ENHANCEMENT OF SOLUBILITY AND EMULSIFYING PROPERTIES OF SOY PROTEIN ISOLATES BY GLUCOSE CONJUGATION

ABSTRACT Soy protein isolate (SPI) was modified with glucose (G-) through the amino-carbonyl reaction (Maillard reaction). Solubility and emulsifying properties of the modified proteins were investigated. G-SPI conjugate was highly soluble at a wide range of pH values, while untreated SPI showed limited solubility especially at pH 4–6. Solubility of modified SPI showed the resistance to heat treatment and high ionic strength. Emulsifying activity and emulsion stability of G-SPI conjugate were much higher than those of native SPI. Comparing with some commercial emulsifiers, G-SPI conjugate showed excellent emulsifying properties in high salt concentration and neutral pH. Sodium dodecylsulfate-polyacrylamide gel electrophoresis was also used to confirm the formation of G-SPI conjugate. PRACTICAL APPLICATIONS Although soybean protein isolate has been used in many food applications, currently its main use in China is only in processed meat products. To meet the requirement of different food systems, the functional properties of local SPI must be modified. In this study, the glycosylated soy proteins exhibited apparent improvements of their functionalities, particularly solubility and emulsifying properties. The advantage of the protein–sugar conjugates could be that it has the potential interests in food formulations. For instance, glycosylated SPI can be readily produced and provides a promising emulsifying ingredient for the food industry.