Thiolation modification of pectin effectively alleviates the weakening of wheat gluten network caused by natural pectin

The addition of natural pectin (NP) usually damages the gluten network structure. In order to improve the damage to gluten network caused by the addition of NP, the effects of different concentrations of NP and thiolated pectin (TP) (1%–9%) on gluten properties (rheological, tensile and thermal properties) and gluten structure (microstructure, free thiol content, secondary structure and surface hydrophobicity) were investigated. The results indicated that the free thiol content of gluten treated with 9% TP increased 5.29-fold compared with the control gluten. Rheological results showed that TP reduced the negative effect of NP on the viscoelasticity of gluten protein at the same concentration of TP and NP (1%–9%). The tensile test indicated that the addition of NP hindered the formation of gluten network whereas the addition of TP (5% and 9%) maintained the tensile properties of gluten at a relatively stable level. Similarly, analysis of the secondary structure and surface hydrophobicity (H0) revealed that the gluten proteins treated with 5% and 9% TP exhibited approximate stability and unfolding degree. Moreover, when the concentration of TP was 5%, the peak temperature (TP, 115.51 °C) and enthalpy (ΔH, 163.31 J/g) of gluten were consistent with the control gluten. This result was also confirmed by very similar SEM images of these two gluten samples. Based on these results, it was believed that the thiolation modification of pectin effectively alleviated the weakening of gluten network caused by NP.