Physical and enzymatic pretreatments of rice bran and their roles in the nutritional value of protein concentrate

Abstract

Protein concentrates from rice bran (DRBC – Defatted rice bran, EDRBC – Deffated rice bran extruded and hydrolyzed, HDRBC – Deffated rice bran hydrolyzed DRB and EHDRBC – Deffated rice bran extruded and hydrolyzed) exhibit not only good content of protein and promising nutritional properties but also appropriate profiles of amino acids to meet daily intake requirements of histidine, lysine, leucine, threonine and valine, in agreement with recommendations issued by the FAO. The average of protein concentrates had a Dig (digestibility) 51% and PDI (Protein Dispersibility Index) 97%. Extrusion resulted in protein concentrate whose content of protein (73%), Dig (65.6%) and recovery (72%) were higher than other pretreatments and had the highest sum of essential amino acids (28.7 g aa .100 g-1 protein). The combination of pretreatments – extrusion and the enzymatic one (EHDRBC) – led to 70% protein, 72% recovery, 67% Dig and low prolamin (30%) in the protein fraction. These concentrates have amino acid profiles similar to commercial whey protein and are good ingredients that may be added to formulations to increase soluble and digestible protein.