- سال دوازدهم شماره 1 (پیاپی 37، فروردین و اردیبهشت 1395)
- تاریخ انتشار: 1395/02/17
- تعداد عناوین: 16
- مقاله پژوهشی فارسی
صفحات 1-11هدف از این پژوهش طراحی ظروف خودگرم کننده و بررسی اثر میزان و نوع ترکیبات گرمازا بر دمای تولید شده، می باشد. شش ترکیب بازی-اسیدی هیدروکسیدسدیم+ اسید سیتریک، هیدروکسیدسدیم+ اسید تارتاریک، هیدروکسید پتاسیم+ اسید سیتریک، هیدروکسید پتاسیم + اسید تارتاریک، اکسیدکلسیم + اسید سیتریک و اکسیدکلسیم + اسیدتارتاریک به نسبت 1: 5/1 در سه میزان 150، 200 و 250 گرم تهیه و در فضای خالی بین دو جداره ی قوطی های طراحی شده، تعبیه شدند. آب به میزان 75/0 وزن ترکیب گرمازا نیز در لفاف قرار داده شد و در فضای مذکور جاسازی شد. برای تعیین بهترین میزان و نوع ترکیب، دمای جدار قوطی و غذا (کنسرو لوبیا و کنسرو خاویاربادنجان) و همچنین پروفایل دما-زمان ترکیبات مختلف ترسیم گردید. نتایج نشان داد، میزان ترکیب قلیا-اسید بر حرارت تولیدی موثر است و بهترین نتیجه در میزان 250 گرم حاصل شد. نوع ترکیب تاثیر معنی داری (05/0>p) بر حرارت تولیدی داشت. بهترین ترکیب هیدروکسیدسدیم- اسیدسیتریک بود. بین انتخاب اسیدسیتریک و اسیدتارتاریک تفاوت معنی داری دیده نشد. با مقایسه میزان و سرعت گرم شدن در کنسرو لوبیا وکنسرو خاویاربادنجان نتایج نشان داد گرمای ایجاد شده در کنسرو بادنجان به طور معنی داری بیش تر از کنسرو لوبیا است. پروفایل دمایی نشان داد 6 دقیقه طول می کشد تا دما به حداکثر خود برسد، 6-10 دقیقه نیز دما ثابت باقی ماند. به این ترتیب مشخص شد، ترکیبات گرمازا انتخاب شده به خوبی توانستند حرارت مناسبی برای گرم کردن مواد غذایی ایجاد کنند و بهترین ترکیب گرمازا هیدروکسیدسدیم - اسیدسیتریک به میزان 250 گرم بود.کلیدواژگان: ظروف خودگرم شونده، ترکیبات گرمازا، پروفایل زمان، دما
صفحات 12-20امروزه افزودنی های رنگی در طیف گسترده ای از محصولات غذایی به منظور ایجاد ظاهر مطلوب و مورد پسند مصرف کننده مورد استفاده قرار می گیرند. عصاره آناتو یک رنگ طبیعی ایمن برای کاربردهای خوراکی است که می تواند به عنوان جایگزین رنگ های سنتزی بکار رود. همچنین عصاره آناتو دارای ویژگی های ضدمیکروبی و آنتی اکسیدانی است و کاربرد آن در محصولات غذایی، لزوم استفاده از نگهدارنده های سنتزی را کاهش می دهد. در این پژوهش از طرح مرکب مرکزی به منظور بررسی تاثیر دما (60- 5 درجه سانتی گراد)، زمان (10- 2 ساعت)، نسبت دانه به حلال (20- 4 درصد) و مخلوط حلال های کلروفرم و استون (100- 0 درصد) بر میزان استخراج رنگ از دانه آناتو و بهینه سازی فرایند استخراج رنگ، استفاده شد. از رویه سطح پاسخ نیز جهت یافتن برآورد بهترین شرایط فرایند با کمترین میزان آزمون استفاده گردید. نتایج آنالیز واریانس نشان داد، فاکتورهای دما و نسبت دانه به حلال بر استخراج رنگ بیشترین اثر را دارند. شرایط عملیاتی بهینه جهت حصول بیشینه ی مقدار رنگ آناتو در فرآینداستخراج شامل دمای 48 درجه ی سانتی گراد، زمان 2 ساعت، نسبت دانه به حلال 9/12 و 100 درصد کلروفرم تعیین گردید که در این شرایط راندمان استخراج رنگ آناتو 95/3 درصد و میزان جذب نوری 597/0 یافت شد که میزان مطلوبیت برای هر دو پاسخ 100 درصد بود.کلیدواژگان: استخراج، آناتو، بهینه سازی، رنگ، روش سطح پاسخ
بررسی سطوح مختلف ریزجلبک Spirulina platensis بر ریز ساختار و ویژگی های فیزیکوشیمیایی و حسی پاستیل کیویصفحات 21-33Spirulina platensis یکی از بهترین ریزجلبک های غذایی است که از سوی سازمان بهداشت جهانی به عنوان غذایی برتر شناخته شده است و می تواند جهت تولید غذاهای عملگر استفاده شود. در این پژوهش تولید فرآورده ای نوین از کیوی تحت عنوان پاستیل کیوی و غنی سازی آن با ریزجلبک Spirulina platensis مورد مطالعه قرار گرفت. اثر سطوح مختلف Spirulina platensis در پنج سطح (صفر، 25/0، 5/0، 1 و 2 درصد) بر میزان رطوبت، پارامترهای بافت، خصوصیات حسی، ترکیبات شیمیایی و مغذی بررسی گردید. نتایج نشان داد در اثر افزودن اسپیرولینا رطوبت به شکل معنی داری افزایش یافت. نتایج آنالیز بافت نشان داد که با افزایش اسپیرولینا سختی و قابلیت جویدن افزایش یافت، در حالی که پیوستگی نمونه ها روند کاهشی داشت. با افزایش اسپیرولینا میزان پروتئین، ویتامین ث، خاکستر تام، آهن و کلسیم افزایش یافت. نتایج تصاویر میکروسکوپ الکترونی ریز ساختار نشان داد افزودن اسپیرولینا منجر به کاهش یکنواختی ساختار نمونه ها شده و شبکه ژلی با منافذ بزرگتری تشکیل گردید. نتایج ارزیابی حسی نشان داد نمونه های حاوی 25/0 درصد اسپیرولینا ویژگی های حسی (رنگ، آروما، طعم و پذیرش کلی) بهتری نسبت به سایر نمونه ها داشتند.کلیدواژگان: آنالیز بافت، ارزیابی حسی، Spirulina platensis، پاستیل کیوی، میکروسکوپ الکترونی
صفحات 34-48در این پژوهش ویژگی های فیزیکوشیمیایی، بافتی، حسی و رئولوژیکی سس مایونز کم کالری با استفاده از ماست مورد بررسی قرار گرفت. چربی مایونز در سطوح 25، 50 و 75 درصد با استفاده از ماست جایگزین گردید و نمونه های مایونز به ترتیب با اسامی SM1 (25 درصد جایگزینی چربی)، SM2 (50 درصد جایگزینی چربی) و SM3 (75 درصد جایگزینی چربی) نام گذاری شدند. نمونه حاوی 66 درصد روغن نیز به عنوان شاهد درنظر گرفته شد. نتایج حاصل از آزمایش های شیمیایی نشان داد که میزان کالری محاسباتی تمامی نمونه های مایونز کم چرب به طور معنی داری کم تر از نمونه شاهد بود اما حاوی مقادیر بیشتری رطوبت بودند. از نظر ویژگی های بافتی کم ترین میزان سفتی مربوط به نمونه SM3 بود. میزان ویسکوزیته نمونه های مایونز کم چرب نیز در مقایسه با نمونه شاهد کمتر بود. به لحاظ ویژگی های رئولوژیکی در تمامی نمونه ها مدول ذخیره بیشتر از مدول افت بود در نتیجه همه نمونه ها در گروه مواد ویسکوالاستیک جامد طبقه بندی شدند. همچنین تانژانت افت در نمونه های مایونز کم چرب بیشتر از نمونه شاهد بود که بیانگر گرایش رفتار این نمونه ها به رفتار شبه مایع می باشد. در ارزیابی حسی بالاترین میزان پذیرش کلی مربوط به نمونه SM3 و SM2 بود، این مطلب بیانگر این موضوع می باشد که ماست می تواند جایگزین چربی مناسبی در فرمولاسیون سس مایونز باشد.کلیدواژگان: رفتار جریان، سس مایونز کم چرب، ماست، ویژگی های ویسکوالاستیک
صفحات 49-60در این پژوهش امکان استفاده از پودر آب پنیر و صمغ کتیرا بعنوان جایگزین تخم مرغ در سس مایونز مورد مطالعه قرار گرفت. به منظور بهینه یابی فرمولاسیون سس مایونز کم کلسترول، از طرح آماری مخلوط استفاده شد. تیمارها با ترکیب تخم مرغ (0-10 گرم)، پودر آب پنیر (0-10 گرم) و ژل صمغ کتیرا (0-10 گرم) با استفاده از نرم افزار مینی تب تعیین شد و پایداری، ویسکوزیته، ویژگی های حسی و بافتی سس مایونز کم کلسترول مورد بررسی قرار گرفت. نتایج آزمون پایداری نشان داد که به استثنای نمونه های M5 (تخم مرغ صفر، صمغ کتیرا صفر و 10 گرم پودر آب پنیر)، M8 (تخم مرغ صفر، 10 گرم صمغ کتیرا و پودر آب پنیر صفر) و M10 (تخم مرغ صفر، 5 گرم صمغ کتیرا و 5 گرم پودر آب پنیر) سایر نمونه ها صد در صد پایدار بودند. به لحاظ ویسکوزیته بیشترین و کمترین مقدار به ترتیب در نمونه های M6 (33/3 گرم تخم مرغ ، 33/3 گرم صمغ کتیرا و 33/3 گرم پودر آب پنیر) و M5 (تخم مرغ صفر، صمغ کتیرا صفر و 10 گرم پودر آب پنیر) مشاهده شد. از نظر سفتی و چسبندگی بیشترین مقدار متعلق به نمونه M6 (33/3 گرم تخم مرغ ، 33/3 گرم صمغ کتیرا و 33/3 گرم پودر آب پنیر) و کمترین مقدار در نمونه M5 (تخم مرغ صفر ، صمغ کتیرا صفر و 10 گرم پودر آب پنیر) بود. بیشترین میزان روشنی نیز در نمونه M1 (5 گرم تخم مرغ ، 5 گرم صمغ کتیرا و پودر آب پنیر صفر) مشاهده شد. در نهایت نتایج حاصل از بهینه یابی فرمولاسیون نشان داد که مقادیر 17/2 گرم تخم مرغ، 28/5 گرم صمغ کتیرا و 74/2 گرم پودر آب پنیر ، ترکیب مناسبی جهت جایگزینی تخم مرغ در سس مایونز و تولید فرآورده کم کلسترول می باشد.کلیدواژگان: سس مایونز، صمغ کتیرا، بهینه یابی، پودرآب پنیر
صفحات 61-78در این پژوهش تولید فراورده ژله ای بر پایه پوره خرما با استفاده از نسبت های مختلف هیدروکلوئیدهای ژلاتین در دو سطح (6 و 8 درصد) و زانتان در دو سطح (25/0 و 75/0 درصد) و آب پنیر تغلیظ شده در سه سطح (5، 10 و 20 درصد) مورد مطالعه قرار گرفت. متغیرهای وابسته شامل میزان رطوبت، فعالیت آب، pH، بریکس، پروتئین و خاکستر بود. ویژگی های بافتی و پارامترهای رنگی اندازه گیری و ارزیابی حسی نیز انجام شد. این پژوهش در قالب طرح کاملا تصادفی انجام شد. نتایج نشان داد با افزایش آب پنیر تغلیظ شده در فرمولاسیون pH کاهش یافت، اما بریکس، خاکستر، رطوبت، فعالیت آب و میزان پروتئین نمونه ها به شکل معنی داری افزایش یافت. اثر زانتان و ژلاتین بر میزان رطوبت، خاکستر و فعالیت آب معنی دار و مثبت بود. آنالیز بافت نشان داد با افزایش ژلاتین سختی، قابلیت جویدن و پیوستگی بافت افزایش یافت اما چسبندگی روند کاهشی داشت. افزایش زانتان در فرمولاسیون منجر به افزایش الاستیسیته و صمغی بودن بافت و کاهش قابلیت جویدن نمونه ها گردید. نتایج پردازش تصویر نشان داد اثر هیچ یک از متغیرها بر پارامترهای رنگی معنی دار نبود. ارزیابی حسی نشان داد نمونه های حاوی بالاترین درصد هیدروکلوئید امتیاز طعم و آرومای کمتری را به خود اختصاص دادند.کلیدواژگان: ضایعات خرما، آب پنیر، هیدروکلوئید، آنالیز پروفایل بافت، پردازش تصویر
صفحات 79-87نرم کننده ها (پلاستی سایزرها) از جمله مواد افزودنی مورد استفاده در پلاستیک ها هستند که می توانند بطور بالقوه طی نگهداری مواد غذایی در بسته بندی های پلاستیکی، به مواد غذایی مهاجرت کرده و مشکلاتی را در ایمنی و کیفیت حسی مواد غذایی ایجاد کنند. استرهای فتالات ازجمله این نرم کننده ها هستند که در تولید پلی اتیلن ترفتالات (PET) بکار می روند. در این تحقیق، مهاجرت مهمترین آنها شامل دی متیل فتالات (DMP)، دی اتیل فتالات (DEP)، دی اتیل هگزیل فتالات (DEHP)، دی ایزوبوتیل فتالات (DIBP) و دی بوتیل فتالات (DBP) از پلی اتیلن ترفتالات PET به مدل غذایی آبلیمو (اسید استیک (w/v) 3% ) بررسی گردید. مدل غذایی(سیمولانت) تهیه شده در دماهای 5، 25 و C ̊40 به مدت 3 ماه در بطری های PET نگهداری شدند و در بازه های زمانی 10، 30، 60 و 90 روز، توسط روش کروماتوگرافی گازی (GC) مورد آنالیز قرار گرفتند. نتایج نشان داد که با افزایش دما و زمان نگهداری، مقدار مهاجرت این مواد افزایش یافت و در تمامی دماهای نگهداری، بعد از90 روز، مقادیر مهاجرت بیش از حد مهاجرت ویژه (SML) (تعیین شده توسط استانداردکمیسیون اروپایی) بود که نشان می داد بطری PET نمی تواند بسته بندی مناسبی برای آبلیمو باشد. ضریب انتشار مهاجرت استرهای فتالات، به داخل مدل غذایی با استفاده از قانون فیک محاسبه شد. ضریب انتشار در دماهای 5، 25 و C ̊40 برای DEHP به ترتیب 159/0، 115/0 وcm2/s 9-10×115/0 و برای DBP به ترتیب 084/0، 105/0 و cm2/s 9-10×138/0 به دست آمد. DIBP در دمایC ̊5 مهاجرتی نشان نداد و ضریب انتشار آن در دماهای 25 و C ̊40 به ترتیب 177/0 و cm2/s 9-10× 125/0 بود. همچنین در تمامی دماها، مهاجرتDEP بعد از گذشت 90 روز تشخیص داده نشد و DMP مقادیر بسیار جزئی را نشان داد. وابستگی ضریب انتشار به دما با استفاده از قانون آرنیوس محاسبه شد و مقدار انرژی فعالسازی برای DIBP، DBP و DEHP به ترتیب 82/2، 06/2 وJ/molK 302/1 به دست آمد.کلیدواژگان: مهاجرت، پلی اتیلن ترفتالات، استر فتالات، سیمولانت آبلیمو، ضریب انتشار، انرژی فعالسازی
صفحات 88-97در تحقیق حاضر به منظور بهبود خواص فیزیکی و مکانیکی فیلم های زیست تخریب پذیر خوراکی ترکیب کردن دو پلیمر کربوکسی متیل سلولز (CMC) و کتیرا مورد مطالعه قرار گرفت. کربوکسی متیل سلولز و کتیرا با نسبت های 25:75، 50:50 و 75:25 با یکدیگر ترکیب شده و میزان نفوذپذیری به بخار آب، درصد حلالیت، خواص مکانیکی و ریزساختار آنها ارزیابی گردید. نتایج نشان داد که در میان سه نسبت مرکب دو پلیمر، میزان استحکام کششی در نسبت 50:50 نسبت به دو ترکیب دیگر بیشتر بود طوری که مقدار آن در نسبت های 50:50، 25:75 و 75:25، به ترتیب 59/44، 82/32 و 59/26 مگاپاسکال بوده است. نفوذپذیری به بخار آب در ترکیب 50:50 و 75:25 نسبت به ترکیب 25:75 از شرایط بهتری برخوردار بود. ویژگی حلالیت در آب در سه فیلم ترکیبی تفاوتی با یکدیگر نداشتند ولیکن دارای کیفیت بهتری نسبت به فیلم خالص CMC بودند طوری که مقدار 52 الی 58 درصد نسبت به فیلم خالص CMC کاهش معنی داری را در میزان حلالیت به نمایش گذاشتند. همچنین، ترکیب کردن دو پلیمر در نسبت های مختلف توانست از میزان حساسیت فیلم ها نسبت به رطوبت بکاهد. بطورکلی، از نتایج این تحقیق دریافت می شود که ترکیب کردن دو پلیمر می تواند برخی ویژگی های فیزیکی- مکانیکی فیلم خوراکی تهیه شده از کربوکسی متیل سلولز- کتیرا را بهبود بخشد.کلیدواژگان: فیلم خوراکی، کربوکسی متیل سلولز، کتیرا، خواص فیزیکی، خواص مکانیکی
تاثیر سازگارکننده های مالئیک انیدرید پلی اتیلن و پلی اتیلن گلیکول بر ویژگی های فیزیکی و مکانیکی کامپوزیت کاه گندم/پلی اتیلنصفحات 98-108در این پژوهش، تاثیر دو سازگارکننده مالئیک انیدرید پلی اتیلن (MAPE1) و پلی اتیلن گلیکول (PEG2 ) بر ویژگی های مکانیکی (خمشی و کششی) و فیزیکی (زیست تخریب پذیری و جذب آب) کامپوزیت طبیعی ساخته شده از 50درصد پلی اتیلن با دانسیته پایین و 40درصد آرد کاه گندم مورد بررسی قرار گرفت. نتایج نشان داد که تاثیر نوع سازگارکننده بر ویژگی های فیزیکی و مکانیکی معنی دار است (05/0pکلیدواژگان: جذب آب، زیست تخریب پذیری، سازگارکننده، کامپوزیت طبیعی، ویژگی های مکانیکی
مدل سازی سینتیک افت رطوبت قطعات سیب زمینی پیش تیمار شده با اولتراسوند و مایکروویو در طی فرایند سرخ کردن عمیقصفحات 109-126مدل سازی فرایند سرخ کردن در جهت آگاهی از روابط بین متغییرهای مختلف، می تواند گامی مناسب در جهت بهبود کیفیت محصول باشد. در این پژوهش، اثر پیش تیمار اولتراسوند تحت فرکانس های 28 و 40 کیلوهرتز به مدت 15 دقیقه و پیش تیمار مایکروویو با توان های 3 و 6 وات بر گرم به مدت 10 دقیقه بر میزان رطوبت سیب زمینی سرخ شده در درجه حرارت های 150، 170 و 190 درجه سانتی گراد به مدت 60، 120، 180 و 240 ثانیه مورد بررسی قرار گرفت. برازش داده های تجربی افت رطوبت نمونه ها در طی فرآیند سرخ کردن با استفاده از شش مدل تجربی پیشنهادی و قانون فیک انجام شد. نتایج نشان داد که هر دو پیش تیمار اولتراسوند و مایکروویو در کلیه سطوح مورد استفاده، میزان رطوبت نهایی نمونه ها را به طور معنی داری در سطح احتمال 5 درصد کاهش دادند. همچنین، با افزایش دما، میزان رطوبت نمونه های سیب زمینی به شکل غیرمعنی دار در سطح احتمال 5 درصد کاهش یافت. از طرف دیگر، با افزایش زمان فرایند، میزان رطوبت نمونه ها به طور معنی دار و بصورت نمایی کاهش پیدا کرد. همچنین، مدل های پیشنهادی در این پژوهش، با داشتن ضریب تبیین بالا (2R( و ریشه میانگین مربعات خطا (RMSE) پایین، به خوبی داده های تجربی را برازش نمودند. ضریب انتشار موثر رطوبت برای نمونه های مختلف در دامنه 8-10×57/3 الی 8-10×08/11 متر مربع بر ثانیه به دست آمد. اعمال پیش تیمارهای اولتراسوند و مایکروویو موجب افزایش ضریب انتشار موثر رطوبت و کاهش انرژی فعال سازی نمونه ها شدند.کلیدواژگان: ضریب انتشار موثر رطوبت، مدل تجربی، محتوای رطوبت
صفحات 127-138کاربرد آنتی اکسیدان های طبیعی به جای انواع سنتزی در مطالعات اخیر بسیار مورد توجه قرار گرفته است. هدف از این تحقیق بررسی عملکرد فیلمهای پلیمری پوشانده شده با آلفا- توکوفرول در جلوگیری از اکسایش چربی در کره بود. محلول اتانولی آلفا- توکوفرول با سه غلظت متفاوت (1/0%، 15/0%، 2/0%) بر روی سطح فیلمهای پلیاتیلن با دانسیته پایین (LDPE)3 و پلیپروپیلن خطیشده (BOPP)4 پوشانده شد. از فیلمهای فاقد آلفا- توکوفرول به عنوان شاهد استفاده شد. مهاجرت آلفا- توکوفرول از سطح فیلمها به اتانول 95 % (ماده مشابه چربی) در دمای22 درجه سانتیگراد اندازهگیری شد. با افزایش زمان و غلظت آلفا- توکوفرول، مهاجرت به اتانول افزایش یافت (05/0 .(P< ثبات اکسایشی قطعات کره سنتی بستهبندی شده با فیلمهای پلیاتلین و پلیپروپیلن (فاقد و حاوی آلفا- توکوفرول) در دمای یخچال (C̊ 4) طی30 روز بررسی شد. مقدار شاخص پراکسید، اسیدهای چربآزاد و ویژگی های حسی نمونه ها در مدت نگهداری مورد ارزیابی قرار گرفت. در دمای یخچال فیلم LDPE در ثبات اکسایشی محصول و حفظ کیفیت آن به طور معنی دار بهتر از فیلمBOPP با غلظت یکسان بود(05/0.(P< فیلم های فاقد آلفا- توکوفرول از این نظر اختلاف معنی داری نداشتند. در دمای یخچال پوشش آلفا- توکوفرول با غلظت 15/0% در هر دونوع فیلم مطلوب ترین ثبات اکسایشی و ویژگی های حسی را ایجاد کرد. بر اساس نتایج پوشش آلفا- توکوفرول روی سطح فیلم های پلیمری در حفظ پایداری و ثبات اکسایشی کره و حفظ ویژگی های حسی کره موثر بود.کلیدواژگان: فیلم های پلیمری، آلفا، توکوفرول، مهاجرت، اکسایش چربی، کره
صفحات 139-151موز میوه ای سرشار از مواد مغذی است که به علت داشتن محتوای رطوبتی بالا استفاده از روش های نگهداری مناسب به منظور افزایش زمان ماندگاری آن ضروری است. آبگیری اسمزی یک فرآیند غیرحرارتی برای کاهش رطوبت و بهبود ویژگی های خوراکی محسوب می شود. با این وجود، این فرآیند کند بوده و همچنین بافت میوه طی فرآیند دچار تغییرات نامطلوبی می گردد. در این پژوهش از لاکتات کلسیم (در غلظت های 0%، 2%، 3% و 4%) و اسید سیتریک (در غلظت های 0%، 5/0%، 1% و 5/1%) برای بهبود استحکام بافت میوه و افزایش سرعت فرآیند طی آبگیری با محلول اسمزی ساکارز استفاده گردید و الگوریتم ژنتیک به منظور بهینه سازی شرایط فرآیند بکار گرفته شد. نتایج نشان داد استفاده از لاکتات کلسیم و اسید سیتریک سبب کاهش میزان جذب مواد جامد و تغییرات رنگ، افزایش افت رطوبت و همچنین بهبود مقاومت مکانیکی بافت میوه می گردد. شرایط بهینه فرآیند نیز برای حصول بیشترین مقدار افت رطوبت و مقاومت مکانیکی و کمترین مقدار جذب مواد جامد و تغییرات رنگ در نظرگرفته شد (غلظت های پیش بینی شده به ترتیب 99/3% و 86/0% برای لاکتات کلسیم و اسید سیتریک بود). شرایط بهینه با استفاده از داده های آزمایشگاهی اعتبارسنجی گردید. مقادیر شاخص های آماریMSE ، NMSE و AME (به ترتیب برابر با 062/2، 021/0 و 099/1) بیانگر توانایی بالای الگوریتم ژنتیک برای بهینه سازی فرآیند آبگیری اسمزی بود.کلیدواژگان: آبگیری اسمزی، الگوریتم ژنتیک، لاکتات کلسیم
صفحات 152-162شناسایی و جداسازی محصولات کشاورزی تازه و سالم از محصولات مانده و آسیب دیده موجب کاهش تلفات و ضایعات ناشی از گسترش بیماری نمونه های ناسالم می شود. هدف از این مقاله بررسی کیفیت ماندگاری انار دانه طی دوره نگهداری 15 روزه با استفاده از سامانه تصویربرداری حرارتی می باشد. برای دریافت تصاویر حرارتی، انار دانه ها با استفاده از روش گرمانگاری فعال در معرض منبع سرد با دمای C◦2- به مدت 60 ثانیه قرار گرفتند. به منظور استخراج مقادیر دمایی دو روش بخش بندی بر مبنای آستانه یابی تصاویر حرارتی و ترکیب تصاویر رنگی و حرارتی به روش ثبت تصویر استفاده شد. از ویژگی های دمایی مستخرج برای ارزیابی و طبقه بندی انار دانه های چهار دوره نگهداری در سه بازه ی زمانی 60 ثانیه ای از تصویربرداری (مجموعا 180 ثانیه تصویربرداری حرارتی) از روش آنالیز تفکیک خطی استفاده شد. میانگین دقت طبقه بندی اناردانه ها در سه بازه ی زمانی 60 ثانیه ی اول، دوم و سوم از تصویربرداری حرارتی 1/62%، 72 % و 8/79 % بدست آمد. برای طبقه بندی دوره ها نیز در سه بازه ی زمانی60 ثانیه بهترین دقت طبقه بندی در 60 ثانیه ی سوم که برای روز اول 7/98 % ، روز پنجم 23/69 % ، روز دهم 38/65 % و روز پانزدهم 85/89 % بدست آمد. نتایج بدست آمده تایید می کند که تصویربرداری حرارتی می تواند به عنوان یک روش غیر مخرب برای شناسایی درجه تازه بودن انار دانه در زمان های متفاوت نگهداری مورد استفاده قرار گیرد.کلیدواژگان: اناردانه، تصویربرداری حرارتی، درجه ی تازگی، ماندگاری
صفحات 163-181موسیلاژ دانه به از جمله هیدروکلوئیدهای بومی است که استخراج آن به علت ویسکوزیته بالا نیازمند روشی است که علاوه بر کاهش زمان و مصرف انرژی، از بازدهی بالایی نیز برخوردار باشد. استخراج به کمک فراصوت به عنوان یکی از روش های نوین می تواند در دستیابی به این هدف نقش داشته باشد. به این منظور در ابتدا شرایط استخراج رایج (زمان 45 دقیقه، دمایC ̊47 و نسبت آب به دانه 1: 5/32)، با هدف تعیین بهترین شرایط هیدراسیون بهینه سازی گردید . در این پژوهش از فراصوت (پروب با فرکانس KHz24 و توان W400) با شدت ها (20،60،100 درصد) و زمان های مختلف صوت دهی (5، 15و 30 دقیقه) استفاده شد. نتایج حاکی از آن بود که طی 30 دقیقه استخراج با شدت 100 درصد، بازده نسبت به نمونه کنترل 7/42 درصد افزایش داشت. مدل هرشل بالکی بهترین مدل رئولوژیکی برای توصیف رفتار جریان نمونه ها انتخاب شد. به علت شکست ساختار پلی ساکاریدی موسیلاژ توسط امواج فراصوت، حلالیت نمونه ها بین 66 تا 92 درصد متغیر بود اما در مقایسه با نمونه کنترل به شدت افزایش یافت. در شدت 60 درصد نیز بالاترین پایداری نمونه ها مشاهده شد. پایداری کف نمونه ها نسبت به نمونه کنترل 31/17 درصد افزایش نشان داد. با وجود کاهش جذب آب موسیلاژهای استخراج شده طی زمان طولانی با شدت بالا، اما این پارامتر تقریبا در بسیاری از تیمارها فراتر از نمونه کنترل بود. نتایج این پژوهش نشان داد استفاده از فراصوت به دلیل تاثیر مثبت بر بسیاری از خواص علمکردی می تواند روش مناسبی برای استخراج موسیلاژ دانه به معرفی گردد.کلیدواژگان: استخراج، خواص عملکردی، فراصوت، موسیلاژ دانه به
صفحات 182-192در این مقاله شیوه ای برای طبقه بندی اناردانه های خارج شده از میوه انار بر مبنای کیفیت رنگ ارائه شده است. هدف از این مقاله استخراج و استفاده از ویژگی های مبتنی بر تصویر برای درجه بندی اناردانه ها در سه گروه رنگی (قرمز، صورتی، سفید) و غشاء می باشد. طی مراحل پیش پردازش با ارزیابی کیفی فیلترهای رنگی برای بخش بندی بر مبنای آستانه، مناسب ترین فیلتر ارائه گردید. در این مطالعه از مجموع 26 ویژگی مورد استفاده، 10 ویژگی ریخت شناسی و شکلی، 10 ویژگی طیفی و رنگی مستخرج از فضاهای RGB، HIS، Lab و 6 ویژگی بافتی مستخرج از ممان های آماری تصویری استفاده گردید. برای طبقه بندی و شناسایی چهار گروه تعریف شده از روش تحلیل تفکیک خطی (Linear Discriminant Analysis) استفاده گردید. دقت طبقه بندی بر مبنای ویژگی های شکلی و اندازه برای جداکردن اناردانه و غشاء 3/ 96%، بر مبنای ویژگی ها رنگی RGB، HSI، Lab بیشترین دقت به ترتیب 87 %، 84 %، 1/89 % همچنین نتایج دقت طبقه بندی بر مبنای ویژگی های بافتی 3/93 % بدست آمد. در پایان با استفاده از روش ترکیب ویژگی ها بعنوان ورودی مدل طبقه بند، دقت طبقه بندی 99 % بدست آمد.کلیدواژگان: اناردانه، پردازش تصویر، طبقه بندی آماری
صفحات 193-200شیرین بیان یکی از مهمترین گیاهان دارویی و صنعتی است که در بسیاری از صنایع کاربرد دارد. ریشه شیرین بیان ترکیبات متنوعی دارد. عصاره آبی ریشه شیرین بیان بدلیل خواص فیزیکی عملکردیش کاربردهای متنوعی در دارو سازی و صنایع غذایی پیدا کرده است. رفتار رئولوژیکی عصاره شیرین بیان و مطالعه اثر درجه حرارت و مواد جامد محلول بر ویسکوزیته عصاره در محدوده دمایی 70-10 درجه سانتی گراد و غلظت 50-5 درصد با استفاده از دستگاه ویسکومتر بروکفیلد بررسی شد. نتایج، رابطه خطی تنش برشی-سرعت برشی را در غلظت های مختلف و دماهای مورد مطالعه نشان داد که بیانگر نیوتنی بودن سیال بود. همچنین کاهش ویسکوزیته در اثر افزایش دما در نمونه ها مشاهده شد و همچنین افزایش درصد غلظت نمونه ها موجب افزایش ویسکوزیته شد.کلیدواژگان: عصاره شیرین بیان، خواص رئولوژیکی، سیال نیوتنی، غلظت، دما
Effect of Type and Amount of Heat-Producing Compositions on the Amount of Heat-Producedand Temperature Profiles of Self Heating CansPages 1-11IntroductionSelf-heating packaging (SHP) is an active packaging with the ability to heat food contents without external heat sources or power. Packets typically use an exothermic chemical reaction and then woul be useful for military operations, natural disasters, or whenever conventional cooking is not available. These packages are often used to prepare main courses such as meat dishes, which are more palatable when hot.The system consists of three compartments that are separated within the can: the first is the packaged food item; the second, exothermic chemical material(such as calcium hydroxide); and in the third, water. Once the calcium hydroxide is dissolved within the water, it generates, in just 3 minutes, a large amount of heat (up to 60 degrees Celsius), which heats the food item that is located in the first compartment of the can and allows for it to remain hot for up to 20 minutes.For consumption,consumer must remove a seal on the base of the can to reveal the activation button. Pressing the button activates the heater. After 2-3 minutes, the contents of the can must be lightly shaken to ensure contents are at an even temperature. Setting the can upright, the consumer opens the package and enjoys a hot food or beverage.
The present study would focuse on finding the new exothermic chemical materials for reducing cost or producing upper temperature.Therefore, the main objectives of this study were to determine the effect of type and amount of heat-producing compositions on heat-produced and temperature profiles of self heating cans.
Material andMethodsIn this study,the designed self-heating canswere consisted of twoseparated compartments within the can.The first section of can was used for putting of food and the second section was used for storage of exothermic chemical materials. A misture of 6 exothermic chemical materials alkali-acidic, (Sodium hydroxide爫殉욜 ,Sodiumhydroxide떪뢜 acid , potassium hydroxide 爫殉 acid, potassium hydroxide 떪뢜 acid, Calcium oxide爫殉욜 and Calcium oxide떪뢜 acid) was selected. alkalian-acidic composition was mixed in the ratio 1:1.5 and mixture weighing 150, 200 and 250 g were used in this investigation and placed in the free space between cans. For added degree of heat insulation using of glass wool as label outer of cans. Cans wall andcanned food (canned beans and eggplant caviar) temperature were investigated to determine the best combination of level and type of heat-producing composition. In addition, Time-Temperature profiles of each combination were plotted.Results and DiscussionObservations indicated that amount of Heat-producing compositions had significant effect on heat-generated and the best result was obtained with 250g of Heat-producing compositions(pKeywords: Self heating can(Hot can), exothermic materials, time, temperature profile
Pages 12-20IntroductionFood consumers tend to use natural products without any synthetic additives. Therefore, many studies have been conducted to investigate the possibility of replacing synthetic additives with natural substances in various food products.
Annatto dye is a natural carotenoid pigment extracted from the pericarp of BixaorellanaL. seeds. The major fraction of the annatto extract is 9´-cis-bixin that is soluble in oil and 9´-cis-norbixin is the major dye fraction of the alkaline extract that is soluble in water. Annatto dye creates orange to red color in food and to be used as a natural pigment in a variety of food materials including cheese, butter, margarine, confectionary and bakery products, different kinds of drinks, snacks and jams. In addition, annatto dye has antioxidant and antimicrobial activity.
Nowadays, the extraction of natural dye from plant resources has become a common technology. However, complementary information using new methods and optimization of the extraction conditions seems to be necessary in order to accomplish the highest yield of extraction. Response surface method (RSM) is effective and efficient in optimizing color extraction conditions.
In this study, the different conditions of extraction process were optimized through RSM in order to obtain maximum yield and best quality of annatto dye.Materials And MethodsMaterials Annatto seeds were purchased from Hyderabad, India. All solvents were analytical grade, Merck, Germany.
Extraction of annatto dye
A certain amount of annatto seeds was soaked in n-hexane for 6 hours in order to remove oils. After filtration, the defatted seeds were used for dye extraction. Since chloroform and acetone showed the highest yields of extraction during preliminary experiments, these two solvents and their mixtures were exploited for the final experiments assigning 0 for pure acetone and 100 for pure chloroform. The extracts were filtered through Whatman filter paper NO.1 and then vacuum-dried in the 1410D-2E vacuum oven (Shel Lab, USA) to produce dye powder. Low temperatures (40°C) were applied to prevent thermal dissociation of conjugated double bonds during drying.
The coloring strength was measured according to Vasu et al. method; model UV-160A spectrophotometer Shimadzu, Japan, at 502 nm in which bixin has the maximum absorbance value when it is dissolved in chloroform.
Determination of extraction efficiency
The obtained powder was weighed and the mass ratio of the powder to the weight of the seeds was taken into account as the extraction yield.
In this study, Minitab® software version 16.1.1 (Minitab Inc. USA. 2010), was used and a five level four factor central composition design was created to investigate the effect of the independent variables such as temperature, extraction time, seed to solvent ratio and chloroform concentration on the dependent variables namely the extraction efficiency and absorbance values.Results And DiscussionThe values of R2, R2-adj and R2-pred revealed that the full quadratic models were the most adequate for the extraction efficiency and absorbance values.
The all of the linear terms show a significant effect except the extraction time (P 0.05). The interactive terms of extraction temperature* seed to solvent ratio(X1X3) and the seed to solvent ratio*Chloroform concentration (X3X4) had a significant effect on the extraction efficiency (P 0.05).For the absorbance values, the all of the linear terms show a significant effect (P 0.05). The all of interactive terms was insignificant (P> 0.05).
An increase in the extraction efficiency was observed with the increasing temperature. Banik and Pandey while extracting oleanolic acid from Lantana camararoots demonstrated that as temperature increases extraction efficiency improves too. However, at temperatures higher than 70 °C, the annatto seed pigments were degraded and the response was reduced so the quadratic effect of temperature was negative.
The absorbance value was increased by increasing the temperature; however, the absorbance value decreased at higher temperature by thermal decomposition and damage of the conjugate double bond.The absorbance value increased by increasing the chloroform concentration and seed to solvent ratio initially, however, subsequently decreased due to the damage of the conjugate double bond in higher chloroform concentration and saturation of solvent in higher seed to solvent ratio.
Temperature of 48.33 ˚C, extraction time of 2 hr, the ratio of seed to the solvent of 12.88 and chloroform concentration of 100% were found to be as the optimum conditions of the process. The extraction efficiency of 3.95 percent of annatto seed and absorbance value of 0.597 were acquired as the predicted results.Keywords: Extraction, Annatto seed, Optimization, Colorant, Response Surface Methodology
Study of different levels of micro-algae SpirulinaPlatensis on the Microstructure and Psychochemical and Sensory Characteristics of Kiwi pastillePages 21-33IntroductionKiwifruit (Actinidia sp.) has many appealing properties for consumers such as flavor, color, and nutritional content, especially vitamin C. Kiwi seems to be used as one of the major ingredients within the formulation of this category of foods.
Microalgae are nutritional and innovative natural sources that can be used in the development of novel foods. Among the known species of algae, Chlorella vulgaris and Spirulinaplatensis are common edible microalgae that have no side effects on health of human. The amino acid, carbohydrate, and fatty acid profiles of these microalgae are very similar to those of other food materials. Spirulina is a multicellular filamentous blue-green microalga, which was introduced as generally recognized as safe (GRAS) after being approved by food and drug administration (FDA). Spirulina can also be incorporated into common food preparations such as pastas, biscuit, bread, snack,pastille, candy, yoghurt, soft drink, causing health-promotion that are associated with microalgae biomass.
The aim of this study was to investigate the possibility of producing new product based on kiwifruit and its enrichment with Spirulinaplatensis microalgae so that this product could replace common snacks, especially the pastilles containing synthetic colors and flavors, which have increasingly been used day by day despite having a low nutritional value and causing a variety of side effects. The role of pHysicochemical and sensory properties is very important in producing new products which can help producers design the products suitably. Therefore, some of the pHysicochemical properties of the kiwi base pastille were examined in this study, as well as the formulation and enrichment of it with Spirulinaplatensis.
Material andMethodsThe ingredients of the formulations consist of 65% w/w kiwifruit puree, 30% w/w sweeteners (sugar, powdered glucose, invert syrup and sorbitol), 0.25% w/w high methoxyl pectin, 0.5% Agar, 0.5% Guar and Spirulinaplatensis(0, 0.25, 0.5, 1 and 2% w/w) as well.In order to produce fruit pastille based on kiwifruit puree, the kiwifruits were fist washed up, peeled and cut into pieces. Then the pieces were grinded. The prepared puree was mixed with Spirulinaplatensis, hydrocolloids and sweeteners at 70°C with specific ratios. Agar was dissolved in distilled water at 90°C and added to the concerned mixture. Finally, after moderating pH to 3.4 by adding 40 M citric acid and controlling the Brix degree in constant Brix of 45, the mixture was prepared. The mixture was then poured into stainless steel mesh molds with cavity dimensions of 1.2 cm × 2 cm × 2 cm and the molds were kept at 4°C for 2 hours to form the gel. Then the obtained gel was taken out of the mold cavities and the samples were dried at 70°Cfor 6 hours in a hot air drier with 1.5 m/s airflow rate. Then the regarded tests were performed on the dehydrated samples. To measure pH, pH meter (Hana, Portugal) was used. The measurement of mixture Brix was performed by an optical refract meter (Carlze, Germany). The drying process of the samples was conducted in a hot air drier (Soroush Medicine Co. Iran).
Moisture, protein, fiber, lipid, ash, vitamin C, calcium and iron elements were measured according to the Iran national standard.
Texture profile analyzer (QTS25 CNS Farnell England) equipped with a software was used to determine the textural properties of the samples. Samples were compressed and decompressed in two reciprocating cycles by a round plate cylindrical probe with 3.5 cm diameter, 1 mm/s probe speed and 5 g force to 30% initial height.Histological properties obtained from force-deformation curve are as follows: Hardness, Cohesiveness, Elasticity, Adhesiveness and Chewiness.
Sensory test was performed with the judgment of 10 trained panelists. In order to evaluate the samples. A 9-point Hedonic method (1: very undesirable - 9: very desirable) was used. 5 sensory attributes (color, texture, flavor, odor and overall acceptance) were evaluated.
SPSS software was used for the statistical analysis of the parameters. Mean of the replicates were compared via the multi-range Duncan`s test at 95% confidence level.
In order to pHotograpHy with Scanning electron microscope, initial preparation should perform on all of samples.The obtained sampleswas removed from the templates and were sectioned on a scale of 2×1×1mm. samples were dehydrated in ethanol solution and then dried in a critical point. Then samples with 30 nm of gold/palladium coated and were tested using SEM (model LEQ1450VP) in the maximum voltage of 15 kv. At least four images with magnification of 500, 1000, 2000 and 5000 were prepared in several different areas of the samples.Results And DiscussionThe obtained results indicated that the effect of Spirulinawas significant on the moisture content and increasing Spirulinaconcentration led to increased moisture content of the product.The results of texture profile analysis indicated that the hardness and chewness was increased, but the cohesivness of samples was decreased when the amount of Spirulina is increased. The amount of protein, vitamin C, total ash, iron and calcium was increased by increasing the amount of Spirulina. SEM microscopic results showed that adding up Spirulina is led to the reduction of the uniformity of samples structure and then the gel matrix will be created with a larger pore. Results of sensory analysis indicate that samples containing 0.25% Spirulina have sensory characteristics (color, aroma, flavor and overall acceptability) than other samples.Keywords: Texture Profile Analysis, Spirulina Platensis, Sensory Evaluation, Kiwi Pastille, Compounds Chemical
Physicochemical, textural, sensory and rheological properties of low-calorie mayonnaise with dairy-basedPages 34-48IntroductionTraditional mayonnaise is probably one of the oldest and most widely used sauces in all over the world. Mayonnaise is a product with particular consistency and is classified as a type of oil in water emulsions. Vegetable oil, acetic acid, and egg yolk are main components of mayonnaise. In addition, mayonnaise may contain salt, sweeteners, spices, effective flavor materials, preservatives and stabilizers. It must contain at least 78.5 % of total fat and 6 % pureegg yolk. Due tohigh levels of oil present in mayonnaise, continuous usageof this product may result in diseases such as obesity,arteriosclerosis, hypertension and cardiovascular diseases.Therefore, consumers tend to consume low-fat products.
Yoghurt is a very useful fermented milk products in terms of lactic acid bacteria that have beneficial effects on human health and Because of the similarity between this productand mayonnaise in terms of rheological properties, Yoghurt have been selected as a fat mimetic in mayonnaise.Therefore, the objective of present study was to investigate the effects of partial fat substitutionby yoghurt on physicochemical, rheological and sensory properties of low fat mayonnaise.Materials And MethodsMayonnaise preparation
One kilogram of each mayonnaise sample was prepared.Different recipes of mayonnaise contained yoghurt asfat mimetic (as % of oil and yoghurt) including (49.5 % & 25%), (33% & 50%), (16.5% & 75%). All formulations contained 13 % Egg yolk, 10 % Vinegar, 1 %Mustard, 1 % common salt ,4 % sugar , sodium benzoate 0.07 % , Xanthan gum 0.2%.Mayonnaise preparation procedure was as follows; firstlyegg and vinegar were mixed together and then all otherIngredients(including Yoghurt for the low fatmayonnaise recipes) except oil were added and mixed well. The oil was finally poured insidethe mixer very slowly and homogenized for 1 min. Subsamples (250 g) of mayonnaise were aseptically transferredto sterile 250 ml, Duran glass bottles withpolypropylenescrew caps and left for one-day at 5 °C.
Proximate composition analysis
Moisture, protein, and ash contents were determined accordingto AOAC (2005) official methods. Fat content wasmeasured by Bligh and Dyer (1959) method, and totalcarbohydrate content was calculated by difference.
Rheological measurements were performed after 24 hstorage using a Brookfield viscometer Model RVDV-IIwith aspindle no.6 at 5 °C and 25 °C. Shear stress data wereplotted versus shear rate for each mayonnaise sample ata range of spindle speed (10200 rpm). Plots of Lnshear stress versus Ln shear rate (for each sample) werethen used to calculate values including flow behaviorindex (n) andconsistency coefficient (K).
Mayonnaise samples were stored in refrigerator for 24 huntil texture analysis. The measurements were carriedout using a Brookfield texture analyzer (BrookfieldLFRA texture analyzer model number 4500 texture prolite) equipped with a 38 mm diameter cylindrical probeat 25 °C.
The condition of the analysis was as follows; one cyclewas applied, at a constant crosshead velocity of 1 mm/s to asample depth of 30 mm, and then returned. From the resultingforce-time curve, the values for texture attributes, i.e.firmness, adhesiveness, and consistency were obtained usingtexture pro lit software.
pH measurement and stability test
pH was determined using AOAC standard method at 25 °C. The samples were assessed for the stability
test after 24 h storage at 35 °C. Mayonnaise stability wasdetermined after centrifugation (10 min, 2,500 rpm), andwas expressed as the volume of separated phase to the totalemulsion volume.
Mayonnaise samples were measured for color in the L*, a*,b* system using a Lovibond Colorimeter.
After 1 day storage Sensory characteristics including appearance,color, odor, texture, taste, and overall acceptabilitywere evaluated by 14 semi-trained panel on 5-point hedonicscale (1 = the least or the lowest; 5 = the most or thehighest).
All the tests were performed in triplicate. The data collectedwere analyzed by one-way analysis of variance (ANOVA),and significant differences of means were compared usingDuncan test at 5 % significance level using SAS softwareprogram.Results And DiscussionIn present study, physicochemical, texture, sensory and rheological properties were evaluated in mayonnaise formulation with dairy-based. Fat was partially substituted by yoghurt at levels of 25, 50 and 75% which were referred respectively as SM1 (25% fat substitution level), SM2 (50% fat substitution level) and SM3 (75% fat substitution level) and the full fat mayonnaise (S) with 66 % oil was used as control sample. Results indicated that low-fat mayonnaise samples had considerably lower energy content compared with control sample, but higher water content than it. In terms of texture, SM3 had lower hardness compared with control sample. The samples exhibited thixotropic and shear thinning behavior through rheological studies and all samples were classified in the group of solid viscoelastic materials because, in all samples, storage modulus was greater than loss modulus. Also, the loss tangent of low-fat mayonnaise samples were higher than the control sample which reflects the tendency of these samples behavior to pseudo-liquid behavior. Results of sensory evaluation demonstrated that SM2 and SM3samples, were more acceptable. It was concluded that yoghurt can be used as a suitable fat replacer in mayonnaise formulation.Keywords: Low, fat mayonnaise, Yoghurt, Viscoelastic properties, Flow behavior
Pages 49-60IntroductionMayonnaise is typical oil in water emulsion prepared from vegetable oil, egg yolk, vinegar, sugar, salt, mustard and a variety of food additives. Among its ingredients, egg yolk is most critical in term of stability of the mayonnaise. Nevertheless, one main problem with egg yolk is its high cholesterol content; therefore different attempts have been carried out to develop low cholesterol sauces with similar characteristics to the real mayonnaise. Employing another emulsifier in addition to egg yolk, or completely replace this important ingredient, provides several advantages, including a decrease in cholesterol content. Therefore, several protein products such as whey and soy protein have been evaluated as emulsifying agents in oil / water emulsions. On the other hand, to achieve mayonnaise with appropriate emulsion properties and high stability, several investigations have been conducted mostly using proteins with various emulsifiers and gums such as xanthan and guar gums. According to the studies identified, whey powder and Tragacanth gum have considerable emulsification and consistency properties. Therefore, the goal of this research was to investigate of the effect of gum tragacanth and whey powder as an emulsifying agent in mayonnaise.
Material andMethodsRaw materials characterization
Raw materials wereused in this research in order to production of mayonnaise included vegetable oil (alia GolestanCompany), water, egg, vinegar (varda company), spices, gum tragacanth (herbal local market in gorgan city) and whey powder (Pegah dairy company).
pH measurement and stability test: pH was determined using AOAC standard method (AOAC 2005) at 25 °C. The samples were assessed for the stability test after 24 h storage at 35 °C. Mayonnaise stability was determined after centrifugation (10 min, 2,500 rpm), and was expressed as the volume of separated phase to the total emulsion volume.
Mayonnaise samples were measured for color in the L*, a*, b* system using a Lovibond Colorimeter (Lovibond CAMSystem500).
After 1 day storage Sensory characteristics including appearance, color, odor, texture, taste, and overall acceptability were evaluated by 14 semi-trained panel on 5-point hedonic scale (1 0 the least or the lowest; 5 0 the most or the highest).
Viscosity measurements were performed after 24 h storage using a Brookfield viscometer Model RVDV-II(Engineering Lab Inc., Stoughton, Mass., U.S.A) with a spindle no.7 at 25°C.
Mayonnaise samples were stored in refrigerator for 24 h until texture analysis. The measurements were carried out using a Brookfield texture analyzer (Brookfield LFRA texture analyzer model number 4500 texture prolite) equipped with a 38 mm diameter cylindrical probe at 25 °C.
Statistical analysis: In this study, to evaluate the effect of gum Tragacanth and whey powder on physicochemical and sensory characteristics of low cholesterol mayonnaise, statistical design was used by statistical software minitab (16) which eventually combining multiple of 10 mixed were obtained and also to draw the charts and calculation software Excel 2010 and minitab (16) were used. For this purpose, to show the relationship of each of the dependent variables in the regression model with independent variables, their mixed contour diagram was drawn by the mentioned software from the appropriate equations and also to model data, the coefficient of determination of R2 model was determined.Results And DiscussionsThe results of physicochemical, rheological and sensory tests of low cholesterol mayonnaise have been illustrated in table 1. In terms of stability, viscosity and textural properties, samples containing whey powder and gum tragacantwere appropriate as an egg substitute. Except M5, M8 and M10 samples, other samples were stable, completely. On the other hand, the maximum and minimum viscosity was observed in M6 and M5, respectively. The highest preference belonged to M9.
Table 1 Experimental results for viscosity, hardness, adhesiveness, cohesiveness, stability and total acceptability for each sample.
sample Viscosity(cp) Hardness(g) Adhessivness(mj) Cohesiveness Stability (%) L* acceptability
M1 8460 213 6.6 0.66 100 81.2 4.28
M2 8615 215.6 6.7 0.65 100 77.6 4
M3 9390 223.2 7.4 0.63 100 77.3 4.14
M4 10910 268.5 9 0.63 100 77.6 3.71
M5 4315 100.6 4.9 0.76 54.3 70.2 4.14
M6 13998 301.5 18.2 0.63 100 78.4 4.28
M7 9925 240 7.7 0.65 100 77.3 4.28
M8 5580 125 5.3 0.69 58.5 74.1 4.28
M9 9700 226.5 7.6 0.66 100 70.2 4.57
M10 5505 111 5.2 0.71 78.7 65.1 4.28
The numbers were obtained from 3 replications.
Considering optimization of low cholesterol mayonnaise formulation and study of its properties, it was revealed that 2.17 g egg, 5.28 g whey powder and 2.74 g tragacanth was an appropriate mixture in order to substitute egg in mayonnaise and making of low cholesterol product.Keywords: Tragacanth gum, optimization, whey powder, mayonnaise
Pages 61-78IntroductionDue to the lack of proper harvest, packaging, transport and storage, about 30% of country dates production cannot be directly absorbed into the consumer market and must be exchanged to valuable products in transformation industries.Hydrocolloids are used in fruit snack formulations to create novel texture, increase stability due to their water-holding capacity, improve texture and have an impact on flavor release and other structural and sensory properties in the respective products. Gelatin is a gel forming hydrocolloid. Xanthangum is a kind of long-chained polysaccharide with high molecular weight. LikeXanthan and guar gums can also interact with some polysaccharides such as gelatin, agar and carrageenan synergistically leading to increased viscosity or gel forming power. This type of synergistic behavior among polysaccharides is commercially valuable, because it creates a novel texture and a more desirable structure.This study on viscosity and textural changes caused by using a mixture of gums in food formulations is important and will affect the cost of various stages of the process.
Material andMethodsThe initial materials containing date(Shahani variety), condensed whey(brix=35) were provided from Asali Mod compony, Xanthan gum from Sigma company. powdered glucose and date were bought from Mashhad bazar.In order to produce gel based on date puree, the date were fist washed up, peeled and cut into pieces. Then the pieces were grinded. The prepared puree was mixed with hydrocolloids and sweeteners at 70°C with specific ratios. The mixture was then poured into stainless steel mesh molds with cavity dimensions of 1.2 cm × 2 cm × 2 cm and the molds were kept at 4°C for 2 hours to form the gel. Then the obtained gel was taken out of the mold cavities and the samples were dried at Environmental drier with 1.5 m/s airflow rate.
In this research, the produce of jelly viable products based on date puree by the different rates of gelatin hydrocolloids in two levels (6 and 8%) and Xanthan in two levels (0.25 and 0.75%) and condensed whey in three levels (5, 10 and 20%) was studied. Dependent variables were consisting of moisture content, water activity, PH, Brix, protein, ash, texture assessment and color parameters. In final has done the sensory evaluation.
To measure pH, pH meter (Hana, Portugal) was used. The measurement of mixture Brix was performed by an optical refract meter (Carlze, Germany).
Moisture, protein and ash were measured according to the Iran national standard.
In order to determine the water activity of the samples, equal weights of the samples were grinded and the water activity was measured by a aw meter (Testo model 200, England) at 20°C.
Texture profile analyzer (QTS25 CNS Farnell England) equipped with a software was used to determine the textural properties of the samples. Samples were compressed and decompressed in two reciprocating cycles by a round plate cylindrical probe with 3.5 cm diameter, 1 mm/s probe speed and 5 g force to 30% initial height. Histological properties obtained from force-deformation curve are as follows: Hardness, Cohesiveness, Elasticity, Adhesiveness and Chewiness.
In order to measure color parameters of samples, three samples were choose randomized from each formulation, and pictures were taken with 90 angle and pictures were saved with IPG format. The other stages of picture processing were done by ImageJ 1.40g software.
Sensory test was performed with the judgment of 10 trained panelists. In order to evaluate the samples. A 9-point Hedonic method (1: very undesirable - 9: very desirable) was used. 5 sensory attributes (color, texture, flavor, odor and overall acceptance) were evaluated.
This study was triplicated through a completely randomized design. Gelatin hydrocolloids in two levels (6 and 8%) and Xanthan in two levels (0.25 and 0.75%) and condensed whey in three levels (5, 10 and 20%)were considered as the independent variables and a design composed of 12 formulations was created. SPSS software was used for the statistical analysis of the parameters. Mean of the replicates were compared via the multi-range Duncan`s test at 95% confidence level.Results And DiscussionThe obtained results showed that with increasing of condensed whey decrease the PH formulation but ash, moisture, water activity and the rate of protein in samples significantly have increased. Also effect of Xanthan and gelatin had an increase trend in water activity of samples. Also with increasing every three variables in formulation, brix had an increase trend. According to results with increasing hardness gelatin has increased the chewing and continuity feature of texture but adhesion had a decreasing trend. The increasing of Xanthan formulation led to increase of elasticity, context chewing of gum and decreasing of samples. Colorimetric results in method of Image processing were not significant on none of colorimetric variables. But in generally with increasing hydrocolloids in formulation had decreasing the light intensity and L*had a decreasing process. Sensory evaluate shows samples containing of 20% whey have less general acceptance. Also the samples containing of highest percentage of hydrocolloids allocated to themselves the less of rating flavors and aromas.Keywords: Date scrap, Whey, hydrocolloid, Texture profile Analysis, Image processing
Pages 79-87IntroductionPolyethylene terphthalate (PET) is one of the materials that are widely used for packaging of beverages and edible oils. In this study, the migration of di(2- ethylhexyl) phthalate (DEHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), di-iso-butylphthalate (DIBP) and di-n-butylphthalate (DBP) from PET bottles into the lemon juice was investigated.
Material andMethodsAccording to European Commission regulations, 3% acetic acid (w/v) was chosen as simulant. The acetic acid samples were stored at 5, 25, and 40°C for three months and analyzed periodically by gas chromatography.Results And DiscussionIt was concluded that the storage temperature and time had a large effect on the migration of phthalet ester. The concentrations of migrating substance were more than its specific migration limit. The release kinetics of phthalet ester from PET bottle was described using Ficks second law of diffusion coefficient, and crank model. The diffusion coefficients (D) determined for DEHP have most migration than other, were 0.084, 0.109, and 0.159 ×10-9 cm2/s at 5, 25, and 40°C, respectively. The diffusion coefficients (D) determined for DBP have most migration than other, were 0.084, 0.105, and 0.138 ×10-9 cm2/s at 5, 25, and 40°C, respectively. The diffusion coefficients (D) determined for DIBP have most migration than other, were 0.084, 0.177, and 0.125 ×10-9 cm2/s at 25, and 40°C, respectively. The temperature dependence of D, Arrhenius equation giving values of activation energy (Ea) for DIBP, DBP and DEHP are 2.82, 2.06 and 1.302 J mol-1 respectively.Keywords: Migration, Polyethylen terphthalate, Phthalate ester, Adipate ester, Lemon juice stimulant, Diffusion coefficient, Active energy
Evaluation of some Physical and Mechanical Properties of Carboxymethyl cellulose/ Tragacanth Edible FilmPages 88-97IntroductionAn edible film is a thin layer, made of edible materials, which once formed can be placed on, or between food components. Protecting the product from mechanical, physical and chemical damages, as well as microbiological activities, are some of its functions (Falguera et al, 2011). The main materials made of these films are proteins, lipids and polysaccharides which are able to be used as alone or in blending form (Hernandez et al, 2008 ;Gennadios, 2004). Carboxymethylcellulose (CMC), is a linear polysaccharide that its natural and biodegradable features cause to exhibit excellent film-forming properties (De Moura et al, 2011). Films prepared with these polymers, generally have good gas barrier properties and moderate to propriate mechanical features (Gutierrez et al, 2012). Using the edible, biodegradable films, due to the sensibility to moisture and poor mechanical properties particularly in moist status, is almost limited (Wang et al, 2009; Silva et al, 2009). Because of high hydrophilic property, CMC films also have a low resistant rate to water vapor permeability (Mohanty et al, 2000). Gum Tragacanth (Astragalus sp.) is another polysaccharide used to produce edible films and coatings. This gum can be widely used as a stabilizer, emulsifier and thickener in food industry, pharmaceutics and cosmetics (Azarikia & Abbasi, 2010). Tragacanth also has a prominent effect on physical and mechanical properties of the potato starch-based edible films (Fazel et al., 2002). It has also a proper blending potential in blending with other hydrocolloids, carbohydrates and most of proteins and lipids (Farahnaki et al., 2009). Yet, not any researches has made about the effect of blending tragacanth gum with other carbohydrate polymers. Blending of polymers can enhance the functional properties of the produced films (Bourtoom, 2008). Hereby, the current study has been done in order to preparate the best edible film with suitable physical, mechanical and biodegradable properties and has tried to introduce an ideal blend film made of different rates of carboxy methyl cellulose and tragacanth.
Material andMethodsIn this research in order to improve the physico-chemical characteristics of biodegradable edible films, blending two polymers of carboxymethyl cellulose (CMC) and tragacanth (Astragalus sp.) was studied. At first, it was tried to making the film. For this purpose in laboratory the solubles of CMC 1% w/w and tragacanth of 0/75% w/w were prepared. In order to dissolute the polymers, both polymers subjected to heat (75 օC) and following the temperature decrease (~ 40 օC), glycerol (20% of the polymer) was added to each one. Therefore, CMC and tragacanth were blended to each other at proportions of 25:75, 50:50, and 75:25 (v/v) and water vapor permeability, solubility, mechanical properties and microstructure were evaluated. Microstructure of the produced films was assigned by an electronic microscope (Philips, made in Netherlands). Thickness of samples was determined by a digital balance (0/0001 mm, Mitutoyo- made in Japan) via measuring in five points of each sample. Water vapor permeability, moisture content and solubility rate were conducted by standard. Tensile strength (TS) and elongation at break (EAB) were determined using an Instron universal testing machine (Model TVT 300 Xp, Sweden) operated according to the ASTM standard method D882-01(ASTM, 2002). Statistical Analysis performed by software of SPSS, ver. 20. Normality of data and homogeneity of data were conducted by Kolmogorov-Smirnov and Levene tests, respectively. For significance of treatments effect One-Way Anova and for statistical comparison of data Duncan test were performed.Results And DiscussionThe results showed that blended film of 50:50, as well as pure CMC film, had a smooth, flat surface without crack, showing that both polymers were properly blended. Among three blend proportions of two polymers, tensile strength was greatest in 50:50 whereas this amount in proportions of 50:50, 75:25 and 25:75 was recorded 44.59, 32.82 and 26.59 MPa, respectively. These results were in line with Ghanbarzadeh et al. (2011), who indicated the quality of maize starch-based films was suited by CMC and citric acid. With decrease of CMC content in blended films the elongation rate of films significantly decreased. This can be attributed to suitable interactions of the two polymers. This is in accordance with report of Tongdeesoontorn et al. (2011) and Mu et al. (2012), who found the different contents of CMC positively affected the films properties. Water vapor permeability was of better status at 50:50 and 25:75 than at 75:25. Solubility in water did not differ among three blend films but it had better conditions in pure CMC film whereas the blend films showed a decrease about 52 to 58% in solubility compared to the pure CMC film. The results of our research is consistent with findings of Tong et al. (2008), who investigated preparation and properties of pullulan -alginate- CMC blend films. The decrease of solubility can probably be due to proper interactions between CMC and tragacanth. Likewise, blending two polymers at different proportions decreased the moisture content of films. It can be stated that because of the linkages between tragacanth and carboxymethyl cellulose polymer chains, a compact structure has been created that not allows water molecules to presence and thus leads to a reduction in moisture content of films. This is in accordance with findings of Gutierrez et al. (2012), who reported that the increase of leaf extract in plant of murta improved the quality properties of the CMC films. Generally, from this investigation it is deduced that blending the two polymers in different proportions can improve some physico-chemical properties of the CMC- tragacanth edible film.Keywords: Edible film, Carboxy methyl cellulose, Tragacanth, Physical properties, Mechanical properties
The Effect of MAPE and PEG Compatibilizer physical and mechanical properties of Wheat straw-Low density polyethylene BiocompositePages 98-108IntroductionOver the past 30 years with population growth, plastics have played an important role in the people's lives and its consumption is increasing. However, the most important problem of synthetic packaging materials is their total non-biodegradability that is causing environmental pollution.
In recent years, concerns about the environmental problems caused by packaging materials and plastic derived from petroleum products as well as consumer demand for qualitative food products, hascaused researchers to find alternative materials with high biodegradability, which has led to the development of biocomposites.
Therefore,wheat straw-low density polyethylene composite (as a renewable material) was prepared in order to reduce the consumption of plastics in the packaging industry and the effect of two different compatibilizers, maleic anhydride polyethylene (MAPE) and polyethylene glycol (PEG) on mechanical and physical properties of obtained biocomposites was investigated.Materials And MethodsWheat straw (WS) was first dried at 30 ℃ for 24 hours. It was then manually cut to 2-3 cmpieces manually and then was milled. The ground wheat straw was screened through 40 mesh sieve. After that, all materials including WS flour, LDPE, MAPE , and PEG were blended to prepare the different biocomposites by twin-screw extruder. The extruded materials were cut into smaller pieces proper for the next processing step by grinder.grinded. The obtained granules were then placed in the injection-molded machineto create the test samples.so combinations, respectively, were considered : WS, LDPE, MAPE (sample 1) WS, LDPE, PEG (sample 2) , LDPE (sample 3) and WS, LDPE (sample 4).
Water absorption test was performed according to ASTM D 570-98 in order to study the amount of moisture absorbed by the composite samples. The samples were weighed for 9 weeks, the first time, after 24 hours, then once a week. For this purpose, samples were taken out of the water then surface moisture was dried, finally moisture absorption was calculated according to weight changes.
Biodegradability test was carried out based on soil burial method for 4 monthsaccording to ASTM 6400-99. In this test, samples were taken out of the soil and washed by water every 15 days. They were thenplaced in an oven at 100℃ for 24 hours. Subsequently, samples were weighed by a digital scale with an accuracy of 0.1 mg.The amount of degradation was calculated by controlling weight changes over the time.
The tensile strength, the maximum amount of force taken by a material before its failure was performed to evaluate the effect of natural fiber on the composite characteristics. It is measured with units (Pa) and (Mpa). The test was done according to ASTM D 638-08by Instron machine.
The flexural strength of a material is defined as its ability to resist deformation under load. The test was done according to ASTM D790-10by Instron machine.It wasalso measured with units (Pa) and (Mpa).
Result andDiscussionThe results showed that the use of PEG compare with MAPE greatly increased the rate of water absorption and biodegradation of samples. It may be because of PEG's hydrophilic property that cannot act well as MAPE. Therefore, it creates an improper and weak interface adhesion between the wheat straw and polyethylene, resulting in gaps and cracks in this section. Thus, water absorption is higher in composites containing PEG. These factors also caused faster degradation in samples containing PEG. However, the use of MAPE in the composites improved surface adhesion between the wheat straw fiber and polyethylene, and therefore less water absorption and degradationwas observed.
In terms of mechanical properties samples containing MAPE had greater tensile and flexural strength compared to samples containing the PEG.Because MAPE creates an ester bond in composite, which improves the interfaceadhesion of wheat straw particles and polyethylene, but when the PEG used, adhesion between wheat straw particles and polyethylene is not enough to increase the efficiency of stress transfer from the matrix to the fibers.
Since almost all properties of materials are associated with each other, it cannot be introduce a combination that all properties is best. Therefore, when high biodegradability is desired, sample containing PEG is suitable but in terms of mechanical properties and resistance to water absorption, the sample containing MAPE is best combination.Keywords: Water Absorption, Biodegradability, Compatibilizers, Biocomposite, mechanical properties
Moisture Loss Kinetics Modeling during Deep-Fat Frying of Potato Strips Pretreated with Ultrasound and MicrowavePages 109-126IntroductionDeep-fat frying is a process of cooking foods through immersing them in edible oils at temperatures above the boiling point of water (150-200°C). During this complex unit operation, heat and mass transfer occur simultaneously.During frying, heat is transferred from edible oil to surface of the food and then transferred into it and at the same time, moisture is transferred from inside the food to outside.As a result of these phenomena and by continuing the process, food temperature increases and its moisture content decreases. This, in turn, creates favorable characteristics such as color, texture and taste of the product.Moisture content is one of the important features in the quality of fried products.In the frying process, moisture loss from food occurs by the mechanisms of molecular diffusion, capillary flow and pressure driven flow.The driving force of moisture loss is the partial water vapor pressure difference between the inside and the surface of the food product due to turning the water into vapor.Rate of moisture loss from the food during the frying process decreases exponentially with frying time and increases with increasing temperature.For information about therelationshipsbetweenvarious variables during the frying process, moisture loss kinetics modelingcan bea suitable steptowards improving thequality offried products.To our knowledge, there has been no study in literature associated with the effect of ultrasound and microwave on moisture loss during deep-fat frying of foods. This study aimed to evaluate the effect of these waves on moisture loss kinetics during frying of potato strips.Materials And MethodsPotatoes (Agria variety) were purchased from a local market and kept in a cold room at 0°C. A mixture of sunflower, soy and cottonseed oil (Behshahr Industrial company), was used for frying potato strips.Inthis study, effect ofultrasound pretreatment at frequencies of 28 and 40 kHz for 15 min and microwave pretreatment at powers of 3 and 6 W/g for 10 min on moisture content of the fried potato slices at 150, 170 and 190°C for 60, 120, 180 and 240 s was investigated.The moisture content of the samples was measured by drying them in a convection oven at 105°C until the weight was constant.Moisture loss experimental data during frying were fitted with six empirical models proposed in this study as well as the Ficks law of diffusion.The effective moisture diffusion coefficient was calculated based on the Fick's law. To calculate the effect of temperature on the effective moisture diffusion coefficient, the Arrhenius equation was used.Results And DiscussionBy increasing frying temperature, moisture content of the potato slices decreased; however the decrease was not significant at a probability level of 5 percent. The positive effect of oil temperature on moisture loss during deep-fat frying of potato strips has been well documented. This is due to the high kinetic energy of water molecules at higher temperatures, leading to a rapid loss of moisture. The moisture loss by diffusion of water molecules as well as the oil uptake during the frying process lead to the formation of cracks in the structure of the solid food. This, in turn, leads to structural damages and significant changes in terms of structural characteristics including porosity.On the other hand, moisture content of the samples significantly decreased in an exponential manner by increasing the process time. Rapid moisture loss in the first moments of frying is associated with the removal of surface moisture. By decreasing surface moisture over time, the rate of moisture loss was reduced accordingly.Results also showed that both the ultrasound and microwave pretreatments at all the studied levels significantly reduced the final moisture content of the samples at a probability level of 5 percent. The difference between the samples pretreated with two ultrasound frequencies of 28 and 40 kHz was not significant (P > 0.05), but with increasing frequency of the pretreatment, the moisture content decreased to a greater extent. Lower final moisture contents of the samples pretreated with ultrasound were probably due to the creation of microscopic channels in the food structure, which may facilitate moisture loss during frying. On the other hand, application of microwave pretreatment at powers of 3 and 6 watts per gram, decreased initial moisture content of the samples by 38 and 80%, respectively. This resulted in significant (PKeywords: Effective moisture diffusion coefficient, Empirical model, Moisture content
The Effect of polyolphine films coated with alpha - tocopherol in preventing the oxidation of traditional butter stored in the refrigeratorPages 127-138IntroductionStudies in recent years have led to the emergence of a new concept in the packaging industry namely Active packaging. Contrary to popular packaging that needs to be completely neutral and ineffective, in different kinds of active packaging, there is an interaction with food or environment, and has an active role in food materials maintenance (Brody et al, 2008). Nowadays, various kinds of polymeric materials and their different characteristics and forms has resulted in easy design and production of packaging based on special requirements of a food product (Lopez-rubio et al, 2004). Polyethylene and polypropylene along with cardboard boxes are used for packing butter (Milts, 1988). It has been proved that Alpha-Tocopherol maintains its stability in the processing conditions and low aw also maintain its stability, alpha Tocopherol has desirable migration characteristics and excellent solubility in polyolephines. use of alpha- Tocopherol is more affordable compared to other antioxidants (Lee, 2005; Wessling et al, 1998).The aim of this study was to investigate the effect of alpha-tocopherol coating on the surface of polymer films in preventing the oxidation of lipid in butter.Materials And Methods: Materials
DL-alpha-tocopherol acetate, low density polyethylene film(LDPE) , biaxial oriented polypropylene film (BOPP), traditional-lactic butter with salt made from cow's milk .
Methods Preparation of films: In this stage, first alpha-tocopherol was prepared with three concentrations of %0.1, %0.15and %0.2, and %70 ethanol was used as solvent. In the next step, low density polyethylene and polypropylene films were prepared in enough dimensions and numbers, and were washed and sterilized by %70 ethanol. Then, different concentrations of alpha-tocopherol (%0.1, %0.15,%0.2) were separately covered on a sufficient number of films via spraying (under identical conditions).to complete coverage of the films surface, spraying alpha-tocopherol was performed 3 times. after drying, films were kept in dark place (Pereira et al, 2011).
Packaging and storage of butter: At this stage, butter pieces weighing 45 grams covered with LDPE and BOPP films with three different concentrations of alpha-tocopherol (%0.1,%0.15,%0.2) were packed. To prepare the control sample, butter was packed with alpha-tocopherol lacked films. The experiments of determining the amount of peroxide and acidity, and Sensory evaluation test was conducted on a sample of butter before packaging, and were repeated in tenth, twentieth ,and thirtieth days.
Determining the amount of alpha-tocopherol remained on the films : At this stage, in order to determine the amount of alpha-tocopherol remaining on the films, weight difference of films before and after spraying alpha-tocopherol, and drying them on the films was measured. The amount was calculated by mg/cm2 stated (Contini et al, 2012).
Measurement of alpha-tocopherol migration to ethanol: The total amount of alpha-tocopherol migrate from the films into the similar lipid matter(%95 ethanol)were calculated by the colorimetric method using a standard alpha-control solution and drawing the calibration curve(Corrales et al, 2009).
The Sensory evaluation test: To evaluate the sensory properties including taste, color, smell and public acceptance, five-point hedonic test was used(Tafreshi et al, 2013).
Methods and tools for data analysis: All tests were repeated three times. For data analysis, a factorial experiment in a completely randomized design was used. Alpha-tocopherol concentration, time and type of film were the main factors. Duncan multiple range test was used to assess the differences between means in the confidence level of %5.For all statistical analysis, MSTAT-C software version 14 was used.Results And DiscussionFindings from surveying the migration process into 95% ethanol solution, indicates that alpha-tocopherol were remained on the surface of polymeric films (LDPE &BOPP) after drying, and migrated from the surface of films into ethanol %95. With the increase of time and concentration of alpha-tocopherol, migration from the surface of films into ethanol increased (pKeywords: polymeric films, alpha, tocopherol, migration, lipid oxidation, butter
Study of osmotic dehydration of banana using calcium lactate and genetic algorithm optimization of processPages 139-151IntroductionBanana is one of the most popular tropical fruits in all over the world with notable post-harvest losses. Due to its high moisture content preventing long preservation period. So, it needs a proper preservation method to prevent product lost especially in main produceing countries. Since banana is an un-freezable fruit, thermal processing such as drying or canning could be more appropriate for prolonging its shelf life. On the other hand, high energy consumption and being cost intensive are two most important disadvantages of thermal processing. In order to decrease the side effects of thermal process on quality parameters, pretreatment of samples could be applied to reduce time of main process.Osmotic dehydration is a non-thermal pretreatment which provides partial removal of water by immersing sample in an osmotic solution.But this process also takes a long immersion time to enough reduction of moisture. So this leads to undesirable effect on texture and colors.This study was performed to eliminate some side effects of osmotic dehydration on quality and finally introduce an optimized condition resulting best performance of process.A novel all-knowing method for optimization of process is genetic algorithm (GA) which is a search heuristic that mimics process of natural selection. It generates solutions for the optimization of problems using techniques inspired by natural evolution, such as inheritance, mutation, selection, and crossover. In this research, genetic algorithm was applied to predict optimum condition of osmotic dehydration.
Material andMethodsOsmotic dehydration was performed using aqueous solution of sucrose in concentration of 45% (w/w) for immersion time of 3 hr. The first challenge was improving mechanical properties of banana slices by adding calcium lactate to sucrose solution in concentrationsof 0, 2, 3 and 4%.For the next step in order to protect samples from enzymatic browning mixture of ascorbic acid (0.25 %) and citric acid (0, 0.5, 1, and 1.5%) were used.The pH of solution was measured for each level of adding citric acids. The efficiency of operation was estimated by computingwater loss and solid gain. Firmness of dehydrated samples wasmeasured using a texture analyzer (INSTRON, 1140, Singapore) and penetration test. Image acquisition technique was applied to measure L*, a* and b* indices.The coefficient of efficiency was defined as the ratio of water loss to solid gain and calculated to estimate performance of treatment in new condition. Finally, optimized conditionsfor maintaining the lowest solid gain and color changes, the highest water loss and firmness waterlosswere predicted by genetic algorithms method. The accuracy of model was investigated using statistical parameters such as mean absolute error (AME), normalized mean square error (NMSE),mean square error (MSE).Results And DiscussionThe results of experiments showed a significant increase of firmness by adding lactate calcium. This observation was due to complex formation between calcium and cell wall ingredients. Thesecomplexes have a decreasing effect on solid gain.Because complexes preventedmacromoleculesentering such as sucrose to the cells.On the other hand,calcium lactate and citric acid had interaction on mentioned parameters.Firmness showed less firmness when citric acid was added to the solution. Because citric acid as a chelating agents can blockdivalent cations and prevent from effective reaction with plant cells.Also citric acid can disconnect methoxyl groups from protopectinproducing softer texture.However, treated samples still showed firmer texture than control sample. It could be due to the additional effect of citric acid which makes carboxyl groups available for divalent calcium cations during conversion of protopectin to the pectin.For color parameters,only use of citric acid could not decrease the total change of color because yellow index increased due to the hydration of citric acids. But for the use of two factors, a significant decrease of total change of color was observed.For water loss, increase of solvents in each treatment led to raise of water loss due to the increase of osmotic pressure.In this circumstance determination of suitable concentration for each factorresulting best performance is complex, so it is necessary to apply a system canpredict optimized conditions. Genetic algorithms estimated optimum condition formaximum firmness and water loss, minimum solid gain and total change of color.In this condition the concentrations of lactate calcium and citric acid were %3.99 and %0.86, respectively. Also predicted values for water loss, solid gain, firmness and total change of color were earned %18.01, %5.07, 1.47 N and 11.37.MAE, NMSE and AME parameters (2.062, 0.021, and 1.099 respectively) were used for investigation of difference between estimated and experimental data which showed high efficiency of genetic algorithm for optimization of osmotic dehydration of banana.Investigating the efficiency ofcoefficient of treatments showed that application of both factors (calcium lactate and citric acid) significantly had more efficiency in comparison to the control samples regarding quality factors.Keywords: Calcium lactate, genetic algorithm, osmotic dehydration
Pages 152-162IntroductionEvery year about 600 million tons of fruits and vegetables are produced in Asia and around 35% out of it is wasted during production, postharvest, processing, distribution and consumption (FAO, 2011). In most cases, the sale rate of agricultural products is affected by their internal quality. Although consumers are unable to detect products internal quality and freshness while buying, their negative perceptioncan be formed against their next buy if the internal quality of what they bought does not meet their satisfaction (Leemans et al., 2002). For assessing fruits quality factors some destructive and non-destructive tests are performed. The qualityfactors are categorized into external quality and internal quality factors. With the visual inspection methods, the external features of Bio-materials (e.g. shape, color and texture) can be evaluated (Shiranita et al., 1998) while the internal quality factors, including freshness, cannot be determined from these apparent visual characteristics (Jha et al., 2002). Therefore, the shelf life of agricultural products that are internally defective is less as they perish sooner and the infection expands quicker (Ohali, 2011). Among the common nondestructive methods for assessing internal quality parameters, MRI, X-RAY, Ultrasonic and NMR can be named (Du et al., 2004; Mery et al., 2011). In fruits, vegetables and fruits, the status of freshness is affected by the changes occurred in their physical, chemical and biological structures. These changes and, therefore, freshness, conventionally, is quantified by parameters such as products mechanical stress, moisture content, temperature and pH.Recently, some advanced technologies such as thermography have been used in quality assessment of agricultural products. Thermography is performed in two types: active and passive. In passive thermography, the heat emitted from the objects is recorded by the camera while in active thermography, which is more common in post-harvest applications, there is an external energy source to produce a thermal contrast between the sample product and the background. The objectives of this research areto use thermography in order to study the effects of time after harvest on the distribution of arils surface temperature and to relate the thermal properties to the freshness of arils.Materials And MethodsFreshly harvested pomegranate fruits of Khazar variety were provided from Kashmar gardens. The arils were extracted from 35 randomly selected fruits. The arils of each fruit were kept for 15 days at 5°C. The arils were thermally and visibly imaged and their physical and mechanical properties were measured every 5 days: first day, fifth day, tenth day and fifteenth day after openingthe fruit to have variations in freshness. The size of thermals images was 320×240 pixels with the temperature resolution of 0.08°C. The images were taken with the emissivity set at 0.95, which was obtained from masking method (using a high-emissivitypatch). This emissivity value was within the range documented for biological products, i.e. 0.93-0.99 (Hellebrand et al., 2006). The thermal images were taken from the arils every 10 seconds for 180 seconds after imposing thermal shock by placing the arils in a freezer compartment at -2°C for 60 seconds. The distance from the thermal camera to the arils was 30cm and the room temperature was 22.5°C. The images were processed and analyzed in Matlab (MathworksInc, US) and the thermal features were extracted from the histogram of each thermal images, which included: mean temperature, variance, third moment, smoothness, homogeneity and entropy.Linear Discriminant Analysis (LAD) was employed for classification based on the mentioned features. The validity of input data was examined using Leave-one-out method. Statistical analysis was carried out using stepwise regression method in SPSS ver. 16.Results And DiscussionThe temperature extraction from the aril regions was done using the fusion of the segmented red/green ratio and the thermal image. The results showed that the temperature gradient with respect to time for one-day was the same as that for the five-day arils. This behavior was probably because the sound and fresh part of these arils was still large enough so that it causes less sensitivity with respect to the temperature change. However, the temperature gradient for ten-day and fifteen-day arils was relatively large. The analysis of temperature variations on arils surface showed that the less fresh the arils were,the more thermally sensitive they were with respect to their surroundings. The less fresh arils were cooler than the one-day and five-day arils. This might be due to the extended evaporation from the surface and the larger emissivity of older arils than fresher ones. The larger emissivity in less fresh tissues cause quicker heat penetration inwards or quicker heat loss from inside out, thus, the tissue become cool or hot quicker. Conversely, the fresh tissues have reduced heat transfer.They release heat in a cold environment or becomes warm it a warmer environment at a slow pace rate.The extracted temperature features were used in a Linear Discriminant Analysis (LDA) model for quality assessment and classification of pomegranate arils stored for three 60-second periods. The mean accuracy of classification of arils for three 60-second periods of imaging were obtained to be 62.1%, 72% and 79.8%. The optimum classification results were obtained from the third 60s. In this range, the accuracy of classification ofone-day, five-day, ten-day and fifteen-day arils were 98.7%, 69.23%, 65.4% and 89.8%, respectively.ConclusionTwelve thermal features were extracted from thermal images of arils for classification in terms of freshness. The results confirm that thermography can be used as a non-destructive method for determining the freshness status of pomegranate arils during storage periods.Keywords: pomegranate aril, thermal imaging, new of degree, shelf, life
Pages 163-181IntroductionExploiting natural substances with dual or multiple functionalities is getting more attention in food industry due to the requirement from the health- conscious consumers and the trends for sustainable environment. Hydrocolloids are high molecular weight macromolecules that can be easily dissolved and dispersed in water under appropriate conditions. They can modulate rheological properties of foods, and are generally used as food thickeners, texture modifier, stabilizers and emulsifiers for various applications. Mucilage is a high molecular weight polyuronides consisting of sugar and uronic acid units. It is partially soluble in water and can form highly viscous solution. It exhibits hampering effect on the diffusion of glucose, help to postpone the absorption and digestion of carbohydrates. The mucilage extracted from the seeds of the quince fruit contained cellulose micro-fibrils strongly associated whit a glucuronoxylan possessing a very high proportion of glucuronic acid residues. Analysis of quince seed mucilage (QSM) has shown the presence of more cellulosic fraction and hydrolysable polysaccharide.Quince seed mucilage is one of the endemic hydrocolloids, which due to high viscosity, its extraction needs a method to reduce the extraction time, energy consumption and especially raise the extraction efficiency. The traditional extraction method of polysaccharide from plant tissues are maceration, mechanical rabbling and heat reflux. Theses extraction methods depend largely on energy input and agitation to improve the solubility and mass transfer efficiency of polysaccharides. Usually, the convention extraction method requires long extraction time and high extraction temperature with low extraction yield, but high energy consumption. Ultrasound in combination with conventional extraction is a potential technique, which is a fully reproducible food process, completed in shorter time with high reproducibility, reduced processing cost, simplified manipulation and work-up. To achieve this goal, in this study ultrasound- assisted extraction (UAE) as a novel extraction method was used.
Materials andMethodsQuince seed used in this study was purchased from a local market (KhorasanRazavi, Mashhad). They were cleaned manually by removing the foreign matter such as stones, dirt and broken seeds. They were packed in hermetic plastic vessels and stored at 5ºC until further use. For mucilage extraction, first conventional extraction was optimized to select the best hydration conditions and after that UAE (24 KHz probe and 400 W power) was performed at three different levels of intensity (20, 60 and 100%) and times (5, 15 and 30 min).All chemicals used were analytical grades. Yield value of hydrocolloid was calculated by dividing the weight of dried hydrocolloid by the weight of initial dry seeds. Emulsion heat stability was determines by the method described in previous studies. In order to measuring the water absorption capacity (WAC), 0.05 g of mucilage was added to deionized water until QSM was completely wet (~ 10ml). The tubes were then centrifuged at 1600×g for 10 min. Excess water was discarded and residue was weighted. Apparent viscosity of QSM solution with 0.1% (w/v) concentration was measured using a rotational viscometer (Brookfield, DV- ІІІ, USA). Shear rate increased linearly from 2.5 - 35 s-1 at 25˚C.For measuring the foam stability and emulsion heat stability, the mucilage dispersions were prepared at 0.25 and 0.5 (w/v) respectively, and kept overnight at 4˚C. After complete hydration, 2% (w/v) egg white powder was added and then foamed by whipping at 8600 rpm for 2 min using adisperser.Results And DiscussionOptimized conditions of conventional extraction were 45 min, 47˚C and 32.5: 1 water to seed ratio. The results showed that extraction at 30 min with 100% intensity raised the extraction yield to 42.7% in comparison with control sample.Improvement in hydrocolloid extraction by ultrasound is attributed to ultrasound pressure wave diffusion which results in cavitation phenomenon.Amplitude level and exposure time had a significant (pKeywords: Extraction, functional properties, quince seed mucilage, ultrasound
Pages 182-192IntroductionPomegranate fruit as one of the most popular fruits native to Iran, belongs to Punica family (Punica granatum L). Iran with an annual production of about 700 tons is the largest producer of pomegranate fruits in the world. Colorfulness and healthiness are two important features of pomegranates, which cannot easily be controlled. Some negative characteristics of this fruit such as sun burning, cracking and scratchingcan reduce its economic value. Moreover, separating the arils from membrane (flesh) and sorting them based on their color and size is a laborious task which still is a challenging concern (Blasco et al., 2003). Despite these challenges, the demand for ready-to-eat of arils is increasing. Up to now several devices have been proposed to remove the arils from membrane with different operation principles. However, these devices leave some membrane segments with arils and also makeit difficult to sort the arils from color and size points of view (Khazaei et al., 2008; Singh et al., 2007). With the visual inspection methods, the external features of Bio-materials (e.g. shape, color and texture) can be evaluated. While for assessing their internal parameters, nondestructive methods such as MRI, X-RAY and NMR are preferred. To classify and identify bio-materials (e.g. fruits), several methods have been examined including Fuzzy technique (Hu et al., 1998), Multilayer (Luo et al., 1999) and Linear Discriminant Analysis (LAD) (Manickavasagan et al., (2010). The primary objective of this research wasto discriminate arils from membrane segments. Subsequently, the fruit components were classified into red, pink, white arils and membrane segments, using LAD method. Ultimately, the accuracy of classifications based on different images features was evaluated.Materials And MethodsPomegranate fruits of Khazar variety were provided from Kashmar gardens. Prior to imaging step the fruits were categorized in four groups each of 50 samples. The arils were ranked as red, pink and white using human sensory. The images of arils samples were prepared using a Nikon Coolpix digital camera (Nikon co, Japan), in a chamber having six LED lamps, from a distance of 15 cm. During image processing, the images were first converted into grayscale format and then transformed into binary images. Subsequently, several morphological (see table 2) and textural image (see Table 3) features were extracted for classification purpose. For color features three color spaces including RGB, HSI and L*a*bwere examined (see Fig 3). The arils were classified and discriminated from membrane using 12 morphological, 10 color and six textural features. Linear Discriminant Analysis (LAD) was employed for classification based on the mentioned features. The validity of input data was examined using theleave-one-out cross validation method. Statistical analysis was carried out using SPSS ver. 16.Results And DiscussionThe classification accuracy of arils based on morphological features was about 97.53% and the membrane segments were discriminated from arils with accuracy of 95.06% (Table 4). The classification with color features provided the accuracy of 45% when the R component of the images was considered (Table 5). This is mainly due to similar red band of the arils classes.The accuracy of classification improved whenHSI components were used andthe accuracy of 84% was achieved (Table 6). The best accuracy of classification with color features observed using L*a*b* color space. In this case the accuracy was 89.1% (Table 6). In the final stage of classification, six textural features obtained from statistical moments including mean grayscale, standard deviation, third moment, evenness, entropy and homogeneity were used. As shown in Table 7 with these components the accuracy of classification improved up 93.3%. Considering the classification with different features (morphological, color and textural) it can be said that, in general, the accuracy of discriminating membranes from arils is less accurate than the accuracy of discrimination between different arils (red, pink and white). This was observed in all methods of classifications with different image features. With regard to the specific functionality of each extracted feature, the combination of the features was used for classification. Due to the increasing number of input features, the stepwise method was used for rankingof input features.Out of 26 input features of classification model, 14 superior features were selected using stepwise method. The results of classificationwith the combination of different features are shown in Table 8. As it can be seen, the average accuracy of classification with the combination of features improved up to 99%. Fig. 4 shows the classification of the pomegranate components based on the combination of the features, using Linear Discriminant Analysis (LDA) method.ConclusionA classification model was employed to classify pomegranate arils and membranes, using Linear Discriminant Analysis method. To improve the accuracy of classification, different image features were extracted and examined. In order to achieve a higher accuracy, the combination of features wasalso tested. This improved the accuracy of classification up to 99%. Since the combination of features is a costly and time-consuming process, the stepwise method was used to rank and select the superior features before their use in classification step.Keywords: Pomegranate aril, Image processing, Classification
Pages 193-200IntroductionLiquorice (Glycyrrhiza glabra) of the family Leguminosae is a 30±60 cm tall shrub having blue or violet flowers. Its roots are 15±20 cm long and have a cylindrical rod shape of 0.5±2.5 cm in diameter. Liquorice root contains a variety of compounds, the most prominent of which is the water soluble triterpenoid glycoside glycyrrhizin that constitutes about 16 %. It is responsible for the characteristic sweet taste of liquorice (50 times sweeter than sucrose). The root also contains various sugars (to 18%), flavonoids, saponoids, sterols, starches, amino acids, gums, and essential oil. The water extract of liquorice root has found wide uses in medicine, pharmacology and food industry because of its physical and functional properties.
In the food industry, its distinctive flavour makes it a popular sweetening/flavouring agent. It is also used as an emulsifier to create foam in drinks and beverages. Liquorice root extract is commonly consumed and marketed in liquid, concentrated, dry and powdered forms.
Knowledge of the flow (rheological) behavior of the concentrates is useful in quality control, sensory evaluation and engineering applications that are related to the proper design and operation of unit operations, as well as for the understanding of the pertinent transport processes in the operations.
The purpose of this investigation was to characterize the rheological behavior of liquorice extract concentrates and study the effect of temperature and soluble solids on the viscosity.Materials And MethodsExtraction was made at 50°C and water to liquorice root mass ratio of 4:1. The mixture was shaken continuously for 100 min, centrifuged for 10 min and then filtered to obtain a clarified extract, which was concentrated to 50°Brix in a laboratory rotary vacuum evaporator.
The rheological behavior of licorice extract has been studied at temperature range 10-70 0C and 5-50 % soluble solids using Brookfield viscometer.Results And DiscussionThe obtained results showed that all the samples exhibited Newtonian behavior at all the studied temperatures and concentrations. The flow index decreased slightly with sample concentration. Several workers observed Newtonian behavior of clarified and depectinated juices.
The shear stress versus shear rate data obtained were well fitted to Newton's model. An increase in temperature decreased the viscosity and this inverse relationship has been likened to the incidence of a freer molecule to molecule interaction at elevated temperatures. Since viscosity is an indication of the resistance to flow such a freer interaction is expected to minimize the resistance.
It was observed that, irrespective of the temperature a decrease in soluble solids content decreased the viscosity. It is due to dilution which increases the separation between the particles, thus decreases interaction between the particles.
In contrast, the opposite effect was observed when soluble solids content became higher. Arrhenius type equation was found to be suitable in describing the relationship with correlation coefficient values between 0.94 and 0.99. The activation energy increased with the soluble solids content; therefore, temperature had a greater effect on samples with higher soluble solids content. The data obtained in this study can be used in designing equipment for handling of concentrated liquorice root extract at the temperature range studied.Keywords: Licorice extract, rheological properties, Newtonian fluid, Concentration, Temperature