Abstract:

In this study, the toxicity of four food preservatives on major postharvest pathogens of citrus and their efficacy
in preserving the quality of Glorious orange were investigated. The results showed that prochloraz EC at 250 g/L had the
strongest toxic effects on both Penicillium italicum Wehmer and Penicillium digitatum Saccardo with median effective
concentration (EC50) of 0.429 3 and 0.532 9 μg/mL, respectively. Thiabendazole SC at 450 g/L exhibited the most potent
toxic effect on Colletotrichum gloeosporiorides Penz with an EC50 of 14.238 3 μg/mL. After being treated with each
preservative, the levels of soluble solids, total sugars, organic acids and vitamin C and other physiological indicators in
Glorious orange were all higher than those of the control group without any preservative treatment. Furthermore our results
demonstrated that prochloraz EC was the most effective of the preservatives tested and its efficacy in preserving postharvest
quality of Glorious orange after 30 days of storage surpassed 90% and 85% for fruits stored for 45 and 60 days, followed by
1×1011 live endospores/g Bacillus subtilis wettable powder, with an efficacy of more than 85% for fruits stored for 30 and
45 days and of more than 80% after 60 days of storage. Thiabendazole SC (450 g/L) was the least effective and its efficacy
was only 60%. This study has indicated that 250 g/L prochloraz EC could be the best preservative.

Key words: preservative, citrus fruit, pathogens, preservation effect