The Mechanism of Cacao Curing

Forsyth, W. G. C.; Quesnel, Victor C.

doi:10.1002/9780470122709.ch10

Cited by 42 publications

(32 citation statements)

References 67 publications

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“…During fermentation of the pulp that surrounds the cocoa beans, they form acetate. Acetate then diffuses into the beans (2)(3)(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)(7)(8)(9)(10)(11)(12).…”

mentioning

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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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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“…The AAB metabolizes the ethanol initially formed by the yeasts to acetic acid through an exothermal process (496 KJ/mol) [ 34 ]. Furthermore, some AAB species are capable of completely oxidizing acetic acid to CO 2 and H 2 O through an exothermal process [ 34,60 ] .…”

Section: Overall Microbial Development During Fermentationmentioning

confidence: 99%

“…The conversion of glucose and fructose to ethanol is an exothermic process producing 93.3 kJ/mol reaction [ 34,50,51 ] . Consequently, the production of ethanol in the initial phases (~ fi rst 24 h) of fermentation is accompanied by a moderate increase in temperature to around 35°C [ 2 ] .…”

Section: Overall Microbial Development During Fermentationmentioning

confidence: 99%

“…However, even though no strict de fi nition of when to terminate the fermentation has been developed, the experienced farmer still has a good idea of when to stop fermenting and start drying. This is based on the smell of the fermenting mass (development of acetic odor from the activity of acetic acid bacteria), the internal and external appearance of the beans, and falling temperature of the fermenting mass [ 33,34 ] .…”

Section: Fermentationmentioning

confidence: 99%

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The Microbiology of Cocoa Fermentation

Nielsen

Crafack

Jespersen

2012

Chocolate in Health and Nutrition

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Raw cocoa has an astringent unpleasant taste and has to be fermented, dried, and roasted to obtain the characteristic "cocoa" taste and fl avor. The fermentation and drying steps are often referred to simply as "curing." The cocoa beans originate as seeds in fruit pods of the tree Theobroma cacao . Each fruit pod contains 30-40 beans embedded in a mucilaginous pulp. The pulp is rich in glucose, fructose, and sucrose (total content 10-15%), and the initial pH is relatively low (pH = 3.3-4.0), primarily due to a high concentration of citric acid (1-3%). A relatively high content of pectin and other polysaccharides (1-2%) makes the pulp viscous, limiting diffusion of air [1][2][3][4] . The actual fermentation takes place in the pulp, where microbiological activity in the pulp leads to the initiation of various biochemical processes important for taste and fl avor development inside the beans, processes that continue during the drying step. A further purpose of the fermentation is to facilitate

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“…Chocolate has been reported to behave as a non-Newtonian fluid due to a thick suspension consisting of non-fat particles dispersed in cocoa butter, which acts as the continuous phase (Landfeld et al 2000;Jolly et al 2003;Afoakwa et al 2007). A chocolate coating is characterized for being a hard material to the touch, which easily breaks under mechanical stress (Forsyth and Quesnel 1963;De Graef et al 2011). These properties not only determine the efficiency of stages such as mixing and pumping, but also play an important role in the different chocolate applications such as enrobing, shell formation and moulding steps (Beckett 2009, Servais et al 2004.…”

Section: Introductionmentioning

confidence: 99%

Rheological of chocolate-flavored, reduced-calories coating as a function of conching process

et al. 2014

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Continuous flow and linear viscoelasticity rheology of chocolate coating is studied in this work using fat substitute gums (xanthan, GX). An alternative conching process, using a Rotor-Estator (RE) type impeller, is proposed. The objective is to obtain a chocolate coating material with improved flow properties. Characterization of the final material through particle size distribution (PSD), differential scanning calorimetry (DSC) and proximal analysis is reported. Particle size distribution of the final material showed less polydispersity and therefore, greater homogeneity; fusion points were also generated at around 20°C assuming crystal type I (β' 2 ) and II (α). Moreover, the final material exhibited crossover points (higher structure material), whereas the commercial brand chocolate used for comparison did not. The best conditions to produce the coating were maturing of 36 h and 35°C, showing crossover points around 76 Pa and a 0.505 solids particle dispersion (average particle diameter of 0.364 μm), and a fusion point at 20.04°C with a ΔH f of 1.40 (J/g). The results indicate that xanthan gum is a good substitute for cocoa butter and provides stability to the final product.

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The Mechanism of Cacao Curing

Cited by 42 publications

References 67 publications

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

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

The Microbiology of Cocoa Fermentation

Rheological of chocolate-flavored, reduced-calories coating as a function of conching process

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