Study On Clear Jujube Juice And Comprehensive Utilization Of Byproducts

Jujube is a kind of food with high nutritional and officinal value. Itcontains many kinds of ingredients with nutritional function or biological activity. It is ofgreat significance to exploit and utilize the jujube resource in China deeply. In this paper,processing technique of clear jujube juice was studied and comprehensive utilization ofjujube peel and residue was also researched.Juice was prepared by pectinase enzymolysis to improve the rate of extraction. Basedon experiment result, the optimum boiling condition and enzymolysis condition weredetermined. The optimum boiling condition was 1∶6 material-liquor ratio, at 100℃ for 20minutes. The optimum enzymolysis condition was 73.83u/g adding amount of pectinase,pH 3.5, at 50℃ for 1.5h. Under the optimal preparing condition, the rate of extractioncould attain 54.17%, 16.9% higher than the extraction ratio of hot water method. The timeused in produce was 2~3 hours sooner than the technique reported. The final juice hadnatural color and good flavor.Based on analysis of precipitate in juice, protein and polyphenol were considered tobe main ingredients of precipitate. Effects of different clarification methods andclarification technique were studied. Ultrafiltration was determined to be the bestclarification method. The optimum condition was membrane with MWCO 30,000 at0.20MPa. The final juice had a transmittancy of 97.1%. After being stored for 3 months,the clear juice remained limpid without precipitate. After being diluted, concentrated clearjuice with soluble solids content of 73% stored for 3 months still remained initialtransmittancy and good stability.Pigment in jujube peel was extracted by alkali method and the extraction method wasoptimized. Under the optimum condition: 3%NaOH concentration, 1∶40 material-solventratio, at 100℃ for 100min, yield of crude pigment could reach 21.27%, with good stabilityfor light, heat treatment, reducer, K+,Ca2+,Zn2+,Mg2+, sugar, citric acid and so on.Residue and fresh jujube mud were mixed to prepare jujube jam. Low sugar jujubejam was manufactured with LM-pectin, calcium chloride and aspartame. The product hadcharacteristics of stable texture, good flavor and low calorie.