Papaya seeds (Carica papaya L. var. Formosa) in different ripening stages: unexplored agro-industrial residues as potential sources of proteins, fibers and oil as well as high antioxidant capacity

The use of whole fruits and vegetables, including the parts usually discarded during food processing, is an alternative to reduce the quantity of agro-industrial wastes. This study aimed to evaluate papaya seeds’ nutritional and bioactive potential in two ripening stages. The seeds in the stages 0 and 5 of ripening were analyzed regarding their physicochemical composition, while the oil and the hydroethanolic extracts of the seeds were studied in respect of their fatty acid profile, total phenolic content, antioxidant and antimicrobial capacities. The seeds in both ripening stages show good nutritional quality, because they are sources of protein, fiber, and oil. The oil extracted from the seeds is majorly composed by oleic fatty acid (around 70%). The seeds extracts did not present antimicrobial activity against Salmonella enteritidies, Escherichia coli e Staphylococcus aureus. However, they presented high contents of total phenols (58.1 and 36.0 mg GAE⁄g dry extract for seeds in the ripening stages 0 and 5, respectively) and good antioxidant capacity, according to the FRAP and ABTS assays. Papaya seeds provide nutrients and bioactive compounds and their use is a promising alternative to reduce the disposal of food wastes in the environment.