Effect of moisture preconditioning on maize (Zea mays L.) kernel behavior and tortilla quality under reduced-time alkaline cooking

Abstract

This study investigates the impact of maize moisture content—achieved through soaking—on starch functionality, cooking behavior, and tortilla quality. The research focuses on how varying pre-soaking times alter the hydration state of maize kernels and influence physicochemical and molecular transformations during lime cooking, offering insight into strategies for reducing energy and time in traditional tortilla processing. White maize kernels were soaked for up to 32 h, with 12 h being chosen for achieving moisture levels (∼38.6 %) conducive to efficient cooking. When cooked for 15 min in alkaline conditions, these pre-soaked kernels reached 49.7 % final moisture content more rapidly than unsoaked controls. This hydration difference significantly affected starch behavior: pre-soaked samples exhibited lower gelatinization temperatures and enthalpy, greater swelling capacity, and higher levels of rapidly digestible starch. Molecular analysis revealed reductions in starch molecular weight and radius of gyration, suggesting partial depolymerization. Tortillas produced from pre-soaked maize demonstrated higher initial softness and extensibility, attributed to enhanced starch gelatinization. However, they also exhibited greater firmness after 3 days of storage due to accelerated retrogradation, highlighting a trade-off between immediate texture quality and shelf stability. Moisture content was a key determinant in these outcomes, reinforcing the central role of water availability in thermal and structural transitions. These findings suggest that pre-soaking maize before cooking is a viable strategy for modulating processing outcomes, reducing cooking time, and tailoring textural properties. Reframing traditional nixtamalization through moisture optimization offers new pathways for improving product quality and energy efficiency in maize-based food systems.