Emulsifying and gelation properties of soybean protein isolates modified by transglutaminase in the presence of glucosamine

A microbial transglutaminase was used to modify soybean protein isolates (SPI) in the presence of glucosamine. SDS-PAGE analysis revealed that glucosamine conjugation and cross-linking occurred during reaction. A modified SPI product with glucosamine conjugation of 3.2 mol·mol^-1 SPI was prepared, and its emulsifying or gelation properties were evaluated. Analysis results showed that its emulsifying activity index and stability index were 98.0 m²·g^-1 and 89.5%, which were about 26 and 38% higher than the original SPI. The heat-induced gel of the modified SPI product also exhibited better gelation property. This technique is an effective approach to improve some functional properties of SPI.