Structural Properties of Homogeneous Polysaccharide Fraction Released from Wheat Germ by Hydrothermal Treatment

Abstract

The work aimed to enhance the extraction of wheat germ polysaccharides (WGPs) by hydrothermal treatment and identify the structural properties of WGPs. Results showed that the extraction yield of crude WGPs reached 18.72% after steam explosion. A homogeneous polysaccharide fraction (steam explosion wheat germ polysaccharides, SEWGPs) was also released and purified by DEAE-cellulose-52 separation and Sephacryl S-500 HR gel filtration with a yield of 3.84%. The SEWGPs had an average molecular weight of 3.34 × 106 Da and was composed of glucose (32.62%), arabinose (28.27%), xylose (27.71%), and galactose (11.40%). Methylation and nuclear magnetic resonance results indicated that the main linkages of the SEWGPs contained →4)-α-D-Glcp(1→3)-β-D-Xylp(1→3)-α-L-Arap(1→4)-α- D-Glcp(1→3)-α-L-Arap(1→ or →3)-β-D-Xylp(1→4)-α-D-Glcp(1→3)-α-L-Arap(1→ 4)-α-D-Glcp(1→3)-α-L-Arap(1→, and the side chains were α-D- Galp(1→ and β-D-Xylp(1→ linked at the C6-position of →4,6)-α-D-Glcp(1→, respectively. Therefore, the steam explosion facilitated the detection of a more structural nature of WGPs and provided the industrial potential of WGPs as functional ingredients for food-making.