Effects of drying and sterilization on the quality and shelf life of semimanufactured soybeans

Traditionally, soybeans are soaked in water for a dozen of hours in soymilk processing. To make instant soymilk, soybeans were semimanufactured (SM) by using different dehydration and sterilization methods, and their effects on the product quality and shelf life were investigated. Results indicated that the instant soymilk made from the SM soybeans using hot-air drying and combined sterilization method exhibited the highest quality. The shelf life of the SM soybeans was determined to be 80 days at 25 °C and 180 days at 4 °C, based on their rehydration ratio, microbial load, and browning index. The SM soybeans only need to be rehydrated for 10 min before being prepared as soymilk, which is very convenient to consume at home and office. Practical applications Soymilk is nourishable and popular to many people worldwide. Besides purchasing processed products from supermarkets, people may choose to make it by themselves using the household soymilk grinder for freshness. However, the preparation is time-consuming and a dozen of hours' soaking process of soybeans is necessary to obtain good quality soymilk. This paper presents an alternative to make instant soymilk, that is, by using semimanufactured (SM) soybeans, through presoaking, dehydration, and sterilization. Experimental results indicated that hot-air drying and combined sterilization had many advantages over the other methods such as longer shelf life of the SM soybeans and better quality of the corresponding soymilk. The SM soybeans may have the potential to be commercialized to for consumers who prefer to make instant soymilk at home or office in a convenient manner.