Abstract: The aim of this study was to investigate the impact of preheated soy protein isolate (SPI) on the gelation and rheological properties of heat-induced myofibrillar protein isolate (MPI) extracted from common carp muscle. SPI heated at 90 ℃ for 0, 30 and 180 min were incorporated into MPI (0:1, 1:1, 1:2, 1:3, and 1:4), and protein content in the mixture solutions was kept at 40 mg/mL. Results showed that the gel hardness, springiness, whiteness, and water-holding capacity of MPI with preheated SPI were significantly higher than those with native SPI (P < 0.05), and a greater increase was observed with longer (180 min) versus shorter (30 min) heating time (P < 0.05). In addition, the hardness, springiness, whiteness and water-holding capacity of the mixed protein gels increased significantly with decreasing SPI/MPI ratio from 1:1 to 1:4 (P < 0.05). The rheological properties suggested that protein denaturation temperature increased after the addition of SPI, and preheated SPI significantly increased protein storage modulus (G’). The results of thermal stability suggested that the maximum transition temperature Tmax3 was significantly reduced with the addition of native SPI to MPI (P < 0.05) while the Tmax1 and Tmax2 were not affected (P > 0.05). However, the addition of preheated SPI to MPI significantly reduced the Tmax1 and increased the Tmax3 (P < 0.05). In short, compared with native SPI, preheated SPI can improve the gelling and rheological properties of myofibrillar proteins.

Key words: soy protein isolate, myofibrillar protein isolate, gelling properties, rheological properties, thermal stability