Development of a starter culture for cocoa fermentation in West Africa

Special Symposium - Innovations in Food Technology (LMC Congress)

White BioTech & Related Processes (Food-2a)

Dr Kwaku Tano-Debrah
University of Ghana
Nutrition & Food Science
Department of Nutrition & Food Science
University bof Ghana
P.O. Box LG 134
Legon-Accra
Ghana

Dr Dennis S. Nielsen
Copenhagen University
Department of Food Science, Food Microbiology
Centre for Advance Food Studies, KVL, Frederiksberg, Denmark
Denmark

Prof Mogens Jakobsen
Copenhagen University
Food Science, Food Microbiology
Department of Food Science, Food Microbioloy, KVL, Rolighedsvej 30, Frederiksberg C, Copenhagen
Denmark

Prof S. Sefa-Dedeh
University of Ghana
Nutrition & Food Science
P.O. Box LG134
Legon, Accra
Ghana

Keywords: Cocoa fermentation, starter culture, inoculum development

Export of cocoa plays a significant economic role in West African countries like Cote d’Ivoire, Ghana and Nigeria - the major cocoa producing countries in the World. Fresh cocoa beans have to go through fermentation and drying steps to obtain the desired characteristic “cocoa flavour”. In practice, cocoa beans are made to ferment spontaneously by the actions of contaminating microorganisms. This work was done to develop a common inoculum that could be used to control the fermentation process to improve the quality of cocoa. Twenty-four yeast, ten acetic acid bacteria (AAB) and ten lactic acid bacteria (LAB) strains from stocks of isolates obtained from fermenting cocoa samples from Ghana were screened based on their contributions to the biochemical changes which take place during cocoa fermentation, to select some for formulating starter cultures. Six of the yeast strains which produced high amounts of ethanol and also showed pectin-degradation activity and three each of the AAB and LAB were selected and used in cocoa fermentation studies. Finally, three of the yeasts, the three selected AAB and one LAB were used to formulate two inocula ready for field fermentation trials. The studies generally confirmed the feasibility of using starter cultures to enhance the rate of fermentation of cocoa. Data obtained in both the initial screening work and the fermentation studies suggested that at least a combination of yeast and AAB would be required to appropriately ferment cocoa. The colour development however seemed to be influenced more by the LAB. pH and organic acid concentration of cocoa fermented with different single or mixed-strain cultures varied and suggested that using an inoculum could improve the quality of the cocoa.

Presented Wednesday 19, 16:20 to 16:35, in session White BioTech & Related Processes (Food-2a).