FROM BY-PRODUCT TO BIOACTIVE SOURCE: ANTIOXIDANT EXTRACTS FROM BLACKBERRY POMACE (Rubus fruticosus)

Lipid oxidation is one of the main causes of food deterioration, compromising food quality and shelf life. In this context, the use of natural antioxidants derived from agro-industrial by-products has emerged as a sustainable alternative for the development of functional ingredients. Blackberry pomace (Rubus fruticosus), a by-product generated during fruit processing, has considerable potential due to its bioactive compound content. This study aimed to characterize blackberry pomace obtained from a local agro-industry (Ponta Grossa, Paraná, Brazil) in terms of its proximate composition and to evaluate the effect of solvent polarity on the extraction of antioxidant compounds. Extracts were prepared using 7.5% dried blackberry pomace and hydroethanolic (ethanol/water) or aqueous solvent systems, with or without citric acid acidification, followed by ultrasound-assisted extraction (40 °C for 30 min). The extracts were analyzed for total phenolic content (TPC), total anthocyanin content (TAC), and antioxidant activity using the DPPH assay. The proximate composition revealed the nutritional potential of the pomace, with carbohydrates accounting for the largest fraction (70.82%), mainly associated with structural fibers derived from the fruit skins, as well as a high lipid content (10.49%), attributed to the presence of seeds. Solvent polarity directly influenced the profile of the extracted compounds. The aqueous extract showed the highest total phenolic content, reaching 126.27 mg GAE/g of dry pomace, whereas the hydroethanolic systems favored anthocyanin extraction, reaching 0.38 mg TAC/g. Regarding antioxidant activity, the hydroethanolic extracts showed greater efficiency, with values reaching approximately 9.34 μmol TE/g, about twice those obtained with the aqueous extracts, demonstrating the superior efficiency of the ethanol/water mixture in recovering antioxidant compounds. Citric acid acidification improved extraction efficiency in the aqueous system. These results demonstrate that blackberry pomace has significant nutritional value and considerable potential for application as a food ingredient. Furthermore, the choice of solvent is crucial for the selective extraction of bioactive compounds from blackberry pomace, highlighting hydroethanolic systems as a promising solvent system for obtaining antioxidant extracts with potential applications in food products.

Acknowledgments: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) and Conselho Nacional de Desenvolvimento Científico e Tecnológico - Brasil (CNPq).