Effects of high hydrostatic pressure treatment on structural, techno-functional and rheological properties of sesame protein isolate

Abstract

In this study, the modification of sesame protein isolate extracted from sesame cake with high hydrostatic pressure (HHP) was carried out. For this purpose, protein dispersions (4 %) were subjected to HHP treatment (up to 600 MPa) and the structural, techno-functional and rheological properties of the sesame protein were determined. Considering the control sample, it was determined that the HHP caused changes in the SDS-PAGE band intensities. The solubility of sesame proteins increased from 54.28 % to 80.12 % with HHP treatment up to 400 MPa and obtained a minimum (11.06 mu m) and maximum (36.96 mV) values in particle size and absolute zeta potential, respectively. The FTIR results indicated that HHP treatment increased beta-sheets, reduced alpha-helix and beta-turn structure. The free-SH group and surface hydrophobicity (H-0) for control were determined as 4.15 mu mol/g protein and 25.47, respectively, and the highest free-SH group (8.21 mu mol/g) and surface hydrophobicity (41.14) were recorded for the protein samples treated at 400 MPa (P < 0.05). Similarly, the maximum WHC and OHC, foam capacity and ESI index of sesame protein were obtained by applying 400 MPa pressure. The samples treated with 0.1 MPa and 600 MPa pressure exhibited shear-thinning behavior, while the others exhibited Newtonian-type behavior. The highest viscosity was determined in the samples subjected to 200 MPa pressure. HHP treated samples were more elastic than control sample and gel formation temperature decreased with increasing pressure. Overall, HHP could constitute an important technological approach for improving the techno-functional properties of sesame protein as a functional ingredient in food system.