Abstract: Soybean protein isolate (SPI) has high nutritional value and good functional properties. The alkali dissolution and acid precipitation method is conventionally used to prepare SPI, which, however, is prone to cause partial protein denaturation, thus yielding thermodynamically stable water-insoluble large aggregates and/or precipitates. This phenomenon has an unfavorable impact on the gel properties of SPI. In practice, SPI can be modified physically, chemically or enzymatically to improve its gel properties. It is difficult to control the degree of denaturation of physically or chemically modified SPI due to low specificity. In contrast, enzymatic treatment has received extensive attention due to its mild reaction conditions, high product yield, and safety in the production process. This article reviews the effects of different enzymatic modification methods on the formation and performance of SPI gel, and describes the formation mechanism of SPI hot gel and cold gel. Meanwhile, an overview of the effects of limited enzymatic hydrolysis, enzyme-induced side chain grafting reaction and enzyme-induced cross-linking reaction on the formation of SPI gel is presented, and future prospects for the development and application of enzymatically modified SPI gel are discussed.

Key words: soybean protein isolate; limited enzymatic hydrolysis; grafting reaction; cross-linking reaction; gel properties