Efficiency of ethyl formate and Vapormate® on dates fumigation: Effects on fruit quality
Dates are subject to infestation by several insect species during and after harvest. In Tunisia, the world first producer of Deglet Nour variety, infestation rate may reach 20%, which leads to serious damages to the fruit rendering it unfit for human consumption and unacceptable for marketing in international trade. The main pest of date is carob moth (Ectomyelois ceratoniae) which develops inside the fruit and continues its growth upon arrival at the packaging plant and during storage.
In this study, ethyl formate (EF) was chosen, as an alternative to methyl bromide, to fumigate dates at the laboratory scale. For this purpose, three EF concentrations (114.4 g m-3 ; 128.7 g m-3 ; 143 g m-3 ) and two exposure durations (2 and 3 hours) were tested. Results showed that the most efficient combination is 143 g m-3 EF during 2 hours which ends up with 98.12% mortality. On a commercial scale, EF is available as a mixture of CO2 and EF: 16.7 wt% EF in liquid carbon dioxide (Vapormate ®, LINDE GROUP). Hence, experiments at semi-industrial scale were run in order to validate previous results. Thanks to the CO2 synergic effect, the mortality rate was confirmed. In addition, effects of EF on fruit quality were investigated through color, sugar content and microbiological analysis.