This study aimed to investigate the effect of heat moisture treatment (HMT) on the granular morphology, crystalline structure, short-range ordered structure and digestibility of waxy rice flour (WRF), and the potential mechanism by which HMT influences its digestibility was also revealed. Results indicated that HMT induced significant aggregation of WRF particles, with the average particle size increasing from 13.38 to 23.27 μm as the temperature rose to 120 ℃. Additionally, the relative crystallinity (RC) of WRF decreased from 38.9% to 34.4%, accompanied by a reduction in the short-range order index from 0.97 to 0.81. Although HMT disrupted the ordered molecular structures of WRF, the synergistic action of thermal energy and moisture strengthened the interactions between molecular chains, thereby promoting the formation of Ⅴ-type starch-lipid complexes. Moreover, the RC of Ⅴ-type complexes increased from 1.5% to 2.9%, and the gelatinization temperature of WRF also increased. The aggregation of WRF particles, enhanced formation of Ⅴ-type complexes and higher gelatinization temperature, together impeded adsorption and specific binding of enzymes to WRF and consequently inhibited its hydrolysis, thereby slowing down the digestion rate of WRF and increasing the proportion of slowly digestible and resistant starch, which reached a maximum of 39.4% at 110 ℃. In conclusion, HMT could effectively reduce the digestibility of WRF by modulating its multi-scale structural features, which provides a theoretical basis for the development of low glycemic index products.

In order to provide basic data for delaying quality deterioration in waxy corn, the microstructure and physicochemical properties of waxy corn starch isolated from fresh and frozen corn (stored at −18 ℃ for 10, 20 or 30 days) were investigated by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffractometry (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and a rapid viscosity analyzer (RVA). The results showed that frozen storage decreased the ratio between the IR peaks at 1045 and 1022 cm^-1 (R_1045/1022) and the relative crystallinity of waxy corn starch, and increased the full width at half height. After frozen storage, pits and cracks appeared on the surface of the starch granules, and their size became smaller. As frozen storage time increased, the microstructure of corn starch was damaged more seriously. After frozen storage, the gelatinization temperature, gelatinization enthalpy, peak viscosity and breakdown value of waxy corn starch decreased, while the final viscosity and retrogradation value increased, indicating that frozen corn starch was more prone to gelatinization and retrogradation. In addition, frozen storage could convert slowly digestible starch and resistant starch into rapidly digestible starch, thereby having the potential to improve the digestion rate and degree of fresh corn.

In this study, dumpling wrappers were made from wheat flour with different amounts of purple sweet potato anthocyanins (PSPA) added. The structural characteristics of wheat gluten proteins and the quality of dumpling wrappers were investigated using Fourier transform infrared spectroscopy, laser confocal Raman spectroscopy, a rheometer, and a texture analyzer. The results showed that the antioxidant activity of dumpling wrappers was improved by adding different amounts of PSPA. The interaction between PSPA added at levels of 0.1%–0.4% and wheat gluten proteins gradually increased the α-helix content and enhanced the orderliness and stability of the gluten network, thereby improving the hardness, chewability and tensile resistance and reducing the cooking loss of dumpling wrappers. However, when the addition amount increased to 0.8%, the reducibility and antioxidant properties of polyphenols played a major role in the destruction of disulfide bonds, thereby weakening the gluten network, reducing the hardness, thus increasing the cooking loss of dumpling wrappers.

Potato protein deaminated for different durations (0, 0.5, 3, 6 and 12 h) were used to prepare emulsions, and the products obtained were evaluated for droplet size distribution, emulsion stability, microrheological properties and microstructure. The results showed that the droplet volume mean diameter and Turbiscan stability index (TSI) of the emulsion decreased first and then increased with increasing deamidation time. The emulsions with potato protein deaminated for 3 and 6 h exhibited uniform droplet size distribution and good stability, which may be because the increased electrostatic repulsion between the modified protein emulsion droplets prevented their aggregation. The droplet size of the emulsion with potato protein deaminated for 12 h increased and the stability decreased, which may be because of the decreased charge repulsion force and consequent droplet aggregation. The microrheological analysis showed that the emulsion with potato protein deaminated for 6 h had the highest macroscopic viscosity index (MVI) value and the highest viscosity, and the speed of droplet movement was slowed down. There was a strong force between the emulsion droplets, which made the system more stable. This study can provide a reference for further research and development of potato protein products in order to improve the utilization rate of potato protein and expand the application range.

Differential scanning calorimetry (DSC), low-field nuclear magnetic resonance (NMR) and in situ Raman spectroscopy were used to explore the cryoprotective effect of enzymatic hydrolysates of flaxseed meal proteins obtained at different hydrolysis times on dough. The results showed that the thermal hysteresis activity of the 60 min hydrolysate, with a 13.62% degree of hydrolysis (DH), was highest (0.83 ℃), and the ice recrystallization inhibitory activity was also highest, minimizing the proportion of large ice crystals. It was found that addition of the hydrolysate had the most significant cryoprotective effect on dough. Compared with the control group, the proportion of strongly bound water in dough increased by 13.2%, and the proportions of weakly bound water and free water decreased by 0.7% and 7.9%, respectively. The maximum fermentation height, the final height and the onset time of CO₂ leakage increased by 18.5%, 24.4% and 34.4%, respectively. Protein structure analysis showed that the relative α-helix content of gluten proteins in dough with the hydrolysate was highest and increased by 35.3% compared with the control group, and the relative random coil content decreased by 28.9%. The intensity (I₇₆₀) of tryptophan band at 760 cm^-1 increased by 282.3%, and the ratio (I₈₅₀/I₈₃₀) between the intensities of tyrosine bands at 850 and 830 cm^-1 decreased by 59.6%. The relative contents of disulfide bond configurations g-g-g and g-g-t were increased by 8.8% and 9.8%, respectively. In conclusion, enzymatic hydrolysates of flaxseed meal proteins improved the water-holding capacity of dough, shortened dough proofing time, and weakened the damage of ice crystals to the network structure of dough, and the effect of the hydrolysate with DH of 13.62% was most pronounced.

This study investigated the effects of adding different amounts of flaxseed gum (0%, 0.2%, 0.4%, 0.6% and 0.8%) on the microstructure and physicochemical properties of starch in frozen dough using scanning electron microscopy (SEM), solid-state nuclear magnetic resonance (SSNMR) spectroscopy, X-ray diffraction (XRD), and rapid visco analysis (RVA). The aim was to reveal the potential mechanism underlying the effect of flaxseed gum on the quality improvement of frozen dough from the perspective of changes in starch characteristics of frozen dough. The results showed that after repeated freeze-thaw cycles, the surface of starch particles appeared sunken, the relative crystallinity of starch decreased, the double helix structure of starch molecules was destroyed, and consequently water molecules were more likely to enter starch particles, thus resulting in an increase in peak viscosity and final viscosity. The addition of flaxseed gum inhibited the formation of ice crystals in frozen dough and delayed the unwinding of the double helix structure of starch molecules, and the hydrogen bond interaction between flaxseed gum and starch molecules increased the relative crystallinity of starch (22.2%–23.8%). As a result, the peak viscosity of starch decreased from 2409.5 mPa·s to 2247.2–2288.5 mPa·s, and the gelatinization temperature gradually increased. In conclusion, flaxseed gum delayed the damage of starch in dough caused by repeated freeze-thaw cycles, thereby protecting frozen dough.