- Valerie Claassen and FJ Kruger
- ARC-Institute for Tropical and Subtropical Crops, Private Bag X 11208, Nelspruit 1200
- 2003
A study was conducted to evaluate an experimental sulphur free modified atmosphere postharvest procedure under commercial conditions. To do this, a mixed pallet containing both HLH Mauritius and McLean’s Red fruit was packed at a packhouse in Tzaneen and transported to Cape Town. The pallet was first stored at the central fruit terminal after which it was transported to a pre-packing facility in Somerset West. Here the fruit were pre-packed and marketed at a chain store. The results were generally positive but certain restraints still exist. An attempt can nevertheless be made to export a pallet of similarly treated fruit to Europe. A very specific marketing strategy will however have to be followed to prevent the project from failing. The initial experimental export consignment will thus have to be co-ordinated and monitored by the researchers.
Summary:
- The study evaluated an experimental postharvest sulphur-free modified atmosphere (MA) storage procedure for litchis under commercial conditions.
- A mixed pallet of HLH Mauritius and McLeans Red litchis was packed and transported from Tzaneen to Cape Town, then pre-packed and marketed at a chain store.
- The fruit were washed with disinfectant and packed in various thickness MA bags (20, 50, 100 microns) with different gas compositions.
- After initial storage, all fruit were in good condition for 4 days; McLeans Red showed slight chilling injury by day 4, mainly black marks on protuberances.
- The HLH Mauritius fruit was more mature and less susceptible to chilling injury compared to McLeans Red.
- At 21 days, fruit showed low fungal infection rates (1.4% for HLH Mauritius, 0.5% for McLeans Red) which increased slightly over time.
- Fungal infections were mostly associated with insect damage and burst or torn fruit; insect control in orchards was identified as important.
- Brown browning was mainly due to anaerobiosis (suffocation) in thicker bags, especially 100 micron; thinner bags showed less browning.
- Pre-packed fruit were well received in stores, though some customers were unaccustomed to sulphur-free fruit and dampness inside bags.
Marketable shelf life in MA bags was about 28 days; by day 32 only about 20% of fruit remained marketable. - Recommendations include careful sorting to remove damaged or over-mature fruit, use of thin (20-30 micron) polyethylene bags, and pre-packing fruit between 21-24 days.
- The study proposes experimental export trials for sulphur-free litchis, targeting organic markets with coordinated marketing and monitoring by researchers.
- Traditional export channels and European wholesalers currently prefer sulphur fumigated fruit, so a specific marketing strategy is necessary.