Study on microwave-vacuum drying of Lycium barbarum polysaccharide extracts and analysis of its quality

The influence of microwave power density on the drying dynamics of Lycium barbarum polysaccharide extracts, and the influence of microwave power density, vacuum degree, material thickness on the quality (blunt tonality and the retention rate) of polysaccharidewere were researched by using single factor experiment.The results showed that the rate was increased with the increasing of the microwave power density.The blunt tonality of sample became worse, while the retention rate of polysaccharide increased and then declined with the microwave power density increase.With the increasing of vacuum degree, the blunt tonality of sample decreased and then increased, and the retention rate of polysaccharide increased and then decreased.Material thickness had no obvious influence on the blunt tonality and the retention rate of polysaccharide.The drying conditions were optimized with quadratic regression rotational composite design.The optimum conditions were showed as follows:34.56min of dying time, 95.14% of retention rate and 2.28min of dissolve time were obtained under 2W/g of microwave power density and 0.08MPa of vacuum degree.