Effects Of Processing Prcocedure On Qulity Characters Of Huyou Juice And Fermented Huyou Juice

In order to develop a fermented Huyou juice product with rich flavor,positive taste and rich nutrition,this project aims to solve the problems of low yield,loss of nutrients,poor flavor of Huyou juice and cooking flavor of fermented products.Firstly,the enzymolysis treatment of Huyou juice was used to solve the problem of low juice yield.The effect of enzymolysis on the quality of Huyou juice and fermented Huyou juice during fermentation were explored.Secondly,the thermal sterilization and non-thermal sterilization methods were compared.The differences in the quality of Huyou juice and fermented Huyou juice products by different sterilization methods were explored.The research results can reveal the quality change regularity of Huyou juice and fermented Huyou juice during the processing,and provide technical guidance for the processing of Huyou Juice and its fermented products.This study is researched about the following three aspects:1.The optimization of enzymatic hydrolysis technology for Huyou juiceThe Huyou juice is an important material for fermented fruit beverage production by probiotics.The enzymatic hydrolysis of Huyou pulp treated with pectinase and cellulose for improving Huyou juice yield was researched in this paper.The effect of composite enzyme dosage,enzyme ratio(pectinase/cellulase),hydrolysis temperature and time on enzymatic hydrolysis was investigated.The response surface methodology was used to optimize the enzymatic conditions and the optimal conditions for enzyme dosage,pectinase-cellulase ratio,hydrolysis temperature and time were obtained as 0.05 %,3,53 ? and 97 min,respectively.Under the optimum conditions,the juice yield reached 65.72 %.The titratable acid in Huyou juice was 1.14±0.10 %.The results was of value for guiding the actual production of Huyou juice.2.Effect of enzymolysis on the quality of Huyou juice and fermented Huyou juiceIn order to clarify the effect of enzymolysis on the quality of Huyou juice and fermented Huyou juice,indicators of juice yield,light transmittance,viscosity,centrifugal sedimentation rate and main nutritional and functional components of Huyou juice under the optimal enzyme treatment conditions were investigated.And the effect of enzyme treatment on the changes of significant indexes in the fermentation process of Huyou juice was studied.The experiment found that enzymatic hydrolysis improved the juice yield and light transmittance of Huyou juice,and the viscosity and centrifugal sedimentation rate were reduced,making it clearer and more stable.Enzymatic hydrolysis had little effect on the p H and titratable acid content of Huyou juice.While the total sugar,reducing sugar,soluble solids content and soluble pectin content were increased.After enzyme treatment,the content of VC in Huyou juice decreased significantly(p<0.05),the total phenol and total flavonoid content increased slightly.Compared with the non-enzymatically Huyou juice,the total phenol content increased by 31.7 mg/L and the flavonoid content increased by 22 mg/L.During the fermentation process,the p H and titratable acid content of fermented Huyou juice in the treatment group were significantly different from the fermented Huyou juice in the control group(p<0.05).At the end of the fermentation,the titratable acid content of fermented Huyou juice in the treatment group was 0.23 % higher than that of the fermented Huyou juice in the control group,and the viable counts was 0.42 lg CFU/m L higher.Enzymatic hydrolysis was more beneficial to the growth of Lactobacillus plantarum L1 and Lactobacillus fermentum L2 in Huyou juice.At the end of the fermentation,the total phenol content of the fermented Huyou juice in the treatment group reached 561.13 mg/L,which was 43.53 mg/L higher than that in the control group.It is shown that the enzymatic hydrolysis can improve the quality of Huyou juice and the quality of fermented Huyou juice.3.Study on sterilization methods for the quality of Huyou juice and fermented Huyou juiceIn this chapter,fresh Huyou juice and fermented Huyou juice were used as research objects.The fresh Huyou juice was pasteurized(85 ?,15 min)and dimethyl dicarbonate(DMDC)sterilized(25 ?,5 h),respectively.The sterilization effects of the two sterilization methods were compared.And the effects of two sterilization methods on the quality and flavor of Huyou juice and the quality of fermented Huyou products were compared.The results showed that the application of DMDC to a Huyou juice preparation can ensure the microbiological safety,keep the flavor of Huyou juice from being destroyed,maintain the original color and reduce the loss of nutritional ingredients.Neither sterilization method would affect the growth of Lactobacillus plantarum L1 and Lactobacillus fermentum L2 in Huyou juice.Compared with fermented pasteurized huyou juice,the fermented DMDC-treated Huyou juice showed a better color,which was closer to fresh huyou juice(p>0.05).It also showed a better odor and overall acceptability in the sensory evaluation,and retained more total phenol and total flavonoid contents.Some indicators of two fermented products showed a slow downward trend such as the viable count,p H,L* value,b* value,ascorbic acid,total phenol content and total flavonoids content during storage at 4 ?.The a* and ?E* value showly increased.The viability counts of lactic acid bacteria in both the pasteurized and DMDC-treated huyou juice maintained at 7.0 lg CFU/m L after 4 weeks of storage at 4 ?.In summary,DMDC can be an ideal alternative to pasteurization of Huyou juice.Compared with pasteurization,DMDC has played a positive role in improving the flavor and quality of Huyou juice and fermented Huyou juice.