Relation between bioactive compounds and free radical-scavenging capacity in berry fruits during frozen storage

In this work the correlation between the free radical-scavenging capacity and bioactive compounds (anthocyanins, ellagic acid, total phenolics and vitamin Q in four Spanish raspberry cultivars (Heritage, Autumn Bliss, Zeva and Rubi) and Spanish wild blackberry as affected by freezing and frozen storage was evaluated. From this mathematical study a significant correlation was obtained between the radical-scavenging capacity and the anthocyanin and total phenolic contents in both raspberry (r = 0.85 and 0.83 respectively) and blackberry (r = 0.84 and 0.68 respectively) fruits, but no correlation was found between this parameter and the ellagic acid and vitamin C contents. A key objective of this study was to select the raspberry cultivar most suitable for freezing preservation in terms of the stability of its health-promoting constituents. A two-dimensional principal component analysis (PCA) of the raspberry cultivars explained 82% of the total variance of the factors mentioned above. The early raspberry cultivars (Heritage and Autumn Bliss) showed a lower content of bioactive compounds and lower radical-scavenging capacity, while the late cultivars (Zeva and Rubi) showed higher values, and these differences were clearly displayed by the PCA.