Dietary fibre enrichment from defatted rice bran by dry fractionation

Abstract

Defatted rice bran is excellent source of dietary fibre. The mostly used lab-scale method to extract dietary fibre is not very efficient; dry fractionation is a more energy efficient alternative at larger scale. Three separation routes were studied: two-step electrostatic separation, sieving and a combination of electrostatic separation and sieving. All yielded fibre-enriched fractions with similar yield (20–21%) and purity (67–68% dm), which recovered 42–48% of the fibre from original rice bran flour. The enriched fraction obtained by two-step electrostatic separation contained more small particles and possibly different DF composition compared to the other two, which resulted in different functional properties. Compared to dietary fibre extracted by enzymatic-gravimetric method, enriched fractions by dry fractionation have a similar water retention capacity and oil bind capacity. This suggests that fibre-enriched fractions by dry fractionation can be applied in foods and provide similar technological and physiological properties as wet-extracted dietary fibre does.