Understanding the mechanism of alkali-soluble glutenin addition on inhibition of wheat amylose retrogradation

Abstract

The retrogradation of wheat amylose during refrigeration results in a hardness enhancement of wheat-based products. It has been found that glutenin serves as an effective additive for retarding retrogradation. The objective of this study was to elucidate the mechanisms by which alkali-soluble glutenin (ASG) hindered wheat amylose retrogradation using a range of techniques, including IR, ¹³C Solid-state NMR, X-ray diffraction, DSC and retrogradation kinetics. The results demonstrated a notable decline in the retrogradation rate of wheat amylose, from 74.26 % to 40.13 % when blended with 12.5 % ASG at 30 °C for 90 min. The ASG exhibited an intermolecular to intramolecular β-sheet ratio of approximately 2:1, accompanied by a considerable number of disulfide bonds in the complex. Infrared spectroscopy revealed that dehydration condensation occurred between the Arg C_ε of ASG and C1 of wheat amylose, while hydrogen bonds were formed between the proline amino group in ASG and C4 of wheat amylose. These interactions led to a significant reduction in the diffraction peak intensity at 2θ ∼22.3° of the complex, offering valuable insights into the mechanism by which ASG inhibited wheat amylose retrogradation. Furthermore, a notable decrease in the retrogradation kinetic index (k and n) was evident. These findings establish a theoretical foundation for the development of technologies aimed at inhibiting the short-term retrogradation of flour-based products.