Combination of sodium dehydroacetate and sodium silicate reduces sour rot of citrus fruit

Sodium dehydroacetate (SD) and sodium silicate (Na 2 SiO 3 ) are food preservatives with antifungal activities against many pathogens. In this paper, the antifungal activity of the combination treatment of SD and Na 2 SiO 3 against Geotrichum citri-aurantii , the postharvest pathogen of sour rot in citrus fruit, was tested. SD and Na 2 SiO 3 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 + Na 2 SiO 3 treatment. The application of various SD + Na 2 SiO 3 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 + Na 2 SiO 3 (10×, 5× or 1× MFC)-treated fruit were only 20%, 30%, 65%, respectively, in contrast to 100% of the control fruit. Meanwhile, SD + Na 2 SiO 3 treatments maintained the fruit quality of citrus fruit. Results indicate that the combination of SD and Na 2 SiO 3 is a promising approach in controlling the postharvest decay of citrus fruit.