Insight into Sequential\nExtrusion and Cysteine Treatment\nfor Improving Rheological Characteristics and In Vitro Digestibility\nof Whey Protein Isolate

The effects of sequential cold extrusion and cysteine\n(Cys) treatment\non the rheological characteristics and in vitro digestibility of whey\nprotein isolate (WPI) were researched in this work. Cold extrusion\nand Cys treatment increased the apparent viscosity, shear stress,\nPéclet number, and viscoelasticity of WPI. Furthermore, the\nemulsifying activity index enhanced in the order of WPI, Cys-treated\nWPI (Cys-WPI), cold-extruded WPI (CWPI), and extrusion-Cys treated\nWPI (Cys-CWPI). The emulsion stability index of Cys-CWPI was increased\nby 29.69% higher than that of WPI. Besides, the α-glucosidase\ninhibitory rate and xanthine oxidase inhibitory activity in the digests\nof Cys-CWPI were markedly increased compared with digests of WPI.\nThe synergism of cold extrusion and Cys provides an effective approach\nfor the application of whey protein-based thickeners and emulsifiers;\nmeanwhile, its digestive products may assist in the development of\nhypoglycemic and uric acid-lowering foods.