Authors: NURTEN SELÇUK, MUSTAFA ERKAN
Abstract: The effects of two different types of modified atmosphere packaging (MAP) on the physicochemical properties, biochemical composition, and storage quality of sweet pomegranate variety Beynarı were investigated during long-term storage. Pomegranates were harvested at the commercial harvest stage and packed in two different commercial types of MAP (MAP1, sealed in packages made of Xtend® film; MAP2, sealed in bags made of ZOEPAC). Unpacked fruits stored in plastic boxes were used as the control. Following packaging treatments, all packed and unpacked fruit samples were stored at 6 ± 0.5 °C and 90 ± 5% relative humidity for 120 days, and they were removed from storage at 40-day intervals for different quality analyses. Furthermore, after each storage period, fruits were removed and kept at 20 °C for 3 days to simulate a period of shelf-life. During storage, O2 levels decreased and CO2 levels increased inside both packages, and a steady-state atmosphere (17.60-11.95 kPa O2 and 4.40-5.00 kPa CO2) was obtained at day 40 in cold storage. The MAPs significantly reduced weight loss and external physiological disorders, maintained visual quality, and prevented the decline of skin color, L* (lightness), C* (chroma), and hº (hue angle) compared to control fruit. MAP2 was the most effective packaging in reducing weight loss both in cold storage and shelf-life conditions. Titratable acidity and total soluble solids decreased during storage and shelf-life, and no significant differences (P > 0.05) were observed between MAP1 and MAP2. Total phenolic and total anthocyanin contents and antioxidant activity increased slightly until the first 40 days of storage and then decreased during the rest of the storage, although ascorbic acid contents were gradually decreased. Ascorbic acid content was found to be the highest in the control fruit by the end of storage. Contents of organic acids were decreased in all treatments during storage, except for tartaric acid. Malic and tartaric acid contents were higher in control fruit compared to the MAP treatments. However, MAP2 treatment had higher citric acid contents than MAP1 and control fruit.
Keywords: Punica granatum L., packaging, storage, quality, organic acids
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