Pg. 42-45 Effect of post-harvest storage temperature and silicon on colour retention and pathogen control of litchi (Litchi chinensis Sonn.)

Due to the need for eliminating sulphur from post-harvest treatments, alternative means of post-harvest colour retention and pathogen control are necessary. Further, access to new markets will require phytosanitary treatments which may include cold sterilisation. Previous work demonstrated that packaging could reduce water loss and extend colour retention. However, effects of storage temperature below 0°C have not been studied. For pathogen control, the GRAS compound silicon has been shown as effective for a number of crops, but sufficient information is not available for litchi. Litchi fruit were packed in punnets and sealed in micro-perforated polypropylene bags before storage at -0.5°C, 1°C or 5.5°C. Half the fruits were untreated controls, while the other half were treated with silicon in the form of SiO₂ before packaging. Evaluations for colour and fungal infections were done after 10, 20, 30 and 40 days while in storage, plus an additional 5 days at room temperature (after removal from storage). Colour retention was retained for up to 40 days, but there was a time / temperature interaction with colour retention. The cold chain needed to be retained to prevent pathogen development. Silicon did not prevent pathogen development and may damage fruit, possibly due to the pH of the dipping solution. While it has been demonstrated that long-term low temperature storage is viable, which will allow for cold sterilisation, further work on pathogen control and cold chain management is necessary.