Soy protein isolate (SPI) is a commonly used food additive, and its excellent functionality can be applied to food to meet people’s needs. In food processing, the natural functional properties of soybean protein are not enough to meet the functional needs of the food industry. Therefore, through the improvement of the molecular structure of soybean protein, the physical and chemical properties are changed, and then the functional properties of the protein are strengthened or improved. the goal of.
Heat treatment is essential in the production and processing processes such as spray drying and renaturation, and it will inevitably affect the structure and functional properties of soybean protein. Epigallocatechin gallate (EGCG), as the main active ingredient in tea polyphenol extract catechin, has strong antioxidant and anticancer effects, but there is little evidence of EGCG monomer’s effect on soybean protein. Research on the mechanism of structural regulation.
The SPI and EGCG self-made in the laboratory were used as raw materials for research to prepare the SPI-EGCG composite system. The quenching mode of the two was static quenching, and the force was hydrophobic interaction. Through the analysis of infrared spectroscopy and Raman spectroscopy, the regulation of EGCG on SPI caused the secondary structure of SPI to change to varying degrees. Before and after heat treatment, the relative content of β-sheet decreased and the relative content of α-helix increased with the increase of EGCG mass concentration in the secondary structure of SPI. And the side chain of Raman spectrum showed that EGCG and the hydrophobic side chain group of SPI combined through hydrophobic interaction, and heat treatment enhanced the interaction between the two. Fluorescence spectra and UV-Vis spectra showed that the regulation of SPI structure by EGCG before and after heat treatment had a quenching effect on the fluorescence of SPI, and the quenching effect after heat treatment was stronger.