Comparison of different technologies for dietary fiber extraction from cold-pressed corn germ meal: Changes in structural characteristics, physicochemical properties and adsorption capacity

Abstract

This study aimed to evaluate the impacts of different extraction technologies, including alkaline extraction (AL), acid extraction (AC), and enzymatic extraction (E), on the structural characteristics, physicochemical properties and adsorption capacity of soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) derived from cold-pressed corn germ meal to realize the potential of corn processing byproducts. Results revealed that alkaline-extracted SDF (AL-SDF) and acid-extracted SDF (AC-SDF) exhibited the best crystallinity and thermal stability. The particles of AL-SDF and AC-SDF were small with a loose microstructure, which might expose more functional groups, such as carbonyl groups. AL-SDF exhibited a smooth microstructure, whereas acid-extracted IDF (AC-IDF) and enzymatic-extracted IDF (E-IDF) exhibited a porous microstructure. In addition, alkaline-extracted IDF (AL-IDF) showed a significantly higher water swelling capacity (12.43 mL/g), AC-SDF possessed a greater water-holding capacity (12.76 g/g), and E-IDF had an increased oil-holding capacity (3.30 g/g). E-SDF and E-IDF demonstrated better cholesterol adsorption properties. Dietary fiber (DF) is non-starch polysaccharide, which can promote peristalsis of gastrointestinal tract and improve immunity. The DF obtained by different extraction methods had good water retention ability, binding action, swelling performance, etc., and was an excellent functional base material for preparing low and medium GI foods. This promotes the comprehensive use of byproducts from corn processing, thereby increasing their added value.