Effect Of Temperature-Controlled Ultrasound-assisted Enzymatic Hydrolysis On Stability And Flavor Of Cloudy Apple Juice

Ultrasonic as a non-thermal processing technology can significantly improve the yield of flavor loss and nutritional quality of fruit and vegetable juice.Enzymatic hydrolysis technology can decompose the cellular material in the pulp and promote the outflow of juice and nutrients in the fruit.The combination of temperature control ultrasonic technology and enzymatic hydrolysis will have a synergistic effect,accelerate the efficiency of enzymatic hydrolysis and improve the quality of cloudy apple juice.Fuji apples were used as the raw material.In this study,the apple juice was studied by temperature control ultrasound and enzymatic hydrolysis technology,aiming at the problems that the pulp cells could not be completely broken and the juice could not be completely outflow during the processing process.First of all,the single factor and response surface experiment were used to determine the addition amount of pectinase cellulase xylanase and the compound of three enzymes according to the juice yield,and to analyze the flavor of fruit juice.Secondly,the key technical parameters of temperature control ultrasonic(ultrasonic temperature,ultrasonic power ultrasonic time)material was explored the apple juice yield stability and flavor.Finally,the temperature controlling ultrasonic joint enzymolysis technology was used to process cloudy apple juice and the quality of juice.This study aims to solve the problems of low juice yield and poor stability and the loss of flavor substances caused by thermal sterilization of cloudy apple juice,to provide technical reference for the application of temperature control ultrasound-assisted enzymatic hydrolysis technology in the production of fruit juice,and promote the further development of cloudy apple juice industry.The main conclusions are as follows:1.Fuji apple was selected as the raw material,the optimal dosage of cloudy apple juice was pectinase 0.15%,cellulase 0.6%,xylanase 0.12%.On the basis of single factor experiment,response surface optimization experiment was carried out for the complex enzyme.The results showed that when pectinase added 0.16%,cellulase 0.57%,xylanase 0.12%,the juice yield of cloudy apple juice was the highest,which could reach 83.02±0.12%.The effects of electronic nose and GC-MS on flavor compounds of cloudy apple juice showed that esters and aldehydes accounted for the largest part in all aromatic compounds.The release of aromatic compounds in apple juice treated with compound enzymes was more,especially aldehydes,esters and alcohols.2.The orthogonal experiment of temperature controlled ultrasonic parameters(ultrasonic temperature,ultrasonic time and ultrasonic power)showed that the optimal ultrasonic conditions were ultrasonic time 10 min,ultrasonic power 750 W and ultrasonic temperature 45?.The experimental results of ultrasonic and compound enzymolysis showed that the apple juice with ultrasonic before enzymolysis had higher juice yield,brighter color,higher cloud degree,highest stability,and higher turbidity degree,and the highest absolute potential.Compared with the control group,the treatment with ultrasonic before enzymolysis could accelerate the release of the contents in the apple juice with better stability.3.The temperature controlling ultrasonic assisted digestion technology was uesd as a technical approach to treat apple juice.The results showed that this technology can effectively increase the juice yield,as high as 86.28±0.04%.Ultrasonic assisted digestion technology has a lot to improve stability and flavor different treatments(ultrasonic processing,enzymolysis processing,ultrasound assisted digestion)of juice.The trend of Zeta potential was changed obviously,the temperature control ultrasonic assisted digestion Zeta potential value of the treatment group is the largest.The stability of cloudy apple juice has a better results on cloudiness value,cloudiness stability and centrifugal precipitation rate.Ultrasonic assisted digestion process full of juice color.Temperature control ultrasonic assisted digestion processing cloudy apple juice can reduce the loss of heat-sensitive aroma substances in the manufacturing process of,to maintain the quality of apple juice original,well can significantly increase the stability.Therefore,this study confirmed the temperature control of ultrasound assisted digestion technology is feasible for cloudy apple juice stability and flavor.