A novel approach to the protection of cocoa beans by preventing free fatty acid formation under hermetic storage

Abstract

Hermetic storage has provided a successful storage method for the protection of dry cocoa beans by replacing fumigants for insect control and for quality preservation. Hermetic storage is achieved in specially constructed flexible plastic structures and is based on the principle of generation of an oxygendepleted, carbon dioxide-enriched interstitial atmosphere caused by the respiration of the living organisms in the ecological system of a sealed storage. An increase in free fatty acids (FFA) content in dry cocoa beans is a significant factor that determines its quality preservation. After fermentation of the beans, moisture content (m.c.) is usually high that poses a risk for the rise of FFA in the beans. Tests were carried out to study the effects of hermetic storage of dry cocoa beans under aerobic and hermetically sealed conditions on the development of FFA's in the beans at 7.0%, 7.5%, and 8.0% m.c. for periods of 90 and 160 d at 30°C. The beans under hermetic conditions responded by creating progressive depleted oxygen conditions that were accompanied by the increased carbon dioxide due to the respiration of the beans. The lowest oxygen concentration took place at 7.0% m.c. after 35 d, at 7.5% m.c. after 29 d, at 8.0% m.c. after 26 d of storage and thereafter, no significant increase in oxygen concentration was observed. The FFA content of cocoa beans at 7.0%, 7.5%, and 8.0% m.c. under hermetic conditions of 30°C remained below or close to 1.0% after 90 and 160 d of storage. This was more comparable to the results obtained when the beans were stored at 4 o C rather than the controls. In comparison, the aerated control stored at 30°C showed marked increase in FFA levels of up to 1.48%.