Effect of NaCl stress germination on microstructure and physicochemical properties of wheat starch

Germination can enhance the nutritional properties of wheat and improve its bioavailability, while simultaneously altering the microstructure of wheat starch, which further impacts its physicochemical characteristics. This work investigated the synergistic effects of germination and NaCl on the microstructure and physicochemical properties of wheat starch by applying a 60 mmol/L NaCl solution. The results indicated that germination significantly influenced both the chemical composition and microstructure of wheat starch, as evidenced by cracks and pores, variations in size, crystallinity, lamellar order, hydrogen bond disruption, branching degree, and molecular weight distribution. These changes affected the pasting and gel properties of the starch. The NaCl treatment enhanced enzyme activity, resulting in a higher phenolic content (4.70 mg GAE/g DW) at 48 h, rougher and irregular surfaces, smaller dimensions (D10 from 3.87 to 2.20 μm), and increased degree of heterogeneity. Over time, the NaCl-induced treatment led to a greater structural disruption, including reduced crystallinity (from 17.93 % to 14.95 %), damage the lamellar structure, and the breaking of hydrogen and glycosidic bonds. The germinated starch exhibited improved solubility and swelling power, thereby altering its pasting, gel, and thermal properties. Overall, this study provides valuable insights for the application of germinated wheat in food. •Germination changed the microstructure and physicochemical properties of wheat starch.•NaCl stress enhanced the enzyme activity and phenolic accumulation over the untreated.•NaCl induced the greater degree of heterogeneity and structural disruption.•The synergistic effects existed for NaCl and germination.•Correlation analysis revealed the effect between the microstructure and gel properties.