Evaluation of application strategies for mexican oregano (Lippia berlandieri) essential oil in corn contaminated by Aspergillus flavus

Introduction Corn contamination by Aspergillus flavus is a critical food safety problem because of the production of aflatoxins. Mexican oregano essential oil (OEO; Lippia berlandieri ) has shown antifungal activity, but its efficacy depends on the application method. This study aimed to evaluate three OEO application strategies (spraying, vapor phase, and encapsulation) on the growth of A. flavus in corn. Methods Corn was inoculated with A. flavus and treated with OEO by spraying (500–8,000 µL/L), vapor phase (400–4,000 µL/L of air), or alginate–gelatin encapsulation (5,000–40,000 µL/L). These doses are equivalent to 45–727, 1,273–12,727, and 9,364–72,776 µL OEO/kg of corn, respectively; the encapsulation values are nominal. Growth was monitored for 7 days and modeled with a modified Gompertz equation to estimate A (maximum growth), V max (rate parameter), and λ (lag phase). Parameters from independent replicate fits were compared among concentrations within each strategy by one-way ANOVA and Tukey’s test (p < 0.05). Results Significant differences among concentrations were found for the three parameters within each application method. Spraying increased the lag phase and reduced maximum growth at 1,000, 2,000, and 8,000 µL/L. In the vapor phase, responses were non-linear and concentration-dependent, and growth resumed after an initial delay at all concentrations. Encapsulation delayed the onset of growth and markedly reduced maximum growth as concentration increased. No detectable growth was observed at 40,000 µL/L during the 7-day period. Discussion Spraying and the vapor phase showed fungistatic, concentration-dependent effects. Under the concentrations and conditions tested, encapsulated OEO produced the strongest inhibition of A. flavus in corn. These results support OEO delivery systems as a natural alternative for controlling toxigenic fungi in stored corn. Validation under realistic storage conditions, including aflatoxin analysis, is still required.