Microwave-assisted extraction of jujube polysaccharide: Optimization, purification and functional characterization

The operational parameters involved in microwave-assisted extraction (MAE) of jujube polysaccharide including microwave power, water to raw material ratio and extraction temperature and time were optimized by RSM. MAE at 400 W, 75 degrees C, 60 min, using 30 g water/g powdered jujube was the best condition for maximum yield (9.02%) of polysaccharide. Two novel water-soluble polysaccharides (JCP-1 and JCP-2) with average molecular weights of 9.1 x 10(4)-1.5 x 10(5)Da in term of the symmetrical narrow peaks were identified using the analytical purification procedures. The JCP-1 and JCP-2 mainly composed of glucose, arabinose, galactose and rhamnose in molar ratios of 1.4: 2.1: 4.2: 0.9 and 1.2: 1.8: 4.1: 1.1, respectively. The use of 1.5% JCP-1 led to a high emulsifying stability (95.5%) in a model oil-in-water type emulsion with a reduced surface tension (44.1 m N/m) and droplet size (1.32 mu m), and an increased apparent viscosity (0.13 Pa s) during 21-day cold storage. The antioxidant activities were increased in dose-dependent manners (25-200 mu g/mL). (C) 2016 Elsevier Ltd. All rights reserved.