Investigation on Cracking Mechanisms of Dehydrated Corn: Multiscale Changes Driven by Temperature Gradient

Abstract

ABSTRACT: This study systematically investigated the impact mechanism of hot-air drying temperature (40°C–80°C) on moisture migration, crack formation, and the microstructural evolution of corn kernels. Using multi-scale characterization techniques such as low-field nuclear magnetic resonance, scanning electron microscopy, and Fourier transform infrared spectroscopy, this study revealed temperature-gradient-driven changes in microscopic mechanical properties. The results showed that increasing the drying temperature accelerated moisture evaporation while exacerbating internal moisture gradients, which led to greater thermal stress and promoted crack formation. Under medium drying conditions (60°C–70°C), the efficiency of moisture migration was optimized, preventing structural hardening and uneven drying caused by high temperatures, thereby significantly reducing crack formation. Further microstructural and correlation analyses indicated that with increasing temperature, cornstarch granules underwent significant morphological changes, while the secondary structure of proteins transitioned from an ordered α-helix to a disordered random coil structure, thereby increasing the risk of crack formation. This study assessed a qualitative relationship between drying temperature, protein conformational changes, and crack formation, thus providing a molecular-level theoretical basis for optimizing the hot-air drying process of corn and offering significant practical value in reducing processing loss rates.