Mechanism of fungal inhibition activity of Nα‐lauroyl‐L‐arginine ethyl ester (LAE) and potential in control of Penicillium expansum on postharvest citrus ‘Benimadonna’ (Citrus reticulata × Citrus sinensis)

Abstract

BACKGROUND: Citrus 'Benimadonna' (Citrus reticulata × Citrus sinensis) is a high-value perishable fruit; thus there is an urgent need for a preservation technology with high effectiveness and low safety risk from industries. N⊍-Lauroyl-L-arginine ethyl ester hydrochloride (LAE) was applied to enhance preservability by compounding with natamycin, and a possible fungal inhibition mechanism based on the hypothesis of an impact on the cell membrane by surfactant was investigated. RESULTS:In vitro testing showed that the minimum inhibitory concentration of LAE against Penicillium expansum (PE), isolated as the predominant spoilage-inducing fungus, was 32 mg L −1 and it was partially synergistic with natamycin. Subsequent in vivo testing proved the inhibition capacity. During 90 days' refrigerated preservation, spoilage rate was significantly decreased by preharvest spraying versus control without extra taste loss, and LAE showed an alleviating benefit on total pectin loss. Subsequently, electron microscopic imaging and intracellular protein levels of PE exposed to LAE indicated that LAE stress led to increased permeability and decreased cell integrity. Moreover, peroxidase, superoxide dismutase and catalase revealed that LAE enhanced oxidative stress, while pectinase was antagonized.CONCLUSION: The present investigation first introduced LAE as a candidate active ingredient for citrus preservative. A theoretical basis was provided for the development of preservation technology for high-value perishable fruit. According to the authors' knowledge this study is the first report on the inhibition mechanism of LAE in terms of oxidative stress.