Changes in phenolic compounds and antioxidant activity of sour–sweet pomegranates cv. ‘Hicaznar’ during long-term storage under modified atmosphere packaging

Abstract

This study was carried out to evaluate the effects of modified atmosphere packaging (MAP) on phenolic compounds and antioxidant activity of sour–sweet pomegranates cv. Hicaznar during long-term storage. Pomegranate fruit were harvested at commercial harvest maturity 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 fruit stored in plastic boxes were used as control. After packaging, all fruit samples were stored at 6±0.5°C at 90±5% relative humidity for up to 210 days, and removed from storage at 60 days intervals for assessing phenolic compounds and antioxidant activity, as well as other quality parameters. After each storage period, fruit were removed and kept at 20°C for 3 days to simulate a period of shelf life. Total phenolic, total anthocyanin contents and antioxidant activity increased slightly until the first 120 days of storage, and then decreased during the rest of the storage. Ascorbic acid, titratable acidity and total soluble solids decreased after cold storage and shelf life, and no significant differences were found among treatments except for total soluble solids. Contents of organic acids were decreased in all treatments during storage, and no significant differences were found among treatments except for tartaric acid. During long-term storage, CO2 levels increased and O2 levels decreased inside both MAPs systems. MAPs significantly reduced weight loss, maintained visual appearance, retarded skin discoloration compared to control fruit. There was no statistical difference in decay incidence between MAPs and control fruit at 210 days of cold storage, while more decay developed on fruit packed in MAPs than on control fruit at 210+3 days SL period. The results indicated that 180 days storage of fruit in the modified atmosphere packaging at 6°C maintained physiological and biochemical properties of pomegranate fruit.