The Research Of Process Crafts And Quality Of High Intensity Pulsed Electric Field Strawberry Juice

The traditional thermal pasteurization processes are effective on sterilization of strawberry juice. However, they cause strawberry color deepened, heat-sensitive material losses, and changes in antioxidant activity etc. In order to produce high quality and antioxidant activity strawberry juice, and to ensure the safety of fruit juice, to evaluate the application of non-thermal processing technology on the processing of high-quality strawberry juice, inactivation of microbe,and effect on the quality of pear juice by PEF were investigated. The main contents are as follows:Process parameters of strawberry juice were optimized by the combination experiments, with strawberry juice and transmittance rate indicators enzymatic. The results showed that the optimal parameters were as follows:0.06%pectin added, enzymolysis time80min, enzymolysis pH3.8, enzymolysis temperature40.0℃. Under the condition, the juice yield was90.40%; the clarity was88.98%, consistent with the prediction value.On the basis of enzymatic hydrolysis, the high-pressure pulsed electric field sterilization effect on the total number of colonies in strawberry juice, sterilization process parameters was optimized by orthogonal. The results showed that:2.5-fold dilution of the enzyme strawberry, select6continuous process chamber, a bipolar pulsed negative; field strength is set to select the30kV/cm, by changing the material flow, fixed pulse width and frequency control of the total treatment time of280μs, water bath temperature30℃(pulse width of2μs, a pulse frequency200Hz), can achieve commercial sterility requirements.To research the effect of heat treatment temperature and time on the quality of strawberry juice, strawberry juice were treated by using45,55,65,75,85,95℃for were5,10,15,20minutes, and determine its quality indicators, the results showed that:not all strawberry quality indicators with the treatment temperature increases, so that the processing temperature conductivity increases; processing temperatures make ascorbic acid content, total acid content, total sugar content decreased; processing temperature makes the class carotene content decreased after the first rise; temperature in the range of45～65℃, strawberry antioxidant activity increased rapidly decline after reaching95℃, due to the carotenoid and antioxidant activity had decreased after an initial increase, heat sterilization strawberry quality indicators are not necessarily lower than PEF sterilization strawberry juice.To evaluate the quality of PEF strawberry juice, strawberry juice were determined not sterilization, heat sterilization strawberry juice, strawberry juice quality and impact of PEF sterilization antioxidant activity, the results showed that:compared with unsterilized strawberry juice, hot sterilization make strawberry conductivity and carotenoid content, hydroxyl radical scavenging capacity increases, and the rest of the indicators reduce the impact on the indicators strawberry significant; HPEF sterilization indicators to make strawberry juice reduced, in addition to ascorbic acid, the total phenol content outside influence not significant; contrast with unsterilized strawberry, strawberry PEF quality indicators change to a lesser extent, nutrition and antioxidant activity more complete reserves the strawberry juice.To further evaluate the commercial value of sterilization PEF strawberry, verification process feasibility, heat sterilization of the experimental comparison strawberry and strawberry PEF sterilization storage stability at4℃,25℃conditions, the following conclusions: Storage two months later, the detection can achieve commercial sterility requirements juices, juice showed good sterilization effect; during storage, two sterilized strawberry growth in both pH and conductivity, high-voltage pulse sterilization strawberry water quality significantly better; Storage during the two sterilization strawberry hydroxyl radical scavenging capacity, DPPH radical scavenging, super overcast oxygen ions clearance rate, ORAC antioxidant capacity were decreased,4℃storage strawberry HPEF sterilization is more stable; PEF sterilization strawberries juice color, aroma, and taste during storage than heat sterilization strawberry juice.