: Soybean straw was utilized as a raw material to extract hemicellulose by employing an alkaline solution. The structure of polysaccharides was analyzed using UV-visible, infrared, and nuclear magnetic resonance (NMR) one-dimensional and two-dimensional spectra. At the same time, the monosaccharide components and surface structure of xylan in soybean straw were analyzed. The in vitro antioxidant activity of soybean straw xylooligosaccharides (XOS) was evaluated using DPPH clearance and reducibility tests. Additionally, the probiotic activity of Lactobacillus acidophilus and Bifidobacterium animalis was assessed. UV-visible light scanning indicates that the proteins and nucleic acids in the hemicellulose have been removed. High-performance liquid chromatography (HPLC) analysis reveals that soybean straw hemicellulose B primarily consists of L-glucuronic acid, D-mannose, D-mannuronic acid, D-galactose, D-aminogalactose, D-glucose, D-xylose, and L-fucose, with a molar mass ratio of D-xylose at 94.33%. After hydrolysis by xylanase, oligosaccharides with a degree of polymerization of 2-3 are obtained. Scanning electron microscopy (SEM) showed that oligosaccharides were polymerized. Fourier transform infrared (FT-IR) spectroscopy, one-dimensional NMR, and two-dimensional NMR analyses indicate that XOS contain methyl and methoxy groups, and sugar residues are primarily linked through β-1-4 glycosidic bonds. In vitro antioxidant tests have shown that soybean straw oligosaccharides exhibit strong DPPH scavenging and reducing abilities. Furthermore, soybean straw oligosaccharides exhibit probiotic activity to Lactobacillus acidophilus or Bifidobacterium animalis.
Wenming Jiang, Xingchen Guo, Mingxing Liao, Chunqing Hao, Jingxia Chen, Fang Li