- Tertia Grové, M S de Beer and W P Steyn
- Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspruit 1200, South Africa
- 2001
The South African litchi industry is striving to gain access to more foreign markets with litchi fruit. Since fruit flies and Cryptophlebia species attack litchi in South Africa, it is important to develop a postharvest quarantine treatment to free fruit from the insects. Therefore, in this study preliminary research was done with hot water immersion as a quarantine treatment.
“HLH Mauritius” and “Red Mclean” fruit were submerged in water at 45°C, 47°C, 49°C en 51°C for 15, 20, 25, 30 and 35 minutes. After hot water immersion fruit were hydro-cooled for 20 minutes in water at ambient temperature. Fruit were then placed in cold storage at 1°C for 26 to 27 days and evaluated. In some of the experiments fruit were sulphur fumigated prior to immersion and in others afterwards. Cryptophlebia leucotreta larvae in “HLH Mauritius” fruit were treated with hot water at 49° C for 20 minutes and the survival rate determined.
Results indicated that both “HLH Mauritius” and “Red Mclean” immersed in hot water were not damaged and were suitable for exportation. Therefore, litchi fruit can tolerate high temperatures. Fruit must be sulphur fumigated before immersion for improved appearance. More fungal infections and a slightly higher moisture loss occurred on fruit treated with sulphur before immersion. No C. leucotreta larvae survived immersion. These experiments were conducted on a small scale and need to be expanded before final conclusions can be made.
Summary:
- Hot water treatment is an effective method for extending the shelf life of litchi fruit after harvest.
- The treatment helps reduce postharvest losses by inhibiting fungal growth and delaying pericarp browning.
- Optimal hot water treatment conditions for litchi include temperatures between 45°C and 55°C for durations ranging from 2 to 10 minutes.
- Hot water treatment can also help maintain fruit quality by preserving color, firmness, and nutritional content.
- The process is considered environmentally friendly and safe for consumers, as it does not involve chemical residues.
- The effectiveness of hot water treatment may vary depending on cultivar, maturity stage, and post-treatment handling.
- Combining hot water treatment with other postharvest technologies, such as modified atmosphere packaging, can further enhance shelf life and quality.