Regulating the interaction between protein and starch in noodles through heat loss: Used to improve the edible quality of noodles

The impact of heat loss during water-cooling process on the edible quality of cooked noodles currently remains unclear. This study aimed to explore the effects of different water-cooling times (0, 20, 40, 60, 80, 100, and 120 s) on changes in gluten and starch structures and their impact on the sensory evaluation and texture of noodles. Results showed that the control group had a higher core temperature, while the core temperature of the noodles equilibrated with the water temperature after water-cooling for 100 s. Within the range of 20–100 s of water-cooling time, a sudden drop in the core temperature of the cooked noodles caused the gluten conformation to transition toward more compact β-sheets. Surface hydrophobicity decreased, while S-S and hydrogen bonds increased. The microstructure of the noodles became more compact, reducing gaps between protein and starch molecules. Small-angle X-ray scattering and atomic force microscopy analyses demonstrated that gluten chains aggregated after water-cooling, resulting in increased chain width and height. The wheat gluten protein structure transitioned from a disordered state to a random coil. Ultimately, the hardness, springiness, and chewiness of the noodles gradually increased. Water distribution results revealed that the free water content of the noodles increased after 120 s of water-cooling, enhancing the hydration between protein and water molecules but decreasing the noodle texture. According to X-ray diffraction and differential scanning calorimeter analyses, heat loss did not alter the gelatinized starch crystal structure of noodles. Therefore, changes in core temperature were the primary cause of gluten structural changes prior to 100 s of water-cooling. After 120 s of water-cooling, increased hydration between noodle surface gluten and water negatively affected the edible quality of noodles. This study provides theoretical data on noodle edible quality and is of significant practical importance.