Mechanistic insights into the modification of peanut protein by novel radio frequency roasting: Revealing multi-scale protein conformational changes

Abstract

Radio frequency (RF) heating, as a promising alternative roasting method, could effectively improve peanut oil quality and degrade aflatoxins. However, during the peanut oil processing, the modification effect and mechanism on protein by RF roasting are still unclear. This study aimed to investigate the influences of RF roasting on the multi-scale structures and functional properties of peanut protein under 150 °C holding for 0 to 15 min. The results showed RF roasting did not alter the primary structure of peanut protein. With the increased holding time, the surface hydrophobicity and the shift of secondary structures from α-helix and β-sheet to β-turn and random coil were significantly enhanced. The changes in the intrinsic fluorescence spectrum and the contents of exposed free sulfhydryl and disulfide bond revealed that the tertiary structure underwent rearrangement and aggregation after roasting. Moderate RF roasting intensities (holding time of 5–10 min) significantly improved the emulsifying properties but had no significant effect on foaming properties of peanut protein. Additionally, the RF-roasted peanut proteins had superior emulsifying properties and formed emulsions with smaller particle size compared with hot-air-roasted ones. Overall, these findings provided new insights for the modification of plant proteins by RF roasting to enhance their value in food applications.