2.6. Infestation
Cocoa beans frequently become infested at origin by several species of insects and other pest species including the tropical warehouse moth (Ephestia cautella), Indian meal moth (Plodia interpunctella), dried fruit beetle (Carpophilus spp.), foreign grain beetle (Ahasverus advena), red-rust grain beetle (Cryptolestes ferrugineus), the tobacco beetle (Lasiodema serricorne) and the coffee bean weevil (Araecerus fasciculatus).
If these infestations are not treated at origin by effective pre-shipment fumigation, these species will survive the voyage to traders, processors and manufacturers. If not then controlled at port of entry, the infestation will spread to cocoa stores and chocolate factories and spoil finished goods.
Over recent years disinfestation in Europe has been complicated by the EU being a signatory to the Montréal protocol, which has banned the use of methyl bromide as a fumigant. This has been further complicated in certain countries where stringent requirements on the fumigation process have been imposed, notably in the Netherlands, which makes fumigation an expensive and lengthy process as the cocoa has to be moved from the warehouse to a fumigation chamber to be processed.
An alternative to methyl bromide is phosphine (hydrogen phosphide PH3), generated from compounds such as aluminium phosphide or in the form of a cylinderised gas. While phosphine is an effective fumigant, it requires much longer to penetrate the stack of cocoa and achieve reliable kill of both the adult and larval stages of pests compared to methyl bromide.
Another fumigant that has been registered for use on stored cocoa in some countries, including the Netherlands and Belgium, is sulfuryl fluoride.
Although trials using this fumigant have shown it be fast and effective, without any adverse effects on the quality of the cocoa beans and their processing (Noppe, Buckley, & Ruebsamen, 2012), EFSA has made only a tentative assessment of maximum residue levels for cocoa since insufficient trial data and an analytical method for the enforcement of the proposed residue definitions are still required (EFSA 2021) and a decision regarding its re-registration for use in the USA is still awaited.
Various alternatives have been offered; ranging from the removal of oxygen from the cocoa stack in order to asphyxiate the pests to putting the cocoa in refrigerated containers and reducing the temperature to well below freezing point to kill the pests.
Other attempts have included storing the cocoa in temperature-controlled warehouses thereby keeping the pest activity to a minimum but without eradicating the infestation. It should be noted that the comments above are related to cocoa stored in bags, the most likely mode of cocoa to be transported and used by the cocoa industry, but given the rise of bulk, loose cocoa, disinfestation still presents issues.
Sieving at points prior to/and during storage, removes insects that are not present within the beans themselves but must be accompanied by appropriate containment and/or fumigation of the sieving residue.
While prevention remains the best option, it is possible that infestation will occur, particularly at origin and in consuming regions where the climate is tropical.
Care needs to be taken at all stages of transport and storage from farm to export that infestation is kept to a minimum by ensuring clean surroundings and that, if required, the cocoa is fumigated by a reputable agent before shipment.
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