Modification of pepper seed protein isolate to improve its functional characteristic by high hydrostatic pressure

Pepper seed protein isolate (PSPI) is a valuable plant-based protein source, yet the impact of processing methods such as high hydrostatic pressure (HHP) on its properties remains unclear. The impact of HHP on the structural and functional properties of PSPI at pH 7 and pH 9 was evaluated. Structural changes in PSPI were analyzed using spectral techniques, revealing significant alterations in the secondary and tertiary structures induced by HHP treatment. HHP treatment caused the unfolding of the PSPI structure, leading to the exposure of previously hidden chromophores and hydrophobic groups. The treatment also led to changes in free sulfhydryl groups and increased average particle size suggesting the formation of macromolecular polymers or insoluble aggregates. Consequently, the water-holding capacity, oil-holding capacity, foaming characteristics, and emulsifying activity index of the modified PSPI were significantly enhanced both at pH 7 and pH 9, with maximum improvements of 121.98 %, 157.29 %, 100.00 %, and 265.78 %, respectively. In conclusion, HHP is a promising strategy for enhancing the physicochemical properties of PSPI for various applications.