Effect of light wavelength and TiO₂ on photocatalytic removal of ethylene under low oxygen and high humidity storage conditions

Being active even in trace amounts (<0.1 ppm), ethylene can cause adverse effects in fruit and vegetables, such as, rapid ripening, senescence and eventual decay.
Thus, removal of ethylene is one of the major challenges in postharvest handling in order to extend the shelf life and to maintain the quality of fresh fruit and vegetables throughout the supply chain.
Photocatalysis is an emerging ethylene removal technique based on the use ultraviolet light (>200 nm) and a photocatalyst (such as titanium dioxide). Even though a few devices based on this technique are available in market for ethylene removal, few studies have been reported on the application of this technique in ethylene removal under realistic storage conditions of fruit and vegetables.
Moreover, use of short ultraviolet radiations with wavelength <200 nm (vacuum ultraviolet light) alone has been reported to be effective in removing ethylene but the available literature is very limited.
Therefore, this study was conducted to evaluate the impact of different types of light wavelengths (UV_365nm, UV_254+185nm, LED_400nm) and titanium dioxide on the efficiency of ethylene removal in a batch reactor and in further tests at different storage conditions (low/high humidity, low/high oxygen at 13°C). A lab scale reactor made of stainless steel (2.5 L) was designed for flushing with ethylene enriched air (20±2 ppm). Among the different UV light sources tested, the UV_254+185nm (major emission at 254 nm and minor at 185 nm) light was found to be the most efficient with >99% ethylene removal in less than 40 min.
Irradiation at 185 nm produced hydroxyl radicals and reactive oxygen species (atomic oxygen, ozone) which rapidly oxidized ethylene in the batch reactor.
High humidity (>90%) as well as presence of oxygen were favourable for rapid removal of ethylene.
The reactor with UV_254+185nm showed good potential for application in fresh produce storage and transport; however, further research is needed.

VIII International Postharvest Symposium: Enhancing Supply Chain and Consumer Benefits – Ethical and Technological Issues

N. Pathak, G. Rux, M. Geyer, W. Herppich, C. Rauh, P. Mahajan

postharvest, titanium dioxide, UV light, storage, photocatalysis

https://doi.org/10.17660/ActaHortic.2018.1194.189