Glycation of rice protein and d-xylose pretreated through hydrothermal cooking-assisted high hydrostatic pressure: Focus on the structural and functional properties

Rice protein (RP) and d-xylose (Xe) glycosylation reaction products were prepared by hydrothermal cooking (HTC)-assisted high hydrostatic pressure (HHP) under different pressures (100–300 MPa). The structural and functional properties of RP, RP-XeH (only by HTC treatment), and RP-XeHP (by HTC-assisted HHP treatment) were investigated. The results revealed that the grafting degree and solubility of RP-XeHP increased with increasing pressure. Moreover, the intrinsic fluorescence intensity of RP-XeHP decreased, whereas the sugar fluorescence spectroscopy increased. SDS–PAGE revealed that soluble aggregates were formed by the covalent interactions between glutelin and d-xylose in RP-XeHP, and the amino acids that participate in the reaction mainly include Cys, Tyr, Lys, and Arg. FTIR spectral analysis further revealed that the secondary structure changed. Moderate pressure (100 MPa) strengthened the emulsifying properties of RP-XeHP, whereas high pressure (300 MPa) had a negative effect on the emulsifying properties. Furthermore, RP-XeHP exhibited outstanding antioxidant activity. This study provides new insight into RP glycated by HTC-assisted HHP treatment.