Biochemical and Techno-Functional Properties of Protein- and Fibre-Rich Hybrid Ingredients Produced by Dry Fractionation from Rice Bran

Rice bran is an underutilized side-stream from white rice production, rich in protein and dietary fibre. The aim of the work was to study dry fractionation as a novel approach to enrich protein from non-heated, supercritical carbon dioxide–extracted milled rice bran. One-step air classification allowed protein enrichment from an original 18.5% up to 25.7% in the fine fraction. Alternatively, air classification of the non-milled raw material resulted in a fine fraction (19.7% protein) that was according to microscopy analysis free of pericarp structures, and a coarse fraction containing protein-rich aleurone and germ particles and pericarp structures. Further milling and air classification of the coarse fraction resulted in higher protein enrichment (to 27.4%). All the fine fractions produced by dry fractionation were also enriched in soluble dietary fibre whereas starch content was decreased. Additionally, the fine fractions showed improved protein solubility and colloidal stability and, thus, elevated applicability in food products as compared to the non-fractionated raw material.