Detection of spoilage-causing yeasts and bacteria in tchapalo, the Ivorian traditional sorghum beer

In this study, we aimed to analyse the spoilage potential of the isolated yeast, LAB and AAB species. Thus, 11 strains were inoculated at 0 center dot 3% (v/v) into a sterile filtered tchapalo and stored for 3 days at ambient temperature (27-30 degrees C). All the tested strains grew well or remained stable except for Limosilactobacillus fermentum and Pediococcus acidilactici, which decreased throughout the storage time. A significant decrease of total soluble solids was observed only for Saccharomyces cerevisiae (from 7 center dot 8 to 5 center dot 8 degrees Brix) and Meyerozyma guilliermondii (from 7 center dot 8 to 5 center dot 5 degrees Brix). The tchapalo samples inoculated with the LAB strains Weissella paramesenteroides, P. acidilactici, L. fermentum and the yeast strain Candida tropicalis were judged similar to the control by the panellists. However, the strains of Lacticaseibacillus paracasei and Latilactobacillus curvatus (LAB), S. cerevisiae, M. guilliermondii and Kluyveromyces marxianus (yeasts) and Acetobacter pasteurianus and A. cerevisiae (AAB) induced the spoilage of the tchapalo appearance, smell and/or taste. In the spoiled tchapalo quantitative and qualitative modification of some volatile compounds (VOCs), such as lilac aldehyde, ethyl acetate, ethyl hexanoate, ethyl octanoate and phenethyl acetate, were observed. These results provide information about the microorganisms that need to be removed to extend the shelf life of tchapalo.

Automated summary

In this study, the spoilage potential of isolated yeast, LAB and AAB species was analyzed. The strains were inoculated into tchapalo and stored for 3 days. Most strains grew well or remained stable, except for two strains that decreased throughout storage. Only two strains showed a significant decrease in total soluble solids. The tchapalo samples inoculated with certain LAB and yeast strains were similar to the control, while other strains induced spoilage in appearance, smell, and/or taste of the tchapalo. Spoiled tchapalo showed quantitative and qualitative modifications in certain volatile compounds. These findings provide valuable information for extending the shelf life of tchapalo.