Micronization of defatted rice bran dietary fiber and its particle size effect on the structure and physicochemical properties of myofibrillar proteins

Abstract

This study investigated the effects of defatted rice bran dietary fiber particle size (D₅₀ 111.01–8.85 μm) on silver carp myofibrillar protein structure and gelation. Smaller particles enhanced the ordered secondary structure, with α-helix and β-sheet contents increasing by 45.7 % and 16.6 %. The primary modes of action were enhanced surface area interactions and tertiary structure unfolding, resulting in a 108 % increase in exposed sulfhydryl groups and greater surface hydrophobicity. As particle size decreased, turbidity increased from 0.43 to 0.89 and mean particle diameter from 342 to 535 nm, indicating larger protein aggregates. Fine fibers facilitated protein cross-linking into dense, continuous gel networks, as evidenced by FTIR, fluorescence, and SEM analyses. Practical applications include improving surimi texture uniformity, elasticity, and water-holding capacity while valorizing rice bran by-products. This study proposes a particle size–structure–function mechanism for DF–MP interaction to be optimized and verified via sensory quality, storage stability, and industrial scalability.