The effects of UV photocatalytic ethylene removal on postharvest disease prevention, fruit physiology and storage environment

Ethylene, a naturally produced gaseous phytohormone, causes many detrimental effects during post-harvest fruit storage. A UV photocatalytic ethylene removal system, designed for use in post-harvest fruit and fresh produce storage and transport, was investigated to determine how it affects storage environment, fruit physiology and fruit resistance to various postharvest plant pathogens. UV photocatalysis was effective in completely oxidising ethylene from the storage environment. However, use of the technology was detrimental in increasing storage temperature and reducing storage RH. Reductions in the treated tomato fruits ripening rate were observed when experimental chambers were subjected to applications of external ethylene, indicating potential benefits of the treatment in increasing fruit shelf life. Treatment appeared to reduce hormone activated defence responses, whilst however also reducing ripening related susceptibility to Botrytis cinerea and Penicillium expansum, therefore demonstrating both positive and negative effects against the pathogens. UV photocatalysis was particularly effective against Colletotrichum gloeosporioides as treatment completely inhibited pathogen activity. This is likely as a result of a combination of ethylene removal and RH reductions preventing C. gloeosporioides conidial germination. Future work must identify optimum UV photocatalytic treatment times to prevent anthracnose, whilst not proving detrimental to fruit physiology. Furthermore, technology must be applied to commercial fruit storage systems and examined to investigate how it affects fruit crops and the storage environment in real-world settings