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Applied and Environmental Microbiology, January 2008, p. 86-98, Vol. 74, No. 1
0099-2240/08/$08.00+0     doi:10.1128/AEM.01512-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Influence of Turning and Environmental Contamination on the Dynamics of Populations of Lactic Acid and Acetic Acid Bacteria Involved in Spontaneous Cocoa Bean Heap Fermentation in Ghana

Research Group of Industrial Microbiology and Food Biotechnology, Department of Applied Biological Sciences and Engineering, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium,¹ BCCM/LMG Bacteria Collection and Laboratory of Microbiology, Ghent University, K. L. Ledeganckstraat 35, B-9000 Ghent, Belgium,² Cocoa Research Institute of Ghana (CRIG), New Tafo, Akim, Ghana,³ Barry Callebaut Ghana Limited, Plot 1 Free Zone Enclave, Tema, Ghana⁴

Received 5 July 2007/ Accepted 27 October 2007

The influence of turning and environmental contamination on six spontaneous cocoa bean heap fermentations performed in Ghana was studied through a multiphasic approach, encompassing both microbiological (culture-dependent and culture-independent techniques) and metabolite target analyses. A sensory analysis of chocolate made from the fermented, dried beans was performed as well. Only four clusters were found among the isolates of acetic acid bacteria (AAB) identified: Acetobacter pasteurianus, Acetobacter ghanensis, Acetobacter senegalensis, and a potential new Acetobacter lovaniensis-like species. Two main clusters were identified among the lactic acid bacteria (LAB) isolated, namely, Lactobacillus plantarum and Lactobacillus fermentum. No differences in biodiversity of LAB and AAB were seen for fermentations carried out at the farm and factory sites, indicating the cocoa pod surfaces and not the general environment as the main inoculum for spontaneous cocoa bean heap fermentation. Turning of the heaps enhanced aeration and increased the relative population size of AAB and the production of acetic acid. This in turn gave a more sour taste to chocolate made from these beans. Bitterness was reduced through losses of polyphenols and alkaloids upon fermentation and cocoa bean processing.

Published ahead of print on 9 November 2007.