DOI: 10.36347/sajb.2019.v07i04.001

Pages: 158-165

Acetic and lactic acids produced during cocoa fermentation impact strongly the quality of fermented cocoa beans and chocolate. In this study, acid production from various carbon source and environmental conditions was analyzed in five lactic acid bacteria previously characterized as citrate lyase producers. It appears that production of acetic and lactic acids by these strains is strongly dependent on environmental conditions such as pH and temperature. Indeed, maximum yield of acids occurred at 30°C and pH 4 in Lactobacillus plantarum strain T11G3 and Lactobacillus casei strain T10G5. On the other hand acid production was maximum at 40°C and pH 4 in Lactobacillus plantarum strains T8N10, T10AG26 and at 40°C and pH 4.5 in Leuconostoc mesenteroides strain T8AB6. These strains also presented variable acid production regarding the sugar tested with sucrose allowing the highest acid yield (38.12 mg/mL) comparatively to that obtained from glucose (23.91 mg/mL) and fructose (26.28 mg/mL). Moreover, maximum acid production in all the strains was rapidly achieved, after 36-48h fermentation with sucrose, whereas a delayed production (around 72 h) was observed with glucose or fructose. Alcoholic conditions were found to particularly enhance acid production in the strains studied (Leuconostoc mesenteroides strain T8AB6). The maximum yield of acetic and lactic acids was 12.7 mg/mL and 14.4 mg/mL respectively in Leuconostoc mesenteroides strain T8AB6 and Lactobacillus plantarum strain T8N10 under citric acid condition. Overall, this study highlights that carbon source and environnemental condition impact on the production of acidic compounds by LAB from fermenting cocoa. Furthermore, variability in acid production was observed between the studied strains in most of the considered conditions. Thus, the different LAB strains studied probably behave as complementary consortium to continuously achieve the process of natural cocoa fermentation.