Mechanistic insights into the improving effects of germination on physicochemical properties and antioxidant activity of protein isolate derived from black and white sesame

Germination is a natural green technology to improve the nutritional and techno-functional quality of plant-based proteins. In this study, the mechanism of improving the functional and antioxidant properties of black and white sesame protein isolates (SPI) through germination process was investigated. Results showed that the surface hydrophobicity and sulfhydryl content increased significantly after germination, which were supported by multispectral analysis suggesting the exposed and unfolded conformational transition of germinated SPI. Moreover, the increased particle size was observed by microscopy analysis and reducing electrophoresis, which indicated that depolymerized protein molecules were rearranged to form protein aggregates during germination. The structural modification induced by germination contributed to the superior solubility (increased to 3.15-fold and 2.36-fold at pH 8 for black and white SPI, respectively), foaming capacity (increased to 3.99-fold and 1.69-fold, respectively), emulsifying ability (increased to 2.84-fold and 2.71-fold, respectively), and diverse chemical antioxidant activities (increased up to 5.60-fold) of SPI in both varieties. This was the first comprehensive study to investigate germination as a promising technology for obtaining high-quality SPI.