Comparisons of the micronization, steam explosion, and gamma irradiation treatment on chemical composition, structure, physicochemical properties, and in vitro digestibility of dietary fiber from soybean hulls

The objective of this study was to compare the effects of the micronization (MT), steam explosion (SE), and gamma irradiation (GI) treatment on the chemical composition, structure, physicochemical properties, and in vitro digestibility of dietary fiber from soybean hulls. GI (1200 kGy) treatment exerted the optimum effects on improving soluble dietary fiber content, in vitro gross energy digestibility (IVGED), and reducing sugar yield (RS) in the three modification methods, increased by 342.88%, 55.24%, and 117.02%, respectively. Compared with GI treatment, MT-GI combined treatment could further enhance the degradation effect of irradiation and improve the physicochemical properties (p<0.05) in soybean fibers. From the results of correlation analysis, RS was a significant positive correlation (p<0.05) with IVGED, and RS = −112.24 + 4.90 × IVGED (r2 = 0.82, p<0.01). In summary, MT-GI combined treatment could be considered the ideal modification method to improve the quality of soybean fiber.