Effect of sanxan on the composition, structure and properties of heat-denatured wheat gluten during freeze-thaw cycles

The interaction between sanxan and heat-denatured wheat gluten protein (HDWG) significantly impacts the quality of prepared cooked noodles (PCNs). This study constructed a sanxan-HDWG modeling system to examine the effects of different concentrations of sanxan (0%, 0.3%, 0.6%, 0.9%, 1.2%, 1.5% w/w) on the composition, structure, and properties of HDWG during freeze-thaw (FT) cycles. The results showed that adding 0.9% sanxan reduced the hardness of HDWG by 3.53% and increased its springiness by 5.37% after FT cycles. This is attributed to the formation of a denser and more continuous HDWG network structure. However, excessive sanxan (1.5%) fails to mitigate HDWG network damage during FT cycles due to steric hindrance and hydrogen bond breakage. Conformational analysis indicated that adding 0.9% sanxan reduced the proportion of gauche-gauche-gauche (g-g-g) decrease (20.81%) and the exposure of tyrosine residues, thereby stabilizing the structural changes of HDWG. The intermolecular interaction forces indicate that sanxan promotes intermolecular cross-linking of HDWG by reducing hydrogen bond breakage and disulfide bond cleavage within HDWG, thereby enhancing the rheological properties and freeze-thaw stability of HDWG. This study revealed the interaction mechanism between sanxan and HDWG, providing theoretical support for the application of sanxan in PCNs.