Research Progress on Walnut Polysaccharide

Walnut is one of the four major dried fruits in the world with high nutrition and health care value. In recent years, the biological activity of plant polysaccharides has been widely concerned, and the research is also gradually deepened, however, there is few study focused on walnut kernel polysaccharides. Polysaccharides are distributed in all parts of walnut tissues, in order to better develop the nutritional and health effects of walnut polysaccharides, especially the extraction and utilization of walnut meal polysaccharides, the domestic and oversea literatures on the extraction, separation, purification, determination, molecular structure characteristics and biological activity of walnut polysaccharides in recent years had been comprehensively sorted and analyzed, a series of meaningful data and information for walnut polysaccharide research were obtained: ultrasonic and microwave-assisted hot water extraction process had good effect. High yield of polysaccharides was obtained under the extraction technology with temperature higher than 85 ℃ and 150 min extraction time, and ethanol volume fraction more than 90%. After deproteinization by Sevag method, different molecular weight cutoffs and purification with DEAE-Sepharose and Sephadex could obtain multiple polysaccharides with molecular weights ranging from 7 015 to 133 021 u. Walnut polysaccharides in different tissues all contained glucose, rhamnose, galactose, xylose, arabinose and mannose, which indicating that walnut polysaccharides were mainly acidic heteropolysaccharides, they also exhibited various biological activities such as anti-cancer, anti-oxidation, hypoglycemic, antibacterial, and prevention of Alzheimer's disease. The research on walnut polysaccharide might have important practical significance for improving the quality and efficiency of walnut industry chain. © 2021, Editorial Department of Journal of Food Science and Technology. All right reserved.