بهینه‌سازی استخراج پکتین از تفاله گوجه‌فرنگی به کمک امواج فراصوت با استفاده از روش سطح پاسخ

پکتین هتروپلی‌ساکارید ساختاری دیواره سلولی گیاهان است و پس از استخراج به‌عنوان عامل ژله‌کننده در محصولات غذایی استفاده می‌شود. این پژوهش با هدف بهینه‌سازی و ارزیابی کمی و کیفی استخراج پکتین از تفاله گوجه‌فرنگی به‌عنوان یکی از عمده‌ترین ضایعات صنایع تبدیلی کشور انجام گرفت. همچنین از امواج فراصوت به‌عنوان روشی نوین و کارآمد جهت استخراج پکتین استفاده شد. راندمان استخراج و درصد گالاکتورونیک اسید پکتین در دامنه ph (25.5/1)، دمای (c°90-60)، زمان استخراج (30-6 دقیقه) و چگالی توان فراصوت (w/ml015.3/0) با روش سطح پاسخ (rsm) بهینه‌سازی شد. همچنین درجه استری، ویسکوزیته ذاتی و خصوصیات امولسیفایری پکتین تفاله گوجه‌فرنگی در شرایط بهینه تعیین گردید. با توجه به نتایج حاصل، بیشترین راندمان (10.5‌%) و درجه خلوص پکتین (65‌%) در شرایط ph برابر 2، دمای c°86، زمان 30 دقیقه و چگالی توان فراصوت w/ml 0.3 به‌دست آمد. تحت شرایط بهینه استخراج، پکتین با درجه استری و ویسکوزیته ذاتی به‌ترتیب 76‌% و dl/g 2.6 حاصل گردید. خصوصیات امولسیفایری پکتین استخراج شده در نقطه بهینه در سه سطح غلظت پکتین 0.25، 0.5 و 1‌% مورد بررسی قرار گرفت. بیشترین فعالیت امولسیفایری (87.5%) در غلظت 1 درصد حاصل شد. با نگه‌داری امولسیون در دو دمای c°4 وc°23، میزان پایداری امولسیون قابل توجهی(99 %) در غلظت 0.25% در دوره‌ زمانی سی روزه به‌دست آمد. نتایج نشان داد، تفاله گوجه‌فرنگی می‌تواند به‌عنوان منبع ارزان قیمتی از پکتین مورد استفاده قرار گیرد.

Optimization of Ultrasoundassisted Extraction of Pectin from Tomato Pomace Using Response Surface Methodology

Introduction: Pectin is a structural heteropolysaccharide in the cell wall of plants and after extraction it is used as a gelling agent in food products. The main sources of pectin are apple and citrus peel, but pectin from various sources, may have unique properties. Therefore, research is ongoing to find new sources of pectin and study their properties. The conventional extracting method is performed using a solution of mineral acids, this process is timeconsuming and has some disadvantages in terms of quantity and quality of extracted pectin. It is very important to look for new methods or modifications to produce pectin with high efficiency and quality. One of the new methods is ultrasonic extraction, which has been studied extensively. The aim of this study was to optimize and quantitative and qualitative evaluation of pectin extraction from tomato pomace as one of the major wastes of industries in Iran. Also Ultrasound was used as a new and effective method for extraction of pectin. Ultrasound assisted extraction (UAE) of pectin from waste tomato pomace was investigated and optimized using Box–Behnken response surface design. The individual and interactive effect of process variables (pH, temperature, extraction time and power density) on the pectin yield and purity was studied. Also, the degree of esterification, intrinsic viscosity and emulsifying properties were determined on optimized conditions.; ;Materials and methods: Tomato pomace was supplied from ATA Company located in Tehran, Iran. It was dried at 60 °C for 36 hours. Then was milled and sieved by 60 mesh size screen. Fatty acids and pigments were removed from tomato pomace and again dried. The obtained powder stored at ambient condition for further uses. Ultrasonic device (Ultrasonic Technology Development Company, IRAN and 400 w, 20 KHz) with 12 mm probe and doubleshell tank was used to carry out the extraction. Response surface methodology (RSM) was carried out to study the effect of pH (1.52.5), temperature (6090℃), extraction time (630 minutes), and power density (0.150.3 W/ml) as input variables on the yield and galacturonic acid (GalA) content as the output (responses). GalA content was determined by colorimetric method (titration), using the 3, 5 dimethylphenol as reagent and Dgalacturonic acid as standard. To determine the degree of esterification, titration method was used. The intrinsic viscosity of pectin was determined by applying a capillary viscosimeter (Cannon Instruments Co., No. 150, CannonFenske, Germany; k = 0.04137 mm2/s2). Emulsifying properties of pectin extracted at the optimal point were investigated at three levels of pectin concentration %0.25,% 0.5 and %1.; ;Results and discussion: The experimental data obtained were analyzed by analysis of variance (ANOVA) and secondorder polynomial models were developed using multiple regression analysis both for pectin yield and GalA content. The models developed from the experimental design were predictive and good fit with the experimental data with high coefficient of determination (R2) value. Pectin yield and GalA content were more influenced by temperature. The highest extraction yield (10.5%) and galacturonic acid content (65%) was obtained at pH of 2, temperature of 86℃, time of 30 min, and power density of 0.3 W/ml, while in the conventional extraction method with the same extraction conditions, extraction yield of 4.5% and galactoronic acid content of 55% was obtained. According to results of this experiment, it can be concluded that main advantage of UAE is considerable shortening of extraction time with enhancement of pectin purity. Under optimal conditions, pectin with a degree of esterification 76% and intrinsic viscosity of 2.6 dl/g was obtained. The highest emulsifying activity (87.5%) was obtained at %1 concentration. By holding the emulsion at a temperature of 4°C and 23°C, the emulsion stability was significant (99%) at the concentration of %0.25 over a period of 30 days. These results showed that tomato pomace could be used as a good source of low cost pectin.