Abstract: The major decay-casuing pathogen isolated from stored litchi fruit was confirmed by Koch’s postulates, examined morphologically and identified by internal transcriptional spacing (ITS) sequence analysis. The formulation of a composite antimicrobial coating containing cinnamaldehyde was optimized and its application in litchi preservation was investigated. Rhizopus nigricans was identified as the major pathogen causing postharvest decay in litchi fruit. The composite antimicrobial coatings markedly inhibited mildew in litchi fruit. The individual components (chitosan, zein and glycerol) significantly attenuated the decrease in soluble solids content and the increase in mass loss percentage and extend the storage period of litchi fruit. Using an orothogonal array design, the optimal combination was obtained as follows: 750 mg/L of cinnamaldehyde, 1.2 g/100 mL of chitosan, 1.6 g/100 mL of zein, and 0.7 g/100 mL of glycerol. The decay index and marketable fruit percentage of litchi fruit treated with the optimized antimicrobial coating were 0.16 and 92.3%, respectively after 8 d of storage at normal temperature. Its peel had a bright color and the sensory quality was good, indicating that the antimicrobial coating had good efficacy in preserving litchi quality.

Key words: litchi fruit, cinnamaldehyde, preservative agent, storage quality, preservative effect, rot fungi