Study Of Processing Technology Of Rosa Roxburghii Tratt Juice

Rosa roxburghii Tratt as the third generation fruit with high nutrition and health value is a unique fruit resource in southwest of China.However,Rosa Roxburghii Tratt is too acidic to eat directly,which should be processed before losing economic value.Therefore,in this study,compounding enzymatic extraction of Rosa roxburghii Tratt juice,kinetics of thermal degradation of Vitamin C in normal and concentrated Rosa Roxburghii Tratt Juice,decolorization and tannin removal efficiency of Rosa Roxburghii Tratt juice with macroporous adsorbent resins were investigated systematically,and changes of the main components of Rosa roxburghii Tratt juice were studied.The main conclusions could be summarized as follows:1.Optimizing compounding enzymatic extraction of Rosa roxburghii Tratt juice by orthogonal design.The results showed that factors affecting yield of Rosa roxburghii Tratt juice were as follows: hydrolysis temperature>hydrolysis time>cellulase dosage>pectinase dosage.Optimal conditions were: pectinase dosage was 0.005%,cellulase dosage was 0.07%,hydrolysis temperature was 45°C,hydrolysis time was 0.5 h.Under this conditions,the yield of Rosa roxburghii Tratt juice was 79.89%,which was 10.5% increasing compared to the blank.2.In order to improve processing quality of juice,the kinetics of thermal degradation of vitamin C of normal and concentrated Rosa roxburghii Tratt juice at different heat treatments at temperature ranging from 30 to 70°C were investigated.The results indicated that higher concentration and concentrations of Rosa roxburghii Tratt juice and temperatures could increase the rate of AA and DHA degradation.For normal juice,the degradation rate of AA and DHA achieved maximum values at 60°C.For concentrated juice,the degradation rate of AA and DHA achieved maximum values respectively at 60°C and 40°C.In addition,the activation energy of concentrated juice was lower than that of the normal juice,the activation energy of DHA was lower than that of AA,which suggested that AA and DHA in normal juice was more stable than that in concentrated juice juice,and AA was more stable than DHA.3.In order to remove tannin and pigment effectively and improve the quality of Rosa Roxburghii Tratt juice,macroporous adsorbent resins of LSA-600,LX-920,LX-60 and LX-8were studied.Effects of adsorbent dosage,adsorbent time and adsorbent temperature on decolorization and tannin removal efficiency were investigated,LX-60 exhibited the highest decolorization capacities for Rosa Roxburghii Tratt juice,decolorization and tannin removal efficiency of which was 88.18% and 44.12% respectively.On the basis of static adsorption,four resins were selected for adsorption isotherms.The experimental data fitted better to Langmuir isotherm model for all four resins.After adsorption the polyphenols and total sugar content in Rosa Roxburghii Tratt juice significantly decreased to 79.47% and 70.18% while the retention rate of soluble solids,titratable acidity and vitamin C were 81.40%,84.62% and96.48% separately and the variation of pH was not obvious.Dynamic testing was employed on a column packed with LX-60 resin.Five bed volumes and 3.3 mL/min of flow rate of Rosa Roxburghii Tratt juice resulted in good decolorization and tannin removal efficiency.4.The impact of different molecular weight cut off(20,67,100 kDa)ultrafiltration membrane on changing clarification and nutrients of Rosa roxburghii Tratt juice was studied.The results showed that flavonoids,polyphenols,total sugar,titratable acidity and soluble solids concentration in permeate of Rosa roxburghii Tratt juice was high with 100 kDa molecular weight cut off.Considering of productivity and nutrient retention,100 kDa ultrafiltration membrane was more suitable for Rosa roxburghii Tratt juice clarification.5.This experiment investigated the impact of concentration temperature,concentration multiples and storage conditions on quality of multiple Rosa roxburghii Tratt juice.The optimum temperature of concentrating Rosa Roxburghii Tratt juice under reduced pressure was 45°C.Different concentration multiples of Rosa Roxburghii Tratt juice were processed at45°C by evaporation in the vacuum of 0.095–0.1 MPa,results showed that the loss rate of nutrients,browning index and the total acidity was increased with higher concentration multiples.Compared with the three-fold and four-fold concentrated juice,the rate of nutrient preservation was higher,browning index was lower in two-fold Rosa Roxburghii Tratt juice.Moreover,different concentration of juice production were placed at room(10 to 25°C)and refrigerated conditions(5 to 8°C)for 50 days,their physicochemical properties changes were as follows: Vitamin C and polysaccharides contents were decreased gradually,pH and total acidity did not change significantly,browning index was increased.In addition,2-fold Rosa Roxburghii Tratt juice was instable at room temperature,but the stability of 2-fold concentrated juice at refrigerated conditions was worse than that of 3-fold and 4-fold concentrated juice.