Synergistic properties of citral and eugenol for the inactivation of foodborne molds in vitro and on bread

Abstract

To control the spoilage of bread products and reduce the costs associated with preventing their spoilage, the synergistic antifungal effects of natural agents against the main bread spoilage fungi Penicillium roqueforti and Aspergillus niger were studied. After screening 66 groups antifungals using the checkerboard method, only one combination, i.e., that of eugenol and citral (SEC), showed synergistic effects against both the fungi. Their average minimal inhibitory concentrations (MICs) decreased significantly when they were present as a combination, i.e., by 3.40-fold, compared to the case when each agent was used separately. SEC inhibited the spore germination of both the fungi by more than 95% at 2 × MIC. At the same time, their mycelial growth was almost completely inhibited. The morphology of the mycelia was further observed by SEM. Serious wrinkles and deformations were found on the surface of the mycelia at 2 × MIC. Finally, the shelf life tests showed that treatment with SEC significantly prolonged the molding time of bread. These results showed that SEC may serve as a spoilage control measure and reduce the costs associated with preventing bread spoilage.