Fermentation Practices and Microbiological Profile of Fermented Cacao Beans (Theobroma cacao) from Mvila Division, South Region, Cameroon

Abstract

Fermentation is an important process in the production of commercial cocoa beans. Conducted in a natural way, it takes place through the action of microorganisms such as lactic acid bacteria (LAB), acetic bacteria and fungi. This generally contributes to obtaining cocoa of different grades. In order to improve the quality of commercial cocoa in the division of Mvila, the aim of this study was to assess the fermentation practices and the microbiological profile of fresh fermented cocoa beans. For this purpose, a survey on the fermentation techniques of the cocoa sector was firstly done with 75 producers. Thereafter, samples of fermented and dried cocoa beans from different producers were collected for commercial quality assessment (grades, impurities rate and water content). Producers with cocoa beans of good quality were retained and the microbial (LAB, yeast enumeration and characterization) quality of their fresh fermented cocoa were monitored after fermentation. The results obtained on the post-harvest treatment techniques of cocoa beans revealed that the technical itinerary is respected with 100% of producers who put the pots in incubation before fermentation. In addition, fermentation techniques are practiced by 87,5% of producers and take place for 6 days long (in 95 %), notably fermentation in wooden box (47.5%), fermentation in heaps (32.50%). According to the commercial quality, the localities of Melane and Nkoemvone have good quality (Grade=1) cocoa with a rate of brown beans of 95.4% and 94% respectively. Lactic acid bacteria, acetic bacteria and yeast were presents in all fresh cocoa beans with the final load of 1.17 × 107 CFU/g, 1.87 × 105 CFU/g and 5.60 × 106 CFU/g respectively. The fermentative capacity revealed that among the 13 isolates of yeasts, 11 were alcohol producers. This study shows that these microorganisms are responsible for the good fermentation of cocoa beans. It would be judicious to make molecular identification of these strains and to use them as a starter for the controlled fermentation of cocoa.