Microbial and Metabolites Dynamics during the Fermentation of Artisanal Drinks: Screening and Estimation from “cha’a” and “arky” Consumed in Yaoundé-Cameroon

Abstract

Objective: The present work aimed at contributing to the mastering of fermentation processes in agricultural products. Methodology: It targeted the identification and enumeration of micro-organisms present in three corn-based substrates namely sweet and fermented ‘‘cha'a’’, and the fermented original juice for ‘‘arky’’. Related investigations also focused on microbial population dynamics, alcoholic strength, reducing sugar concentrations, and pH values during fermentation. To achieve these goals, 10 specimens of fermented ‘‘arky’’ juice, 10 of sweetened ‘‘cha'a’’ and 10 of fermented ‘‘cha’a’’ were collected in some districts of the Yaoundé neighborhood and conveyed in refrigerated containers (≈2°C) to the laboratories where analyses were conducted. Culture, isolation, identification and enumeration were done according to the standard protocols. Results: The microbial screening revealed the presence of Lactobacillus spp., Corynebacterium xerosis, Candida zeylanoides, Enterococcus faecalis, and Bacillus spp. It also indicated that the populations of fermenting organisms were optimal between the 4th and the 5th days of fermentation, with an increase of alcohol degree. Meanwhile, the contents in reducing sugars decreased in the three resources, like the pH values. Optimal microbial growth was observed at 30°C. All microbial populations persisted although the experiment. Identification of bacteria from the Enterococcus genus appeared as evidence of contamination of the substrates subjected, implying adulteration. Conclusion: Combined, these findings indicate that with minimal financial resources Zea mays may contribute to health benefits (presence of probiotics) and serve for the production of alcohol; but ingesting the substrates studied in the present works also represents a health risk for two reasons: the high alcohol contents and potentially infectious disease etiologies.