Modulating the Structural, Thermal and Techno-Functional Properties of Sesame Protein Isolate Using Nonthermal Techniques

Abstract

Sesame protein isolate is a promising sustainable plant-based protein due to its high nutritional value and unique flavor. However, due to several challenges related to its functional characteristics, sesame protein can only be used sparingly in food applications. Therefore, the main objective of this study was to investigate the effects of nonthermal techniques including high-pressure homogenization (HPH, 100 MPa), high-intensity ultrasound (US, at a frequency of 20 kHz for 6 min), and high hydrostatic pressure (HHP, 400 MPa for 5 min) on the structure and functional properties of sesame protein isolate from sesame cake as a by-product. The results indicated that all nonthermal treatments encouraged the sesame protein insoluble suspension to change into a consistent protein dispersion, increasing the stability of the protein while reducing particle size (from 65.73 to 1.48 μm), increasing zeta potential (from −24.57 to −42.8 mV), and unfolding the molecular structure. All treatments led to an increase in β-sheets and reduced α-helix, and the most remarkable change in secondary structure occurred in the HPH treated sample that exhibited the highest UV absorbance. Minimal impact on the protein's thermal properties was monitored. Compared with the untreated sample, the techno-functional properties were significantly enhanced after modification, and the highest protein solubility (88.18%), EAI (62.09 m²/g), ESI (65.43 min), and OHC (1.89 g oil/g protein) obtained in the sample treated with HPH. Therefore, this work suggests that HPH could be a more promising technique than US and HHP to enhance the techno-functional properties of sesame protein isolate.