Changes in Fruit Quality and Antioxidant Activity Depending on Ripening Levels, Storage Temperature, and Storage Periods in Strawberry Cultivars

The aim of this work was to study the changes in fruit quality and antioxidant activity depending on ripening levels, storage temperature and storage periods in two strawberry cultivars (Fragaria × ananassa cvs. Daewang and Seolhyang). Fully ripe strawberry fruits (100% colored fruits) and unripe strawberry fruits (50% colored fruits) were harvested and then stored at 4℃ and 15℃ for 10 days, respectively. Hardness, phytochemicals, sugars, organic acids and antioxidant activity of strawberry fruits were measured after storage for 5 and 10 days, respectively. When fruit hardness was compared between the two cultivars, Daewang showed a greater degree of fruit hardness than Seolhyang. Daewang also showed higher amounts of phenolic compounds and sucrose than Seolhyang. In contrary to this, Daewang was shown to contain lower amounts of anthocyanin and fructose than Seolhyang. However, antioxidant activities of both cultivars were almost identical. When the effects of storage temperature were examined on fruit hardness, fruits stored at 4℃ showed a higher degree of hardness than those stored at 15℃. During the period of fruit storage at 4℃ or 15℃, both cultivars showed marked decline in the contents of phenolic compounds as well as sucrose. Contrastingly, they showed higher amounts of anthocyanin and glucose after 10 days of storage. On the other hand, the contents of organic acids in strawberry fruits were influenced only by the period of storage, not depending on cultivars or temperatures. Antioxidant activities of fully ripe fruits declined remarkably after 10 days of storage, as compared to unripe fruits which showed a minor decrease or increase. When fully ripe fruits of both cultivars were stored at different temperatures, those stored at 15℃ showed a significant decrease in the antioxidant activity as compared to those stored at 4℃. However, changes of antioxidant activity in unripe fruits were minor. These observations in order to supply high quality strawberry suggest that fully ripe strawberry fruits should be harvested for the short-term storage and the appropriate ripe level fruit should be harvested for the long-term storage. Storage temperature is appropriate at 4℃.