Research On The Marinating, Drying And Sterilization Process Of Dried Tofu

Dried bean curd(DBC)is a reprocessed product of tofu with high nutrition.Except abundant protein,carbohydrates and fat,it also contains minerals needed by the human body such as iron,calcium,phosphorus,magnesium and so on,which is popular at home and abroad for the function of protecting the heart and supplementing calcium,improving blood circulation and other functions.With wide expansion of the market demand for DBC,the scale and quality of production of DBC in China has increased obviously.Stewed,drying and sterilization are three important links in the process of DBC production.However,some problems as long time and not uniform in the stewed process,the operation based on experience,fuzzy process parameters,high waste,low drying efficiency in drying process,hardening of DBC in the sterilization process led to unstable production and quality of the product,difficulty in adapting to the large-scale and industrial production of modern food,and thereby hindering the further development of the DBC processing industry.In response to these problems,the current study tends to apply ultrasonic stewed technology,air-impingement jet drying technology and thermosonication sterilization technology to the processing of tofu,improving the quality of production and reducing energy consumption.The research results were as follows:1.Taking ultrasonic time,ultrasonic power,temperature and salt concentration as factors,the salt content,unit energy consumption,color and texture of the tofu as evaluation indexes,the optimal process parameters of ultrasonic stewed on the tofu determined by response surface optimization test was:ultrasonic power at 500w,time 22min,temperature at 76℃,salt concentration at 5.0%.Under this condition,the salt content was 1.16%,the unit energy consumption was 8.04 KJ/g,the color difference was 15.98,the chewiness was 1609.49,and the recovery was 0.34.Ultrasonic stewing promoted uniform penetration of salt and shortened the stewed time.Compared with the traditional stewed method,the ultrasonic stewed treatment has low energy consumption and the treated tofu has better flavor,taste and color.2.Taking the air temperature,air velocity and time as the factors,the color,texture and moisture content of the DBC as indicators,the optimal parameters with better product quality of the air-impingement jet drying obtained by the response surface optimization was:air velocity at 9 m/s,air temperature at 72℃,and time was 200 min.Under such conditions,the color difference of DBC was 40.35,the hardness was 1536.41 g,the springiness was 0.98,and the dry basis moisture content was 130.55%.Air-impingement jet drying can significantly improve the drying efficiency of the DBC,shorten the drying time and optimize the drying quality.3.The quality characteristics of the DBC extracted by the factor analysis method were color difference,chewiness and recovery.The optimal parameters of the thermosonication sterilization process was 90 minutes,ultrasonic power at 876 watts,and temperature at 78℃.Under this condition,the color difference of the DBC was 3.91,the chewiness was 1270.5,and the recovery was 0.38.The number of colonies of DBC met the national standard and none of the three pathogenic bacteria were detected.The thermosonication treatment has the advantages of low temperature,high sterilization efficiency,and good preservation of the texture and color.The application of Ultrasonic stewed,air-impingement jet drying,and thermosonication sterilization technology to the production of DBC can improve the efficiency of stewed and drying process,lower the temperature of sterilization,and better maintain the texture and color of the product.Research is of great significance for realizing the upgrading of traditional soybean products industry and promoting the social development and economic benefits.