Comparison of Insoluble Dietary Fibers From Sesame Meal by Three Preparation Methods: Structural, Physicochemical,...

Sesame (Sesamum indicum L.) meal, a by-product of sesame oil production, is rich in dietary fiber (DF). However, research on the extraction and utilization of its insoluble dietary fiber (IDF) remained limited. This study investigated the effects of three preparation methods, including the alkaline method (AM), the enzymatic method (EM), and the enzymatic-assisted-alkaline method (EAM), on the structural, physicochemical, and functional properties of sesame meal insoluble dietary fiber (SM-IDF). All three SM-IDFs exhibited characteristic DF Fourier transform infrared (FT-IR) spectra. Scanning electron microscopy (SEM) revealed that the EM prepared SM-IDF (E-IDF) had a looser and more porous structure compared to the AM prepared SM-IDF (A-IDF) and the EAM prepared SM-IDF (EA-IDF). Among them, E-IDF had the smallest particle size of 1.86 µm and the largest specific surface area (S/V) of 7.31 m²/kg. Physiochemically, A-IDF showed the highest water-holding capacity (WHC) of 3.99 g/g and oil-holding capacity (OHC) of 2.23 g/g, whereas E-IDF had the best cation exchange capacity (CEC) of 0.70 mmol/g. Functionally, E-IDF showed good results in hypoglycemic, hypolipidemic, and antioxidant in vitro tests. Compared to A-IDF and EA-IDF, E-IDF had the best glucose adsorption, sodium cholate adsorption, and ·OH radical scavenging capacities, with values of 2.72 mmol/g, 53.09%, and 66.38%, respectively. Pearson's correlation analysis showed that the reduction of particle size and the increase of S/V value significantly improved some of the functional and physicochemical properties of SM-IDF. This study laid the groundwork for further application of SM-IDF in functional foods.