Effect of applying cinnamaldehyde incorporated in wax on green mould decay in citrus fruits

BACKGROUND Green mold caused by Penicillium digitatum is the most damaging postharvest diseases of citrus fruit. Cinnamaldehyde (CA) is a food additive that has potential use in controlling postharvest disease of fruits and vegetables. In this study, the effectiveness of wax with CA (WCA) in controlling Ponkan (Citrus reticulata Blanco) green mold was investigated. RESULTS The mycelial growth of P. digitatum was inhibited by CA in a dose-dependent manner. The minimum inhibitory concentration and minimum fungicidal concentration (MFC) were both 0.50 mL L−1. In vivo test demonstrated that WCA (1 × and 10 × MFC) applied to Ponkan fruits inoculated with P. digitatum could significantly decrease the incidence of green mold up to 5 days. The WCA treatment increased the activities of catalase, superoxide dismutase, peroxidase, phenylalanine ammonia lyase, polyphenol oxidase, as well as the total phenols and flavonoids contents. Meanwhile, the treatment remarkably decreased the weight loss rate of fruits and maintained fruit quality. These results indicated that WCA treatment might induce defense responses against green mold in citrus fruit. CONCLUSION Our findings suggest that WCA might be a promising approach in controlling green mold of citrus fruits.