Microbiological and Physicochemical Characterization of Small-Scale Cocoa Fermentations and Screening of Yeast and Bacterial Strains To Develop a Defined Starter Culture

Abstract

Spontaneous cocoa bean fermentations performed under bench-and pilot-scale conditions were studied using an integrated microbiological approach with culture-dependent and culture-independent techniques, as well as analyses of target metabolites from both cocoa pulp and cotyledons. Both fermentation ecosystems reached equilibrium through a two-phase process, starting with the simultaneous growth of the yeasts (with Saccharomyces cerevisiae as the dominant species) and lactic acid bacteria (LAB) (Lactobacillus fermentum and Lactobacillus plantarum were the dominant species), which were gradually replaced by the acetic acid bacteria (AAB) (Acetobacter tropicalis was the dominant species). In both processes, a sequence of substrate consumption (sucrose, glucose, fructose, and citric acid) and metabolite production kinetics (ethanol, lactic acid, and acetic acid) similar to that of previous, larger-scale fermentation experiments was observed. The technological potential of yeast, LAB, and AAB isolates was evaluated using a polyphasic study that included the measurement of stress-tolerant growth and fermentation kinetic parameters in cocoa pulp media. Overall, strains L. fermentum UFLA CHBE8.12 (citric acid fermenting, lactic acid producing, and tolerant to heat, acid, lactic acid, and ethanol), S. cerevisiae UFLA CHYC7.04 (ethanol producing and tolerant to acid, heat, and ethanol), and Acetobacter tropicalis UFLA CHBE16.01 (ethanol and lactic acid oxidizing, acetic acid producing, and tolerant to acid, heat, acetic acid, and ethanol) were selected to form a cocktail starter culture that should lead to better-controlled and more-reliable cocoa bean fermentation processes.

The impact of yeast starter cultures on the microbial communities and volatile compounds in cocoa fermentation and the resulting sensory attributes of chocolate

“…Batista et al (2015) also showed this species to have a similarly low population (around 3 Log cell/g) during spontaneous fermentation process. Researchers from Brazil have also found similar species in cocoa fermentation (Moreira et al 2013;Pereira et al 2012;Ramos et al 2014;Schwan and Wheals 2004).…”

“…Species belonging to the genera Acetobacter and Gluconobacter have been described in different cocoa fermentations (Ardhana and Fleet 2003;Garcia-Armisen et al 2010;Lima et al 2011;Moreira et al 2013;Pereira et al 2012;Ramos et al 2014;Schwan and Wheals 2004). The species A. pastorianus and G. oxydans were detected by PCR-DGGE during both fermentations.…”

Impact of multi-metals (Cd, Pb and Zn) exposure on the physiology of the yeast Pichia kudriavzevii

“…The yeast P. kudriavzevii has been isolated from different food fruit sources, such as cocoa beans, as the strain used in the present work (Pereira et al 2012). This yeast has a biotechnological potential for bio-ethanol (Dhaliwal et al 2011) production, in agriculture practices as bio fertilizer (Chan et al 2012) or in the bioremediation of heavy metals (Ubeda et al 2014).…”

Cocoa Fermentation from Agnéby-Tiassa: Biochemical Study of Microflora

“…Among the 155 strains, 26 (16.77%) were Acetobacter genus. were able to oxidize acetic acid and O indicated by turning of medium This observation was not the same observation has been regularly recorded in cocoa beans fermentation [8,14].…”

“…This microbial activity generates a range of metabolites end-products such as alcohols and organic acids which diffuse into beans to cause their death. The change triggers an array of biochemical reactions and chemical changes within the beans, that are essential for the development of the characteristic cocoa flavour [12,13,14].…”