Effects of Wheat Amylose on the Formation of Disulfide Bonds in Urea-Soluble Glutenin

The addition of excessive amylose to the dough leads to a deterioration in the quality of the gluten network. Disulfide bond is the main factor influencing the quality of gluten network structure. In this paper, wheat amylose was mixed with urea-soluble glutenin (USG) under different conditions to investigate its effects on the disulfide bond formation of USG. The results showed that the addition of 5% wheat amylose stirred at 45 degree celsius for 1 h could sharply increase the disulfide bond contents of USG from 0.85 to 4.35%. The results of microscopy showed that the formation of wheat amylose/USG gel was unfavorable/favorable to the formation of the disulfide bond in complex. FTIR and C-13 solid-state NMR results showed that the alpha-helix secondary structure of USG was transformed into intermolecular beta-sheet and beta-turn after mixing with wheat amylose. Ser of USG interacted with wheat amylose through dehydration condensation and hydrogen bonds formed between Pro of USG and C2, 3, 5, 6 of wheat amylose during the interaction of both. The X-ray diffraction pattern of USG was 2 theta 22.06 degrees, 23.56 degrees, 29.10 degrees, and 35.30 degrees, and they all disappeared after mixing with wheat amylose. USG with the highest disulfide bond contents in complex showed lower peak denaturation temperature and melting enthalpy. A possible interaction way of wheat amylose and USG was deduced. Wheat amylose could regulate the disulfide bond formation of USG under appropriate conditions.