Effects of galactooligosaccharide glycation on the functional properties of soy protein isolate and its application in noodles

Soybean protein has high nutritional value, but its functional properties are easily affected by external factors, which limits its application in food industry. In the study, soybean protein isolate (SPI) was modified by dry heat glycation of galactooligosaccharides (GOS). The gel properties, antioxidant properties and structural changes of SPI-GOS conjugates were investigated. The application of SPI-GOS conjugates in noodles was also explored. The results observed that the glycation degree of SPI increased with the increasing reaction time. SDS-PAGE and spectral analysis showed the changes of spatial conformation of SPI after glycation. The antioxidant activity of SPI increased after glycation and DPPH radical scavenging activity of SPI-GOS peaked at 48 h of reaction. The hardness, elasticity and resilience of soybean protein gel reached their relative maximum at 48 h, 48 h and 12 h of glycation reaction, respectively. Moreover, the appropriate addition of glycated SPI improved the quality of noodles. The noodles with 4% addition of SPI-GOS had the higher hardness, elasticity and tensile properties. This study will provide an effective method to modify soybean protein and expand the use of soybean protein in food industry. Short Abstract In this paper, the gel properties, antioxidant properties and structural changes of soybean protein isolate (SPI) and galactooligosaccharide (GOS) (SPI-GOS) conjugates were investigated. The application of SPI-GOS conjugates in noodles was explored. The results showed that the antioxidant activity and gel properties of SPI were enhanced after glycation, and the spatial conformation was changed. In addition, noodles with 4% SPI-GOS addition had higher hardness, elasticity and tensile properties.