Extraction of Rice Bran Protein Screening of enzymatic digestion, solubilization using pH shift and mechanical disruption through bead milling

Abstract

Due to the amino acid composition, protein digestibility and protein functionalities, the abundant side stream rice bran has potential as a plant-based protein source for human nutrition. Valorizing this side stream would reduce food losses in an already existing food processing chain and thereby reduce climate impact. This project aimed to find a protein extraction method suitable for rice bran. Three methods were investigated, separately and in combination: Enzymatic digestion, solubilization using pH shift, and mechanical disruption using bead milling in water phase. The protein yield from different extraction conditions were compared and analyzed. In addition, the protein yields were compared between rice bran with different pretreatments. Defatted, heat stabilized, and unprocessed rice bran were evaluated. It was concluded unprocessed rice bran consistently resulted in the highest protein yields. The best extraction method was mechanical disruption through bead milling in combination with solubilization using pH shift. Using several extraction steps also increased the protein yield. The study confirms previous studies where pH shift and mechanical disruption increased protein yields. Further studies are needed to understand how these treatments affect unprocessed rice bran protein functionalities and taste.