Combination of sodium dehydroacetate and sodium silicate reduces sour rot of citrus fruit
Abstract
Sodium dehydroacetate (SD) and sodium silicate (Na2SiO3) are food preservatives with antifungal activities against many pathogens. In this paper, the antifungal activity of the combination treatment of SD and Na2SiO3 against Geotrichum citri-aurantii, the postharvest pathogen of sour rot in citrus fruit, was tested. SD and Na2SiO3 combination (1:4, w/w) showed a synergistic inhibitory effect compared to single compound on the mycelial growth of G. citri-aurantii, with the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) being 1.8 and 3.6 g L?1, respectively. The spores’ germination and the plasma membrane integrity of the pathogen could also be visibly influenced by the 1× MFC SD + Na2SiO3 treatment. The application of various SD + Na2SiO3 concentrations (1×, 5×, and 10× MFC) to citrus fruit inoculated with G. citri-aurantii significantly (P < 0.05) decreased the incidence of sour rot during the entire storage period. After 8 d of storage, the disease incidences in SD + Na2SiO3 (10×, 5× or 1× MFC)-treated fruit were only 20%, 30%, 65%, respectively, in contrast to 100% of the control fruit. Meanwhile, SD + Na2SiO3 treatments maintained the fruit quality of citrus fruit. Results indicate that the combination of SD and Na2SiO3 is a promising approach in controlling the postharvest decay of citrus fruit.