Cysteine-induced disulfide cleavage enhances the solubility of alkali-treated pea protein and its elasticity contribution in low-salt hybrid meat gels

This study investigated the effectiveness of cysteine in improving the functional properties of pea proteins within low-salt myofibrillar protein (MP) gels. Cysteine treatment, at a concentration of 3.3 mM/g protein, cleaved 71-82 % of the disulfide bonds in native and pH-shifted pea protein isolates (PPI_N and PPI_pH), which increased the solubility and hydrophobicity of PPI_pH. PPI_N showed slight changes, primarily an increase in tryptophan fluorescence. The cleavage of disulfide bonds improved the hardness, elastic component (G'), and network integrity of hybrid gels. When combined with transglutaminase, the MP + PPI_pH gel reached its maximum hardness (0.38 N) at a cysteine concentration of 1.7 mM/g protein. SDS-PAGE patterns and gels treated with additional N-ethylmaleimid confirmed the involvement of cysteine-treated PPI in the gel matrix. Consequently, cysteine-mediated disulfide bond disruption effectively modifies pea proteins, rendering them a more suitable functional ingredient for enhancing the texture of low-salt meat products.