Effect of thawing methods on antioxidant capacity of frozen strawberry (Fragaria x ananassa) and mulberry (Morusnigra)

The aim of this study was to evaluate the antioxidant capacity of thawed frozen strawberries (Fragariaananasa) and mulberries (Morusnigra). Both types of fruit were frozen in a freezer with a cooling rate of 1oC/min and stored at -18oC in 1 week before thawed at ambient temperature, cold temperature (4oC) and in a microwave oven. ANOVA, LSD test and Principle Component Analysis (PCA) were applied to compare the effect of thawing methods. Results showed that different thawing methods significantly affected (P < 0.05) drip loss, vitamin C content, total phenolic content (TPC) and antioxidant capacity of strawberries and mulberries. The strongly negative correlation was found between the drip loss and the remaining vitamin C as well as between the thawing time and the antioxidant capacity of thawed fruit. Among three thawing methods, microwave was considered as the most effective method to retain antioxidant capacity, vitamin C and total phenolic content for both strawberry and mulberry