Background, Context or Rationale As a thiol reagent, glutathione (GSH) was demonstrated to affect the structure and function of proteins by thiol/disulphide exchange reactions. Meanwhile, gelation is a key functional characteristic of whey protein isolate (WPI). Nevertheless, no studies have been conducted on how different GSH concentrations regulate the formation mechanism and properties of WPI gels. Aim(s) Therefore, this study would deeply explore the influence mechanism of different GSH concentrations (from 40 to 300 mmol/L) on the gel properties of WPI. Methods This study systematically analysed GSH at different concentrations to regulate the formation mechanism and characteristics of WPI gels by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE), macroscopic and microscopic observation, texture properties, gel water distribution and rheology analysis. Major Findings Whey protein isolate without addition of GSH did not form a gel heated at 65°C for 30 min and remained in a liquid state. The results showed that hardness, water‐holding capacity (WHC), apparent viscosity and viscoelastic modulus of WPI gels were significantly enhanced, and their dense gel network structure was formed by increasing the GSH concentration from 40 to 100 mmol/L. Whey protein isolate gel exhibited the optimal performance at 100 mmol/L GSH; its hardness, WHC and consistency index were increased by 158%, 14% and 134% compared with WPI gel at 40 mmol/L GSH, respectively. Conversely, with GSH concentration increased from 100 to 300 mmol/L, WPI gel structure gradually loosened and its hardness, WHC and rheological properties decreased. Scientific or Industrial Implications Results indicate the addition of GSH could contribute to the formation of WPI gel and improve the physicochemical characteristics of WPI gels, providing an effective strategy for the future development of novel foods or protein ingredients with enhanced gel properties.
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