Antioxidant capacity, vitamin C, phenolics, and anthocyanins after fresh storage of small fruits

Fresh strawberries (Fragaria x ananassa Duch.), raspberries (Rubus idaeus M ichx.), highbush blueberries (Vaccinium corymbosum L.), and lowbush blueber ries (Vaccinium angustifolium Aiton) were stored at 0, 10, 20, and 30 degre es C for up to 8 days to determine the effects of storage temperature on wh ole fruit antioxidant capacity (as measured by the oxygen radical absorbing capacity assay, Cao et al., Clin. Chem. 1995, 41, 1738-1744) and total phe nolic, anthocyanin, and ascorbate content. The four fruit varied markedly i n their total antioxidant capacity, and antioxidant capacity was strongly c orrelated with the content of total phenolics (0.83) and anthocyanins (0.90 ). The antioxidant capacity of the two blueberry species was about 3-fold h igher than either strawberries or raspberries. However, there was an increa se in the antioxidant capacity of strawberries and raspberries during stora ge at temperatures >0 degrees C, which was accompanied by increases in anth ocyanins in strawberries and increases in anthocyanins and total phenolics in raspberries. Ascorbate content differed more than 5-fold among the four fruit species; on average, strawberries and raspberries had almost 4-times more ascorbate than highbush and lowbush blueberries. There were no ascorba te losses in strawberries or highbush blueberries: during 8 days of storage at the various temperatures, but there were losses in the other two fruit species. Ascorbate made only a small contribution (0.4-9.4%) to the total a ntioxidant capacity of the fruit. The increase observed in antioxidant capa city through postharvest phenolic synthesis and metabolism suggested that c ommercially feasible technologies may be developed to enhance the health fu nctionality of small fruit crops.