Study On The Stability And Quality Degradation Kinetics Of Cloudy Strawberry Juice

The processing technology ,storage stability and degradation kinetics of quality degradation kinetics of cloudy juice strawberry were systematically studied on strawberry in this paper. And it provides scientific basis for design of processing technology, quality control and storage technology of cloudy juice strawberry. The main research content as follows:It mainly studied the enzymatic process of strawberry pulp, and researching the change of vitamin C proportion during the processing of cloudy strawberry juice. The study shows: a. Based on single-factor experiment, it analyzed the effects of one degree term, quadratic term and interaction of enzymatic hydrolysis conditions on rate of juice, anthocyanin content and turbidity. A analysis of perpendicularity and universal design, the best hydrolysis condition: enzyme concentration is 6.22mg/100ml, digesting temperature is 47.76℃, hydrolytic time is 63.56min. Under this condition, the juice yield is 83.80%,anthocyanins content is 15.87mg/100ml, turbid is 333NTU. The optimal enzymatic hudrolysis condition is reliable verified by experimental verification. b. Research shows: Pretreatment has remarkable effect on the proportion of vitamin C.And the vitamin C had higher proportion after washing for 2 min in 0.05%KMnO4, blanching for 2 min in 95℃water. During enzymolysis procedure, it was useful for keeping higher proportion of proportion by adding 0.02% phytic acid and 0.03% tea polyphenol. And it can reach the best effect of 90.92% after sterilizing for 10 min when the temperature at 100℃.In stability study of cloudy strawberry juice, it mainly studied the effects of stabilizing agent and homogenizing conditions on suspension stability of cloudy strawberry juice, and primarily discussed storage stability mechanism of cloudy strawberry juice. The research shows: the optimum composition of mixed stabilizers: xanthan gum: acid resistance CMC-Na: guar gum=2:3:1;It could keep the better stability of cloudy juice to add 0.12% mixed stabilizers for improving the viscosity of cloudy juice and the absolute value of negative Zeta; The best homogeneity process conditions is 60℃,30Mpa, 2 homogenates, it can effectively reduce the unstable suspended substance; storage temperature had the maximum influence on cloudy strawberry juice, low temperature storage was beneficial to the stability, the cloudy strawberry juice still had better stability after 6 months storage under the conditions of 0℃and 4℃. In order to propose a degradation dynamic model of anthocyanin in cloudy strawberry juice, the thermal of anthocyanin in cloudy strawberry juice was studied under different pH values,temperature and heating time. The results shows that the degradation rate is actually accelerated along with the increase of temperature and pH value , the degradation of anthocyanin in cloudy strawberry juice follows the first-order reaction kinetics, the activation energy is 63.69 kJ·mol-1 and the reaction constan(tA)is 1.24×109 when pH is 3.3.The related coefficient between theoretical value and experimental value is 0.9876, which indicate that this kinetics model of anthocyanin is effective.In order to clarify the influence of storing temperature on degeneration of the vitamin C in cloudy strawberry juice, its degeneration dynamic model was established,and the foundation for cloudy strawberry storing was provided.The relationiships among storage temperature,storage time and degradation of ascorbic acid(AA) and dehyd roascorbic acid (DHAA) in the process of cloudy strawberry juice storage were analyzed, and the degradadion dynamic model of ascorbic acid and dehydroascorbic acid was established.Results show that ascorbic acid and dehydroas- corbic acid of cloudy strawberry juice in the storage process are unstable to the heat treatment; the degradation of ascorbic acid and dehydroascorbic acid accords with first-order kinetics, which indicates that this degeneration dynamic model is logical and effective, and can be used in selection of storing temperature and prediction of storage period at different temperatures.