اثر دما و نوع بسته بندي بر ماندگاري ميوه تمشك سياه وحشي تابستانه

Evaluation of Temperature and Container Material Effects on SummerWild Blackberry Postharvest Life

تمشك سياه به علت فسادپذيري سريع و عمر پس از برداشت كوتاه ، امكان نگهداري به مدت طولاني را ندارد. جهت ارزيابي شرايط بهينه نگهداري تمشك، سه دماي نگهداري (صفر، 4 و 25 درجه سلسيوس) و دو نوع بسته بندي (ظروف تجديدپذير و پلاستيك تجديدناپذير) طي چهارده روز مقايسه شدند. صفات مختلف كيفي در قالب كيفيت ظاهري، كيفيت خوراكي و ارزش غذايي مورد ارزيابي قرار گرفتند. نتايج نشان داد وزن ميوه ها طي مدت نگهداري در ظروف و دماي مختلف كاهش يافت. با گذشت زمان علاوه بر وزن، رنگ، عطر، طعم و بازارپسندي ميوه نيز كاهش يافت. كيفيت ظاهري ميوه ها در دماي صفر درجه سلسيوس در ظرف پلاستيكي بهتر از ظرف تجديدپذير بود و مواد جامد محلول در ظرف تجديدپذير به طور معني داري بيشتر از ظرف پلاستيكي بود. يشترين مقدار فنل كل (به مقدار 33/ 62 گرم گاليك اسيد در گرم آبميوه) در روز سوم، دماي چهار درجه سلسيوس و در ظرف پلاستيكي ثبت شد. دماي صفر درجه سانتيگراد، در هر دو ظرف، نسبت به دو دماي ديگر، ميزان كاهش فلاونوئيد كمتري را نشان داده است. ميزان آنتوسيانين در طول آزمايش روند كاهشي نشان داد به طوريكه در دماي صفر درجه سانتيگراد از 90/ 224 در روز نخست به ۵۷/۸۹ و ۹۰/۷۳ ميلي گرم سيانيدين در ليتر آبميوه به ترتيب در ظروف تجديدپذير و تجديدناپذير در روز چهاردهم رسيد اثر مثبت دماي صفر درجه در نگهداري تمشك سياه كاملاً معني دار بوده است. استفاده از ظروف تجديدپذير با وجود اهميت زيست محيطي كه دارد به دليل نفوذپذيري بالاتر نسبت به گازها و رطوبت از كارآيي كمتري در مقابل ظروف پلاستيكي براي نگهداري پس از برداشت تمشك سياه برخوردار است و نيازمند پژوهشهاي تكميلي با بكارگيري فناوري هاي نوين همچون نانو فناوري در ظروف جهت كنترل تبادلات رطوبتي مي باشد.

Background and Objectives Blackberry cannot be conserved for long time due to its short post-harvest shelf life and rapid perishability. Recently, using small plastic containers has become popular that but is unfortunately non-biodegradable and incompatible with the environment so these materials are dangerous for the environment. But using biodegradable packages which are made up by natural materials like starch, corn, potato and wheat can be a suitable substitution. This research aimed to evaluate optimum conditions including temperature and container material for increasing summer wild blackberry shelf life. Material and Methods With the aim of evaluating summer wild blackberry optimum storage conditions, its fruits were compared via three levels of temperature (0, 4 and 25˚C) and two kinds of containers (biodegradable and non-biodegradable) during 14 days. Different characteristics comprising visual quality (fruit weight, fruit weight loss and market acceptance), edible quality (TSS, pH, TA, TSS/TA, flavor and taste) and health value (total antioxidant activity, total phenol content, total flavonoid content and total anthocyanin) were evaluated. Results The obtained results showed fruit weight loos. During postharvest maintenance in all treatments, the highest fruit weight recorded on the first day and after that decreased significantly. In addition to fruit weight, length, width, flavor, taste and market acceptance of fruit decreased during storage, significantly. Visual quality of fruits packed in polystyrene container was better than bio based one. Total soluble solids of blackberries stored in biodegradable package were significantly higher than non-biodegradable container. Inhibitory percentage of DPPH radicals in all treatments showed powerful antioxidant properties of blackberry. The highest phenol content (62.33 gGalicacid/ g fruit juice) of fruits was recorded on the 3rd day at 4˚C in polystyrene container. The lowest amount of total phenol in the same temperature was observed after 8 days storage in biodegradable container. In both containers, the temperature of 0 ˚C showed less decrease of flavonoid content. During the experiment anthocyanin content decreased generally but on the 8 th and 14 th days in polystyrene container and 0˚C, its content increased from 224.99 on the first day at 0oC to 57.89 and 90.3 mg Cyanidin/Lit fruit juice in both containers types on the 14th day, significantly. Discussions Water loss due to transpiration and respiration is the main reason for weight loss during postharvest period. Because of this, using Nano particles in container materials around the fruits to control water exchange can reduce weight loss and influence different fruit characteristics as well. The positive effect of the 0 ˚C temperature on blackberry shelf life was significant. Using a biodegradable package despite its environmental importance showed less efficiency for increasing blackberry postharvest life in comparison with a plastic package and requires further research.