Abstract:In this work, the changing trends of the amount, composition and bioactivities of oat polysaccharides were investigated using oat as the fermentation substrate and through the combined use of enzymatic pretreatment and Monascus fermentation technology., Results revealed that the yield of polysaccharides reached to 4.50% (W/W) after β-glucosidase hydrolysis followed by Monascus fermentation, which was 1.21 times as high as that for the conventional fermentation group, and 2.23 times as high as that for the unfermented group. HPLC analysis revealed that the fermentation process led to increased molecular weights: 91.12% for molecules in the range of 10~100 ku before fermentation whilst 83.91% with molecular weights greater than 100 ku after fermentation, with the highest molecular weight up to 2.57×103 ku. The composition of monosaccharides changed significantly after fermentation, the proportions of mannose and galactose significantly increased, whilst the proportion of glucose decreased with rhamnose not detected. After fermentation, the oat polysaccharides were composed of mannose (Man), glucose (Glc), galactose (Gal), xylose (Xyl) and arabinose (Ara), at a molar ratio of 2.50 : 6.81: 4.14 : 1.09 : 2.13, and had improved bioactivities. The polysaccharides from fermented oats exhibited a higher hydroxyl radical scavenging activity, ABTS+ radical scavenging ability and a-amylase inhibitory activity, compared to those from unfermented oats. The results of this research present a new approach for deep processing of oats.
