Hierarchical response surface methodology for optimization of postharvest treatments to maintain quality of litchi cv. 'Thieu' during cold storage

Pericarp browning and microbial decay considerably reduce the shelf life and economic value of litchi fruit. In this study a hierarchical response surface methodology with a multiple response criterion was applied to litchi cv. 'Thieu' cultivated in Vietnam to determine the optimal postharvest treatment factors throughout the whole storage period. Instrumental measurements were used to analyze quality attributes of fruit at harvest and after 10 d, 20 d, 30 d, and 38 d. Sensory quality was evaluated after 30 d and 38 d of storage. The optimal postharvest treatment for export fruit in which no fungicide residue is allowed consisted of dipping fruit for 10 min in a 5.84 mM oxalic acid solution and draining them. For fruit intended for local and regional consumption, the optimal treatment consisted of dipping it for 1 min in a 0.053% solution of carbendazim then for 10 min in a 5.14 mM oxalic acid solution, and finally draining. In both cases, fruit were packed in a polypropylene bag with a relative perforation area of 0.011% and stored at 4 ± 1 °C. The overall quality of litchi fruit was thus maintained throughout 38 d of storage.