Abstract: The effects of drying pretreatments (oven drying and vacuum freeze drying) and factors of reduced pressure boiling method (vacuum degree, temperature, water/solid ratio, extraction time, et al.) on the polysaccharides and protein yield of Ziziphus jujube Mill.cv.Hupingzao were investigated in this study.The result showed that drying methods had significant effects on color difference of jujube powder and its polysaccharides and protein yields,but little effect on moisture content.With comprehensive consideration,vacuum freeze drying was a better method for jujube drying pretreatment with lower color difference and protein yield as well as higher polysaccharides yield.The optimum extraction conditions of reduced pressure boiling method were:system temperature of 60 ℃,water/solid ratio of 50:1 (mL:g),time of 30 min,vacuum degree of 80 kPa,external temperature of 71 ℃.Under these conditions,the protein and polysaccharides yields were 2.14 mg/g and 26.05 mg/g,respectively.Compared with traditional water extraction,the polysaccharides yield was improved by 16.66%.

Key words: Ziziphus jujube Mill.cv.Hupingzao, drying, reduced pressure boiling method, polysaccharides, protein