Study On Pasteurization-ultrasonic Sterilization Performance Of Soymilk

As a traditional beverage in China,soybean milk is deeply loved by the domestic public.At present,pasteurization is commonly used in industry,but due to its long sterilization time and great damage to nutrients,it has gradually been unable to meet the needs of the market.In order to improve the quality of soybean milk and shorten the sterilization time,a set of ultrasonic pasteurization device was developed in this paper.Compared with pasteurization technology and ultrasonic sterilization technology,the influencing factors in the operation process were analyzed and optimized by orthogonal experiment.The conclusions are as follows:(1)In the single factor experiment of pasteurization,in a certain range,the sterilization rate of soybean milk increased with the increase of sterilization time and sterilization temperature;When the pasteurization conditions were changed,the p H value of soybean milk was between 6.6 and 6.8,and there was no significant change;With the increase of sterilization time and temperature,the brightness value of soybean milk gradually decreased and the color difference gradually increased.(2)In the single factor experiment of ultrasonic sterilization,in a certain range,the sterilization rate of soybean milk increased with the increase of ultrasonic power and ultrasonic power,and increased with the extension of ultrasonic action time;The p H value of soybean milk decreased slightly with the increase of ultrasonic frequency and ultrasonic power,and decreased slightly with the extension of ultrasonic action time;With the increase of ultrasonic power,ultrasonic frequency and ultrasonic action time,the brightness value of soybean milk gradually decreases and the color difference gradually increases.(3)Comparing pasteurization with ultrasonic sterilization,it is found that the sterilization time of ultrasonic sterilization is shorter and the sterilization effect is slightly better than pasteurization,but the color difference of soybean milk is large after ultrasonic sterilization.The two sterilization methods have no great influence on the p H value of soybean milk.(4)The sterilization rate,p H value and color change of soybean milk after ultrasonic pasteurization were compared with pasteurization and ultrasonic sterilization respectively.It was found that ultrasonic pasteurization could improve the sterilization rate of soybean milk,shorten the sterilization time,and had no significant effect on the change of p H value of soybean milk.When the best sterilization effect was achieved,the color difference was less than that of ultrasonic sterilization,which was close to that of soybean milk after pasteurization.(5)Through orthogonal experimental design,the regression models of sterilization rate and color difference of soybean milk with ultrasonic frequency,ultrasonic power,sterilization time and sterilization temperature are obtained,and the best operating parameters are obtained.When the ultrasonic frequency is 28 k Hz,ultrasonic power is 113 w,sterilization temperature is 88 ℃,sterilization time is 12 min,the sterilization effect is the best and the color difference is small.At this time,the sterilization rate of soybean milk is 98% and the color difference is 8.66.