Changes in chemical interactions and protein conformation during heat-induced wheat gluten gel formation

In order to elucidate the heat-induced wheat gluten gel formation mechanism, changes in chemical interactions and protein conformation were investigated during gelation. The contribution of ionic and hydrogen bonds were found to decrease from 0.746 and 4.133 g/L to 0.397 and 2.733 g/L, respectively, as the temperature increased from 25 to 90 °C. Moreover, the free SH content remarkably decreased from 37.91 to 19.79 μmol/g during gelation. Ultraviolet absorption spectra and intrinsic fluorescence spectra suggested that wheat gluten unfolded during the heating process. In addition, wheat gluten gels treated at 80 and 90 °C exhibited a “steric hindrance” effect, which can be attributed to the formation of aggregates. Fourier transform infrared spectra suggested that the random coil content increased at low temperatures (40 and 50 °C), whereas the content of intermolecular β-sheets due to protein aggregation increased from 38.10% to 44.28% when the gelation temperature was 90 °C.