Microbial and Chemical Dynamics during Marula Wine Fermentation

Marula wine is traditionally produced through a spontaneous fermentation process and has a huge economic potential in Africa. The current study investigated the contributing microbiota and the metabolites produced during the wine fermentation process. Microbial communities were analyzed by selective cultivation and identified by biotyping and rDNA sequencing. Sugars and volatile compounds were determined with the high performance liquid chromatography and gas chromatography, respectively. Different Lactobacillus spp. were present throughout the fermentation process but dominated the earlier stages of fermentation, together with non-Saccharomyces yeasts, whereas Saccharomyces cerevisiae and acetic acid bacteria dominated the latter stages. Sucrose, glucose and fructose were detected during the early stages, while ethanol and butanol were present during the latter stages of fermentation. Interestingly, acetic acid and formic acid were detected in relatively high amounts at the latter stages of fermentation. Lactobacillus spp. and S. cerevisiae were identified as the primary contributing microbiota, and Acetobacter aceti and Acetobacter pasteuriannus were associated with the off taste and spoilage of the marula wine.