Impact of drying techniques on the physicochemical, structural, thermal, techno-functional, rheological properties, and in vitro digestibility of sesame protein isolate

Abstract

Sesame protein isolate (SPI) is emerging as a valuable plant-based protein with promising nutritional and functional properties. This study examined the influence of three drying techniques-hot air drying (OD), spray drying (SD), and freeze-drying (FD)-on the physicochemical, structural, thermal, techno-functional, rheological properties, and in vitro digestibility of SPI. While proximate composition remained unchanged, notable variations were observed in particle size, zeta potential, FTIR spectra, free sulfhydryl (-SH) groups, and surface hydrophobicity (H₀), reflecting conformational modifications. OD-PI exhibited the highest denaturation temperature (81.83 °C) and lowest enthalpy (28.86 J/g). SD-PI demonstrated superior functional traits, including emulsion capacity (29.91 %), stability (64.83 min), foaming capacity (127.78 %), stability (47.78 %), water-holding capacity (1.81 %), and rheology, attributed to its small particle size (4.51 μm) and high solubility (72.62 %). FD-PI showed the greatest -SH and H₀ values. Importantly, SD-PI displayed enhanced digestibility, establishing spray drying as the most effective method for producing high-quality SPI for food applications.