فهرست مطالب

پژوهش های صنایع غذایی - سال سی و یکم شماره 4 (زمستان 1400)
  • سال سی و یکم شماره 4 (زمستان 1400)
  • تاریخ انتشار: 1400/09/03
  • تعداد عناوین: 12
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  • علی قربانی، رضا امیری چایجان*، علی قاسمی صفحات 1-17
    قرص سازی سبب افزایش چگالی توده در مواد غذایی می شود. همچنین تسهیل در حمل و نقل و کاهش هزینه های انتقال و ذخیره سازی را در پی دارد. در این پژوهش به منظور انجام آزمایش های قرص سازی از پودر سویا استفاده شد. اثر شرایط مختلف فرآیند قرص سازی روی چگالی ذره ای، استحکام فشاری و چروکیدگی قرص مورد مطالعه قرار گرفت. به منظور قرص سازی، از پودر سویا در محتوای رطوبتی 30، 40 و (w.b.) 50%، دمای مواد خام ورودی به قالب 25، 45 و C° 65، قطر قالب 6، 8 و mm 10 و زمان آسایش تنش 5، 10 و s 15 استفاده شد و فرآیند با استفاده از روش سطح پاسخ بهینه سازی شد. بیشترین مقدار چگالی ذره ای (kg/m322/3714) طی فرآیند قرص سازی از پودر سویا تحت شرایط دمای مواد خام ورودی به قالب C° 25، زمان آسایش تنشs 5، محتوای رطوبتی w.b. 50% و قطر قالب mm 10 به دست آمد. بیشترین مقدار استحکام فشاری (N 58/518) در قرص سازی از پودر سویا در دمای مواد خام ورودیC ° 65، زمان آسایش تنشs 5، محتوای رطوبتی w.b. 50% و قطر قالب mm 10 حاصل شد. بیشترین مقدار چروکیدگی قرص فشرده سویا (57%) طی فرآیند قرص-سازی در دمای مواد خام ورودی اولیه C° 65، زمان آسایش تنش s 15، محتوای رطوبتی 50% و قطر قالب mm 10 به دست آمد. شرایط بهینه فرآیند تولید قرص از پودر سویا، دمای مواد خام ورودیC ° 03/42، زمان آسایش تنشs 5، محتوای رطوبتی w.b. 50% و قطر قالب mm 10 بود. تحت این شرایط بهینه، مقادیر متغیرهای پاسخ چگالی ذره ای kg/m3 49/4895، استحکام فشاری N 31/432 و چروکیدگی 03/9% با شاخص مطلوبیت 853/0حاصل شد.
    کلیدواژگان: قرص سازی، زمان آسایش تنش، استحکام فشاری و چروکیدگی
  • فریده قادری*، نفیسه جهان بخشیان، مریم جعفری صفحات 19-33
    با توجه به ارزش تغذیه ای بالای آب شلغم، روشی که بتواند محصولی از آن تولید نماید که مواد مغذی آن حفظ شده و در طی سال و در همه جا در دسترس باشد بسیار مفید است. در این تحقیق به مقایسه ویژگی های کیفی آب تغلیظ شده ریشه گیاه شلغم به دو روش مایکروویو (180 و 540 وات) و تغلیظ معمول در فشار اتمسفریک در زمان های مختلف پرداخته شده و خواص کیفی محصول شامل میزان اسکوربیک اسید، درصد مهارکنندگی رادیکال آزاد DPPH، شاخص های رنگ، بریکس و خواص ریولوژیکی مورد بررسی قرار گرفت. نتایج نشان داد با افزایش زمان تغلیظ میزان بریکس افزایش می یابد. همچنین با افزایش میزان بریکس، از میزان شاخص های L* و b* کاسته و به شاخص a* افزوده میشود. نتایج نشان داد که با افزایش زمان تغلیظ درصد مهارکنندگی افزایش و درصد ویتامین ث باقیمانده در تمامی روش ها کاهش پیدا میکند. نتایج خواص ریولوژیکی نشان داد تمامی روش ها و زمان های تغلیظ از قانون هرشل بالکی تبعیت می کنند. به طور کلی در ارتباط با تغییرات کلی رنگ نمونه ها در طی تغلیظ و همچنین در زمینه خواص تغذیه ای عصاره شلغم تغلیظ شده، روش مایکروویو به خصوص در توان پایین تر، موثرتر از روش اتمسفریک عمل کرده و می توان گفت استفاده از روش مایکروویو یک روش بالقوه برای تغلیظ آب شلغم می باشد.
    کلیدواژگان: بریکس، تغلیظ، شلغم، فشار اتمسفریک، مایکروویو
  • حسن صباغی*، امان محمد ضیائی فر، مهدی کاشانی نژاد صفحات 35-49
    پرتودهی متناوب مادون قرمز با ثابت نگه داشتن دمای سطحی محصول، یک روش خشک کردن نوین در تولید میوه ها و سبزیجات آبزدایی شده با کیفیت بالا است. در این پژوهش، اثر این روش حرارت دهی روی خصوصیات کیفی- فیزیکی برش های سیب خشک شده شامل حجم، دانسیته، چروکیدگی و رفتار بازجذب آب مطالعه شد. بدین منظور، برش های سیب (واریته زرد لبنانی) در سه ضخامت 5، 9 و mm 13 و با قطر mm 20 تهیه شدند. عملیات پرتودهی مادون قرمز با روش حرارت دهی متناوب در سه دمای ثابت 70، 75 و °C 80 انجام شد. ضریب چروکیدگی محصول با دو روش تیوری (βtheo) و عملی (β) تخمین زده شد. همچنین، مدل های ریاضی پلگ و نمایی برای توصیف فرآیند بازجذب رطوبت محصول با ضریب همبستگی تصحیح شده (Adj.R2) و ریشه میانگین مربعات خطا (RMSE) مقایسه شدند. نتایج نشان داد که افزایش دما موجب تغییرات بیشتر حجم و دانسیته حین آبزدایی سریع محصول شد. تغییر چروکیدگی در محصول طی فرآیند الگوی نمایی افزایشی داشت و تحت تاثیر مقدار آب تبخیر شده بود. ضریب چروکیدگی به طور معنی داری در دمای فرآوری بالا و ضخامت بیشتر محصول افزایش یافت (β برابر با 164/0)، که نشان دهنده شدت بیشتر پدیده فروپاشی ساختاری در محصول است. محدود شدن ظرفیت بازجذب آب (RC) در برش هایی با تنش چروکیدگی بالا، تاییدکننده آسیب بافتی محصول بود (کاهش محتوی رطوبت تعادلی پیش بینی شده: Xe از 523/6 تا 148/4 بر حسب kg/kg, db). فرآیند بازجذب در ضخامت های مختلف نیز توسط مدل پلگ با برازش مطلوب تری (Adj.R2 بالاتر و RMSE کمتر) در مقایسه با مدل نمایی توصیف شد.
    کلیدواژگان: مادون قرمز، خشک کردن، سیب، دانسیته، چروکیدگی، بازجذب آب
  • سارا خیابانی، بابک قنبرزاده، محمدیار حسینی* صفحات 51-63
    پوشش دهی مواد غذایی قبل از آبگیری اسمزی، راه حل موثری برای کاهش جذب مواد جامد معرفی شده است. در این مطالعه، دو نوع پوشش (بر پایه پکتین و کربوکسی متیل سلولز) حاوی دو ترکیب آنتی اکسیدانی و احیاکننده (اسید آسکوربیک و سیستیین) برای پوشش دهی انگور شاهرودی قبل از فرآیند اسمزی استفاده شدند. برای آبگیری اسمزی از ترکیب محلول اسمزی ثابت و مشابه ترکیب طبیعی میوه ها (حاوی فروکتوز، کلرید کلسیم و اسید سیتریک) استفاده شد (با نسبت نمونه به محلول 1 به 10). نمونه های بهینه (پوششهای حاوی سیستیین 5/0٪ و اسید اسکوربیک 5/0٪) بر اساس حداکثر ضریب کارآیی اسمزی و آبگیری اسمزی و حداقل میزان جذب مواد جامد انتخاب گردیدند. سپس نمونه های اسمز شده برای خشک کردن تکمیلی در دستگاه آون با هوای داغ قرار گرفتند. تاثیر پیش تیمارهای پوشش دهی و اسمز بر ویژگیهای کیفی کشمش حاصل (میزان ویتامین ث، رنگ و جذب مجدد آب) مورد بررسی قرار گرفت. نتایج نشان داد نمونه های دارای پوشش و اسمز، دارای بالاترین میزان ویتامین ث و کمترین میزان جذب مجدد آب نسبت به نمونه شاهد و بدون پوشش بودند. همچنین پوشش دهی و اسمز موجب کاهش تغییر رنگ کلی کشمش نهایی گردید.
    کلیدواژگان: پوشش های فعال، آبگیری اسمزی، رنگ سنجی، ویتامین ث، جذب مجدد آب
  • مریم معینی نیا، زهرا علی بابایی، نفیسه زمین دار* صفحات 65-78
    زمینه مطالعاتی

     بتاسیکلودکسترین یک الیگومر حلقوی متشکل از هفت مولکول گلوکوپیرانوز می باشد که جهت جداسازی کلسترول مواد غذایی مورد استفاده قرار می گیرد.

    هدف

    این مطالعه با هدف بررسی اثر استفاده از کاتچین هیدرات جهت کاهش سطح مورد نیاز بتاسیکودکسترین برای دستیابی به حداکثر کاهش کلسترول شیر هموژنیزه و استریلیزه می باشد.

    روش کار

    در این مطالعه از روش سطح پاسخ و طرح مرکب مرکزی جهت ارزیابی تغییرات میزان کلسترول شیر به عنوان متغیر وابسته استفاده شد. متغیرهای مستقل شامل بتاسیکلودکسترین از غلظت 12/0 تا 48/2 % ، کاتچین هیدرات از غلظت 01/0 تا 12/0% و زمان مخلوط کردن نمونه های شیر تیمار شده با کاتچین هیدرات و بتاسیکلودکسترین از 48/6 تا 52/48 دقیقه بودند. میزان پروتئین و چربی شیر، اثر ممانعت-کنندگی از فعالیت رادیکال آزاد و میزان فعالیت آنتی اکسیدانی کل در نقاط مرکزی اندازه گیری شدند. ارزیابی حسی برای نمونه های شیر کنترل و تیمار شده انجام گرفت.

    نتایج

    نتایج نشان دادند حداکثر کاهش میزان کلسترول (96/96%) در غلظت کاتچین هیدرات 01/0 % ، بتاسیکلودکسترین 12/0 % و زمان مخلوط کردن 38 دقیقه حاصل شد. میزان چربی و پروتئین در نمونه های تیمار شده نسبت به کنترل کاهش معنی داری یافت. میزان فعالیت آنتی اکسیدانی و فعالیت رادیکال آزاد افزایش معنی داری یافت. ارزیابی حسی بین نمونه های شاهد و بهینه تفاوت معنی داری نشان نداد و نمونه ی بهینه مورد پذیرش ارزیاب ها قرار گرفت.

    نتیجه گیری نهایی

    نتایج نشان دادند کاتچین هیدرات می تواند میزان بتاسیکلودکسترین مورد نیاز جهت جداسازی کلسترول شیر را کاهش دهد و کمترین تاثیر را بر سایر ریزمغذی های شیر بگذارد

    کلیدواژگان: بتاسیکلودکسترین، کاتچین هیدرات، کلسترول، شیر هموژنیزه، روش سطح پاسخ
  • شیلا برنجی*، شیما رهبری نژاد، لیلا ناطقی صفحات 79-95
    مقدمه

    ویتامین D برای تنظیم جذب کلسیم و فسفر از رژیم غذایی و قراردهی آن ها در استخوان مورد نیاز می باشد. همچنین مصرف ناکافی کلسیم نیز می تواند منجر به نرمی استخوان در کودکان و دردهای استخوانی، ضعف عضلات و پوکی استخوان در بزرگسالان شود.

    روش کار

    هدف کلی از این پژوهش بررسی امکان غنی سازی پاستیل با ویتامین D3 و کلسیم بود. بنابراین ویتامین D3 (با غلظتهای g 100/ IU 100 و 70 ، 40) از نوع پودری و محلول در آب و کربنات کلسیم (g 100/ mg 1000و 750 ، 500) به فرمولاسیون پاستیل اضافه گردید. آزمون های شیمیایی (میزان بریکس، اسیدیته و خاکستر) و خواص بافتی (سختی، پیوستگی و قابلیت جویدن) در روز اول و آزمون های میزان پایداری کلسیم و ویتامین D3 و ویژگی های حسی (رنگ، مزه و بو، بافت و پذیرش کلی) طی 60 روز نگهداری مورد ارزیابی قرار گرفتند.

    نتایج

    استفاده از کلسیم و ویتامین D3 و افزایش غلظت آن ها اثر معنی دار (05/0>p) بر خواص شیمیایی، خواص بافتی، میزان پایداری کلسیم و ویتامین D3 و ویژگی های حسی پاستیل داشت در حالی که زمان نگهداری تاثیر معنی داری (05/0<p) نداشت و بین تیمار شاهد با سایر تیمارها اختلاف معنی دار (05/0>p) وجود داشت.

    نتیجه گیری

    مطابق با نتایج این تحقیق می توان از کلسیم به میزان mg/100g 1000 و ویتامین دی به میزان IU/100mg 100درفرمولاسیون پاستیل استفاده نمود بدون اینکه اثر نامطلوب بر خواص حسی (پذیرش کلی) داشته باشد.

    کلیدواژگان: پاستیل، فراسودمند، کلسیم، ویتامین D3
  • مصطفی شاه ملکی، فرانک بیگ محمدی*، فرناز موحدی صفحات 97-113
    مقدمه

    مشکل عمده دانشگاه و صنعت آلودگی پلاستیک ها به ویژه با کاربرد بسته بندی ست. بیوکامپوزیت زیست تخریب پذیر نشاسته به دلیل قیمت پایین، فراوانی و زیست تخریب پذیری جایگزین مناسبی برای نشاسته است.

    هدف

    در این پژوهش با استفاده از نشاسته ذرت و تقویت کننده طبیعی سلولز از 0 تا 20 درصد و نسبت های مختلف نرم کننده گلیسرول/سوربیتول از 10 تا 20 درصد به روش اختلاط مذاب با اکسترودر دو مارپیچ ورق های مختلف نشاسته تولید گردید.

    روش کار

    در این مطالعه تاثیر سلولز به عنوان یک عامل تقویت کننده و نسبت های متفاوت گلیسرول/سوربیتول به عنوان نرم کننده برای بهبود خواص در بیوکامپوزیت نشاسته مورد بررسی قرار گرفت. نقطه بهینه بیوکامپوزیت نشاسته توسط نرم افزار دیزاین اکسپرت بدست آمد و آزمون های ساختاری XRD، TGA بر روی نمونه بهینه انجام شد.

    نتایج

    نقطه بهینه تیمار با 5 درصد سلولز و درصد 5/17 از هرکدام از نرم کننده ها بود که نفوذپذیری به بخارآب معادل10-10×81/7 gs-1m-1Pa-1، استحکام کششی 85/0 مگاپاسکال، مدول یانگ 56/377 مگاپاسکال و افزایش طول تا نقطه شکست 08/7 درصد داشت. دمای انتقال شیشه ای بیوکامپوزیت نشاسته بهینه به حدود 130 درجه سانتیگراد افزایش یافت. اگرچه XRD بیوکامپوزیت بهینه پیک های تیزی مبنی بر وجود کریستال هایی را نشان داد، ولی نتایج وزن سنجی حرارتی نشان داد که بیوکامپوزیت بهینه در حدود 300 تجزیه می شود با توجه به دمای تجزیه نشاسته طبیعی که 220 درجه سانتیگراد است، مقاومت حرارتی آن را می توان به وجود سلولز در ساختارش نسبت داد.

    نتیجه گیری نهایی

     نتیجه گیری می شود که تیمار با %5 سلولز و % 5/17 گلیسرول و % 5/17 سوربیتول (تیمار شماره 11) به عنوان یک نقطه بهینه این مدل در نظر گرفته می شود. با در نظرگیری نقطه بهینه در این تحقیق، به نظر می رسد که سلولز، گلیسرول و سوربیتول اثرات مثبتی بروی صفات بیوکامپوزیت نشاسته دارند. نتایج حاصل از این پژوهش می-تواند دریچه جدیدی به سوی استفاده از بسته بندی های زیست تخریب پذیر در صنایع غذایی جهت بهبود کیفیت و ایمنی مواد غذایی و کاهش زباله های حاصل از غذا بگشاید.

    کلیدواژگان: بیوکامپوزیت نشاسته، بهینه سازی، مدول یانگ، سلولز، نرم کننده
  • حسین کریم زادگان، فروغ محترمی*، هادی الماسی صفحات 115-128
    زمینه مطالعاتی

    تریتیکاله گیاهی نسبتا جدید و حاصل هیبرید بین گندم و چاودار است و به علت ترکیبات تغذیه ای مطلوب جایگزین خوبی برای گندم است. همچنین اثر بهبود دهندگی آردتریتیکاله ناشی ازفعالیت آلفاآمیلازی بالای آن است که فعالیت پایین آلفا آمیلازی در آرد گندم ر ا جبران می نماید. آرد بلوط نیز به علت غنی بودن از لحاظ فیبر و املاح باعث حفظ رطوبت، افزایش ارزش تغذیه ای و بهبود ویژگی های بافتی محصول می شود. بنابراین آرد بلوط و آرد تریتیکاله به دلیل داشتن ویژگی های تغذیه ای مطلوب مورد توجه بوده و می توان برای غنی سازی فراورده های غله ای از آن ها استفاده کرد.

    هدف

    هدف از این پژوهش تولید بیسکوییت غنی شده با آرد بلوط و آرد تریتیکاله با کیفیت بافتی و تغذیه ای مناسب بود.

    روش کار

    به منظور بهینه سازی فرمولاسیون بیسکوییت اثر جایگزینی آرد بلوط و آرد تریتیکاله در سطوح 30-0% با آرد گندم در 13 تیمار مطابق با به کار گیری طرح آزمایشی آمیخته در قالب طرح D-optimal بر روی ویژگی های فیزیکی شیمیایی، بافتی و حسی بیسکوییت مورد بررسی قرار گرفت.

    نتایج

    نتایج حاصل نشان داد که با افزایش سطح آرد تریتیکاله و آرد بلوط محتوای رطوبتی و فعالیت آبی نمونه ها افزایش یافت (P<0.05). با افزایش سطح آرد بلوط چربی، ظرفیت آنتی اکسیدانی و ضریب پخش و قرمزی(a*) نمونه ها افزایش و شاخص روشنی (l*)، کربوهیدرات و کالری کاهش یافت (P<0.05)؛ درحالیکه افزودن آرد تریتیکاله تاثیر قابل توجهی بر این ویژگی ها نداشت. جایگزینی آرد گندم با آرد بلوط و آرد تریتیکاله، اثر معناداری بر محتوای پروتئین، خاکستر ، دانسیته وb* نمونه ها نداشت (P>0.05). همچنین پذیرش کلی در ارزیابی حسی با جایگزینی آرد تریتیکاله و آرد بلوط کاهش یافت؛ درحالیکه تمامی نمونه ها از امتیاز پذیرش قابل قبولی (74/0) برخوردار بودند.

    نتیجه گیری نهایی

    با توجه به نتایج حاصل از بهینه سازی عددی، فرمولاسیون بیسکویت با 15٪ آرد تریتیکاله+15٪ آرد بلوط+70٪ آرد گندم بعنوان نمونه بهینه با کیفیت تغذیه ای بالا مشخص گردید.

    کلیدواژگان: آرد بلوط، آرد تریتیکاله، ویژگی های فیزیکوشیمیایی، بافت، بیسکوئیت
  • ستاره میرحسینی، هاجر عباسی* صفحات 129-153
    زمینه مطالعاتی

    بیماران مبتلا به سلیاک به دلیل حساسیت به گلیادین گلوتن باید از مصرف محصولات دارای گلوتن اجتناب کنند.

    هدف

    هدف از این پژوهش، تهیه فرمولاسیون بهینه کیک فنجانی بدون گلوتن بر پایه نسبت های متفاوت آرد بلوط به آرد برنج (10 تا 50 درصد) است.

    روش کار

    در این راستا، تاثیر افزودن نسبت مساوی هیدروکلویید مرو و گوار (6/0-0%) وامولسیفایر داتم (1-0%) برمهم ترین خصوصیات کیفی محصول شامل ویژگی های بافتی (سفتی، ارتجاعیت، پیوستگی)، دانسیته و تخلخل ارزیابی، توسط روش سطح پاسخ مدل سازی گردید. سپس ویژگی های کیفی نمونه های شاهد و منتخب حاصل از مدل، در طول 14 روز مورد ارزیابی و مقایسه قرار گرفت. همچنین این دو نمونه از نظر خصوصیات حسی با هم مقایسه شدند.

    نتایج

    نتایج این پژوهش نشان داد که افزایش سهم آرد بلوط و استفاده از هیدروکلوییدها در سطوح بالا، باعث افزایش دانسیته و سختی محصول می شود، درحالیکه سطوح متوسط این متغیرها بر ویژگی های کیفی محصول تاثیر مناسبی دارد. افزودن امولسیفایر داتم نیز افزایش میزان تخلخل محصول را موجب می گردد. با درنظر گرفتن ویژگی های کیفی محصول و سطوح مطلوبیت به دست آمده، دو نمونه بهینه با مقادیر متفاوت از متغیرهای مستقل حاصل شد. مقایسه محصول بهینه با نمونه شاهد در طول مدت نگهداری، نشان دهنده ی پایداری بیشتر ویژگی های بافتی آنها در مقایسه با نمونه شاهد بود که به حفظ رطوبت مواد اولیه و افزودنی های فرمولاسیون و کاهش سرعت رتروگراداسیون نشاسته مرتبط می باشد.

    نتیجه گیری نهایی

    درنهایت با درنظرگرفتن همه فاکتورهای کیفی محصول، 67/16% نسبت آرد بلوط به آرد برنج، 1/0% صمغ (نسبت مساوی مرو و گوار) و 83/0% امولسیفایر داتم به لحاظ وجود خصوصیات تغذیه ای، ویژگی های بافتی و حسی مطلوب و قیمت مناسب، برای تهیه این فرآورده با کیفیت مطلوب معرفی می گردد.

    کلیدواژگان: کیک بدون گلوتن، صمغ مرو، صمغ گوار، آرد بلوط، آرد برنج، روش سطح پاسخ
  • مهرداد عاشوری، مریم قراچورلو*، مسعود هنرور صفحات 155-168
    زمینه مطالعاتی

    آکریل آمید توسط آژانس بین المللی تحقیقات سرطان (IARC) در دسته مواد احتمالی ایجاد سرطان طبقه بندی می شود که در اثر حرارت شدید در مواد غذایی ایجاد می گردد.

    هدف

    با توجه به اینکه بیشترین مقادیر آکریل-آمید در سیب زمینی سرخ شده و فراورده های مشابه آن تشکیل می شود، در این مطالعه به تاثیر نوع روغن بر میزان تشکیل آکریل آمید در سیب زمینی سرخ شده پرداخته شده است.

    روش کار

    چهار نوع روغن، آفتابگردان، سویا، کانولا و یک نوع روغن سرخ کردنی (حاوی ترکیبات روغن پالم اولیین، پالم سوپر اولیین و روغن آفتابگردان) به مدت 10 ساعت در دمای °C180 تحت حرارت قرار گرفته و در فواصل زمانی 3 ساعت، سیب زمینی ها داخل روغن به مدت 5 دقیقه سرخ شده و در هر مرحله از سرخ شدن، نمونه روغن و سیب زمینی تهیه گردید. مقادیر آکریل آمید، عدد پراکسید، عدد آنیزیدین، عدد توتوکس و پروفایل اسیدهای چرب اندازه گیری شدند.

    نتایج

    با افزایش یافتن طول مدت حرارت دهی روغن، مقادیر عدد پراکسید، عدد آنیزیدین و در مجموع عدد توتوکس نیز افزایش یافت. بیشترین مقدار عدد توتوکس پس از 10 ساعت حرارت دهی به ترتیب در روغن سویا (76/46)، روغن آفتابگردان (14/42)، روغن سرخ کردنی (45/32) و روغن کانولا (57/29) اندازه گیری شد. مقادیر آکریل آمید سیب زمینی نیز با افزایش زمان حرارت دهی روغن روند افزایشی داشت، بطوریکه محدوده مقادیر آکریل آمید در سیب زمینی های سرخ شده در روغن سویا (µg/kg1056-73)، روغن آفتابگردان (µg/kg963-72)، روغن سرخ کردنی (µg/kg465-60) و روغن کانولا (µg/kg394-57) بدست آمد.

    نتیجه گیری نهایی

     بر اساس میزان اکسیداسیون روغن های مورد مطالعه که در اثر آن ترکیبات ثانویه ایجاد می شوند، روغن سویا که دچار بیشترین اکسیداسیون شده بود دارای بالاترین مقدار آکریل آمید بوده و در روغن های دیگر نیز بین میزان اکسیداسیون و تشکیل آکریل آمید همبستگی بالایی وجود داشت.

    کلیدواژگان: آکریل آمید، اکسیداسیون، اسیدهای چرب، عدد آنیزیدین، عدد پراکسید، عدد توتوکس
  • محمد نوشاد، بهروز علیزاده بهبهانی، محمد حجتی* صفحات 169-186
    زمینه مطالعاتی

     باکتری های اسید لاکتیک می توانند علاوه بر اثرات مفیدی که بر سلامتی مصرف کنندگان ایجاد می-کنند، خصوصیات متعدد تکنولوژیکی و ضدمیکروبی در ارتباط با استفاده های غذایی نیز داشته باشند.

    هدف

    هدف از این پژوهش بررسی پتانسیل پروبیوتیکی، تکنولوژیکی و ضدمیکروبی سویه های اسید لاکتیک جداشده از دوغ محلی شهرستان بهبهان می باشد.

    روش کار

    در این مطالعه ابتدا ویژگی های پروبیوتیکی باکتری های اسید لاکتیک از قبیل زنده مانی تحت شرایط اسیدی، زنده مانی در محیط شبیه سازی شده معده و روده، هیدروفوبیسیتی، خود و هم-تجمعی مورد بررسی قرار گرفت. سپس پتانسیل تکنولوژیکی آن ها با آزمون های قابلیت تولید اسید، فعالیت اتولیتیکی و مقاومت در برابر حرارت تعیین شد. در نهایت فعالیت ضدمیکروبی سویه هایی که ویژگی های پروبیوتیکی و تکنولوژیکی بهتری داشتند علیه 5 پاتوژن شاخص غذایی مورد بررسی قرار گرفت.

    نتایج

    سویه های لاکتوباسیلوس پلانتاروم و لاکتوباسیلوس دلبروکی زمانی که در معرض شرایط اسیدی و همینطور، شرایط شبیه سازی شده معده و روده قرار گرفتند کمترین کاهش در تعداد را نشان دادند. هیدروفوبیسیتی سویه ها 3/58-5/17 درصد گزارش شد که بیشترین درصد مربوط به لاکتوباسیلوس پلانتاروم بود. خود تجمعی باکتری های اسید لاکتیک در محدود 2/48-3/25 درصد محاسبه گردید و بیشترین میزان خود تجمعی مربوط به پدیوکوکوس پنتوزاسیوس بود. همچنین تمامی سویه ها فعالیت هم تجمعی علیه اشرشیاکلی از خود بروز دادند که بیشترین مقدار مربوط به لاکتوباسیلوس پلانتاروم با 3/46 درصد بود. در ارتباط با ویژگی های تکنولوژیکی، باکتری های لاکتوباسیلوس دلبروکی و پدیوکوکوس پنتوزاسیوس بهترین پاسخ را در تمامی آزمون ها از خود نشان دادند. همچنین فعالیت ضدمیکروبی باکتری های لاکتوباسیلوس پلانتاروم، لاکتوباسیلوس دلبروکی و پدیوکوکوس پنتوزاسیوس علیه پاتوژن های اشرشیا کلی، سودوموناس آیروژینوزا، سالمونلا تایفی موریوم، میکروکوکوس لوتیوس و استافیلوکوکوس اوریوس مورد بررسی قرار گرفت که بیشترین حساسیت در باکتری های میکروکوکوس لوتیوس و استافیلوکوکوس اوریوس و بیشترین مقاومت نیز توسط باکتری اشرشیا کلی مشاهده شد.

    نتیجه گیری نهایی

    با توجه به نتایج به دست آمده باکتری های لاکتوباسیلوس دلبروکی و پدیوکوکوس پنتوزاسیوس خصوصیات مناسبی جهت استفاده به عنوان کشت الحاقی برای تولید محصولات تخمیری لبنی از خود نشان دادند.

    کلیدواژگان: باکتری های اسید لاکتیک، پروبیوتیک، نوشیدنی لبنی، فعالیت ضدمیکروبی
  • جعفر میلانی*، خالق کلکار، پریسا فلاح صفحات 187-200

    در این پژوهش، تاثیر چهار روش پخت شامل مایکروویو، گریل کردن، کباب کردن و سرخ کردن بر روی میزان نه عنصر فلزی سمی شامل سرب، کادمیوم، آرسنیک، روی، مس، نیکل، کروم و منگنز در بافت عضله سه گونه از ماهی های پرمصرف دریای خزر همچون، ماهی سفید (Rutilus kutum)، کپور معمولی (Common carp) و کفال (Liza aurata) مورد بررسی قرار گرفت. برای این منظور ابتدا مرحله هضم اسیدی با کمک اسید نیتریک صورت گرفت. عناصر مورد نظر توسط دستگاه نشر القای پلاسما قرایت شد. در ارتباط با اثر فرآیند پخت بر فلز کادمیم، در ماهی سفید کادمیوم در همه تیمار ها کاهش یافته بود و کمترین میزان کادمیوم در ماهی سفید کباب شده مشاهده شد. در ماهی سفید کمترین میزان کروم در تیمار های گریل شده و مایکروویو شده، مشاهده شد. در ماهی سفید گریل کردن و مایکروویو باعش کاهش کروم شدند. بیشترین میزان نیکل در ماهی سفید در نوع کباب شده آن مشاهده شد و نمونه گریل شده کمترین میزان را داشت. در ماهی سفید فقط روش کباب کردن باعث کاهش معنی دار مس گردید. در ماهی کفال همه تیمار ها باعث کاهش معنی دار این عنصر شدند؛ اما در سرخ کردن کمترین میزان این عنصر مشاهده شد. مقدار روی در دو ماهی کفال و کپور نسبت به سایر عناصر چشمگیر بود. فرآیند کباب کردن منجر به کاهش این عنصر گردید. کباب کردن و گریل کردن باعث کاهش معنی دار منگنز شد. در ماهی کفال و کپور بیشترین افت مربوط به نمونه های سرخ شده بود. در مجموع ماهی سفید سالم ترین گونه و ماهی کپور ناسالم ترین ماهی از بین سه گونه مذکور بودند. در مقایسه بین فرآیند های مختلف پخت نیز کباب کردن و پس از آن گریل کردن باعث بیشترین کاهش در مجموع فلزات سنگین سه ماهی و هفت عنصر شده بود و در مقابل، مایکروویو در اکثر موارد باعث حفظ این عناصر در ماهی پخته شده گردید.

    کلیدواژگان: ماهی، فلزات سنگین، مایکروویو، گریل کردن، کباب کردن، سرخ کردن
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  • Ali Ghorbani, Ali Ghasemi Pages 1-17
    The tabletting process increases the density of the food. This process also facilitates transportation and reduces transmission and storage costs. In this research, soybean powder was used for tabletting experiments. The effect of the tabletting process on particle density, compressive strength and shrinkage of soybean tablet was studied. The experiments were carried out using soybean powder at feedstock moisture content of 30, 40 and 50% w.b., feedstock temperature 25, 45 and 60 °C, relaxation time of 5, 10 and 15 s, and die diameter of 6, 8 and 10 mm. The response surface method (RSM) with central composite design was also used to analyze the data and optimize the process. The result showed that the highest particle density was 3714.32 kg/mm3 under conditions of the feedstock moisture content of 50% w.b., feedstock temperature of 25 °C, relaxation time of 5 s, and the die diameter of 10 mm. During the tabletting prosses, the highest compressive strength (518.18 N) was obtained at the feedstock moisture content of 50% w.b., feedstock temperature of 65 °C, relaxation time of 5 s, and the die diameter of 6 mm. The highest shrinkage of soybean powder (57%) was obtained at the feedstock moisture content of 50% w.b., feedstock temperature of 65 °C, relaxation time of 15 s, and the die diameter of 6 mm. The best optimization results for tabletting conditions for soybean powder was under feedstock moisture content of 50% w.b., feedstock temperature of 42.03 °C, relaxation time of 5 s and die diameter of 10 mm. The predicted values of particle density, compressive strength and shrinkage at the optimized conditions were 4895.49 kg/mm3, 433.17 N and 9.03% with a desirability of 0.853, respectively.
    Keywords: Tabletting, Relaxation time, compressive strength, Shrinkage
  • Farideh Ghaderi *, Nafiseh Jahanbakhshian, Maryam Jafari Pages 19-33
    Given the high nutritional value of turnip, a method that can produce a product that maintains its nutrients and is available throughout the year and everywhere is very useful. In this research, the qualitative properties of condensed water of turnip roots were investigated by microwave (180 and 540 W) and conventional concentrations at atmospheric pressure at different times. The qualitative properties of the product were ascorbic acid, the percentage of free radical inhibitory DPPH, Color indexes, brix and rheological properties were investigated. The results showed that with increasing concentration time, the amount of brix increased. Also, by increasing the amount of brix, the amount of L * and b * indices is reduced and added to the index a *. The results showed that increasing concentration time increased the inhibitory percent and the percentage of remaining vitamin C in all methods decreased. The results of rheological properties showed that all methods and condensation times follow the Herschel-Balkh's law. In general, in conjunction with the general changes in the color of the samples during condensation, as well as in the nutritional properties of the condensed turnip extract, the microwave technique, especially in lower power, is more effective than the atomic method, and it can be said that the use of The microwave method is a potential way to congeal turnips.
    Keywords: Brix, Condensation, Turnip, Atmospheric pressure, microwave
  • Hassan Sabbaghi *, Aman Mohammad Ziaiifar, Mahdi Kashaninejad Pages 35-49
    Introduction
    Dehydration of fruits and vegetables is a widely used unit operation (Funebo et al., 2000). Intermittent infrared radiation, in which the product surface maintained at constant temperature, is a novel drying method to produce high quality dehydrated fruits and vegetables (Zhu & Pan, 2009; Zhu et al., 2010). One of the most important physical changes in the quality of food during drying is the decrease in external volume. This change in volume is called shrinkage and is an unavoidable phenomenon during the dehydration process. Shrinkage is usually expressed by the ratio between the volume of the sample after and before drying (Yan et al., 2008). Shrinkage also affects the porosity of dried materials and it is the parameter determining about the mass transfer properties, mechanical properties, and the texture of food product (Witrowa-Rajchert & Rząca, 2009). The three qualitative parameters such as the degree of shrinkage, density and firmness of the product are related to each other (Funebo et al., 2000). Maximal shrinkage and structural collapse were shown to decrease until kept quality characteristics (Barzaghi et al., 2008). The factors affecting shrinkage include volume of water extracted from the product, mechanical mobility of the solid matrix, drying rate, and process conditions such as temperature, air flow rate, and relative air humidity (Moreira et al., 2000). The important consequences of shrinkage occurring during drying result in a loss of rehydration ability. Dehydrated products are usually rehydrated prior to their use (Krokida, M, & Marinos-Kouris, 2003). The rehydration behavior is studied as an indicator of texture damage (Giraldo et al., 2006). Rehydration is a complex process that is intended to restore the properties of the fresh product by contacting dehydrated products with a liquid phase. This process to be composed of three simultaneous steps: (1) absorption of water into the dry material, (2) swelling of the rehydrated product, and (3) loss or diffusion of soluble components. Rehydration ability or capacity measures the ability of a dehydrated product to rehydrate (Maldonado et al., 2010). Mathematical models of rehydration will be useful in designing and optimizing this operation that have been applied as exponential models or capillary absorption theory or Fick’s diffusion laws (Lee et al., 2006). In this research, the effect of this heating method on the physical-qualitative characteristics of dried apple slices, including volume, density, shrinkage and behavior of rehydration were studied.
    Materials and Methods
    Apples (Golden Delicious variety) were purchased from a local market and according to Acevedo et al., 2008 kept in 0°C±1°C and relative humidity ranging from 90% to 95%. The samples were skinned manually and then cut into slices with different thicknesses of 5mm, 9mm and 13mm and all with 20mm in diameter. The average moisture content of apple was measured using oven (Binder FD53) at 103 °C for 24 hours and it was equal to 84.11% based on wet weight (AOAC, 2000). Operation of infrared radiation with intermittent heating method was performed at three constant temperatures of 70, 75 and 80 °C using the infrared dryer similar to Liu et al., 2014. Shrinkage coefficient of product was estimated with both theoretical (βtheo) and practical (β) methods according to Talla et al., 2004. Also, the mathematical models as Peleg (Reyes et al., 2011) and Exponential (Krokida et al., 2003) equation were compared to describe the rehydration process in dried product using adjusted R-squared (Adj.R2) and root mean squared error (RMSE). Statistical analysis of the effect of thickness and temperature on the shrinkage coefficients (βtheo, β) was performed in SPSS software in version of 19. To achieve this aim, a completely randomized design (CRD) with factorial arrangement with two factors as thickness (at three levels) and temperature (at three levels) was used. Also, two methods of computing the shrinkage coefficients (theoretical and practical) were compared together with one-way F test. Mean comparison was performed by Duncan test with 95% confidence level (P<0.05). All experiments were performed in three replications.
    Results and Discussion
    The results showed that increasing of the temperature caused greater volume and density changes during rapid dehydration of the product. The density changes were more intense for the thin product (reducing the final density to about 0.6 g/cm3). Also for thicker products, the density changes were slower during the process (reducing the final density to about 0.7 g/cm3). During process, the variation of product shrinkage indicated an exponential rising trend which was influenced by the amount of evaporated water. Shrinkage coefficient is significantly increased at higher processing temperature and thickness of product (β equal to 0.164), representing that the product is heavily affected by the structural collapse phenomenon. The observations were similar to those reported by many researchers (Mayor & Sereno, 2004; Nowak & Lewicki, 2004; Katekawa & Silva, 2006). The temperature of 80 °C showed significantly higher theoretical and practical shrinkage coefficient than the other two tested temperatures (70, 75 °C). The difference between the two methods of calculation in shrinkage coefficient (theoretical and practical) was also significant and the difference increased with the increase of temperature (more than 6%). Jannot et al., 2002 reported that the error in the practical method can be due to the noisy data (deviation from the actual value). Limitation of rehydration capacity (RC) in slices with high shrinkage stress confirms the damage of the texture of the product (reduction in predicted equilibrium moisture content: Xe from 6.523 to 4.148 kg/kg, db). Rehydration process in different product thicknesses is described better using Peleg model (higher Adj.R2 and lower RMSE) compared with the exponential one. The observations were similar to those reported by many researchers (Krokida, M, & Marinos-Kouris, 2003; Nathakaranakule et al., 2010).
    Conclusion
    The physical properties including shrinkage and density in the dried product are affected by process and product conditions. The low occurred shrinkage that reflects the preservation of the internal structure of the product and will be effective in rehydration behavior. In fact, reabsorption cannot be simply defined as the returned process of dehydration. Because of moisture reabsorption is completely affected by the texture, structure and properties of the dried product. Therefore, mild thermal conditions prevent the structural breakdown of apple slices and, at low thicknesses, due to the reduced volume of water evaporated from the slices, the shrinkage coefficient is reduced, thus preserving the internal physical structure of the infrared dried product.
    Keywords: Infrared, Drying, Apple, Density, Shrinkage, Rehydration
  • S Kheyabani, Babak Ghanbarzadeh, Mohammadyar Hoseini * Pages 51-63
    The application of coating on food prior to osmotic dehydration has been introduced as an effective solution to decrease the solid gain. In this research, two types of coatings (based on pectin and carboxymethyl cellulose) containing two antioxidant and reducing ingredients (ascorbic acid and cysteine) for pretreating of Shahroodi grapes were used before osmotic process. For osmotic dehydration, constant osmotic solution with similar composition to natural fruits ingredients (containing fructose, calcium chloride and citric acid) were used (sample of solution 1 to 10). The optimum samples were chosen according to the maximum osmotic efficiency coefficient, maximum water loss and the minimum solids gain. The control and pretreated samples were subsequently dried by air drying and the effects of coating solutions and osmotic dehydration on dried raisins quality attributes (including vitamin C, color and rehydration ratio) were studied. The coated and osmotic samples showed the highest amount of vitamin C than the control and uncoated samples and the least rehydration ratio than the control and uncoated samples. Coating and osmotic dehydration also caused the decrease in overall color change.
    Keywords: Active coating, Osmotic dehydration, Colorimetry, Vitamin C, Rehydration ratio
  • Maryam Moeininia, Zahra Alibabaei, Nafiseh Zamindar * Pages 65-78
    Introduction

    Cholesterol with the formula of C27H45OH is a requisite component in cell membrane and cell growth (Nataf et al 1948). The compound has a major role in human heart health. It has been proved that high cholesterol is a risk factor for human cardiovascular diseases and coronary heart diseases. Cholesterol is synthesized in mammalian cells (Ma and Shieh 2006). It is mostly found within the milk fat globule membrane and asymmetrically distributed in the both layer of the outer bilayer and it is found in triglyceride core in less amount (Lopez and Menard 2011). Beta-cyclodextrin (βCD) is known as a safe food ingredient which is a cyclic oligosaccharide consisting of seven glucopyranose molecules that are linked together with α 1- 4 bonds. The size and geometry of the βCD hydrophobic internal cavity allows good complexing with free and esterified cholesterol (Chafic Awad & Gray 1999). Absorption of cholesterol in human intestine decreases by consumption of green tea catechins. Phosphatidylcholine (PC) is an important substance for cholesterol solubility in micelles containing of bile salts, PC and cholesterol. This effect is probably due to the interaction of catechins and PC in bile salts micelles (Ogawa et al 2016). It is assumed that catechin hydrate can help cholesterol removal from fat globules with similar mechanism. Then, separated cholesterol molecules can be easily entrapped in βCD cavity. The aim of this study is evaluating the effect of using catechin hydrate to decrease the amount of necessary beta- cyclodextrin for achieving maximum cholesterol reduction in homogenized and sterilized milk.

    Material and Methods

    Sterilized and homogenized milk with 3% fat was purchased from Pegah Dairy Co (Isfahan, Iran). Beta-cyclodextrin was purchased from Merk and catechin hydrate was purchased from Sigma Chemical CO (St. Louis, MO, USA). All reagents and solvents were of analytical grade.Response Surface Methodology (RSM) was used to optimize conditions that affect milk cholesterol reduction. Central composite design with 20 experimental points (6 center points, 6 axial points, 8 corner points, 3 blocks, 3 factors and 5 levels) was used. 70 ml of milk with different catechin hydrate concentrations was stirred (Alfa D 500 stirrer) at 750 rpm for 30 min at 25℃. Then, samples were stirred with different beta-cyclodextrin concentrations at various mixing time (according to RSM design) and centrifuged at 1000 × g, 25℃, for 10 min. The supernatant was separated and used for cholesterol determination by gas chromatography (GC)(Alonso et al 1995). Protein and fat content of milk were assayed at central points of experimental design using milkoscan. Radical scavenging and total anti- oxidant capacity were measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) (Balakrishnan and Agrawal 2014) and ascorbic acid methods (Taj khan et al 2017), respectively. Sensory evaluation of samples was carried out with 10 panelists (5 females and 5 males, ages 25 to 40 years old). A five- point hedonic scale was provided to the panelists (Keshtkaran et al 2012). The amount of fat, protein, radical scavenging DPPH and total antioxidant capacity were measured in central points. The statistical analyses were based on the mean ± standard deviation (SD) in experimental samples. Mean value of control and treated samples were compared using studentʹs t- test (P ≤ 0.05). Sensory evaluation data was analyzed by SPSS software.

    Results and Discussion

    The interaction between βCD and mixing time at constant catechin hydrate concentration (0.01%) showed that maximum cholesterol reduction (96.96%) was obtained at βCD concentration of 0.12% and mixing time of 38 min. The reason for this result is due to the interaction of catechin hydrate with some of fat globule membrane components such as PC and casein in homogenized milk that decreases cholesterol solubility. So cholesterol can be easily separated from milk fat globules. Then, maximum cholesterol reduction was achieved at low concentration of βCD (βCD: cholesterol molar ratio of 4:1). The interaction between catechin hydrate and mixing time at constant concentration of βCD 0.12% showed that by increasing catechin hydrate concentration to more than 0.03%, cholesterol reduction decreased. This effect is due to the competition between cholesterol and catechin hydrate for entrapping in βCD cavity. The interaction between catechin hydrate concentrations and mixing time at constant βCD concentration (1.3%) showed reverse correlation between these two factors. Maximum cholesterol reduction was obtained at catechin hydrate concentration from 0.01% to 0.08% and mixing time from 27.5 to 49 min; or catechin hydrate concentration from 0.08% to 0.12% and mixing time from 6 to 27.5 min. Comparison between control and treated milk at central points showed that fat content decreased in treated samples. Because cholesterol molecules are a part of milk lipids that is separated from treated milk. On the other hand, some of milk free fatty acids could be entrapped in βCD cavity. Also, the amount of protein in treated samples decreased because of entrapping of amino acids in βCD cavity and absorption of negative charge of proteins on the outer surface of βCD. Therefore, part of milk proteins together with βCD– cholesterol complex leaves the environment during centrifugation process (Maskooki et al 2013). While, the amount of antioxidant activity measured by ascorbic acid and DPPH methods increased which was due to the residual catechin hydrate in treated milk. Sensory evaluation results showed that no significant difference was observed between control and treated sample.

    Conclusion

    According to results, it seems that catechin hydrate has dual effects on cholesterol reduction from sterilized and homogenized milk. A positive effect is observed at the low concentration of catechin hydrate due to the separation of cholesterol from fat globules that decreases the needed amount of βCD and negative effect is due to the competition between catechin hydrate and cholesterol for entrapping in βCD cavity. Overall, the positive effect dominates the negative one at low concentration of catechin hydrate. It should be mentioned that the reasonable βCD: cholesterol molar ratio for cholesterol separation is 1:1 but practically this molar ratio is not enough, because cholesterol is placed in fat globule membranes. In previous studies βCD: cholesterol molar ratio was 34:1 while in this study the molar ratio decreased to 4:1, because catechin hydrate separates cholesterol from fat globule membranes and cholesterol easily entraps in βCD cavity. Therefore, by decreasing the amount of needed βCD for milk cholesterol removal, this process can be done in industrial scale.

    Keywords: Beta-cyclodextrin, Catechin hydrate, Cholesterol, Homogenized milk, Response surface methodology
  • Shila Berenjy *, Shima Rahbarinejad, Leila Nateghi Pages 79-95
    Introduction

    In recent years, adequate intake of vitamin D has become an important issue that has been the cause of the strong development of bone disease worldwide (Pearce & Cheetham, 2010; Clarke & Page, 2012). Bone softness is a progressive disease in childhood that results in bones softening and bending under body weight (Wharton & Bishop, 2003). Extensive studies have shown that high dietary calcium intake is associated with reduced risk of osteoporosis, hypertension, colon cancer, and renal stones (Singh & Muthukumarappan, 2008). The absorption of calcium in the blood takes the form of calcium ions from the intestinal wall. Increased calcium absorption is due to vitamin D, which is why calcium supplements usually contain vitamin D, so if you consume sources that contain these two substances, the calcium in them will be better absorbed. If there is a substance in the food called oxalate, its calcium absorption is reduced. The regulation of calcium levels in the body is caused by hormones secreted by the thyroid gland (Lau et al., 2000). Vitamin D3 is required to regulate the absorption of calcium and phosphorus from the diet and placement of bone in it. Inadequate calcium intake can also lead to bone softness in children and bone pain, muscle weakness and osteoporosis in adults. The daily requirement for vitamin D3 per adult is 10 micrograms or up to 2000 units per day. This is even higher in childhood and aging (Braegger et al., 2013; Glerup, 2000). Enriching popular foods among children and adolescents, such as snacks and confectionary products, can be a good solution to this problem. Vitamins are one of the most important micronutrients that are vital to human health and are essential for survival in the body. Vitamins are organic compounds that are essential to the metabolism of nutrients, vital to the body, and to the growth and development of health (Dennehy and Tsouronis, 2010). Adding one or more micronutrients to the staple diet is said to be one of the most effective strategies to prevent micronutrient deficiency (Jafarpour and Mazandarani, 2013).

    Material and methods

    For pastel production, 6 g of gelatin was first dissolved in bloom 260 in distilled water (twice the weight of gelatin) using a magnetic stirrer at 60 ° C in 12 g of water. Simultaneously, sugar syrup (boiling liquid glucose (35 g), sugar (35 g) in 20 ml of water and bubbling to 77-78) was prepared and after lowering the temperature, the gelatin solution was added and the resulting mixture was added to the water bath. Heat (70 °C) (Abbasi et al., 2011) and to reach pH 3± 0.25, citric acid (1.5 g), cherry color (0.03 g) and cherry essential oil (07 (0) g) was added with vitamin D3 (100, IU 100, 70, 40 g) and calcium (1000, 750, 500 g, 100 g / 100 g) and mixed gently to prevent air bubbles from entering . Calcium-free and vitamin D3 samples were used as controls. It should be noted that the calcium consumed was calcium carbonate and the vitamin D3 used in this study was powdered and water soluble. After mixing, the gelatin-sugar solution was poured into the mold with 40 × 5 3 3 mm dimensions and placed in the oven at 37 ° C for 24 hours at room temperature for 24 hours and then cooled to room temperature. The mold came out (Demars & Ziegler, 2001). Chemical tests (amount of brix, acidity and ash) and tissue properties (hardness, cohesiveness and chewiness) were evaluated on the first day, and tests of calcium and vitamin D3 stability and sensory properties (color, taste and odor, texture and acceptance overall) were evaluated at the first day of production, 30 and 60 days. In order to evaluate the quantitative and qualitative characteristics of the data with 10 treatments and 3 replications, one-way ANOVA was used and for comparing the mean of data, Duncan's test was used at 95% confidence level and the two-way ANOVA was used to evaluate the interaction of factors It turned out Minitab 16 software was used to analyze the statistical data and Excel software was used for drawing graphs.

    Results and discussion

    The results showed that the type of treatment (different percentages of calcium and vitamin D3) had a significant effect on chemical properties (brix, acidity and ash content), tissue properties (hardness, cohesiveness and chewiness), calcium and vitamin D3 stability and sensory properties Color, taste and smell, texture and overall acceptance) was positive (p<0.05) while maintenance time had no significant effect (p>0.05). Also, there was a significant difference between control treatment and other treatments (p<0.05). Increasing the amount of calcium, the amount of brix, ash, acidity, tissue properties (hardness, cohesiveness and chewiness), calcium stability and sensory properties of the posterior tissue increased (p<0.05), while there was a significant difference between treatments (p<0.05). The amount of bricks in the present study was higher than the minimum standard of 2682 (80%) in all treatments. The amount of ash obtained in all treatments was lower than the maximum value of 2682 (0.5%) in all treatments. It should be noted that the amount of acidity in the present study was lower than the maximum value of 2682 (2.5%) in all treatments. As the amount of calcium increased due to the increase in calcium, tissue density increased and eventually resulted in increased chewing ability of pastel (Rezaee et al., 2011). There was no significant difference in vitamin D3 between treatments (p>0.05). With the increase in calcium content, the sensory properties of color decreased and there was a significant difference between treatments, while there was no significant difference between the samples with increasing vitamin D3 levels. With the increase of vitamin D3, vitamin D3 increased in Gummy candy, while there was no significant difference between treatments with increasing calcium. By increasing the amount of calcium and vitamin D3, the taste and odor scores and overall acceptance decreased. Treatments 10 (containing 100 mg/100 mg of calcium and 100IU/100mg of vitamin D3) were identified as superior treatments for acidity, ash, brix, vitamin D3 and calcium stability and sensory evaluation (overall acceptance).

    Conclusion

    According to the results of this study calcium in 1000 mg / 100g and vitamin D in 100 mg IU / 100mg can be used in pastill formulation without adverse effect on sensory properties (general acceptance).

    Keywords: Gummy candy, Functional, Calcium, vitamin D3
  • Mostafa Shahmaleki, Faranak Beigmohammadi *, Farnaz Movahedi Pages 97-113
    Background

    Plastic contamination, especially in packaging application, has been the main issue for universities and industry. Bio-composite of biodegradable Starch is considered as an appropriate replacement for starch due to low price, availability and biodegradability.The film or coating is placed on the food as an integrated and thin layer of different polymer compounds. Today, contaminants from synthetic polymers have drawn attention to the use of biodegradable materials, and over the past two decades, the study of biodegradable materials derived from proteins and carbohydrates has expanded. These macromolecules could potentially be a viable alternative to synthetic polymers derived from petroleum products.Goal: In the present study, different starch films have been produced by corn starch and natural cellulose booster from 0% to 20% applying melt mixing with twin extruder. The aim of this study is to obtain a suitable combination of starch with cellulose (natural and degradable) that makes starch similar to synthetic polymers with low water permeability and high mechanical strength and can be a good alternative for them. In addition, food additives such as citric acid and stearic acid are used in a constant amount to facilitate the process and improve the properties of the film

    Methodology

    The current study aims at investigating the effect of cellulose, as an intensifier, and different ratio of glycerol/sorbitol, as an emollient, on the improvement of starch bio-composite. The optimum point for starch bio-composite is obtained by Design Expert Software and structural tests, TGA and XRD, were conducted on this point.For this study, corn starch was purchased from Qazvin Glucose Company, microcrystalline cellulose (Avisel) from Chengdu (China) and glycerol, citric acid and stearic acid from Merck (Germany). Other materials used were prepared using laboratory grade. First, a suspension of cellulose and a certain amount of water were homogenized or subjected to ultrasound so that the starch could be well dispersed in the matrix. Raw material for the production of starch biocomposites, including corn starch (as a matrix), glycerol and sorbitol (as a softener and each from 10 to 20% by weight of starch), different amounts of cellulose fiber (from 0 to 20% by weight of starch), citric acid 1% by weight To improve the biocomposite, starch and stearic acid were physically mixed as a process aid (to prevent starch from adhering to equipment and 1% by weight of starch) (Landavi et al. 2015). The main mixing was done uniformly in the two-screw face extruder. The produced starch biocomposite or sheet was exposed to 50% relative humidity and 30°C for one week and then the necessary tests were performed on them. In the next step, the mold was used under pressure, until a starch sheet with a thickness of 1 mm was produced. The sheets were produced at a temperature of 160°C and a pressure of 25 MPa for 2 minutes. The temperature reached 50-40°C by the flow of cold water flowing around the mold and the pressure was removed. Then each sheet was qualified separately at 58% RH and 30°C and entered the test stage. The thickness of the film was measured randomly in 5 positions with the micrometer of incision (model W-3275-A, USA) with a resolution of 0.01 mm and their average was used for calculations.In order to investigate the mechanical properties of nanocomposite films, mechanical properties including tensile stress, elongation at break (strain) and Young's modulus were calculated. Mechanical properties were determined at each rupture. Fracture stress and strain (σ, ε) were calculated for each sample. The film strips were cut to a length of 100 mm and a width of 20 mm and adjusted for 48 hours at a temperature of 23°C and a relative humidity of 53%. Tissue analysis performed by TA.XT plus histometer device made by Stable Microsystem of England and with Texture Expose 32 software was used to measure the mechanical properties of the film. Separation initial velocity and shear rate were 50 and 30 mm/ min, respectively. The elongation and tensile strength at the point of rupture were calculated from the deformation and the force of the data recorded by the software. 8 replicates of each sample were evaluated

    Findings

    optimum point was 5% cellulose and 17.5% of each emollient which has Water Vapor Permeability (WVP) as 7.81*10-10 gs-1m-1Pa-1, tensile strength of 0.85 MPa, Young module 277.56 MPa and elongation at break point 7.08%. The optimum glass transition temperature of bio-composite starch increases to 130o C. Although optimum bio-composite XRD show high picks demonstrating crystals, the findings from thermal weighting reveal that optimum bio-composite will be decomposed about 300. According to decomposition of natural starch at 220oC, this thermal resistance can be ascribed to the cellulose in its structure.Final

    Findings

    It is concluded that the composition of microcrystal cellulose and equal glycerol/sorbitol ratio lead to the development of starch bio-composite properties.The aim of this study was to obtain a suitable combination of starch with cellulose (natural and degradable) and glycerol and sorbitol softeners that make starch similar to synthetic polymers with low water permeability and high mechanical strength. Be a good substitute for them. In this study, optimization of starch biocomposite formulation was performed by epithelial mixing method. The main purpose of optimization was to place the parameters of tensile strength, elongation and elastic modulus in the desired range and to minimize water vapor permeability. According to the modeling, the optimal treatment in the production of starch biocomposite was 5% cellulose, 17.5% glycerol and 17.5% sorbitol. The validation results of the answers showed that the results of the model have an acceptable similarity with the practical results. X-ray diffraction test to investigate the distribution of particles in the polymer matrix showed that the components of the composites are well dispersed. Behavioral patterns related to heat-weight changes of starch biocomposite showed that three main stages of degradation and weight loss were observed in starch biocomposites. The results of this study can open a new window towards the use of biodegradable packaging in the food industry to improve food quality and safety and reduce food waste. More research is needed to replace conventional plastics with green composites to at least protect human health and the environment.

    Keywords: starch bio-composite, optimizing, Physical properties, cellulose, emollient
  • Hosein Karimzadeghan, Forogh Mohtarami *, Hadi Almasi Pages 115-128
    Introduction

    Functional food represents food that can be healthier than the usual ingredients in the food (Majzoobi et al., 2013). Cereal products are the main source of calories and energy in the diet. Among them, biscuits are popular because of their lower moisture, higher shelf life, relatively low cost and a wide variety of flavors (Anton et al., 2009; Hager et al., 2011). In recent years, there has been many of research on the effect of adding various compounds to cereal products such as mango peel powder (Ajila. Partners 2008), date juice (Majzoubi et al. 2016), lecithin in biscuits (facts and angles 2017), vegetable and fruit wastes (Sharboa et al. 2013), potato peel powder in cakes (Jedo et al., 2017) and pineapple powder in bread (Solani et al. 2014) has been done to improve the nutritional properties of the products. Oak fruit contains nutrients such as magnesium, calcium, minerals, fiber and biologically active compounds with antioxidant properties and tannins that make it practical and functional (Ozkan and Baiko 2005). Acorn also has useful properties including disinfectant; eliminate anemia, vascular swelling reduction and more. Recently, studies on the use of acorn flour in Barbari bread (Majzoubi et al. 2013), sponge cake (Rumi et al. 2014), and cupcake (Roshani and Naghipour 2018) acorn flour with soy flour in cake (Sorouki et al. 2013) And baguette bread (Hojjati and Atash Saz 2013) was made to enrich cereal products. Triticale is a new plant from hybrid between wheat and rye (Nassimento 2003) that contains high amounts of protein, minerals, vitamins, and high phenolic content compared to other cereal especially wheat, as well as it has rapid growth and production capacity in poor and low-yielding lands(Serena et al. 2004). This flour is more suitable for making bulgur bread, thin and flat breads and extruded products (Farash et al. 2016). Triticale flour has been used to enrich products such as crackers (Cabreilla et al. 2003), biscuits (Blanco et al. 2017) and cookies (Alberto et al. 2000). In recent years, extensive efforts have been made to improve and enrich cereal products; Therefore, according to the society's need to improve the nutritional value of foods, the purpose of this study is to investigate the possibility of replacing wheat flour with acorn flour and triticale flour in the production of biscuits and to study the physical, chemical, textural and sensory properties of the product.

    Purpose

    Acorn flour and Triticale flour have been considered because of their good nutritional properties and can be used to enrich cereal products; so the aim of this study was to produce biscuits enriched with acorn flour and Triticale flour with texture quality and suitable nutrition.

    Methods

    In this study, the effect of replacing acorn flour and Triticale flour at levels of 0-30% with wheat flour on the physical, chemical, texture and sensory properties of biscuits was investigated with using the mixture design based on D-optimal. For this purpose acorn fruit was harvested from the forested areas of West Azerbaijan in early autumn and after separating the outer hard layers and the second layer (pair), dried at room temperature for 72 hours and then the acorn kernel was milled and after sieving, it was kept in thick polyethylene bags in the refrigerator until consumption.Formulation of control biscuit dough was included 200 grams of wheat flour, 100 grams of granulated sugar, 70 grams of margarine, 2-3 grams of vanilla, 1-2 grams of baking powder and 1 egg. Replacement of acorn flour and triticale flour at the level of 0-30% with wheat flour was based on mixture design. To make the biscuit, all the ingredients were well mixed after weighing. The resulting dough was rested for 15 minutes after kneading and uniformity of texture. After this time, the doughs were spread with a rolling to 2-3 mm of thickness and after molding (with a diameter of 5 cm), it was baked in an industrial oven at 160oC for 12 minutes. After leaving the oven and cooling, the samples were thermally packaged in polyethylene bags and kept at room temperature until the tests (Caponio et al. 2007). Biscuits were characterized for moisture, fat, protein, ash, carbohydrates, calories, water activity, antioxidants capacity, density, spread ratio, and colorimetric indices, textural, and sensory properties.

    Results

    Triticale is a good alternative to other cereals, especially wheat, due to its good nutritional composition such as protein, minerals, vitamins, and high fiber content. Also, the improvement effect of triticale flour is due to its high alpha-amylase activity, which compensates for the low activity of alpha-amylase in wheat flour. acorn flours On the one hand, acorn flour is rich of fiber and minerals, so adding acorn flour to biscuits could improve maintenance of moisture, increase nutritional value, and improve the texture properties of the product. Therefore, this study was designed to evaluate the effect of replacing acorn flour and triticale flour on the physico-chemical, textural and sensory properties of biscuits.The results showed that moisture content and water activity of the samples containing triticale and significantly increased(P<0.05) due to the high mineral and fiber content of triticale flour and acorn flour compared to wheat flour, which absorbs more water and thus increases moisture. The fat content of the samples significantly increased with replacement of acorn flour due to the high fat content of acorn flour (9%) compared to other consumed flours. Also, with replacement of acorn flour, the amount of carbohydrate and calorie of the samples decreased (P≤0.05). With replacement of acorn flour, the spread ratio of the samples increased which is due to the decrease of gluten in wheat flour and the inability to retain gas and water vapor in the biscuit and thus reduce the thickness of the biscuit. The replacement of triticale flour with wheat flour had no significant effect on spread ratio. With replacement of acorn flour, the antioxidant capacity of the samples significantly increased that due to the presence of alpha and gamma-tocopherols, gallic acid, tannins and phenolic substances in acorn fruit. Interaction effect of acorn-triticale flours was significant on textural parameters. By addition of triticale flour up to 10% (at low levels of acorn flour), the required force and energy for penetration of the samples increased, but with more substitution, these properties decreased. Addition of acorn flour at high levels of triticale led to decrease of firmness and energy. The replacement of triticale and acorn flours had no significant effect on protein, ash, density and b* value of samples (P>0.05). Also, overall acceptance in sensory evaluation decreased with the replacement of triticale and acorn flour, but all samples had acceptable grade (0.74) in the range of 0-1.

    Conclusion

    The results of optimization showed that the biscuits with high desirability in terms of textural and sensory properties can be developed by the substitution of 15% triticale and 15% acorn flour together. In general, according to the results replacement of wheat flour with acorn and triticale flours in biscuit formulation, let to producing functional biscuit with low calorie and high nutritional value.

    Keywords: Acorn Flour, Triticale Flour, Physico-chemical properties, Texture, Biscuit
  • Setareh Mirhosseini, Hajar Abbasi * Pages 129-153
    Introduction

    Celiac disease is an immune-mediated enteropathy triggered bythe ingestion of gluten in susceptible patients (Kennedy et al., 2000). The reaction of celiac patients to gluten leads to the malabsorption of several main nutrients such as folic acid, iron, soluble vitamins, etc. Gluten is the main structural forming protein in baked products which cause the elasticity, cohesiveness and viscosity characteristics of dough. Gluten eliminatiom and its replacement with other protein causes technological problems like poor quality mouthfeel, crumbly structure, and a quick staling (Miñarro et al., 2012). Therefore, a redesign of the gluten-free bakery goods is necessary for obtaining products with suitable qualitative properties and nutritional composition. Therefore, to overcome these technological problems, several additives have been employed to mimic gluten properties. Emulsifiers are used in the baking industry because of their ability to interact with different flour components and other dough ingredients, which causes the softer crumbs (Khatami et al., 2015). Hydrocolloids have positive effects on crumb structure, taste, global acceptability and shelf life. Rice and oak flour also has been used to prepare gluten-free bakery products, such as bread and cake. Rice is naturally gluten-free and contains proteins that are known to be nutritious and hypoallergenic. (Gadallah et al., 2017). The compounds in free gluten oak flour also increase the porosity of product and the consistency of the dough during mixing. This research has developed a cup cake formulation which contains sage seed, guar gum and DATEM based on rice and oak Flour using Response Surface Methodology.

    Methods

    The purpose of the present study is to prepare an optimal formulation of gluten-free cup cake based on different ratio of oak flour to rice flour (10:50 ratio). In this regard, the effect of equal ratio of hydrocolloids Sage seed and Guar (%0 to 6) and DATEM (%0 to 1) on quality properties of product, including moisture, porosity, density and texture characteristics (firmness, springiness and cohesiveness) were evaluated and modeled using Response Surface Methodology. To compare the control cupcake with optimum samples, chemical and physical analysis, Ash, color (crust and crum) and sensory characteristics were performed to introduce the best products with high nutritional quality, favorable textural features, and reasonable price.

    Results and discussion

    According to the results, by increasing the ratio of oak flour to rice flour and also enhancing the hydrocolloid concentrations, the density of samples were increased. Fiber in oak flour increased water absorption and delayed gelatinization of starch, which caused a large amount of air bubbles leave the dough before setting the cake texture. The higher concentration of hydrocolloids also prevented the expansion of air bubbles in dough due to higher viscosity and increased the density of sample. The porosity of cake texture was due to stability of gas cells in dough. The porosity was reduced in high concentration of oak flour and hydrocolloids due increasing dough viscosity and non-uniform distribution of gas bubbles. However, emulsifier at suitable concentration reduced the interfacial tension of the liquid phase of the dough. Therefore, the air bubbles can distribute constantly in dough and suitable porosity in cake was created. The effect of Independent variables (ratio of oak flour to rice flour, amount of hydrocolloids and emulsifier) on textural characteristics of gluten-free cake showed that by increasing the ratio of oak flour to rice flour and the amount of Sage seed and Guar, the hardness and cohesion of tissue was increased. This is due to the presence of insoluble fibers of oak flour. Furthermore, by increasing the hydrocolloid concentration, the viscosity was increased and the cell wall of the gases was gotten strengthened, which resulted an increase in tissue hardness. On the other hand, water absorbability and gel-like network of hydrocolloid improved the elasticity and cohesiveness of the tissue. Suitable concentration of DATEM improved textural properties of gluten-free cake. Based on the results, 2 formulations were considered as the best. The level of oak flour to rice flour in the first and second optimal samples were respectively 16.67% and 27.76%, while the amount of hydrocolloid and DATEM were 0.1% and 0.83% in both samples. Textural hardness of control sample was more than optimal samples during storage. The presence of emulsifier and gums in the gluten-free cakes were the main factors in maintaining moisture and elasticity of texture and reducing staling of samples. Using oak flour in the sample affects the organoleptic properties of product. For example, the presence of oak flour reduces the brightness of gluten-free cake compared to the control. Also, in the sample containing emulsifier (DATEM) and hydrocolloids, the brightness of cake crust was decreased due to the reduction of moisture removal rate. The desirability of texture in control sample was higher than optimal samples, which could be attributed to the presence of oak flour compounds such as fiber, natural pigments, and creation of new colors and odors in product. However, the presence of Sage seed, Guar and emulsifier at suitable levels improve organoleptic properties of product. In nutritional aspect, the content of Mg, P and Fe in both selected optimized samples were significantly higher than the control sample, which was due to the high nutritional value of oak flour.

    Conclusion

    In this study, different ratio of oak to rice flour was used to produce gluten-free cake with appropriate quality and high nutritional value. Sage seed, Guar gums and DATEM were used for improving quality of free gluten product. By considering the quality characteristics of product, two samples with different levels of oak to rice flour ratio (16.67 and 27.76), 0.1% Sage seed and Guar gum and 0.83% DATEM were introduced as appropriate levels of independent variables in this study. Investigation staling process of samples during storage was found that the use of appropriate amount of gums and emulsifier at medium level of oak flour reduce staling of product. Also, in terms of nutritional, qualitative and overall acceptance of the product, the optimized sample No. 1 (oak flour to rice flour was 16.67%, the amount of hydrocolloid was 0.1% and the DATEM emulsifier was 0.83%) was selected as the best.

    Keywords: Gluten free cake, Sage seed gum, Guar gum, Oak flour, Rice flour, Response surface methodology
  • Mehrdad Ashouri, Maryam Gharachorloo *, Masoud Honarvar Pages 155-168
    Introduction

    Acrylamide, also known as acrylic amide and prop-2-enamide, is a white, odorless, crystalline, water-soluble solid, with the chemical formula C3H5NO and relative molecular mass of 71.08. Acrylamide is classified by the International Agency for Research on Cancer (IARC) as a probable human carcinogen. Acrylamide is formed in some foods such as potato chips, French fries, and toast due to heating. French fries are one of the most popular products in the world; their texture characteristics and special taste are attractive to customers. The sensory attributes of French fries depend both on the raw material and technological parameters used for French fries production. A factor affecting the flavor and texture of French fries is the frying (temperature, time, and type of frying oil). They are widely consumed among teenagers and young people in the community, which makes this age group more exposed to the dangers of acrylamide. The major pathway leading to acrylamide formation in foods is a part of the Maillard reaction with free amino acid (Asparagine) and reducing sugars through the decarboxylation of the Schiff base in a Strecker-type reaction. Although the formation of acrylamide in foods has its major routes through asparagine and reducing sugars, several other formation routes are suggested via Acrolein and ammonia. Oil is one of the most important components in the preparation of French fries due to its heat transfer and effects on taste. Due to the use of oil at high temperatures for a long time, the deteriorative chemical processes of hydrolysis, oxidation, and polymerization occur. Finally, various compounds such as aldehydes, epoxides, hydroxy ketones, and decarboxylated compounds are formed; these compounds can be reacting with amino acids. Therefore, these compounds may react with the asparagine in potatoes and increase the concentration of acrylamide in fried potato products.

    Materials and methods

    15 kg of Agria potatoes were prepared from the (SPI) Institute. Four kinds of oil (Sunflower oil, frying oil, and canola oil) were purchased from a chain store and soybean oil prepared from Korosh food industries. 1.5 liters of oil were poured into the fryer, the temperature reached 180°C and, stabilized. After 1 hour, 200 g of sliced potatoes (2×2×2 cm) was poured into the hot oil. Frying time was 5 min. Heated oil and fried potatoes were sampled for testing. The fryer remained on at 180°C. After 3 hours, the second sample of raw potatoes was fried for 5 min. The third and fourth samples were prepared 3 hours apart. GC-ECD method was used for acrylamide measurement. 2 g of sample and 20 ml of distilled water were poured into the Falcon tube. Then 3 ml of Carrez I, II solution was added to the solution and centrifuged at 5000 rpm. The water layer was discarded. Then 2 ml of hexane was added. The solution was centrifuged again. The hexane layer was discarded. 10 ml of the remaining solution was extracted with potassium bromide, bromic acid, and bromine water and injected into the GC. The fatty acid profile test was performed by ISIRI 13126 2 & 4 methods. ISIRI 4093 was used as a method for Peroxide value measurement. Anisidine and totox values are determined by methods defined in ISIRI 4093 was calculated by the ISIRI 4093 method. Data were verified by ANOVA variance analysis.

    Results and discussion

    According to the obtained results, values of total monounsaturated fatty acids are canola oil (%65.74), frying oil (%39.32), sunflower oil (%23.11), and soybean oil (%22.00). Also total polyunsaturated fatty were determined 65.41, 61.04, 26.21 and 43.99% for sunflower, soybean, canola and frying oils respectively. Oils containing polyunsaturated fatty acids (PUFAs) have less resistant to oxidation than monounsaturated fatty acids (MUFAs). Oxidative stability decreases with increasing number of double bonds. Accordingly, oleic acid has the highest thermal stability among unsaturated fatty acids, followed by linoleic acid and the lowest stability of linolenic acid. The results of peroxide, anisidine, and totox values determination showed that changes in these factors are affected by time (P<0.05). At most heating times, the highest values of peroxide were observed in soybean oil, and the lowest values were observed in frying oil (P<0.05). In all treatments by increasing of heating time, the amounts of anisidine and totox values increased significantly (P<0.05). The results of statistical analysis of different treatments indicated that in most heating times, the highest levels of anisidine and totox values and the lowest values were observed in soybean oil and canola oil respectively. Increased Peroxide value indicates that the level of the primary lipid oxidation products increased, which resulted in the formation of hydroperoxides. Peroxide and anisidine values indicate the rate of oxidation reactions at the beginning and the end of the process. In fact, the totox values simultaneously measures the amount of peroxides and their degraded products and provides a better estimate of the progress of oxidative degradation of oils and fats. Based on the results obtained from calculate of the totox value, the oxidation ratio of the studied oils was as follows:Soybean oil > Sunflower oil > Frying oil > Canola oil.According to the results, by increasing of heating time, the amounts of acrylamide in all treatments increased significantly (P<0.05). Therefore, the highest amounts of acrylamide were obtained in soybean oil and the lowest values were observed in canola oil (P<0.05). The correlation coefficient between totox value and acrylamide at different heating time was as follows: In the first hour of heating (R2 = 0.967), in the fourth hour of heating (R2 = 0.95), after 7 hours (R2 = 0.646) and in the tenth hour of heating was equal (R2 = 0.98), respectively. It shows that the levels of totox and acrylamide had a high correlation with each other and in fact the values of totox had a direct effect on the values of acrylamide.

    Conclusion

    The amounts of unsaturated fatty acids are effective in the oxidation of oils, and this effect is mostly due to double bonds. Oxidation of oils produces primary oxidation (hydroperoxides) that are degraded and secondary oxidation products such as aldehydes, ketones, and other might be produced. Secondary oxidation products in oil might be converted to acrylamide precursors in food without the presence of sugars, and by increasing the production of these products, more acrylamide might be formed. The results of this study showed that there is a high correlation between acrylamide in fried potato samples with the totox values in the oils. Therefore, the type of oil and heating duration influenced on formation of acrylamide in French fries.

    Keywords: Acrylamide, Anisidine value, Fatty acid, Oxidation, Peroxide value, Totox value
  • Mohammad Noshad, Behrooz Alizadeh Behbahani, MOHAMMAD HOJJATI * Pages 169-186
    Background and Objectives

    During thousands of years, human has unconsciously benefited from lactic acid bacteria (LAB) in the production of fermented food. This is due to the potential of these bacteria to release odor and flavor, and inhibit the growth of pathogens and food-spoilage microorganisms. LAB is Gram-positive, catalase-negative, microaerophilic and non-spore forming. In addition to their health-promoting effects, they have numerous technological and microbiological properties in food products. LAB is usually known as the microorganisms highly consumed in food products, which can be utilized as protective culture media, owing to their specific characteristics. The present study aims to examine the probiotic potential (viability in acidic and simulated gastrointestinal conditions, hydrophobicity, auto- and co-aggregation) of the LAB isolated from Behbahan local Doogh. Next, their technological properties (acidification and autolytic activities, and heat resistance) were determined. Finally, the antimicrobial activity of the strains was measured against some food pathogens.

    Materials and methods

    In this study, the LAB strains of Behbahan local Doogh were identified through 16S rRNA gene replication by a polymerase chain reaction. First, 85 Gram-positive and catalase-negative isolates were categorized using biochemical and sugar fermentation tests. One representative was selected from each group for the molecular identification test. In order to investigate the resistance of the bacteria to acidic conditions, their viability was examined at pH values of 2.5, 3.5 and 5. For determining the LAB viability in the gastrointestinal system, 30 µl of each bacterium was added to 270 µl of simulated gastric juice (2.5 g pepsin/l and 2 g NaCl/l) whose pH had been set at 2.75 and incubated at 37°C for 1.5 h. Then, 30 µl was mixed with 270 µl of simulated intestinal juice (1 g trypsin/l, 5 g bile salt/l, 2 g pancreatin/l, 11 g sodium bicarbonate/l and 2 g sodium chloride/l) whose pH had been adjusted to 8 and incubated at 37°C for 4 h. Afterwards, the bacteria were cultured on MRS agar at 1.5, 2, 3 and 4 h. The results were expressed as the reduction of log CFU/ml relative to time zero (time zero: 8 log CFU/ml). The other probiotic properties of the LAB, including hydrophobicity, auto- and co-aggregation were also investigated. Their technological potential was determined though acidification ability, autolytic activity and resistance to heat. Eventually, the antimicrobial activity of the strains with better probiotic and technological properties was examined against 5 food pathogens (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Micrococcus luteus and Staphylococcus aureus). One-way analysis of variance was conducted using statistical package for the social sciences (SPSS) version 22. Duncan`s multiple range test was employed for mean comparison at 95% confidence level.

    Results and discussion

    Lactobacillus plantarum, Lactobacillus delbrueckii and Pediococcus pentosaceus were the most resistant strains to the pH values of 2.5 and 3.5, while Lactobacillus pentosus and Enterococcus faecium showed the most pronounced reduction of log CFU/ml. At the pH value of 5, all the bacteria were able to grow without being reduced. Relative to the simulated gastric juice, L. plantarum was the most resistant one with a reduction of zero log CFU/ml and E. faecium was the most sensitive one with a reduction of 3 log CFU/ml. After 3 h of digestion by the simulated intestinal juice, L. plantatum and L. delbrueckii were the most resistant strains with a reduction of 1 log CFU/ml and E. faecium was the most susceptible one with a reduction of 5 log CFU/ml. The hydrophobicity of the strains was reported to be 17.5-58.3%, the highest of which belonged to L. plantarum. The co-aggregation of the LAB varied from 25.3 to 48.2%, the highest of which was associated with P. pentosaceus. In addition, all the strains showed co-aggregation activity against E. coli, and L. plantarum had the highest value of co-aggregation (46.3%). In terms of the technological properties, the results revealed that all the strains were capable of acid reduction up to 0.4 except L. pentosus. During 24 h of incubation, P. pentosaceus and L. delbrueckii caused the largest pH variations. The results of the autolytic activity of the LAB isolates indicated that all the L. pentosus, L. plantatum and L. delbrueckii could be grouped as relatively good. The highest viability and heat resistance belonged to P. pentosaceus and L. delbrueckii and the lowest viability was related to L. pentosus and E. faecium. In general, L. delbruckeii and P. pentosaceus showed the best results in all the technological tests. Moreover, the antimicrobial activity of L. plantarum, L. delbrueckii and P. pentosaceus was investigated against E. coli, P. aeruginosa, S. typhimurium, M. luteus and S. aureus. In all the samples, the acidic cell-free supernatant had a greater antimicrobial effect than the neutralized cell-free supernatant. The neutralized supernatant of L. plantarum and L. delbrueckii had no antimicrobial effect on E. coli. The shortest inhibition zone diameter of the acidic supernatants of L. plantarum, P. pentosaceus and L. delbrueckii was associated with E. coli. Furthermore, S. aureus was the most sensitive strain against the acidic supernatant of L. plantatum and S. aureus, whereas M. luteus had the longest inhibition zone diameter against the acidic supernatants of L. delbrueckii and P. pentosaceus.

    Conclusion

    Considering the obtained results, L. delbrueckii, L. plantarum and P. pentosaceus had superlative performances and can be used as complementary strains in the production of food products. It is suggested that supplementary tests, including the adhesion ability to intestinal epithelial cells, anti-adhesion ability against specific pathogens, and the lipolytic and proteolytic activity of these three strains be evaluated.

    Keywords: Lactic acid bacteria, Probiotic, Dairy beverage, Antimicrobial activity
  • Khalegh Golkar, Parisa Fallah Pages 187-200
    Introduction

    Environmental pollution represents a major problem in both developed and underdeveloped countries. These metals are toxic to aquatic life at low concentrations, particularly in soft-water Such metals may be accumulated from water to higher levels in fish (USEPA, 1977). Fish species can accumulate heavy metals in their muscles. The content of metals in fish tissues and organs indicates the concentration of metals in the water and their food. Therefore, the problem of heavy metal contamination in fish is increasing global attention. Meanwhile, different fish tissues have different abilities to accumulate these metal elements due to the different chemical composition. The heavy metals concentrations of fish fillets can be affected by processing or cooking methods and therefore, it is important to determine the concentrations of heavy metals in raw and cooked fish fillets and it is possible to reduce the heavy metal concentration in fish fillets by choosing a suitable method of cooking (Atta et al., 1997; Ersoy et al., 2006; Diaconescu et al., 2013).

    Materials and methods

    Specimens of white fish (Rutilus kutum), carp (Common carp), mullet (Liza aurata) each in three numbers in equal sizes were purchased freshly from Sari fish market in December 2017 and after unloading The viscera and scales were immediately transferred to the laboratory of the Department of Food Science and Engineering of SANRU and stored in the refrigerator. Fish samples were prepared by four different cooking methods. For this purpose, a sample weighing 100 g was removed from the inner tissue of each fillet and in the next step, each sample was cooked for the required time for optimal consumption. These conditions are for microwave (Solardem model, made by LG company) for 10 minutes at 900 watts, grilling (in a one-floor electric oven made by Baking Industries Company, Mashhad) for 20 minutes at 180 °C, roasting (in an electric oven one Construction floor of Mashhad Baking Industries Company) was 180 degrees for 20 minutes and frying (made by Pars Khazar Company) was 180 degrees for 4 minutes. Measurement of heavy metals: For this purpose, the acid digestion step was performed with the help of nitric acid. To digest the samples, the first one gram of each sample was dissolved in 10 ml of 1 M nitric acid, then boiled until complete digestion. In the next step, the filtration operation was performed and the resulting precipitate was washed with 1 M nitric acid and transferred to a 25 ml test tube and the rest was made up to volume with distilled water. The desired elements (lead, cadmium, zinc, copper, nickel, chromium, and manganese) were read by the plasma induction diffuser (ICP_AES model 4100).

    Results

    Regarding the effect of the cooking process on the cadmium element, cadmium was decreased in all treatments and the least amount of cadmium was observed in roasted white fish. In the white fish, the lowest chromium content was observed in grill and microwave treatments. Grill and microwave processes were reduced in chrome in the white fish. The highest amount of nickel element in the white fish was observed in the roasted type and the lowest amount of grilled sample. In the white fish, only the roasting method caused a significant decrease in copper. In mullet fish, all treatments reduced this element significantly, but the lowest amount was found in frying. Zinc content in mullet and carp fish was significantly higher than other elements. The roasting process resulted in a decrease in this element. The roasting and grilling process significantly reduced Mn. In the white fish, the least amount was related to the frying method. In mullet and carp fish, the highest decrease was in fried samples.

    Conclusion

    Overall, whitefish and carp fish were the unhealthiest fish among the three species. In comparison between different cooking processes, roasting and after that grilling resulted in the highest reduction in the sum of three heavy metals and seven elements, in contrast, in the most cases microwaves preserved these elements in cooked fish.

    Keywords: Fish, Heavy metals, microwave, Grilling, Roasting, Frying