Grapefruit seed extract (GSE)-incorporated carnauba wax (CW) coating was developed to preserve Satsuma mandarins (Citrus unshiu Marc.). GSE (1.00%, w/w)-incorporated CW (GSE-CW) coating emulsions and GSE (0.50%)-oregano oil (OO, 0.50%)-incorporated CW (GSE-OO-CW) coating emulsions reduced Penicillium italicum disease incidence (%) on mandarin surfaces by 23.6 ± 3.6 and 25.0 ± 5.0%, respectively, relative to that on uncoated mandarin samples (100%). GSE (1.00%)-CW coating emulsions exhibited a higher colloidal stability than GSE (0.50%)-OO (0.50%)-CW coating emulsions. During storage at 25 °C, GSE (1.00%)-CW coating was superior to CW coating in reducing P. italicum disease incidence. CW coating significantly reduced weight loss, respiration rate, and firmness loss during storage at 4 and 25 °C (P < 0.05). The ascorbic acid concentration and peel color were not affected by GSE-CW coating (P > 0.05). These results suggest that GSE-CW coating can extend the post-harvest shelf life of mandarins by inhibiting the growth of P. italicum.
Keywords: Carnauba wax; Edible coating; Grapefruit seed extract; Mandarin; Penicillium italicum.