RESUMO
Recently, the isolation of new health-related bioactive molecules derived from agro-food industrial by-products by means of environment-friendly extraction processes has become of particular interest. In the present study, a protein by-product from the rice starch industry was hydrolysed with five commercial proteolytic enzymes, avoiding the use of solvents or chemicals. The digestion processes were optimised, and the digestates were separated in fractions with four different molecular weight ranges by using a cross-flow membrane filtration technique. Total hydrolysates and fractions were tested in vitro for a wide range of biological activities. For the first time rice-derived peptides were assayed for anti-tyrosinase, anti-inflammatory, cytotoxicity and irritation capacities. Antioxidant and anti-hypertensive activities were also evaluated. Protamex, Alcalase and Neutrase treatments produced peptide fractions with valuable bioactivities without resulting cytotoxic or irritant. Highest levels of bioactivity were detected in Protamex-derived samples, followed by samples treated with Alcalase. Based on the present results, a future direct exploitation of isolated peptide fractions in the nutraceutical, functional food and cosmetic industrial fields may be foreseen.