Local Nixtamalization Processes Reduce Aflatoxin B1 Concentration and Shift Metabolome in Naturally Contaminated Maize

Nixtamalization is an alkaline cooking process known to lower aflatoxin B1 (AFB1) in maize, yet reported efficacy varies (28-100% reduction). Thus, existing data are not sufficient to inform nixtamalization practices in specific local contexts. To investigate this, we conducted a controlled lab study using AFB1-contaminated Guatemalan maize to evaluate the effect of current rural Guatemalan cooking practices on the AFB1 concentration. We evaluated nine conditions varying calcium hydroxide concentration, steeping duration, maize washing, and tortilla-cooking parameters. Across all conditions, the AFB1 concentration decreased by 81%, with extended steeping achieving an 86% decrease. As expected, nixtamalization substantially increased calcium content (808.22%) with modest increases in iron, copper, and magnesium, while untargeted metabolomics identified processing-associated chemical changes and preliminary annotations to inform future targeted analysis. We demonstrate that incorporating local cooking practices into systematic laboratory evaluation provides useful food safety and nutrition data, offering a scalable model for household-level interventions in toxin-exposed populations worldwide.