Effect of temperature of preheated soy protein isolate on the structure and properties of soy protein isolate heated-vitamin D complex.

In this paper, soy protein isolate (SPI) was preheated and combined with vitamin D (VD ) to study the protective effect of modified SPI on VD . The structure and properties of the SPI with heat treatment-VD (SPI(H)-VD ) complex were determined. The secondary and tertiary structure of SPI(H)-VD results showed that the content of α-helix decreased and the content of random coil increased, indicating that the rigid structure of the protein decreased, the flexibility increased, and the maximum fluorescence intensity wavelength was red shifted. When the heat treatment temperature was 85°C, the embedding rate of SPI(H)-VD composite was the highest. As the heat treatment temperature increased, the internal hydrophobic groups of SPI were exposed, and the average particle size decreased significantly. The light stability results showed that the content of VD in the SPI(H)-VD composite at a heat treatment temperature of 85°C was significantly increased compared with the unheated SPI. PRACTICAL APPLICATIONS: This article mainly discusses the structure and properties of modified soy protein isolates bound to VD by preheating soy protein isolates at different temperatures. It provides more possibilities for the application of VD in food.