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

Abstract

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 ℃ 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 ¹³C solid-state NMR results showed that the α-helix secondary structure of USG was transformed into intermolecular β-sheet and β-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 2θ 22.06°, 23.56°, 29.10°, and 35.30°, 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.