Valorization of rice by-products: Protein-phenolic based fractions with bioactive potential

Supplementary data to this article can be found online at https://doi.org/10.1016/j.jcs.2020.103039.Rice bran (RB) is an important by-product from the rice production with a high valorization potential. The aim of the present work was to explore this potential by considering combined protein and phenolic fractions and enzymatic hydrolysis. The influence of different protocols in the recovery/fractioning of protein were evaluated, including defatting procedures, in rice brans from two very different locations: Portugal and Colombia. The different protein fractions achieved were characterized. Proteins were further hydrolyzed using trypsin and their hydrolysates were characterized in terms of degree of hydrolysis and peptide size. Moreover, the total phenolic content (TPC) and phenolic compoundsâ profile on extracted fractions and hydrolysates of RB from Portugal and Colombia were determined. The functional potential was assessed in terms of antioxidant and antihypertensive activities. Though the protein concentrates had already significant potential bioactivities, protein hydrolysates showed that the TPC, antioxidant and antihypertensive activities significantly increased with the digestion by trypsin. Hydrolysates of RB from Portugal presented a higher antioxidant and hypertensive activities in comparison with hydrolysates of RB from Colombia, moreover it presented a higher content of TPC. This study indicated that the exploitation potential of rice bran can be increased with simple fractioning procedures, that combined protein/phenolic fractions are important to deliver functionality and that hydrolysis can be a relevant tool to release that functionality. Furthermore, regional differences in rice bran composition are also important factors to consider. Overall, this knowledge can be used to increase the industrial potential of valorization for this by-product.The authors acknowledge the financial support of the National University of Colombia, call to International Mobility 2017–2018, COLCIENCIAS call 727 National Doctorates, the ErasmusþProgramme Key Action 1, the Portuguese Foundation for Science and Technology FCT under the scope of the strategic funding of UID/BIO/04469/2019 unit, the European Regional Development Fund and the European Social Fund under the scope of Norte 2020 - Programa Operacional Regional do Norte (BioTecNorte operation - NORTE-01-0145-FEDER-000004 and doctoral advanced training call NORTE-69-2015-15 - ref. NORTE-08- 5369-FSE-000036).