Oxidation of Metabolites Highlights the Microbial Interactions and Role of
            <i>Acetobacter pasteurianus</i>
            during Cocoa Bean Fermentation

Moens, Frédéric; Lefeber, Timothy; Vuyst, Luc De

doi:10.1128/aem.03344-13

Cited by 100 publications

(109 citation statements)

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“…The species A. pastorianus and G. oxydans were detected by PCR-DGGE during both fermentations. A. pasteurianus is a species commonly found at the end of cocoa fermentation, capable of oxidizing both ethanol and lactic acid produced by yeast and LAB, respectively, contributing to increased acidity and temperature, and death of the bean (Moens et al 2014). The temperature of fermentations reached 50°C (data not shown).…”

Section: Discussionmentioning

confidence: 98%

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

et al. 2015

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Theobroma cacao seeds are the main raw material for chocolate production. During their fermentation, a succession of microorganisms are responsible for the physicochemical changes occurring in the pulp and inside the beans. The aim of this study was to investigate the effects of yeast inoculation (Saccharomyces cerevisiae UFLA CA11, Pichia kluivery CCMA0237, and Hanseniaspora uvarum CCMA0236) on the profile of the volatile compounds and microbial communities in cocoa fermentation. The resulting chocolate was also evaluated by temporal dominance of sensations (TDS) analyses. The dominant microorganisms during spontaneous fermentation were S. cerevisiae, H. uvarum, H. guilliermondii, Lactobacillus fermentum, Pediococcus sp., and Acetobacter pasteurianus. Similarly, S. cerevisiae, P. kluyveri, Candida sp., Pediococcus sp., and A. pasteurianus were the predominant microorganisms assessed by Denaturing Gradient Gel Electrophoresis (DGGE) in inoculated fermentation. Sixtyseven volatile compounds were detected and quantified by gas chromatography/mass spectrometry (GC/MS) at the end of fermentation and chocolates. The main group of volatile compound found after the inoculated and spontaneous fermentations was esters (41 and 39 %, respectively). In the chocolates, the main group was acids (73 and 44 % from the inoculated and spontaneous fermentations, respectively). The TDS analyses showed a dominance of bitter and cocoa attributes in both chocolates. However, in the inoculated chocolate, lingering fruity notes were more intense, while the chocolate produced by spontaneous fermentation was more astringent. Thus, the inoculation of yeast influenced the microbial profile, which likely affected the volatile compounds that affect sensory characteristics, resulting in chocolate with dominant bitter, cocoa, and fruity attributes.

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Section: Discussionmentioning

confidence: 98%

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

et al. 2015

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“…Lactate is metabolized via lactate dehydrogenase and further metabolized into acetate (26). It has been reported that A. pasteurianus strains accumulate acetoin, when incubated with lactate (23)(24)(25). Indeed, two different pathways for acetoin formation are annotated.…”

Section: Methodsmentioning

confidence: 99%

“…As a central finding, the concerted use of lactate and ethanol enables optimum fluxes with regard to growth and energy metabolism. Considering recent insights into the extracellular and molecular fluxes of LAB during cocoa fermentation (12,20,23,30), this suggests that the efficiency of AAB depends on compositional traits provided by LAB and yeasts during the initial fermentation process so that the overall success of cocoa fermentation requires a well-balanced microbial consortium. …”

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confidence: 99%

“…Acetobacter pasteurianus NCC 316 and A. ghanensis DSM 18895 were selected as representative strains of two major species of AAB naturally occurring in cocoa pulp (23,31). A validated setup (12) unraveled the metabolic fluxes in AAB under cocoa pulp fermentation-simulating conditions.…”

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confidence: 99%

“…The basic knowledge that we share indicates a unique metabolism among members of the genus Acetobacter, including a nonfunctional Embden-Meyerhof-Parnas (EMP) pathway and the generation of energy from the incomplete oxidation of ethanol into acetate (21,22). A few species are able to catabolize lactate (23)(24)(25)(26). A pathway from lactate to acetate as the final product has been proposed; however, the role of some of its enzymes remains unclear (26).…”

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The Key to Acetate: Metabolic Fluxes of Acetic Acid Bacteria under Cocoa Pulp Fermentation-Simulating Conditions

Adler

Frey

Berger

et al. 2014

Appl Environ Microbiol

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c Acetic acid bacteria (AAB) play an important role during cocoa fermentation, as their main product, acetate, is a major driver for the development of the desired cocoa flavors. Here, we investigated the specialized metabolism of these bacteria under cocoa pulp fermentation-simulating conditions. A carefully designed combination of parallel 13 C isotope labeling experiments allowed the elucidation of intracellular fluxes in the complex environment of cocoa pulp, when lactate and ethanol were included as primary substrates among undefined ingredients. We demonstrate that AAB exhibit a functionally separated metabolism during coconsumption of two-carbon and three-carbon substrates. Acetate is almost exclusively derived from ethanol, while lactate serves for the formation of acetoin and biomass building blocks. Although this is suboptimal for cellular energetics, this allows maximized growth and conversion rates. The functional separation results from a lack of phosphoenolpyruvate carboxykinase and malic enzymes, typically present in bacteria to interconnect metabolism. In fact, gluconeogenesis is driven by pyruvate phosphate dikinase. Consequently, a balanced ratio of lactate and ethanol is important for the optimum performance of AAB. As lactate and ethanol are individually supplied by lactic acid bacteria and yeasts during the initial phase of cocoa fermentation, respectively, this underlines the importance of a well-balanced microbial consortium for a successful fermentation process. Indeed, AAB performed the best and produced the largest amounts of acetate in mixed culture experiments when lactic acid bacteria and yeasts were both present.A cetic acid bacteria (AAB) play an important role in cocoa fermentation (1). During fermentation of the pulp that surrounds the cocoa beans, they form acetate. Acetate then diffuses into the beans (2-4), where it initiates a cascade of chemical and biochemical reactions leading to precursor molecules for cocoa flavor (2, 5, 6). Potential substrates for AAB are lactate and ethanol, which are individually produced by lactic acid bacteria (LAB; mainly Lactobacillus fermentum) and yeasts (diverse yeasts such as Saccharomyces cerevisiae, Hanseniaspora opuntiae, and Candida krusei), respectively, during the fermentation process (6-12). Hereby, the degradation of lactate by AAB is desired, since the remaining lactate may provide an off flavor in the final cocoa product (11,13,14). In recent years, AAB have been extensively analyzed for their contribution to cocoa fermentation. Obviously, the most prevalent AAB species is Acetobacter pasteurianus (13,(15)(16)(17). In addition, Acetobacter ghanensis and Acetobacter senegalensis are found during spontaneous cocoa bean fermentation (9,13,17,18). Further studies provided first insights into the basic microbiological properties of such strains and macroscopic dynamics during cocoa pulp fermentation (12,15,(18)(19)(20). At this point, it appears to be relevant to resolve the metabolic contribution of AAB in greater detail. The basic know...

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The Functional Role of Lactic Acid Bacteria in Cocoa Bean Fermentation

Vuyst

Lefeber

Papalexandratou

et al. 2015

Biotechnology of Lactic Acid Bacteria

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Oxidation of Metabolites Highlights the Microbial Interactions and Role of Acetobacter pasteurianus during Cocoa Bean Fermentation

Cited by 100 publications

References 51 publications

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

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

The Key to Acetate: Metabolic Fluxes of Acetic Acid Bacteria under Cocoa Pulp Fermentation-Simulating Conditions

The Functional Role of Lactic Acid Bacteria in Cocoa Bean Fermentation

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