Fracture Behavior and Mechanisms of Wheat Kernels Under Mechanical Loading

Wheat milling efficiency and flour quality are fundamentally governed by kernel fracture behavior during mechanical processing. This study systematically investigated the fracture characteristics of wheat kernels through a multi-stage experimental approach. Rupture tests comparing shear and compression loading revealed that shear reduced fracture energy by 40%, with vitreous kernels (16.13 mJ) showing greater resistance than floury types (10.45 mJ) at 13% moisture. Microstructural characterization revealed distinct fracture modes: vitreous kernels fractured intercellularly, while floury kernels fractured intracellularly—quantified via fractal geometry (vitreous: fractal dimension D = 1.262; floury: D = 1.365). Controlled bran removal experiments demonstrated that outer bran layers provide 40% of total fracture resistance, with vitreous kernels depending primarily on endosperm properties beyond 5% peeling, whereas floury kernels exhibited progressive strength loss with each layer removed. These findings enable optimized milling strategies: shear-based systems for energy efficiency, minimal processing (≤5% bran removal) for vitreous wheat, and moderate peeling (≤10%) for floury wheat, ultimately advancing both scientific understanding and industrial practice in cereal processing.