Effect of process variables on ethylene removal by vacuum ultraviolet radiation: Application in fresh produce storage

Detrimental effects of ethylene on fresh produce make ethylene removal one of the major challenges in storage of horticultural commodities. Novel techniques based on advanced oxidation processes such as photocatalysis and photolysis by vacuum ultraviolet light (VUV) offer good potential for ethylene removal. This study focused on the use of VUV photolysis and the impact of different process variables on the efficiency of this technique. The set objectives of this study were to investigate the combined effects of three process variables; flow rate, initial ethylene concentration, and ultraviolet radiation on the efficiency of VUV photolysis for removal of ethylene at normal atmospheric conditions. Response surface methodology along with Box-Behnken design was applied to determine the combined effect of these variables. Flowrate exerted the most significant effect on the amount of ethylene removed, followed by initial ethylene concentration and ultraviolet lamp power. The combined effect of these three process parameters exerted a significant effect on percentage ethylene removal. Reducing the flowrate and increasing the lamp power as well as the initial ethylene concentration had a positive effect on the amount of ethylene removed. For an initial ethylene concentration of 5 ppm, the percentage ethylene removal (76%) was highest under optimised process variable of 9 W lamp power and 0.5 L/min flowrate. The developed reactor was tested on short term storage of apples and kiwifruit. The reactor effectively reduced ethylene concentrations in storage space of both products. Kiwifruit storage connected to the reactor had higher flesh firmness compared to the control samples.