Unraveling the molecular mechanisms of high hydrostatic pressure in enhancing emulsifying properties: insights from main fractionations in pepper seed protein.

High hydrostatic pressure (HHP) effectively enhances the emulsifying properties of pepper by-product - pepper seed protein (PSP), but the underlying mechanisms require further elucidation. This study investigated the molecular mechanisms of HHP-induced changes in protein emulsification by comparing predominant fractions (pepper seed albumin (PSA) and glutelin (PSG)) obtained by two extraction methods. Results showed that with higher emulsifying activity of PSA increased by 23.49 % compared to the control, surpassing PSG (13.46 %), due to looser secondary, tertiary structure and higher free thiol groups. PSG, with high β-sheet content (>45 %) and structural stability, demonstrated weaker pressure sensitivity. These findings indicate that the conformational changes of PSA, which play a dominant role in HHP-induced emulsifying properties and reflected similar trends of the two extracted PSP. This study reveals the mechanism of PSP from common extracted methods emulsification changes under HHP and provides a theoretical basis for the application of PSP as clean-label emulsifiers.