SuperGrainBag:A Hermetic Bag Liner for Insect Control of Stored Cocoa Beans in Ghana

摘要

This paper reports the development of hermetic storage in Ghana by highlighting the scientific research conducted using GrainPro SuperGrainBagTM in controlling insects of stored cocoa beans as an alternative to chemical treatment. Three stacks, all of which were composed of hermetically sealed bags of SuperGrainBag TM of 40kg dry cocoa beans each inserted into standard cocoa jute sacks were built in the same warehouse close to each other for sampling and observation at the Research Department,Quality Control Division of Ghana Cocoa Board facilities in Tema, Ghana. Two additional stacks of 64 kg per bag of dry cocoa beans were also built for sampling and observation; one stack for conventional storage (without fumigation) the other for standard storage (fumigated with phosphine).Oxygen concentration inside the SuperGrainBagTM of cocoa beans was monitored daily. Sampling was done after 30 days to observe changes in insect density. There was a steep decline in oxygen concentration in all SuperGrainBagTM during the storage with the lowest concentration of 0.0% being recorded from the fifteenth day of storage. This depleted oxygen concentration was maintained throughout the storage period. The depleted oxygen atmosphere was attributed to activity of all living organisms within the SuperGrainBagTM, including the micro organism activity due to the cocoa beans moisture content which was 7%. Although this level of moisture content reflects the normal storage conditions in Ghana,it still permitted the generation of a depleted oxygen atmosphere. After 30 days of storage, 100% mortality of high populations of insects were observed in all cocoa beans stored in SuperGrainBagrM liners except one single bag in which a few individual insects were alive. The insect population consisted of adults of Carpophilus hemipterus and Tribolium castaneum. The conventional stack containing the control bags remained highly infested with insect counts reaching 88 live insects/64kg bag of cocoa beans. The standard stack recorded 100% mortality of insects in each 64kg bag of cocoa beans. These trials indicate that hermetic storage provides an environmentally safe solution for preventing development of insects in cocoa beans and thus avoid the use of chemical fumigations.