Element Composition, Total Phenolics and Antioxidant Activity of Wild and Cultivated Blackberry (Rubus fruticosus L.) Fruits and Leaves during the Harvest Time

Abstract

In Europe, blackberry (Rubus fruticosus L.) fruits are cultivated for fresh or processed products, and the leaves are collected for medicinal uses mainly from wild-grown populations. In this study, mineral composition, total phenolic content (Folin-Ciocalteu’s method), and total antioxidant capacity (ferric reducing ability of plasma, FRAP) of blackberries were determined during the harvest period. Leaves and fruits were harvested from wild-grown and cultivated plants at the same locations. Results showed that sampling time and growing place influenced the element composition. Concentration of Ca, Fe, K, Mg, P, Zn was significantly higher in cultivated fruits, however, content of Al, Cu, Mn was higher in wild-grown samples. Total phenolic content (TPC) and FRAP values in the leaves increased slightly during the vegetation period. Fruits were harvested at the same maturity stage, their TPC and FRAP level were not influenced by the harvest time. TPC and FRAP levels were higher in blackberry fruits than that in leaves. Significant differences were obtained for TPC and FRAP between wild and cultivated plants, both parameters were higher in the cultivated blackberries. Positive linear correlation was found between the TPC results of wild and cultivated blackberry leaves and fruits, and the same was true for FRAP values. Between TPC and FRAP also a strong positive relationship was observed both in leaves and fruits. Our findings suggest that cultivated blackberry fruits had higher mineral level and antioxidant properties than the wild ones; however, the antioxidant power of leaves from wild populations was similar to that of cultivated plants.