The effects of the organic acids in cocoa on the flavour of chocolate

Holm, Camala S; Aston, John W.; Douglas, Keith

doi:10.1002/jsfa.2740610111

Cited by 71 publications

(35 citation statements)

References 5 publications

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“…Reversely, the production of mannitol enabled the production of extra acetic acid and ATP, contributing to both volatile acidity (desired for cocoa beans) and enhanced growth competitiveness, respectively (80). Both physiological characteristics likely influence the quality of fermented cocoa beans (29,34). Finally, AAB, in particular A. pasteurianus, grew on ethanol, mannitol, and lactate and converted ethanol into acetic acid.…”

Section: Discussionmentioning

confidence: 99%

Dynamics and Biodiversity of Populations of Lactic Acid Bacteria andAcetic Acid Bacteria Involved in Spontaneous Heap Fermentation of Cocoa Beans inGhana

Camu

Winter

Verbrugghe

et al. 2007

Appl Environ Microbiol

290

424

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The Ghanaian cocoa bean heap fermentation process was studied through a multiphasic approach, encompassing both microbiological and metabolite target analyses. A culture-dependent (plating and incubation, followed by repetitive-sequence-based PCR analyses of picked-up colonies) and culture-independent (denaturing gradient gel electrophoresis [DGGE] of 16S rRNA gene amplicons, PCR-DGGE) approach revealed a limited biodiversity and targeted population dynamics of both lactic acid bacteria (LAB) and acetic acid bacteria (AAB) during fermentation. Four main clusters were identified among the LAB isolated: Lactobacillus plantarum, Lactobacillus fermentum, Leuconostoc pseudomesenteroides, and Enterococcus casseliflavus. Other taxa encompassed, for instance, Weissella. Only four clusters were found among the AAB identified: Acetobacter pasteurianus, Acetobacter syzygii-like bacteria, and two small clusters of Acetobacter tropicalis-like bacteria. Particular strains of L. plantarum, L. fermentum, and A. pasteurianus, originating from the environment, were well adapted to the environmental conditions prevailing during Ghanaian cocoa bean heap fermentation and apparently played a significant role in the cocoa bean fermentation process. Yeasts produced ethanol from sugars, and LAB produced lactic acid, acetic acid, ethanol, and mannitol from sugars and/or citrate. Whereas L. plantarum strains were abundant in the beginning of the fermentation, L. fermentum strains converted fructose into mannitol upon prolonged fermentation. A. pasteurianus grew on ethanol, mannitol, and lactate and converted ethanol into acetic acid. A newly proposed Weissella sp., referred to as "Weissella ghanaensis," was detected through PCR-DGGE analysis in some of the fermentations and was only occasionally picked up through culture-based isolation. Two new species of Acetobacter were found as well, namely, the species tentatively named "Acetobacter senegalensis" (A. tropicalis-like) and "Acetobacter ghanaensis" (A. syzygii-like).Cocoa beans are the principal raw material for chocolate production (39,43,73,81). These seeds are derived from the fruit pods of the cocoa tree (Theobroma cacao L.), which is cultivated in plantations in the equatorial zone, with the Ivory Coast, Brazil, and Ghana as the major producers (2). The cocoa beans are embedded in a mucilaginous pulp inside the pods. Raw cocoa beans have an astringent, unpleasant taste and flavor and have to be fermented, dried, and roasted to obtain the desired characteristic cocoa flavor and taste (26, 73). The final chocolate flavor is influenced by the origin and cultivar of the cocoa beans, the on-the-farm fermentation and drying process, and the roasting and further processing performed by the cocoa and chocolate manufacturer (4,10,32,33,57,75).After removal of the beans from the pods, the first step in cocoa processing is a spontaneous 3-to 10-day fermentation of beans and pulp in heaps, boxes, baskets, or trays, of which spontaneous heap fermentation is the most widely used method in Ghana ...

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Section: Discussionmentioning

confidence: 99%

Dynamics and Biodiversity of Populations of Lactic Acid Bacteria andAcetic Acid Bacteria Involved in Spontaneous Heap Fermentation of Cocoa Beans inGhana

Camu

Winter

Verbrugghe

et al. 2007

Appl Environ Microbiol

290

424

View full text Add to dashboard Cite

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“…Ethanol supplied by yeasts is required for the synthesis of acetate by the acetic acid bacteria and suppression of acetate-degrading enzymes. Furthermore, LAB reduce the amount of citrate and AAB degrade lactate, which positively affects the flavor of the cocoa beans (14). When the cultivation is performed with only L. fermentum NCC 575 in the first phase of cultivation, A. pasteurianus NCC 316 even degrades acetate.…”

Section: Discussionmentioning

confidence: 99%

“…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)(7)(8)(9)(10)(11)(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.…”

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confidence: 99%

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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“…If LAB constitute a high percentage of the total microbial population during cocoa bean fermentation, high concentrations of lactic acid will be produced, as the breakdown of carbohydrates then contributes mainly to total acidity (more lactic acid formation by LAB and less ethanol production by yeasts) of the cocoa beans. Since lactic acid is not volatile, it will remain in the chocolate after manufacturing, producing excessive sourness that masks the chocolate fl avor (Holm et al 1993 ;Jinap 1994 ;Jinap and Zeslinda 1995 ). However, as described above, the functional role of LAB in developing well -fermented cocoa beans has been underestimated, and a noncompetitive cooperation between yeasts and LAB exists in the fermenting mass .…”

Section: Optimal Fermentation Course and End Of Fermentationmentioning

confidence: 99%