Abstract: To explore the changing trend of the inner quality of Lycium barbarum fruits,single factor and orthogonal test were used to optimize the extraction process Lycium barbarum polysaccharide (LBP) of dried fruit of Lycium barbarum by method of microwave extraction,combined with the multivariate statistical analysis to discriminate internal quality for Lycium barbarum fruits.The results showed that the extraction rate of LBP changed with microwave power,extraction time and liquid ratio,and the optimized processes for microwave extraction method for LBP was A1B2C3,extraction power 210 W,material liquid ratio 1∶20 g/mL,extraction time 20min.For Lycium barbarum fruits produced in different,the content of LBP declined with storage time,and Canonical discriminant analysis could divide it into three categories,fresh,stale and aged stale fruits.For 15 brands of Lycium barbarum fruits commercially available,principal component analysis could divide it into three categories,qinghai,ningxia and other production area.The results monitored the changes of Lycium barbarism polysaccharide content,laid method foundation for the detection of the freshness and producing area of Lycium barbarum fruits.

Key words: Lycium barbarum polysaccharide (LBP), microwave assisted extraction, orthogonal test, internal quality