Preliminary Evaluation of Bioactive Compound Profiles and Antioxidant Properties of Selected Agri-Food Wastes

The increasing generation of agri-food waste represents a significant environmental challenge, but also a valuable source of bioactive compounds with potential industrial applications. In this study, selected minimally processed agri-food wastes from the food processing industry were evaluated as potential sources of bioactive compounds and antioxidants. Seven types of agri-food waste were investigated: green bean cutting waste, yellow bean cutting waste, sweet corn waste from the air selector, edamame pods, pepper seed by-products, potato peels, and potato waste from the air selector. Solid–liquid extraction was performed using ethanol at different concentrations (20, 40, 60, 80, and 96%, w/w) as a green solvent. Total polyphenol content (TPC) and antioxidant activity (DPPH, FRAP, and ABTS assays) were determined. The results demonstrated significant differences among the investigated raw materials, with the highest antioxidant activity observed in the potato peel extracts. Specifically, the strongest activity was recorded using 40% ethanol, yielding values of 3.9596 mg TE/g DW for DPPH and 11.4555 mg TE/g DW for ABTS assays. In contrast, the highest FRAP value (2.3970 mg Fe2+/g DW) was obtained with 60% ethanol. The highest TPC was detected in pepper seed by-products, reaching 6.7829 mg GAE/g DW when extracted with 20% ethanol. Furthermore, selected extracts were subjected to LC-MS analysis to obtain a preliminary characterization of their chemical profiles. Untargeted LC-MS analysis identified 115 metabolites belonging to different chemical classes, highlighting agri-food waste as a rich source of bioactive compounds, particularly flavonoids and phenolic acids. These findings demonstrate agri-food wastes as sustainable sources of bioactive compounds and support their valorization within circular economy and green processing frameworks.