Pg. 26-30 Litchi post-harvest preservation using packaging and biological control techniques

The majority of litchi fruit produced in South Africa is treated post-harvest with sulphur to decrease fruit browning and control post-harvest diseases. However, 79% of exported fruit are sold in the European Union, which has deemed sulphur to be unacceptable. Alternative forms of fruit quality maintenance are thus necessary. The primary cause of fruit post-harvest browning is believed to be desiccation. Previous work using PVC bag packaging has, however, resulted in enhanced postharvest fungal decay, due to excessive condensation. In the work reported on in this paper, 2 sites of origin were used, with a total of 3 harvest dates. Fruit were packaged in polypropylene bags, with specific anti-mist and gas exchange properties. Three atmosphere environments within the bags were tested, while unpackaged (standard carton) fruit were used as controls. For post-harvest decay control, a systemic resistance inducer applied pre- and post-harvest, as well as a microorganism containing component were tested. Fruits were stored at 1 °C for 30 days, with evaluations at 10-day intervals. Packing in bags significantly reduced fruit water loss and enhanced retention of
fruit colour for up to 20 days, while control fruits were brown within 10 days. There was no advantage of modified atmosphere over standard atmosphere packaging. Most water loss occurred during the first 10-day period of storage. No measurable decay was found within the context of the study.