High-pressure in situ methods revealing the effect of pressure on glutathione structure.

High-pressure processing is a nonthermal method of food processing that is widely used in sterilization and enzyme inactivation. Although some works on technological parameters and quality evaluation have been performed, the mechanism of high pressure on food is still unclear. Due to the complexity of food ingredients, a tremendously important tripeptide in food proteins, orthorhombic l-glutathione, was employed in this work. In addition, in situ methods such as high-pressure Raman, infrared, and X-ray diffraction were used to investigate the structural changes in the pressure range of 0-10 GPa. Experimental results showed that the sample underwent two phase transitions in pressure intervals of 1.8-2.2 and 4.1-5.3 GPa. In addition, the strength of the hydrogen bonds (NH⋯O; OH⋯O; SH⋯O; CH⋯O) also changed in the two pressure intervals. This work may have potential research value for revealing the mechanism of high-pressure processing on food proteins.