بررسی پیش‌تیمارهای اتیل‌اولئات، کلرید‌سدیم و آنزیم‌بری بر خشک شدن تحت خلاء فلفل دلمه‌ای

فلفل دلمه ای جایگاه بسیار مهمی را در میان صیفی جات تولیدی در جهان به خود اختصاص داده است. بنابراین به‌کارگیری راهکارهای عملی برای افزایش ماندگاری آنها برای توسعه و بهبود تولید، ضروری به‌ نظر می‌رسد. عدم پذیرش افزودنی های شیمیایی و تقاضا برای محصولات طبیعی‌تر، توجه به برخی روش ها از جمله روش خشک کردن را افزایش داده است. هدف از انجام این مطالعه، بررسی تاثیر فاکتورهای مختلف به عنوان پیش تیمار شامل آنزیم بری با سه روش، آب 0c100 به مدت 3 دقیقه، اتیل اولئات (با غلظت های 0، 2 و 4 درصد) به مدت 1 دقیقه، کلرید سدیم (با غلظت های 0، 2 و 4 درصد) به مدت 3 دقیقه و عدم انجام آنزیم بری بر سینتیک خشک شدن، خواص فیزیکی، ترکیبات شیمیایی و مواد مغذی فلفل دلمه ای سبز، تحت خشک کردن در خلاء در دمای 60 °c و فشار kpa 10 با استفاده از روش سطح پاسخ است. نتایج نشان داد که کل فرآیند خشک شدن فلفل دلمه ای در محدوده سرعت نزولی بوده و همچنین اثر پیش تیمارهای آنزیم بری در آب 100 °c به مدت 3 دقیقه و غوطه وری در محلول قلیایی اتیل اولئات و کلرید سدیم با غلظت های 2 و 4 درصد به مدت 1 دقیقه، بطور قابل توجهی موجب افزایش سرعت خشک شدن شدند. نمونه های پیش تیمار شده، میزان کلروفیل، ترکیبات فنولی و ویتامین ث بیشتری را نسبت به نمونه کنترل نشان دادند. در حالیکه فرآیند آنزیم بری و محلول اتیل اولئات تاثیر مثبتی بر رنگ نمونه ها نداشته و موجب تیرگی نمونه های فلفل خشک شده گردیدند. مطلوب ترین نمونه از لحاظ حفظ کیفیت شامل بیشترین میزان کلروفیل، ترکیبات فنولی و ویتامین ث، مربوط به نمونه آنزیم بری شده، تیمار شده با غلظت 4 درصد محلول اتیل اولئات و کلرید سدیم بود. بهره گیری از پیش تیمارهای اتیل اولئات و کلرید سدیم را به عنوان روشی مناسب قبل از عمل خشک کردن با مزایایی از جمله حفظ میزان کلروفیل، ترکیبات فنلی و ویتامین ث با صرفه جویی در زمان خشک کردن را به اثبات می رساند.

evaluation of ethyl oleate, sodium chloride and blanching pretreatments on vacuum drying of sweet pepper (capsicum annum)

 sweet pepper (capsicum annum) has a very important place among the vegetables produced in the world. therefore, it is necessary to apply practical solutions to increase their sustainability to develop and improve production. the growing consumer rejection of chemical additives and the demand for more natural products have increased attention to some methods, including the drying method. one of the physical changes that occur during the drying of food is its reduction in volume. vacuum drying is a method in which water and other solvents that have been absorbed into the volume or surface of the material are removed. combining vacuum with heating can be an effective way to dry; because in this case, a high level of dryness can be achieved without the need for a large increase in temperature. a thermal process that is applied to vegetables and fruits as a pre-process step for freezing, drying and canning to inactivating enzymes, modifying texture, preserving flavor and nutrients, and extracting interstitial air.  materials and methods this study aimed to investigate the impact of various factors ethyloleate (concentrations 0,2,4%), sodium chloride(concentrations 0,2,4%) and blanching on the drying kinetics, physical properties, chemical composition and nutrients of green bell pepper, dried under vacuum at 60°c and pressure of 10 kpa using the response surface methodology. at the end of the drying time, 10 g of the treated samples were weighted to investigate the drying kinetics and the rest of the samples were kept for analysis. to achieve the drying kinetics, the samples were taken out of the oven (behdad company, model 3494, made in iran) at 30 minute intervals and weighed by a digital scale, and dried down to moisture content of 12% ., and then for relevant analyzes on dried samples, the samples were stored in plastic packages until the day of experiments. investigation of independent and interaction effects of immersion in different concentrations of sodium chloride and ethyloleate solution on the kinetics and drying time separately in blanching and non-blanching samples on the parameters of color, chlorophyll content, phenolic substances and vitamin c remaining in dried sweet peppers were evaluated using minitab16 software and response level method (rsm). results and discussion the results showed that the drying process occur in the range of falling rate and also effect blanching in boiling water for 3 minutes and immersed in an alkaline solution of ethyloleate and sodium chloride with concentrations of 2 and 4% for 1 minute, significantly increase the drying rate. in blanching and treated samples with 4% ethyloleate and sodium chloride, the drying time was about 3.5 hours, while the control sample was dried under the same conditions for 7.5 hours. pretreatment of samples, showed the chlorophyll content, phenolic compounds and vitamin c were higher than the control sample. due to the effectiveness of ethyloleate in the protection of ascorbic acid, phenolic compounds and residual chlorophyll, the highest amount of ascorbic acid with a value of 39.77 was related to the samples treated in ethyloleate solution with a concentration of 4% and 4% nacl and the minimum value of 17.98 was related to the control treatment. the highest amount of residual chlorophyll was 23.6 in the pretreated samples with a concentration of 4% ethyloleate and 4% nacl and the lowest amount was related to the control sample with a concentration of 12.9%. the color of the dried samples showed that the lowest amount of color changes was related to the non-blanching sample with 4% ethyloleate and 4% nacl with a value of 4.94. while the blanching and ethyloleate solution had no positive effect on the color of pepper and dried samples were dark. comparison of blanching with non-blanching shows that blanching samples cause darkening of the primary color of the samples.the best sample in terms of quality and speed of drying, was belonged to the samples which blanched, treated with 4% solution of ethyloleate and sodium chloride. conclusion in order to achieve the best quality in vacuum drying of pepper samples, pretreatments of blanching and using a concentration of 4% solution of ethyloleate and sodium chloride showed the most desirable quality. the best quality of dried samples were obtained when subjected to constant temperature and pressure during drying conditions. the benefits obtained using the pretreatment of ethyloleate and sodium chloride as an appropriate method of drying include increasing the absorption of water, keeping the chlorophyll, phenolic compounds and vitamin c content with time-saving in drying.