POSTHARVEST ETHYLENE APPLICATION AFFECTS ANTHOCYANIN CONTENT AND ANTIOXIDANT ACTIVITY OF BLUEBERRY CULTIVARS

Blueberries are highly perishable fruit valued for their high content of phytochemicals with antioxidant activity. Ethylene triggers gene expression related to anthocyanin biosynthesis. If this effect is observed in blueberry (Vaccinium corymbosum) there is a possibility for modulation of flavonoid content and antioxidant activity in this fruit. Northern highbush blueberry fruit from cultivars ‘Bluecrop’, ‘Goldtraube’, and ‘Ozarkblue’ were harvested at commercial maturity in the region of Sever do Vouga, Portugal, cooled to 4°C, and treated with ethylene at 1000 µl/L for 24 h. Fruit were subsequently packaged in ventilated PET clamshells and stored at 4°C, 70-80% RH, for 56 days. The rate of weight loss and titratable acidity were not affected by the ethylene treatment in ‘Bluecrop’ and ‘Ozarkblue’, but the acidity in ‘Goldtraube’ treated with ethylene is higher. The soluble solids content was higher in ethylene-treated ‘Bluecrop’ and ‘Goldtraube’, but was not in affected ‘Ozarkblue’. Color and firmness were not affected by ethylene. The anthocyanins and antioxidant activity were enhanced by the treatment of ethylene in ‘Bluecrop’ and ‘Goldtraube’, but were not in ‘Ozarkblue’; total phenol content was higher in ‘Goldtraube’ treatment with ethylene. In conclusion, exogenous ethylene induced a cultivar-specific increase in anthocyanin content and antioxidant activity of blueberry without significant depreciation of other quality attributes.