Structure, physicochemical and bioactive properties of dietary fibers from Akebia trifoliata (Thunb.) Koidz. seeds using ultrasonication/shear emulsifying/microwave-assisted enzymatic extraction

Dietary fiber extracts from Akebia trifoliata (Thunb.) Koidz. seeds were generated using alkaline extraction, enzymatic hydrolysis as well as physical pretreatments including ultrasonication, shear emulsifying and microwave. Compared with the basic alkaline hydrolysis, cellulase-assisted extraction exhibited the highest water holding capacity (7.99 g/g), cation exchange capacity (0.55 mmol/g), glucose adsorption capacity (1352.33 μmol/g) and pancreatic lipase inhibition (37.69%). Ultrasonication pretreatment before both the preceding procedures increased the oil holding capacity (3.95 g/g) and α-amylase inhibition (6.81%) of the extracted fiber. Microwave pretreatment generated fiber possessing the greatest specific surface area (137.70 m²/kg), water swelling capacity (1.25 mL/g), adsorption capacity (4.14 mg/g, pH = 2) and sodium cholate adsorption capacity (38.68%). However, shear emulsifying gave the lowest crude yields (57.72%), glucose absorption capacity (22.09 mg/g), α-amylase inhibition (2.77%) and pancreatic lipase inhibition (22.61%) though it contained highest levels of soluble fiber (6.40 g/100 g) and lowest crystallinity (33.6%). A fuzzy statistical evaluation indicated that ultrasonication assisted enzymatic hydrolysis was the most efficient improvement in the overall properties of the dietary fiber. These results provide valuable information for the potential use of A. trifoliata seeds as a new food ingredient and for extraction of dietary fiber from this plant.

Keywords: Akebia trifoliata (Thunb.) Koidz. seeds; Dietary fiber; Hypoglycemic; Hypolipidemic; Physiochemical properties; Ultrasonication assisted enzymatic hydrolysis.