Effectiveness of Hermetic Storage in Insect Control and Quality Preservation of Cocoa Beans in Ghana

摘要

This paper reports the development of hermetic storage in Ghana by highlighting the scientific research conducted using GrainPro CocoonsTM in controlling insects and preserving the quality of cocoa beans as an ahemative to chemical treatment. Three stacks for hermetic storage and one stack each for conventional storage (without fumigation) and standard storage (with fumigation) were built for sampling and observation. The CocoonTM stacks were 3.40m(long)×2.95m(wide)×2.0m high and contained 220 bags （64 kg per bag) of sundried （average of 7.0% moisture content) cocoa beans. Oxygen concentration and temperature inside the stack of cocoa beans were monitored daily.Sampling was done at 0,3,6 and 9 week intervals to observe changes in insect density and product quality eharacterisation. There was a steep decline in oxygen concentration in all CocoonsTM during the storage with the lowest concentration of 0.0% being recorded in all the CocoonTM from the fifteenth day of storage, maintained throughout the storage period. The temperature was almost uniform inside the CocoonTM throughout the storage period. After three weeks of storage, the first CocoonTM was found to be infested with live adults of Cryptolestes ferrugineus, Cryptolestes pusillas,Araecerus fasciculatus, Lasioderma serricorne, and Ephestia cautella larvae and some fruit flies. However, these live insects were few compared with the high insect population which was dead inside the CocoonsTM. Most of the Las/oderma serricorne and Tribolium castaneum introduced at the beginning of the experiment were dead at the third week;100% mortality was recorded for all inseets at the sixth week of storage. All the cocoa beans inside the CocoonTM maintained their quality level throughout the storage period;the grade remained the same after nine weeks of storage as it was at the beginning of the experiment.