•The disulfide/sulfhydryl exchange reactions were affected to modulate MP gels.•The effects of GSH on MP gels were in dose and temperature dependence.•Low contents of GSH promoted aggregation and gel properties at low temperature.•High contents of GSH inhibited aggregation and improved gels at high temperature. The present study illustrated modulation of protein aggregation by affecting disulfide/sulfhydryl exchange reactions by adding different concentrations of free thiol represented by reduced-glutathione (GSH) for modulating myofibrillar protein (MP) gel properties at 75 °C or 95 °C. Gel strength and rheological results showed the effects of GSH were dependent on the concentrations (5, 10, 20, 40, and 80 g/kg) and heating temperatures. SEM results showed that the addition of GSH improved the gel microstructure at 95 °C. AFM and DLS results indicated that protein aggregation was also inhibited. At 75 °C, the addition of GSH influenced both MP aggregation and gel properties. Low concentrations (5, 10 g/kg) of GSH promoted aggregation, whereas high concentrations (20, 40, and 80 g/kg) of GSH inhibited this. By analyzing the protein structure and cross-linking pattern changes of MP and MP/GSH composites, a pathway involving GSH influencing MP gel properties was determined.