بررسی اثر نگهداری در دمای محیط (25 درجه سلسیوس) بر خصوصیات فیزیکوشیمیایی و ترکیبات زیست‌فعال میوه زغال اخته

زغال اخته (cornus mas l.) یکی از محصولات باغی ایران است که دارای مزیتهای زیادی از قبیل ارزش غذایی و دارویی، سودآوری و حتی صادراتی میباشد. هدف از این تحقیق بررسی تاثیر نگهداری و حمل و نقل در دمای محیط (روش رایج) بر ویژگیهای فیزیکیشیمیایی و ترکیبات زیست‌فعال زغال اخته میباشد. دو روش نگهداری زغال اخته عبارتند از نگهداری زغال اخته در دمای محیط و نگهداری به‌صورت خشک شده. در این بررسی، میوههای زغال اخته در داخل انکوباتور (25 درجه سلسیوس) به مدت 9 روزنگهداری شده و درفواصل زمانی معین (24 ساعته) پارامترهای شیمیایی (ph، اسیدیته، ماده خشک و خاکستر) و میزان افت ترکیبات زیست‌فعال (فنل کل، فلاونوئیدکل، آنتوسانین کل، ویتامین c و ظرفیت آنتی‌اکسیدانی) نمونه ارزیابی شد. نتایج نشان داد که پس از نه روز نگهداری مقدار آنتوسیانین کل از 379 به195 (میلی‌گرم در 100 گرم ماده خشک)، ویتامین c از 1385 به 354 (میلی‌گرم در 100 گرم ماده خشک) کاهش و مقدار فنل کل از 1237 به 2067 (میلی‌گرم در 100 گرم ماده خشک) و فلاونوئید از 491 به 943 (میکروگرم در 100 گرم ماده خشک) افزایش یافت. همچنین فعالیت آنتی‌اکسیدانی به مقدار33% کاهش یافت. با توجه به نتایج حاصل توصیه میشود زغال اخته پس از برداشت در دماهای پایین نگهداری شود و در مدت زمان کوتاهی مصرف شود تا ویژگیهای تغذیهای آن بیشتر حفظ شود.

Changes of bioactive compounds and physicochemical properties of cornelian cherry fruit during storage at ambient temperature (25˚C)

Introduction: Cornelian cherry is one of horticultural crops in Iran. There are about 1094.26 hectares of cornelian cherry orchards in Iran and 2329.36 ton cornelian cherry fruit are produced annually based on statistics of the Ministry of AgricultureJahad. Cornelian cherry fruit is usually consumed in fresh form, but it products are also used in form of dried fruit, jam, pickles, sauce, juice, jelly, marmalade, vinegar, fruit rollups (Golriz et al., 1996; Demir and Kalynoco, 2003; Gulcin et al., 2005) and syrup (Damir et al, 2003; Jayaprakasam et al., 2006). Cornelian cherry fruit is a rich source of antioxidant compounds and has different benefits such as nutritional, medicinal value, profitability and export values (Panatelidis et al., 2006).Total anthocyanins content of most varieties of Cornus are 1510 times higher than other fruits more that are used as anthocyanins source (Vareed et al., 2007). Although it is obvious that bioactive compounds of cornelian cherry fruit are valuable, but there is little information about changes of their composition and activity during postharvest storage. Some parameters such as Storage temperature, light and exposure to oxygen have great influence on the stability of the composition during postharvest storage of the fruits (Kalt et al., 1999). Since cornelian cherry is a climacteric fruit, the aim of the research was studying the effect of storage and transport of cornelian cheery in ambient temperature on physicochemical properties and bioactive compounds. Two ways of cornelian cherry preservation are included storage of cornelian cherry at room temperature and storage in dried form.Materials and methods: Cornelian cherry fruit is supplied from an orchard in the city Horand in east Azerbaijan Province from a high yielding tree. After picking, fruits were sorted and held in incubator (25 ˚C) for 9 days and were sampled at intervals of 24 hours up to 9 days and physicochemical parameters of samples such as pH, acidity, dry matter, Total ash and loss of their bioactive compounds (total phenols, total flavonoids, total anthocyanin, vitamin C and antioxidant capacity) were evaluated. In this research, the effects of storage time on the physicochemical properties and bioactive compounds contents of cornelian cherry fruit during storage at room temperature (25 ˚C) were analyzed by means repeated measurements in time method in three replications. The results obtained were analyzed by using analysis of variance and mean comparison using the least squares (p≤0.05).Results and discussion: The results showed that pH and acidity significantly increased and decreased during storage time respectively. It could be attributed to consumption of organic acids in the respiration pathways as a substrate and use of them by mold. It gradually led to an increase of pH and improved the condition for yeast growth. The results showed that after 9 days storage at 25 ˚C the amount of Vitamin C decreased from 1385 to 354 (mg/100 gd. b). It could be ascribed to oxidation of Vitamin C during storage in presence of air. Total anthocyanins decreased from 379 to 195 (mg/100 gd. b) which is the result of degradation of the compounds in presence of oxygen and condensation of them with tannin and protein compounds during storage at ambient condition) PiljacZegarac et al., 2011). The amount of total phenols increased from 1237 to 2067 (mg/100 gd. b) During 9 days of storage at ambient conditions. The increase of phenolics compounds could attributed to release of them from protein and carbohydrate complexes (Doshi & Adsule, 2008). Prior et al. (2005) concluded that increase of phenolic compounds during storage of fruits could be the result of moisture decrease and reducing sugar content increase and their interaction with folin ciocalteu reagent. Also flavonoid content of cornelian cherries increased from 491 to 943 (mg/100 gd. b) During storage which probably is due to release of flavonoid compound during ripening process in postharvest storage time. Also, the antioxidant activity was reduced to 33%. According to the results, it could be concluded that storage of cornelian cheery fruit in ambient condition significantly decreased the bioactive compounds. Therefore it was recommended that cornelian cheery should be stored in low temperature condition and consumed in fresh form in short time after harvesting in order to remain nutritional properties and bioactive compounds.