酶法修饰对大豆分离蛋白凝胶性质影响的研究进展

大豆分离蛋白（soybean protein isolate，SPI）具有高营养性和良好的功能特性，但是，采用“碱溶酸沉”的传统方法所获得SPI往往会发生部分变性，最终常会以热力学稳定的水不溶性大聚集体和/或沉淀形式出现，对其凝胶性能产生不利影响。在实际生产中为改善SPI的凝胶性质，可进行物理、化学改性或酶法修饰，其中物理和化学改性反应特异性低，难以控制蛋白变性程度；而酶法修饰手段因具有反应条件温和、产品得率高、生产过程安全等特点得到广泛关注。本文综述了不同酶法修饰手段对SPI凝胶形成及性能的影响，通过描述SPI热凝胶和冷凝胶的形成机制，讨论限制性酶解、酶诱导的侧链接枝反应以及酶诱导的交联反应对SPI凝胶形成的影响，并对酶法修饰SPI凝胶的开发应用进行展望。

Progress in Understanding the Effect of Enzymatic Modification on Gel Properties of Soy Protein Isolate

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.