Resarch On The Key Concentrating Processing Technology Of Red Jujube Juiace And Its Quality Eveluation

Red jujube, which is rich in a variety of nutrition function composition and physiological active substances, has very high value. Red jujube and its products are favored by consumers. In this study, the Qingjian red jujube, purchased from shaanxi Yulin, was used as basic raw material and red jujube juice concentrate processing system was studied. All of the results were as follows:(1) The main composition of red jujube was analyzed and the key factors of softening and extraction were optimized. The results showed that the selected red jujube had high content of sugar, crude protein, fiber, ash, fat, and flavonoids. On the single factor of increasing extraction rate of red jujubet was studies to determine the key factors and orthogonal experiment based on the software of DPS were applied to optimize the best process parameters. The results indicate that the best process parameters of softening as follows: the ratio of material to water is 1:4, treatment temperature is 60 ℃ and time is 25 min. The best process parameters of extraction are also shows that the enzyme adding amount is 0.05%, temperature is 50 ℃ and time is 90 min. In this condition, the extraction rate of jujube red jujube 65%.(2) Based on the pectin enzyme and ultrafiltration method, the clarification process of red jujube juice was evaluated and response surface method based on the software of Design Expert7.0 and SAS 9.0 were applied to optimize the best process parameters.. The results indicated that the best process parameters of enzymolysis as follows: the enzyme adding amount is 0.13 %, temperature is 48 ℃ and time is 120 min. In this condition, the light transmittance of red jujube juice is 96.12%. Besides, the best process parameters of ultrafiltration method are also shows that ultrafiltration pressure is 0.7 Mpa, temperature is 25 ℃ and feeding velocity is 5.5 mL/min,. in this condition, the membrane flux is 39.42% and the light transmittance of red jujube juice is greater than 95%. Red jujube juice treated by ultrafiltration clarification process has a better quality than that was clarified by pectinase.(3) The relationship between soluble solids content and viscosity of red jujube juice was established and the best concentration process parameters of red jujube juice were obtained. The rotary speed was 100 rpm/min, vacuum was 0.095 MPa, concentration temperature was 60 ℃ and the soluble solids concentration was 60 Brix. Under this condition, the red jujube juice concentrate has very good storage stability and quality. The established method can be used for the production of jujube juice concentrate. At the same time, GB/T 18963-18963 of concentrated apple juice was used as reference and the quality standard of red jujube juice concentrate was established.