بهینه‌سازی شرایط تولید ژله با استفاده از پکتین استخراج شده از پوست سیب‌زمینی و بررسی خواص بافتی، فیزیکوشیمیایی و حسی آن در مقایسه با پکتین‌های تجاری

پکتین مخلوط پیچیدهای از پلی‌ساکاریدها است که به فراوانی در صنعت غذا به‌عنوان ژل‌کننده، ثبات‌دهنده و امولسیفایر مورد استفاده قرار می‌گیرد. پوست سیب‌زمینی منبع غنی از پکتین با درجه استفریفیکاسیون پایین است که عموما به‌عنوان ضایعات دور ریخته می‌شود. برای تشکیل ژل توسط پکتین‌‌های با درجه استری کم، غلظت پکتین، کلرور کلسیم و میزان ph بسیار موثر است. لذا هدف از این پژوهش بهینه‌سازی خواص بافتی ژله حاوی غلظت‌های مختلف پکتین (0.5 و 1 درصد)، کلرور کلسیم (15، 30 و 45) و ) ph2.5 و 4) و مقایسه خواص فیزیکوشیمیایی،  بافتی و حسی ژله تولید شده در شرایط بهینه با ژله حاصل از پکتین تجاری مرکبات و سیب بود. مطابق با نتایج شرایط بهینه برای تولید ژله با استفاده از پکتین استخراج‌شده از پوست سیب‌زمینی با هدف دستیابی به بالاترین میزان سختی ژل (30.0959 نیوتن) و نیروی لازم برای شکستن ژل (27.3431 نیوتن) به‌صورت هم‌زمان با 94.33 درصد مطلوبیت در شرایط ph برابر با 4، میزان کلرور کلسیم 35.2286 میلی‌گرم/ گرم پکتین و غلظت پکتین 1 درصد مشاهده گردید. شرایط بهینه تولید ژله حاوی پکتین پوست سیب‌زمینی برای ژله‌های تجاری حاوی پکتین مرکبات و سیب اعمال گردید و خواص فیزیکوشیمیایی، بافتی و حسی ژله‌ها با یکدیگر مقایسه گردید. نتایج نشان داد اختلاف معنی‌داری بین خواص فیزیکوشیمیایی، بافتی و اورگانولپتیکی ژله‌های تهیه‌شده با پکتین پوست سیب‌زمینی با ژله‌های تجاری مرکبات و سیب مشاهده نگردید. نتایج تحقیق حاضر نشان داد با استفاده از بهینه‌سازی شرایط تولید می‌توان از پکتین پوست سیب‌زمینی در فرمولاسیون ژله استفاه نمود و ژله‌ای با خواص کیفی مطلوب و قابل مقایسه با پکتین‌های تجاری متداول تولید نمود.

Optimizing of production conditions of jelly using pectin extracted from potato peel and examining its texture, physicochemical and sensory properties comparison with commercial pectin’s

Introduction: Nowaday, the demand for low calorie food based and keeping primary features including texture and taste is increasing. Jelly is one of low calorie products produced from fruits and other components, and its consumption is increasing for human health. Jelly is semisolid and transparent product that prepared with the use of sugar or juice and pectin or gelatin and flavor and color may also be added. Potato peels contain valuable substances such as pectin. Using potato peels to produce pectin with appropriate properties can solve the environmental issue resulting from these wastes in addition to make value added product. Pectin is a complex polysaccharide that is found in the wall of early plant texture and in the intercellular layer. Pectin contains a group of rich polysaccharides of galacturonic acid units with lower amounts of different sugars (Baiano, 2014). Two commercial forms of pectin are available: highmethoxyl and lowmethoxyl pectin (high ester and low ester pectin). Highester pectin forms a gel in a solutions containing high soluble solids and acidic systems, whereas lowester pectins form more gel at wider pH and range of solids content but they do require divalent cations to form the gel (Kratchanova et al., 2012). In the food industry, pectin is used as a jellymaking agent, especially in the production of jellies and jams. Pectin is also used in fillers, medicine, pastries, bakery products and also as a stabilizer in juices and beverages, as well as in dietary fiber (Sharma, 2006). Pectin also has therapeutic benefits such as lowering blood cholesterol levels, removing heavy metal ions from the body, stabilizing blood pressure and facilitating intestinal activity (Ptichkina et al., 2008). Temperature, pH, and acid extraction time are the most important factors affecting the extraction yield and quality of produced pectin (Yapo et al., 2007). Currently, almost all commercial pectins are produced from citrus or apple peels, both of which are juices byproducts (Thirugnanasambandham et al., 2014). Therefore, the main objective of this study was to optimize the conditions of extraction of pectin from potato peel by response surface methodology and to compare the physicochemical properties of Jelly produced from potato peel under optimum conditions with Jelly produced from apple and citrus   Material and methods: Potato of Granola variety was purchased from the local market in Ardebil. The chemicals used for the tests include: citric acid, sodium hydroxide, phenolphthalein, and Calcium chloride were purchased from Merck Company (Germany). The method of Hoseeni et al (2017) was used for jelly production with slight modification as follows. In the First step,0.5 and 1% pectin extracted from potato peelings, 30 % Sugar, 0.014 % Cherry edible color and 0.75 % Cherry essential oil were mixed then 100 CC Boiling water was added to the mixture and mixed again. After the sugar was completely dissolved, 15, 30, and 45 mg of calcium chloride was added per gram of pectin. The pH of the samples was regulated by citric acid solution on 2.5 and 4. The heating of the samples was continued until the brix of the treated treatments was set to 42. The prepared samples were kept at room temperature for half an hour. The treatments were then refrigerated for 2 to 3 hours to complete the jelly closing process. For this purpose some jelly characteristics such as texture properties, physicochemical (pH, acidity, brix, moisture and Drainage) and sensory properties of samples were investigated using five point hedonic scale. A oneway analysis of variance and Duncan test (P≤ 0.05) in three replications were used to establish the significance of differences in the experimental data. The results were analyzed using the Minitab version 16.   Results Discussion: Results showed that by increasing calcium chloride, pH and Pectin concentration had a significant effect on increasing the hardness of the gel and the strength needed to make the gel brittle (P≤0.05).The highest hardness of the gel in pectin emulsion extracted from potato peel was 30.0959 N and highest force required to break the gel was 27.3431 N in the most severe extraction conditions at Calcium chloride 35.2286 mg/g, Pectin concentration 1% and pH 4. Results of physicochemical properties showed that there was no significant difference between pH, acidity, brix and moisture of jelly made from apple pectin and citrus and apple commercial pectin. The results of the syneresis showed that the syneresis by the jelly of potato pectin is not similar with jelly from apple pectin and citrus and apple commercial pectin significantly different. Also Results of sensory properties showed that it was no significant difference between jelly from apple pectin and citrus and apple commercial pectin. The results of this study showed that by optimizing the production conditions, potato pectin can be used in jelly formulation and jelly can be produced with desirable and comparable quality compared to the commercial pectins