a key step in the way of valuable bioactive compounds preparation which greatly influenced by several parameters (Samavati and Manoochehrizade 2013). Extraction method, solvent type, solvent pH, temperature, extraction time, raw material to solvent ratio, raw material particle size and different pretreatments have a significant effect on the efficiency of valuable bioactive compounds extraction process (Chirinos et al. 2007). Knowledge on the kinetics of mass transfer during the extraction process is required for adequate control and the correct operational design. Different empirical and semi-empirical models such as Pseudo-first order, film Theory, Minchev and Minkov, Peleg, nth order, and Weibull presented to predict the kinetics of mass transfer without taking into account the underlying phenomena. These models represent data at conditions similar to those upon which such models were developed. However, far too little attention has been paid to study the kinetics of bioactive compounds extraction from agricultural wastes/byproducts. Thus, the present study was designed to determine the effect of different drying methods and type of solvent on the kinetics of phenolic compounds extraction from green pea pods. Finally, the antiradical activities of green pea pods extracts containing phenolic compounds were determined.
    Material and methods
    The green pea pods were washed and dried using different drying methods including shade, hot air (50 and 70 ºC), and freeze-drying to the final moisture content of 9.5%±0.22. Dried pods were grounded and pass through a 35-mesh sieve to produce homogenous dried green pea pod powder. Phenolic compounds were extracted from green pea pods through maceration technique using different solvents including water, acetone, ethanol and n-hexane. The sample to solvent ratio, temperature and extraction time was 1:20 (w/w), 25 ºC, and 1440 min, respectively. Total phenolic content (TPC) of extracts was determined using the Folin–Ciocalteu method, based on the colorimetric reaction of the sample with the Folin–Ciocalteu reagent and reported as a milligram equivalent gallic acid per gram of sample (mg GAE/g) (Amin et al. 2004). The antiradical activities of phenolic extracts were measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide (H2O2) methods. Different empirical models including nth order, Peleg and Weibull were used for fitting experimental data using non-linear regression through Gauss–Newton method. The quality of the fit between the experimental and predicted data was determined according to values of correlation coefficient (R2), the root mean square error (RMSE), and the mean relative percentage deviation modulus (E). The best model was chosen as one with the highest R2 and the least RMSE and E values.
    Results and discussion
    The results revealed that drying method and solvent type have a significant effect (P<0.05) on phenolic compounds extraction. The amount of phenolic compounds under different conditions was in the range of 0.24-14.44 mg GAE/g. The highest amount of phenolic compounds was obtained using freeze-drying and ethanol as solvent equivalent to 14.44 ± 0.27 mg GAE/g. While the lowest total phenolic content (0.22 ± 0.02 mg GAE/g) was related to the hot air dried (70 °C) green pea pods treated with n-hexane as solvent. The experimental data fitted well with Peleg model considering maximum correlation coefficient (0.9908-0.9979), minimum root mean square error (0.001-0.140) and mean relative percentage deviation modulus (3.443-9.704). Based on the Peleg model, Peleg rate constant (K1), Peleg capacity constant (K2) and equilibrium of phenolic compounds (Ceq) were estimated. The lower Peleg rate constant described the higher initial mass transfer rate. The minimum Peleg rate constant was obtained for the dried samples by freeze drying and using ethanol as solvent. The lower Peleg capacity constant also represented the higher equilibrium content. Similar trend have been also observed for Peleg capacity constant. The equilibrium point (Ceq) is reached when phenolic content of matrix and solvent become equal. The high correlation coefficient (R2=0.991) was found between experimental values and predicted values by the Peleg model confirmed the precision of the Peleg model for estimation of the phenolic compounds extracted from green pea pods. Antiradical activity assessment of green pea pod phenolic extracts showed the high capacity for inhibiting DPPH (up to 48.85%) and hydrogen peroxide (up to 14.51%) free radicals. The highest antiradical activity of phenolic compounds was related to the green pea pods which treated by freeze-drying method and ethanol as solvent whereas the lowest antiradical activity was obtained for air-dried samples at 70 ºC and n-hexane as extraction solvent. A linear relationship with the high correlation coefficient (R2=0.70-0.80) was found between the total phenolic content and the free radicals inhibitory activity.
    Conclusion
    The current study found that drying methods and solvent types have a significant effect (P>0.05) on the extraction of phenolic compounds from green pea pods. The highest amount of phenolic compounds was extracted from green pea pods by using freeze-drying and ethanol as solvent. In addition, the Peleg model can be used to study the kinetics of mass transfer during phenolic compounds extraction. As a result, green pea pod can be introduced as a low-cost source for the extraction of phenolic compounds. This finding has important application for developing natural ingredients to be used in the food and pharmaceutical industries.
    Keywords: Extraction, Phenolic compounds, Kinetics of mass transfer, Green pea pod, Antiradical activity
  • I Sardarifar, H Almasi *, L Roufegarinezhad Pages 47-63
    Introduction
    Fortification is an efficient method for supplying of nutrient deficiency in society. Zinc is one of the main micronutrients that its deficiency in the Iranian people has been approved. This element has many important roles in body metabolisms such cell proliferation, control of growth, improving of immunological system, growth of nail, hair, bones, etc (Zlewski 1996). Fruit juice is a most popular beverage between children and adults and its fortification with zinc element can be a good criteria for compensate of its deficiency (Villalpando et al., 2006). The aim of this research was to produce apple juice fortified with zinc as a new functional and fortified food. Introducing of a novel fortified beverage for supplying of zinc element can open a new insight of the production of fortified foods and beverages.
    Materials and methods
    Zinc sulphate was encapsulated with pectin and gum Arabic at ratio of 1:10 by spray drying method. Drying was applied at 180 ºC and the obtained powders were stored at refrigeration temperature. The particle size and zeta potential of microcapsules were analyzed by DLS test and SEM microscopy was utilized to study the morphological characteristics of microcapsules (Hosseinnia et al., 2017). At the second step, the produced microcapsules and also free zinc sulphate were added to the apple juice at concentration of 2.5 mg/L. This concentration was selected according to the ADI (acceptable daily intake) value of zinc. The physicochemical properties including pH, acidity, turbidity, color, formalin index and viscosity were investigated. The microbial properties and also sensorial characteristics of the fortified apple juice samples were also evaluated during 60 days storage at refrigerator temperature. One-way ANOVA and Duncan test were used for statistical analysis of obtained data.
    Results and discussion
    Studying of the morphology of microcapsules revealed that size of capsules produced with pectin (430 nm) is smaller than gum Arabic (760 nm) stabilized capsules and its surface charge is higher. The Zeta potential of gum Arabic stabilized microcapsules was -18 meV but it was equal to -28.6 meV for pectin stabilized samples, revealing the higher stability of pectin microcapsules in comparison to gum Arabic. The SEM images indicated that the homogenous microcapsules are produced by both of biopolymers but the uniform dispersion of pectin microcapsules was higher than gum Arabic. Results of the apple juice fortification indicated that the addition of microcapsules or free zinc had no significant effect on pH, acidity and formalin index of apple juice. These parameters were in the standard range of fruit beverages. This is an important factor for a fortified food that its characteristics are similar to the pure and non-fortified food (Younas et al., 2014). Effect of gum Arabic stabilized microcapsules on turbidity of apple juice was more than pectin-zinc microcapsules. Higher molecular weight and lower purity of gum Arabic in comparison to pectin was the reasons of this observation. On the other hand, gum Arabic enhanced the color index of apple juice but pectin had no effect. Addition of microcapsules increased the viscosity of juice and the effect of gum Arabic was more than pectin. Fortification of apple juice with microcapsules increased the psychrophilic counts during storage. This observation can be attributed to the cross contamination of microcapsules during production and storage of them. However, by a good heat processing of apple juice after fortification, this problem can be resolved. Also, the total acceptance of apple juice samples containing microcapsules had no significant difference with control sample. At 60th day of storage the sample fortified with pectin stabilized microcapsules had the highest total acceptance storage. The consumer acceptability is the most important factor for designing of fortified foods. Because the fortification can adversely affect the acceptance of fortified food or beverage by consumers (Das and Green 2016).
    Conclusion
    This research revealed that the encapsulation of zinc with gum Arabic and pectin biopolymers is possible and these microcapsules had acceptable characteristics for using in food fortification. But the efficiency of pectin was more than gum Arabic and it was suggested as the best candidate for production of zinc microcapsules with spray drying method. The spry drying method was proposed as a suitable method for production of zinc loaded microcapsules by both of biopolymers. According to the results of the second stage, fortification of apple juice with zinc microcapsules had no significant effect on the most of physical and chemical properties of beverage and thus the fabricated microcapsules can be used in food and beverage fortification. Generally, the results indicated that a new fortified product could be produced by incorporation of zinc coated microcapsules to apple juice without any altering in its physicochemical properties. The lower changes in the physicochemical characteristics of apple juice after incorporation of zinc microcapsules was the best achievement of this research. This product can be proposed to food and beverage companies as a new fortified product for zinc supplying and increasing of the absorption of this element with consumers. However, it should be noted that a comprehensive research is required for determining the bioavailability of zinc micronutrient in the fortified beverages and in the different consumers regarding their age and gender. Further studies on the bioavailability of encapsulated zinc and its release profile in gastrointestinal simulants are suggested to complete this research.
    Keywords: Apple juice, Zinc, Fortification, Encapsulation, Morphology, Physicochemical properties
  • F Khalifezadeh, I Shahabi * Pages 65-79
    Introduction
    It seems that by 2050 the world's population will increase up to 50%. Hence, human beings are looking for ways to increase productivity, reduce food waste and reduce energy consumption in order to cope with the sudden increase in population and the supply of foods. According to the FAO report, about one-third of annual agricultural production will be lost during production process to consumption. In this regard, oxygen is considered as one of the most important causes of food and agriculture spoilages. Oxygen by oxidation of oxygen-sensitive food can be directly (i.e. corrosion in metals, oxidation of fatty acids, formation of red color in meat and oxidation to metmyoglobin, oxidation of ascorbic acid, natural pigments and aromatic substances) and indirectly (with the growth of aerobic microorganisms) lead to food spoilage. In this way, the aroma, taste, color and nutritional properties of the food will change. Therefore, in order to remove oxygen and increase the shelf life of food in packaging, e.g. vacuum filling, hot filling, neutral gas injection and modified atmosphere packaging are used. Increasing production costs and reducing the nutritional value of these products, has been increased the attention of researchers to alternative methods. One of the best alternative methods to reduce the side effects of oxygen is the development of oxygen scavengers in food packaging. The general principles of the oxygen scavenger are based on one or more principles e.g. oxidation of antioxidant compounds, iron oxidation, oxidation of acid ascorbic, oxidation by glucose oxidase and alcohol oxidase, oxidation of unsaturated fatty acids, stabilized yeasts on the substrate, photosynthesis, ascorbate salt / metals, metal catalysts. The effectiveness of some of these adsorbents is affected by some reasons i.e. lack of iron-based adsorbents activity of at the absence of moisture, limited oxygen absorption capacity, low absorption rates, especially at low temperatures, color change in packaging and the possibility of food contamination. In this research, we were going to develop a nano-oxygen scavenger based on the photocatalytic activity of nano-TiO2 on the electrospun poly-caprolactone (PCL) as an oxygen scavenger in food packaging. The photo oxygen scavenger (e.g. electrospun poly-caprolactone-TiO2) can be used to reduce the photo-oxidation of foods by reducing the available oxygen and block the UV as initiator, simultaneously.
    Material and methods
    In this study, a 15% solution of PCL and different TiO2 content (1%, 3% and 5%) were prepared in a chloroform:methanol (4:1) solvent. The solution were loaded in a plastic syringe and the syringe was placed on a syringe pump. The electric potential was applied to the metallic needle (23 gauge) by the high voltage power supply. The fibers were collected on an aluminium foil. The applied voltage was 22 kV, the solution flow rate was 0.6 ml/h, and the tip of the needle to collector distance was 15 cm. The microstructure of nano fibers was investigated by SEM microscopy. The volatile compound content (i.e. residual chloroform:methanol) of the nano fiber was measured by weight differences at 50 °C. The porosity of the electrospun nano fiber was measure by 50% ethanol solution using with pycnometer. The nanofibres were exposed to UV-C ray in an air tight chamber. Changes in oxygen content were measured for 72 hours.
    Results and discussion
    Oxygen absorption, porosity and mean diameter of nanofiber were increased with increasing TiO2 content of the nanofibers. On the other hand, the volatile compounds of the nanofibers was decreased, simultaneously. Regard to the result of current study the maximum oxygen absorption was achieved after 24 hours by PCL- TiO2 (5%). After that the oxygen content remained constant up to 72 hours. The visual properties of the electrospun nano fiber contain TiO2 showed the increasing of darkness of the specimens after the UV-C irradiation. Whereas, the irradiated PCL nano fiber by UV-C ray was white. It seems, it was due to the acceleration of photo-degradation of nano fibers under UV-C by TiO2. The color of aluminum was appeared in the background of the nano fibers, consequently.
    Conclusion
    The electrospun PCL nanofibres contain nano-TiO2 where exposed to UV-C ray can be used as an oxygen scavenger in the oxygen-sensitive food packaging. However, the oxygen scavenging capacity of the nanofibers is not high. Furthermore, the nano oxygen scavenger is photoactive. So, it is not appropriate oxygen scavenger at no light condition. In the future study, development of photoactive oxygen scavengers under long wavelength (i.e. UV-A and visible) should be considered.
    Keywords: Polycaprolactone, Nanofiber, Nano titanium dioxide, Electrospinning, Oxygen scavenger
  • AR Sadeghi Mahoonak, R Heidari, A Sepahvand, M Soleimani Fard * Pages 81-96
    Introduction
    As the demands for functional foods are on the rise, manufacturers have been seeking methods to use compound ingredients that make health promotion feasible. Nanoscience and nanotechnology have gained popularity in the 21st century. Scientists believe that nanotechnology can be used to handle matter at nano-dimensions. Nano powders, having a wide range of applications, were developed following the introduction of nanotechnology (Ananthu & Renjanadevi, 2016). It is believed that one the ways to save bioactive food ingredients from environmental damage and disguise their displeasure attributes is through encapsulation. Solid lipid nanoparticles (SLN) and nanostructure lipid carriers (NLC) are the novel types of nanostructures; researchers argue that they are the novel colloidal sensitive carriers that can be used for scientific and industrial applications (Pardeike, Hommoss, & Muller, 2009). Traditionally, the Mediterranean diet has been consisted of olive tree (Olea europaea) products that led to decreased risk of chronic diseases such as cardiovascular diseases and several cancers. Phenolic acids, phenolic alcohols, flavonoids, and secoiridoids are the usual phenolic compounds found in olives. Olives are rich in oleuropein, demethyloleuropein, and ligstroside (Yoon, 2018). Several pharmacological features have been reported in oleuropein such as antioxidant (Visioli, Poli, & Galli, 2002), anti-inflammatory (Visioli, Bellosta, & Galli, 1998), anti-atherogenic (Carluccio et al., 2003), anti-cancer (Owen et al., 2000), antimicrobial (Tripoli et al., 2005), and antiviral ones (Fredrickson & Group, 2000); hence, it has been used commercially as food supplement in Mediterranean countries. Besides, research shows that oleuropein exerts cardio-protective effect against acute adriamycin cardiotoxicity (Andreadou et al., 2007); it was also reported that they are involved in anti-ischemic and hypolipidemic activities (Andreadou et al., 2006). Oleuropin is the most abundant type of phenolic compounds in olive leaf and its therapeutic effects are well known as a potent antioxidant. Extraction of oleuropein from olive leaves as a rich source of this compound is very valuable. On the other hand, the encapsulation efficiency of this compound is an effective way to maintain its characteristics during storage. The present research tried to investigate the synthesis method, characterization, and physical stability of nanostructured lipid carrier containing of olive leave extract. Various methods including high mechanical shear, high-pressure melt-homogenization method can be applied to synthesize the novel nanoencapsulation system (NLC). Since data on the effects of formulation compound on physicochemical properties of oleuropein-loaded NLC is scarce, the present research attempted to study the effect of concentrations of solid and liquid lipid, surfactant and olive leaf extract powder on physical and chemical characteristics of oleuropein-NLC by the application of one-at-time method.
    Materials and methods
    Initial component concentrations were chosen by the Design Expert Software (version 7.0.0) and one-factor-at-a-time method/one-variable-at-a-time method at various levels. In a study an extract containing oleuropein, was extracted from olive leaves, was prepared in the form of lipid nanocarriers. Extraction was performed by combining solvents ethanol: water (70:30) in a warm bath (40 °C for 30 minutes) using an HPLC apparatus. By designing 15 formulas for the nano-structured lipid carrier, the particle size and encapsulation efficiency were determined by a zeta sizer and HPLC, respectively. After determining the optimal formulation, zeta potential was also evaluated using a zeta sizer.
    Results and discussion
    The results showed that the extraction method of oleuropein from olive leaf with ethanol and water (70:30) contained 221.37 mg/g of oleuropein with a purity of oleuropein 137.22. The large amount of olive leaf extract in extraction with ethanol could be due to the better solubility of the active compounds (polyphenols) in organic solvents, such as ethanol. Result is showed the average particle size for all freshly produced oleuropein-loaded NLC formulations with diameters of ~0.10±0.00 and 5767± 640.15 nm. Also, the results of the dynamic light scattering test showed that the optimal formulation had a mean particle size of 12.19 nm, a scattering index of 0.153, a zeta potential of -43.3-millivolt. The negative loads on the surface of nano-carriers were probably due to the presence of lipophilic surfactants with negative load (lecithin) and free fatty acids (linoleic acid and linolenic acid, oleic acid, and free fatty acids in soybean oil). Probably the hydroxyl group in the encapsulant (oleuropein) has a hydrogen bond with a choline group in the polar head of the phosphatidylcholine and the choline group with the positive load is pulled inside and the phosphatidyl group with negative load is driven to the membrane surface. Therefore, the negative load of the nano-carriers is increased, which leads to electrostatic disposal of particles and, finally, stability of these particles. Microencapsulation values of nano-carriers varied from 1.27 ± 0.10 to 82 ± 0.41 and the formula with code 12 had the highest efficiency of microencapsulation. Adding liquid lipid to the lipid mixture and increasing the liquid part to solid part ratio resulted in the formation of a more amorphous state and less crystalline state of the nano-carriers and, finally, led to the defective and increased encapsulation material in nano-carriers (increased efficiency of microencapsulation). This could be probably due to more solubility of the encapsulation material in the liquid part of the lipid. Finally, the results of the encapsulation efficiency showed that the nano-carrier had 82% of the overlapping oleuropein.
    Conclusion
    One of the aims of the application of nanocarriers in the food industry is to improve bioavailability, cover the undesirable odor, flavor, color, and improve solubility of some materials. Results of this work depicted that adding nanocarriers containing olive leaf extract powder as the source rich of oleuropein to the food, such as sauce, could improve the undesirable appearance, color, odor and flavor of the extract powder (polyphenols such as oleuropein) and also enjoy high durability of antioxidant properties of the polyphenols existing in the nanocarrier. A practical opinion/idea is that encapsulation of olive leaf extract powder as nutraceutical component can be applied to nutritive and pharmaceutical industries as well as production high quality products with whiteness, uniformity/homogeneity, appropriate flowability and flavor properties. Finally, the nano carrier with the lowest olive leaf extract powder, had the highest encapsulation efficiency, the lowest dispersity index and particle size.
    Keywords: Nanostructured lipid carriers, Oleuropein, High performance liquid chromatography, Encapsulation efficiency
  • F Badiei *, N Maftoon Azad, S Maadani, M Shahamirian Pages 97-108
    Introduction
    Fig (Ficus carica L.) is a very nutritious fruit with high amounts of carbohydrates, minerals and vitamins (Doymaz 2005). This fruit is highly perishable with a very short storage life even in refrigerator. Therefore, it is mostly used in dried form (Farahnaky et al., 2009). Although drying is a suitable way to improve its shelf-life, producing semi-dried fig leads to improving the marketability of this fruit. However, due to higher water activity, semi-dried figs with intermediate moisture content have short storage life and undergo physical, chemical and sensorial changes. Browning is the major problem that takes place in dried and semi-dried fruits during storage and has a great negative impact on their consumption and marketability. The browning of food products results from enzymatic and non-enzymatic reactions. Polyphenol oxidase is the major enzyme responsible for enzymatic browning in fruits (Giang et al., 2016). However, non‐enzymatic browning is often associated with maillard reaction and ascorbic acid degradation (Yamada et al., 2009). Controlling water activity plays an important role in reducing non-enzymatic browning. Plasticizers like mono-, di- and oligosaccharides (glucose and sucrose syrup and honey), polyols (glycerol, sorbitol and glycerol derivatives) and fats and their derivatives can reduce water activity and change the glass transition temperature. The objective of this study was to produce semi-dried figs using different plasticizers and to investigate the effects of plasticizers on browning kinetics and stability of fig with intermediate moisture content.
    Material and methods
    Semi-dried figs (cv. Sabz) were obtained by adding different plasticizers of sucrose syrup at concentrations of 25, 50 (W/V), glucose syrup at concentrations of 25 and 50 % (W/V) and glycerol at two concentrations of 25 and 50 % (V/V). The rehydrated figs were considered as control. All the samples were kept in airtight containers at three temperatures of 5, 25 and 35oC. Thermal properties of the samples were measured using differential scanning calorimetry (DSC). Browning index was obtained by measuring three color dimensions of L* (lightness or brightness), a* (redness or greenness) and b* (yellowness or blueness) values of the plasticized figs and control. Microscopic structures of different fig samples were observed by scanning electron microscopy. A completely randomized design was used to assess the effect of adding different plasticizers and storage temperature on the browning index of figs independently. All the experiments were carried out in three replications. Analysis of the results (ANOVA one-way) was done using SPSS statistical software version 19 at probability value of 5% (p < 0.05) and the mean significant difference was assessed using Duncan's multiple range tests.
    Results and discussions
    DSC thermograms of fig samples showed a stepwise change associated to the glass transition of amorphous regions. By adding different plasticizers, the moisture content of semi-dried figs decreased and their Tg shifted to higher temperatures compared to the control. The results showed that the glass transion temperature (Tg) of the rehydrated fig (control) was lower than that of other plasticized figs, which shows that water is the most effective plasticizer for food systems. Then, browning index of the figs was measured after 3 months. Browning index rose significantly during storage time. Furthermore, by increasing storage temperature, the values of browning index increased significantly and it was higher for the control compared to the other plasticized samples. This means that control figs were darker than the plasticized samples over the whole storage time. Finally, the concept of shifted temperature parameter (T-Tg) was used to account for the effects of storage temperature (T) and plasticizers (through Tg) on the changes of fig browning index. Microscopic images of fig samples showed that rehydrated fig had a porous structure. By increasing the concentration of glucose syrup to 50%, the structure of fig became less porous and as a result of saturation, glucose crystal was appeared on the surface. The same structure was observed for the plasticized figs with sucrose syrup. Plasticized figs with glycerol had denser and non-porous structure.
    Conclusion
    Fig browning is a biochemical change which is dependent on glass transition. The rate of browning was expressed by the shifted temperature parameter (T-Tg) and increased by increasing shifted temperature, regardless of whether T or Tg was varied.The overall results showed that 50 % glucose syrup and 50 % sucrose syrup are the most effective treatments to control the browning of fig fruit.
    Keywords: Browning index, Fig, Glass transition temperature, Plasticizer, Shifted temperature
  • M Razpour, J Farmani *, R Esmailzadeh Kenari Pages 109-119
    Introduction
    Chicken fat is obtained from chicken skin and abdominal fats. With about 30 % saturated fatty acids (mainly palmitic and stearic acid), 30-45 % oleic acid and 15-30 % linoleic acid, chicken fat has a similar fatty acid composition to the rice bran oil. It contains lower saturated fatty acids, cholesterol, and higher polyunsaturated fatty acids (PUFA) content than butter, tallow and lard. It is mainly used in animal feed industry and soap making. However, it has good potential for application in food industry. With a melting point of about 25 °C, it has a semi-solid state and is fluid at room temperature. However, it solidifies in cold seasons which makes its discharge from packaging or tanks difficult. Accordingly, the aim of this research was to produce a cold-stable chicken fat using winterization method. Winterization of oil is a process that uses cold temperatures to separate high-melting triacylglycerol and waxes from oil. Winterization is a type of fractionation (also known as fractionate crystallization), the general process of separating the triacylglycerol found in fats and oils, using the difference in their melting points, solubility, and volatility.
    Material and methods
    Chicken fat was extracted from chicken skin by dry rendering. In this research, the effect of winterization temperature (10, 15, 20, 25 and 30 °C) and time (16 and 24 hours) on physicochemical properties of chicken fat (yield, cold test, cloud point, iodine value, slip melting point, oxidative stability, fatty acid composition and cholesterol content) was studied. Experiments of the effect of winterization time and temperature were performed using a factorial design. Data were analyzed for ANOVA (One-Way) and comparison of means (Duncan's multiple range test) at p<0.05 using SPSS software. Physicochemical tests were run at least in three replications.
    Results and discussion
    Statistical analysis showed that winterization time had not a significant effect on cold stability of the winterized fat (P<0.05). However, the effect of winterization temperature was significant (P<0.05). Results showed that with increase of winterization temperature from 10 to 30 °C, cold stability of the product decreased (from 4.25 to 0.45 h), but cloud point increased (from 1.0 to 8.5 °C) and the yield of winterized oil increased (from 74.4 to 98.1 %) (P<0.05). With the increase of winterization temperature, stearic and linoleic acid content decreased slightly (P<0.05). Furthermore, stearic and linoleic acid content of the winterized samples was lower than those of the chicken fat (P<0.05). Cholesterol content of chicken fat samples winterized at 10-20 °C was not significantly different from that of the chicken fat (P>0.05). However, when fat samples were winterized at 25 or 30 °C, lower cholesterol content was remained in the winterized fat samples (P>0.05). Winterization had not any effect on iodine value and oil stability index of chicken fat (P>0.05). However, iodine value of stearin samples obtained from winterization was lower than chicken fat and winterized chicken fat (P<0.05). The stearin fractions obtained in this study had slip melting point between 42-50 °C. Application of higher winterization temperature resulted in lower yield of stearin but a higher melting point. Stearin samples had higher saturated fatty acid content and lower iodine value than chicken fat or winterized chicken fat (P<0.05).
    Conclusion
    Generally, none of the winterized samples could pass the cold stability test (which should be higher than 5.5 hours at 0 °C). However, winterization could enhance the cold stability of chicken fat, significantly (P<0.05). Though a cold-stable liquid oil was not obtained in this study, the improvement in cold stability of chicken fat may result in delayed solidification of chicken fat. The effect of winterization temperature on cholesterol content of chicken fat was more complicated than that of the other properties. This means, winterization of chicken fat may or may not be accompanied with cholesterol decrease. When choosing the winterization temperature, the yield of the winterized oil should be considered, as well. Application of lower winterization temperature will result in more cold-stable oil, but at a lower yield. Optimization of the winterization condition for production of a cold-stable oil with the highest yield is suggested for further study. In this study, chicken fat stearin was obtained as a by-product which can be used as a hard stock for formulation of margarines and shortenings.
    Keywords: Winterization, Chicken skin fat, Stearin, Physicochemical properties
  • M Hajhoseini, SP Hoseini *, SE Hoseini Pages 121-136
    Introduction
    Instant soup is a type of convenience food which is commercially produced for ease of consumption, portable and has a long shelf life. According to quick preparation and inexpensive, it becomes quite popular for people too short on time in the modern world. Instant dried soup powder is meat or vegetable-based product and generally constituted mixture of dehydrated cereals, vegetables and spices. However, interesting in consuming convenience foods has been received criticism due to lack of nutritive value and other health concerns. On the other hand, seafood industry generates great amount of edible wastes or by-products which can be highly perishable and needed to process in various value added products. Beluga or great sturgeon (Huso huso) is an endemic fish species of the Caspian Sea and extremely cultured for meat and caviar purposes in many countries in particular Iran. According to big size of farmed sturgeon, the fish fillet is commonly raw material for consumers, but unfortunately the wastes from the fillet producing and trimming are usually discarded or used for relatively low commercial value products (e.g. fishmeal and oil production). Treated fish waste described as an edible offal or edible by-product which can also be used for various value added products instead of being discarded and causes potential adverse environmental impacts. Fisheries products are highly perishable, while dried fish soup powder can be stored for a long time due to lower water activity. On the other hand, protein deficiency in some countries or low per capita consumption of seafood can be compensated by the production of a variety of fish products. The production of ready-to-eat soups from fish due to their high nutritional value can be considered as a healthy food among other instant foods. This study aimed to use farm-raised beluga sturgeon by-products in instant soup powder, as well as its shelf-life at ambient temperature for 120 days.
    Material and methods
    At first, the fresh beluga fish wastes were processed and dried till lower 10% moisture. Then, the beluga fish powder at 0% (control; vegetable soup), 20%, 35%, 50%, and 65% was used in instant soup formulas to specify the best formula. Then, some physical properties (i.e. color, water activity, and water holding capacity) and chemical properties (i.e. proximate composition, pH, TVN, PV, TBARS, FFA, and fatty acids profile) were compared among the best formula fish soup and control.
    Results and discussion
    The highest overall acceptance score (4.70) was obtained in 50% beluga fish formula and selected as a best formula. After 4 months of storage, free fatty acid (8.87%), peroxide value (7.30 meq. O2/kg), thiobarbituric acid-reactive substances (0.1 mg of malondialdehyde in kg), and total volatile basic nitrogen (2.87 mg/100 g) was within the permitted ranges. Also, pH of vegetable soup (7.57) was lower than fish soup (7.82). Water activity was lower than 0.5 in both types of soup samples during storage. The amount of E in fish soup was changed from 1.21 at the begging of the experiment to 2.83 after 120 days. The results showed that fish soup is a good source of high unsaturated fatty acids, and their amounts were decreased during the storage time, especially eicosapentaenoic acid and dicosas hexanoic acid were decreased to 2.01% and 4.14%, respectively.
    Conclusion
    The results of this study showed that the use of 50% of dried beluga sturgeon fish meat in the instant soup formulation received the highest sensory evaluation points compared to other formulas and was selected as the best formula. Study of changes in chemical indices showed that all the measured factors were in the allowed range after 4 months of storage under ambition condition. Also, water activity was lower than the critical level for the growth and activity of spoilage microorganisms. Increasing in the storage time led to a decrease in water holding capacity and whiteness of the fish soup. In addition, unsaturated fatty acids including oleic acid, linoleic acid, and linolenic acid were more susceptible to oxidation during storage, and decreased over the shelf-life. Therefore, fish soup with high protein content (55% in dry weight) and high unsaturated fatty acids has a high nutritional value and can provide an enriched instant soup with a high nutritional value and appropriate shelf life up to four months.
    Keywords: Beluga sturgeon, Physicochemical properties, Shelf-life, Soup
  • F Salehi * Pages 137-149
    Introduction
    Frying is a complex unit operation that is widely used in the food industry. During the process, food is immersed in an oil bath at a temperature above the boiling point of water. This results in counter flow of water vapour and oil at the surface of the product (Moyano et al., 2002; Salehi, 2018). The colour of the fried eggplant slice is one of the most significant quality factors of acceptance for fried products. Heat and mass transfer phenomena take place during frying cause physicochemical changes, which affect the colour and surface of the fried products (Choe and Min, 2007; Bingol, 2012). Process variables such as oil temperature and oil type are expected to affect the colour of the fried products. Although, the investigation on colour properties of fried products has started many years ago, it has continued with increasing interest in recent years (Bingol et al., 2012, Salehi, 2019). Color changes measured may be used to predict both chemical and quality changes in a food. The color parameters have previously proved valuable in describing visual color deterioration and providing useful information for quality control in fruits and fruit products (Krokida et al., 2001, Salehi, 2017). Krokida et al. (2001) studied the effect of oil temperature, oil type and sample thickness on colour changes during deep fat frying of french fries. They reported that oil temperature and thickness of potato strips have a significant effect on the colour parameters, which are not affected by the use of hydrogenated oil in the frying medium. Color changes of redness may he associated to Maillard reactions (Krokida et al., 2001; Pedreschi et al., 2005). The aim of this research is to study the effect of changes in frying temperature on the colour parameters, surface changes and heat transfer during fat frying of eggplant slice and to specifically investigate changes in these quality attributes at each frying time, and determine kinetic parameters for these changes.
    Material and methods
    Eggplants (Solanum melongena. L) were purchased from a local supermarket. Slices of eggplant with 1 cm thickness were prepared with the aid of a steel cutter and were immediately placed into the fryer. Refined sunflower oil (Ladan oil, Iran) was used as the frying media. Frying temperatures of eggplant slices were set at 150, 175 and 200°C. All experiments were performed in triplicate and the present results are the average of the obtained individual values. In order to investigate the effect of frying temperature on color changes of fried eggplant, a computer vision system was used. Sample illumination was achieved with HP Scanner (Hp Scanjet 300) (Salehi, 2017). L* (lightness-darkness that ranges from 0 to 100), a*(redness-greenness that ranges from -120 to 120) and b* (yellowness-blueness that ranges from -120 to 120) were measured in this study (Salehi, 2017). In this study, the image analysis of dried gums was performed using Image J software version 1.42e, USA. The estimation of the model parameters for each one of the colour parameters was carried out using a non-linear regression analysis method, separately for each colour parameter during frying of eggplant. In addition, power and quadratic models were chosen to describe the colour changes intensity (ΔE) within the frying process. The experimental data were modeled by using non-linear regression in Curve Expert 1.34 software. A thin thermocouple (Type K) was inserted in the center of the eggplant samples, assuring the position by measure of the sample dimensions. The temperatures at the geometric center of the sample and bulk oil were measured, with sampling time (t) frequency of 5 s by means of the thermocouples (Lutron, TM-916, Taiwan).
    Results and discussion
    Color is one of the most important appearance attributes of food materials, since it influences consumer acceptability. Besides of consumer acceptability, color is also used for process controlling. Figure 1-3 shows changes in L*, a* and b* values of eggplant slices for increasing frying times and temperature during frying. L* is a critical parameter in the frying industry as it is usually the first quality attribute evaluated by consumers when determining product acceptance. Low L* values indicate a dark colour and are mainly associated with non-enzymatic browning reactions. The results of the experimental lightness data are shown in figure 1. As shown in figure 1, L* value of fried eggplant decreased during frying. Oil temperature has a negative effect on the lightness of fried eggplants. The change in L* value was less at lower frying temperature. In figure 4 colour change (ΔE) is presented as functions of frying time. The colour change intensity gets more intense at higher temperatures (200°C). The mathematical models were fitted to the color change (ΔE) data. The results of fitting the proposed model to the experimental data are reported in table 2. The high coefficient of determination and small standard error of estimate of fitting showed that the color change (ΔE) during frying of eggplant could be modeled by this model. Surface change % is a common phenomenon during frying. Rapid water loss resulted in significant shrinkage in chips during frying. In figure 5 surface change is presented as functions of frying time and oil temperature. As shown in this figure, the surface change % was increased with the progression of frying time and temperature. As soon as the eggplant slices were introduced in the hot frying medium, the slices shrunk. High surface change was seen in eggplant slices fried at 200 °C which may be due to fast removal of moisture. Similar behavior was also reported in change in shrinkage during vacuum frying of banana chips.
    Conclusion
    The results showed that most of the color changes occur in the early stages of the process. Color changes during frying process were depends on the processing temperature and time. The higher temperatures cause less lightness and yellowness, but redness increases. In sum, the high temperature and short time process can be suitable for controlling color quality and thus product safety. The kinetics of the surface color changes of the eggplant followed an incremental exponential function. Fried samples at a temperature of 200°C were more dropped in surface and had smaller size.
    Keywords: Color, Eggplant, Frying, Heat transfer, Kinetic