Effects of Micro-pressure Boiling Process on Formation of Protein Particles in Soybean Milk and Its Processing Characteristics

Abstract:

The processing characteristics of soybean milk were directly affected by properties of protein particles. The formation of protein particles in soybean milk was closely related to heating temperature and heating method. At present, micropressure boiling has become a kind of important method of cooking soybean milk in China. However, up to now there were no reports on the influence of micropressure boiling on the changes of soybean milk processing characteristics. Through the contrast and analysis of the changes in the content of protein particles in soybean milk between ordinary pressure boiling and micropressure boiling, this article studied the effects of the micropressure boiling method on the stability of soybean milk, rheological properties and the textural characteristics of soybean curd. The experimental results showed that micropressure boiling method changed the composition of protein particles in soybean milk, after boiling for 10 min, the content of protein particles in soybean milk would reach 52%, which was 13% higher than that in ordinary pressure boiling, and as a result, there were significant changes of soybean milk processing characteristics. Soybean milk after micropressure boiling would possess particles with much smaller average diameter (0。3257μm after 10min boiling), which was beneficial for the stability of soybean milk in longterm storage. Fluid properties indexes of micropressure boiling soybean milk and ordinary pressure boiling soybean milk were both approximate to 1, showing Newtonian fluid properties. But as protein particle numbers increasing after micropressure boiling, there were more acidic peptides and α and α′ subunit in 7S distributing in the surface of protein particles, which improved protein hydrophilicity and increased the viscosity of soybean milk. In the gelation process of soybean curd, more protein particles were involved in the formation of network structure, which made the network structure more compact, thus enhanced the interaction between proteins, as a result, the hardness, elasticity and glue viscosity of soybean curd gel were all increased, and the gel texture of soybean curd was significantly improved.