Abstract: Candida oleophila is an efficient antagonist. Many studies have shown that it can control postharvest diseases in various fruits. However, because of difficulties in its transportation and storage, C. oleophila is difficult to apply commercially. Freeze-drying is widely used to preserve microorganisms. Thus, in the present research, the selection and optimization of cryoprotectant components (sugars and sugar alcohols including trehalose, sucrose, lactose and sorbitol; the antioxidant sodium glutamate; excipients including skim milk and β-cyclodextrin) as well as their levels for vacuum freeze-drying of C. oleophila were optimized using one-factor-at-a-time and orthogonal array design methods. The optimal formulation was composed of 15% trehalose, 2% sodium glutamate, and 10% skim milk powder. A survival rate of 69.7% was obtained using this formulation. The effects of fresh and freeze-dried C. oleophila on the incidence of blue mold and lesion diameter in apple were compared, and the growth dynamics of the yeast inoculated in apple wounds. Through this study, we hope to obtain a good biocontrol agent against blue mold in apple.

Key words: Candida oleophila, cryoprotectant, freeze-drying, biological control