Raspberry and blackberry pomaces as potential sources of bioactive compounds

Abstract

Introduction. The concern for obtaining some secondary metabolites with health-beneficial effects has initiated studies on valorization of by-products. In this sense, fruit processing by-products have attracted great interest as sources of bioactive compounds. Materials and methods. Pomaces of rasnberry and blackberry were obtained after juice separation. These byproducts were characterized in terms of total phenolic content (TPC) by Folin-Ciocalteu method and total monomeric anthocyanins content (TAC) by pH differential method. Also, antioxidant activity of pomaces against stable 1,1-dipheny1-2-picrylhydrazyl (DPPH) radicals was evaluated. Results and discussion. Pomace of blackberry was characterized by significantly higher TPC (10.1 mgGAE/g) and TAC (6 mg C3GE/g) compared to raspberry (8.2 and 3.6 mg/g, respectively). DPPH radical scavenging activity was similar, with slightly higher values in pomace of raspberry (11.7 mu molTrolox/g) than in blackberry (10.9 mu molTrolox/g). The total soluble solids was 9.3 degrees Bx in RP sample, significantly lower than in BP sample with value 14.5 degrees Bx. This study indicates that both, raspberry and blackberry pomaces, as wastes of juice production, could be used as a cheap source of bioactive compounds with strong antioxidant activity. Therefore, these pomaces should be considered as a raw material for production of valuable dietary supplements and natural colorants for development of new products with high value added. By-products of fruit processing could be used due to convenience, accessibility and low cost, as suitable way to increase health properties of food. The potential utilization of fruit pomaces could be the enrichment of different products such as bakery products, biscuits, cookies, paste, ice cream, fruit yogurts etc. Additionally, the potential applications of the ethanol used for bioactive compounds extraction in this study must be considered on the basis of the solvent percent choice, liquid-solid ratio, temperature, and time applied. Conclusion. Raspberry and blackberry pomaces, discarded during juice production, represent significant sources of bioactive compounds, such as phenolic antioxidants.