Comparative Analysis of Polyphenolic Content and Antioxidant Capacity in By-Products of Different Berry Species and Cultivars

Berry leaves and pomace, which are often considered waste after processing, contain a significant amount of bioactive molecules. This study investigated the polyphenolic content and antioxidant capacity in leaves and pomace of various berry species and cultivars. Samples of five blueberry, three blackcurrant, two redcurrant and two chokeberry cultivars were analyzed to compare the total polyphenol and anthocyanin content and their antioxidant properties using ABTS, DPPH and FRAP assays. The results showed significant differences in the content of bioactive compounds and antioxidant capacity of the different berry cultivars. In general, polyphenol content ranged from 48.55-145.70 mg/g dw in leaves and 7.25- 91.20 mg/g dw in pomace. Anthocyanin content in pomace was between 0.06-10.21 mg/g dw, and all samples showed a high antioxidant capacity. Blueberry leaves and pomace, particularly cv. Aurora, showed the highest polyphenol and anthocyanin concentrations and the strongest antioxidant capacity among all analyzed samples. In blackcurrants, the cv. Titania had the highest values of polyphenols and antioxidant capacity in the leaves, while in the pomace it was cv. Gofert. When analyzing the redcurrants, cv. Rotet stood out in bioactive molecules in both leaves and pomace. For chokeberries, cv. Viking stood out for the bioactive potential of its leaves and cv. Nero for the pomace. These findings highlight the potential of berry leaves and pomace, commonly discarded as by-products, as valuable sources of antioxidants for the development of functional products.