Chemical modification of soy proteins

This selective review, which deals primarily with the chemical modification of soy proteins, is further limited to nondestructive chemical reactions which alter physical and biochemical properties of importance in food systems. Soy protein products have been modified by various chemical reactions including (a) treatment with alkalies and adds, (b) acylation, (c) alkylation and esterification, and (d) oxidation and reduction. In most instances these reactions have been applied to heterogeneous protein mixtures containing nonprotein impurities, and often to proteins of unknown prior history. Nonetheless, these reactions indicate that protein functional properties of value in food fabrication can be altered significantly through reaction with chemical reagents. It is recognized that chemically modified proteins must be critically evaluated for food safety. 

Examination of the literature on the chemical modification of proteins and protein-containing products derived from soybeans reveals that the major motivation for such studies was often the development of improved products for industrial rather than food or feed utilization (21, 22, 23, 24). Such research activity was at the heart of the Chemurgic movement begun in the early thirties. Hence it becomes understandable that the patent literature dealing with the chemical modification of soy protein products is much more extensive than the periodical literature. This, together with our imperfect understanding of the basic structure of the soy proteins, explains why many of the reactions cited in this... 

A review of the patent and periodical literature reveals that the intentional chemical modification of soy protein products for food use has received little attention. Such work as has been described is concerned with crude protein-containing fractions and heterogeneous protein mixtures. The full nature and extent of these chemical reactions have not been defined. In spite of the lack of definitive chemical modification studies, there is evidence of the beneficial alteration of gross properties related to potential food use. 

Liu, Y. K. Li. Chemical modification of soy protein for wood adhesives. Macromol. Rapid Commun. 2002,23, 739-742. 

---