Specialized metabolites profile of strawberry fruit during flash-freezing

Strawberry fruit species given an extremely high water content (90-92%) are prone to rapid spoilage and therefore it is difficult to preserve its fruits for a longer time period. An effective method to preserve strawberry fruits with significant preservation of nutritional and sensory quality is freezing. One of the methods increasingly in use, alternative to conventional freezing, is flash-freezing which implies significantly lower freezing temperatures (cryogenic) allowing freezing for just a few minutes. The aim of this study was to evaluate the effect of freezing method (conventional, flash-freezing) on the content of predominant specialized metabolites of strawberry fruit. Also, to determine the effect of storage period (10, 20 and 30 days) on the content of specialized metabolites. According to the obtained results, significantly higher values of vitamin C (5 times), total phenolic compounds (2 times), non-flavonoids (1.5 times), flavonoids (50%), total anthocyanins (3 times) and antioxidant capacity (2.7%) were determined in strawberry fruits frozen by flash-freezing compared to the conventional method. Also, as expected regardless of the freezing method, content of all analysed specialized metabolites significantly decreased during storage period. It should be emphasized that during storage, however, nutritional quality of flash-frozen samples was better preserved compared to the samples frozen by conventional method. Based on the stated, it can be concluded that flash-freezing significantly preserved the content of all analysed specialized metabolites in strawberry fruits, thus can be recommended as effective method for strawberry processing and storage.