scholarly journals A mathematical model of cocoa bean fermentation

2018 ◽  
Vol 5 (10) ◽  
pp. 180964 ◽  
Author(s):  
Mauricio Moreno-Zambrano ◽  
Sergio Grimbs ◽  
Matthias S. Ullrich ◽  
Marc-Thorsten Hütt
Keyword(s):  
Mathematical Model ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Quantitative Model ◽  
Cocoa Bean ◽  
State Variables ◽  
Experimental Conditions ◽  
Fermentation Time ◽  
Cocoa Bean Fermentation ◽  
Starting Point

Cocoa bean fermentation relies on the sequential activation of several microbial populations, triggering a temporal pattern of biochemical transformations. Understanding this complex process is of tremendous importance as it is known to form the precursors of the resulting chocolate’s flavour and taste. At the same time, cocoa bean fermentation is one of the least controlled processes in the food industry. Here, a quantitative model of cocoa bean fermentation is constructed based on available microbiological and biochemical knowledge. The model is formulated as a system of coupled ordinary differential equations with two distinct types of state variables: (i) metabolite concentrations of glucose, fructose, ethanol, lactic acid and acetic acid and (ii) population sizes of yeast, lactic acid bacteria and acetic acid bacteria. We demonstrate that the model can quantitatively describe existing fermentation time series and that the estimated parameters, obtained by a Bayesian framework, can be used to extract and interpret differences in environmental conditions. The proposed model is a valuable tool towards a mechanistic understanding of this complex biochemical process, and can serve as a starting point for hypothesis testing of new systemic adjustments. In addition to providing the first quantitative mathematical model of cocoa bean fermentation, the purpose of our investigation is to show how differences in estimated parameter values for two experiments allow us to deduce differences in experimental conditions.

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

2012 ◽  
Vol 78 (15) ◽  
pp. 5395-5405 ◽  
Author(s):  
Gilberto Vinícius de Melo Pereira ◽  
Maria Gabriela da Cruz Pedrozo Miguel ◽  
Cíntia Lacerda Ramos ◽  
Rosane Freitas Schwan
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Citric Acid ◽  
Dominant Species ◽  
Starter Culture ◽  
Physicochemical Characterization ◽  
Cocoa Bean ◽  
Small Scale ◽  
Content Type ◽  
Cocoa Bean Fermentation

ABSTRACTSpontaneous 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 (withSaccharomyces cerevisiaeas the dominant species) and lactic acid bacteria (LAB) (Lactobacillus fermentumandLactobacillus plantarumwere the dominant species), which were gradually replaced by the acetic acid bacteria (AAB) (Acetobacter tropicaliswas 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, strainsL. fermentumUFLA CHBE8.12 (citric acid fermenting, lactic acid producing, and tolerant to heat, acid, lactic acid, and ethanol),S. cerevisiaeUFLA CHYC7.04 (ethanol producing and tolerant to acid, heat, and ethanol), andAcetobacter tropicalisUFLA 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.

scholarly journals Dynamics and Biodiversity of Populations of Lactic Acid Bacteria and Acetic Acid Bacteria Involved in Spontaneous Heap Fermentation of Cocoa Beans in Ghana

2007 ◽  
Vol 73 (6) ◽  
pp. 1809-1824 ◽  
Author(s):  
Nicholas Camu ◽  
Tom De Winter ◽  
Kristof Verbrugghe ◽  
Ilse Cleenwerck ◽  
Peter Vandamme ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Fermentation Process ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Acetic Acid Bacteria ◽  
Cocoa Bean ◽  
Rrna Gene ◽  
Cocoa Bean Fermentation ◽  
Leuconostoc Pseudomesenteroides

ABSTRACT 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).

scholarly journals Oxidation of Metabolites Highlights the Microbial Interactions and Role ofAcetobacter pasteurianusduring Cocoa Bean Fermentation

2014 ◽  
Vol 80 (6) ◽  
pp. 1848-1857 ◽  
Author(s):  
Frédéric Moens ◽  
Timothy Lefeber ◽  
Luc De Vuyst
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Starter Culture ◽  
Acetic Acid Bacterium ◽  
Microbial Interactions ◽  
Cocoa Bean ◽  
Acid Oxidation ◽  
Functional Roles ◽  
Cocoa Bean Fermentation ◽  
Oxidation Of Ethanol

ABSTRACTFour cocoa-specific acetic acid bacterium (AAB) strains, namely,Acetobacter pasteurianus386B,Acetobacter ghanensisLMG 23848T,Acetobacter fabarumLMG 24244T, andAcetobacter senegalensis108B, were analyzed kinetically and metabolically during monoculture laboratory fermentations. A cocoa pulp simulation medium (CPSM) for AAB, containing ethanol, lactic acid, and mannitol, was used. All AAB strains differed in their ethanol and lactic acid oxidation kinetics, whereby onlyA. pasteurianus386B performed a fast oxidation of ethanol and lactic acid into acetic acid and acetoin, respectively. OnlyA. pasteurianus386B andA. ghanensisLMG 23848Toxidized mannitol into fructose. Coculture fermentations withA. pasteurianus386B orA. ghanensisLMG 23848TandLactobacillus fermentum222 in CPSM for lactic acid bacteria (LAB) containing glucose, fructose, and citric acid revealed oxidation of lactic acid produced by the LAB strain into acetic acid and acetoin that was faster in the case ofA. pasteurianus386B. A triculture fermentation withSaccharomyces cerevisiaeH5S5K23,L. fermentum222, andA. pasteurianus386B, using CPSM for LAB, showed oxidation of ethanol and lactic acid produced by the yeast and LAB strain, respectively, into acetic acid and acetoin. Hence, acetic acid and acetoin are the major end metabolites of cocoa bean fermentation. All data highlight thatA. pasteurianus386B displayed beneficial functional roles to be used as a starter culture, namely, a fast oxidation of ethanol and lactic acid, and that these metabolites play a key role as substrates forA. pasteurianusin its indispensable cross-feeding interactions with yeast and LAB during cocoa bean fermentation.

scholarly journals Interesting Starter Culture Strains for Controlled Cocoa Bean Fermentation Revealed by Simulated Cocoa Pulp Fermentations of Cocoa-Specific Lactic Acid Bacteria

2011 ◽  
Vol 77 (18) ◽  
pp. 6694-6698 ◽  
Author(s):  
Timothy Lefeber ◽  
Maarten Janssens ◽  
Frédéric Moens ◽  
William Gobert ◽  
Luc De Vuyst
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Citric Acid ◽  
Lactic Acid Bacteria ◽  
Starter Culture ◽  
Lactobacillus Fermentum ◽  
Cocoa Bean ◽  
Bacterial Strains ◽  
Content Type ◽  
Cocoa Bean Fermentation

ABSTRACTAmong various lactic acid bacterial strains tested, cocoa-specific strains ofLactobacillus fermentumwere best adapted to the cocoa pulp ecosystem. They fermented glucose to lactic acid and acetic acid, reduced fructose to mannitol, and converted citric acid into lactic acid and 2,3-butanediol.

scholarly journals Towards a Starter Culture for Cocoa Fermentation by the Selection of Acetic Acid Bacteria

Fermentation ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 42
Author(s):  
Lucie Farrera ◽  
Alexandre Colas de la Noue ◽  
Caroline Strub ◽  
Benjamin Guibert ◽  
Christelle Kouame ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Acid Production ◽  
Acetic Acid Bacteria ◽  
Intraspecific Diversity ◽  
Cocoa Bean ◽  
Acetic Acid Production ◽  
Cocoa Bean Fermentation ◽  
The Impact ◽  
Selection Of

Acetic acid bacteria are involved in many food and beverage fermentation processes. They play an important role in cocoa bean fermentation through their acetic acid production. They initiate the development of some of the flavor precursors that are necessary for the organoleptic quality of cocoa, and for the beans’ color. The development of starter cultures with local strains would enable the preservation of the microbial biodiversity of each country in cocoa-producing areas, and would also control the fermentation. This approach could avoid the standardization of cocoa bean fermentation in the producing countries. One hundred and thirty acetic acid bacteria were isolated from three different cocoa-producing countries, and were identified based on their 16S rRNA gene sequence. The predominate strains were grown in a cocoa pulp simulation medium (CPSM-AAB) in order to compare their physiological traits regarding their specific growth rate, ethanol and lactic acid consumption, acetic acid production, and relative preferences of carbon sources. Finally, the intraspecific diversity of the strains was then assessed through the analysis of their genomic polymorphism by (GTG)5-PCR fingerprinting. Our results showed that Acetobacter pasteurianus was the most recovered species in all of the origins, with 86 isolates out of 130 cultures. A great similarity was observed between the strains according to their physiological characterization and genomic polymorphisms. However, the multi-parametric clustering results in the different groups highlighted some differences in their basic metabolism, such as their efficiency in converting carbon substrates to acetate, and their relative affinity to lactic acid and ethanol. The A. pasteurianus strains showed different behaviors regarding their ability to oxidize ethanol and lactic acid into acetic acid, and in their relative preference for each substrate. The impact of these behaviors on the cocoa quality should be investigated, and should be considered as a criterion for the selection of acetic acid bacteria starters.

scholarly journals Indigenous Yeast, Lactic Acid Bacteria, and Acetic Acid Bacteria from Cocoa Bean Fermentation in Indonesia Can Inhibit Fungal-Growth-Producing Mycotoxins

Fermentation ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 192
Author(s):  
Endang Sutriswati Rahayu ◽  
Rokhmat Triyadi ◽  
Rosyida N. B. Khusna ◽  
Titiek Farianti Djaafar ◽  
Tyas Utami ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Ochratoxin A ◽  
Lactobacillus Plantarum ◽  
Acetic Acid Bacteria ◽  
Starter Cultures ◽  
Cocoa Bean ◽  
Cocoa Bean Fermentation ◽  
Candida Famata

Cocoa bean fermentation is an important process in the manufacturing of cocoa products. It involves microbes, such as lactic acid bacteria, yeast, and acetic acid bacteria. The presence of mold in cocoa bean fermentation is undesired, as it reduces the quality and may produce mycotoxins, which can cause poisoning and death. Aspergillus niger is a fungus that produces ochratoxin A, which is often found in dried agricultural products such as seeds and cereals. In this study, we applied indigenous Candida famata HY-37, Lactobacillus plantarum HL-15, and Acetobacter spp. HA-37 as starter cultures for cocoa bean fermentation. We found that the use of L. plantarum HL-15 individually or in combination Candida famata HY-37, Lactobacillus plantarum HL-15, and Acetobacter spp. HA-37 as a starter for cocoa bean fermentation can inhibit the growth of A. niger YAC-9 and the synthesis of ochratoxin A during fermentation and drying. With biological methods that use indigenous Lactobacillus plantarum HL-15 individually or in combination with Candida famata HY-37 and Acetobacter spp. HA-37, we successfully inhibited contamination by ochratoxin-A-producing fungi. Thus, the three indigenous microbes should be used in cocoa bean fermentation to inhibit the growth of fungi that produce mycotoxins and thus improve the quality.

scholarly journals MICROBIAL SUCCESS OF ETHANOL, LACTIC ACID AND ACETIC ACID DURING FERMENTATION OF COCOA SEEDS

2019 ◽  
Author(s):  
mulono apriyanto bin sugeng rijanto
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Microbial Population ◽  
Acetic Acid Bacteria ◽  
Microbial Populations ◽  
Cocoa Bean ◽  
Microbial Succession ◽  
Cocoa Beans ◽  
Cocoa Bean Fermentation ◽  
Fermentation Substrate

The objectives of the study are: 1) to determine the composition of the original cocoa bean pulp as a substrate for fermentation; 2) evaluating the effect of variations in random cocoa bean fermentation techniques on microbial populations. The stages of research carried out are as follows (1) testing the composition and moisture content of asalan cocoa beans as a fermentation substrate. (2) Fermented cocoa beans with 3 variations of fermentation techniques namely first treatment without addition of inoculum (control), second using S. cerevisiae (FNCC 3056) inoculum, L. lactis (FNC 0086) and A. aceti (FNCC 0016), respectively. - about 108 cfu / g is given simultaneously at the beginning of fermentation (IA). (3) gradual administration of inoculum yeast at the beginning of fermentation, lactic acid bacteria at 24 hours and acetic acid bacteria at 48 hours with a microbial population equal to the second treatment (IB). Fermentation is carried out for 120 hours. The temperature is set during fermentation, respectively 35 oC (first 24 hours), 45 oC (second 24 hours), 55 oC (third 24 hours) and 35 oC (last 48 hours). The results showed that during the fermentation of random cocoa beans showed that all treatments increased ethanol consumption in line with the increasing population of S. cerevisiae at the beginning of fermentation. Furthermore, L. lactis increases followed by lactic acid, at the end of A. aceti fermentation increases with acetic acid. From the results of this study it can be concluded that the rehydration of asalan cocoa beans can improve the composition of the pulp as a fermentation substrate. Microbial population shows that microbial succession has been demonstrated by the gradual addition of the inoculum.

Dynamics and species diversity of communities of lactic acid bacteria and acetic acid bacteria during spontaneous cocoa bean fermentation in vessels

2011 ◽  
Vol 28 (3) ◽  
pp. 457-464 ◽  
Author(s):  
Timothy Lefeber ◽  
William Gobert ◽  
Gino Vrancken ◽  
Nicholas Camu ◽  
Luc De Vuyst
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Species Diversity ◽  
Lactic Acid Bacteria ◽  
Acetic Acid Bacteria ◽  
Cocoa Bean ◽  
Cocoa Bean Fermentation

scholarly journals Kinetic Analysis of Strains of Lactic Acid Bacteria and Acetic Acid Bacteria in Cocoa Pulp Simulation Media toward Development of a Starter Culture for Cocoa Bean Fermentation

2010 ◽  
Vol 76 (23) ◽  
pp. 7708-7716 ◽  
Author(s):  
Timothy Lefeber ◽  
Maarten Janssens ◽  
Nicholas Camu ◽  
Luc De Vuyst
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Citric Acid ◽  
Lactic Acid Bacteria ◽  
Starter Culture ◽  
Acetic Acid Bacteria ◽  
Cocoa Bean ◽  
Cocoa Bean Fermentation ◽  
Acid Tolerant ◽  
Species Specific

ABSTRACT The composition of cocoa pulp simulation media (PSM) was optimized with species-specific strains of lactic acid bacteria (PSM-LAB) and acetic acid bacteria (PSM-AAB). Also, laboratory fermentations were carried out in PSM to investigate growth and metabolite production of strains of Lactobacillus plantarum and Lactobacillus fermentum and of Acetobacter pasteurianus isolated from Ghanaian cocoa bean heap fermentations, in view of the development of a defined starter culture. In a first step, a selection of strains was made out of a pool of strains of these LAB and AAB species, obtained from previous studies, based on their fermentation kinetics in PSM. Also, various concentrations of citric acid in the presence of glucose and/or fructose (PSM-LAB) and of lactic acid in the presence of ethanol (PSM-AAB) were tested. These data could explain the competitiveness of particular cocoa-specific strains, namely, L. plantarum 80 (homolactic and acid tolerant), L. fermentum 222 (heterolactic, citric acid fermenting, mannitol producing, and less acid tolerant), and A. pasteurianus 386B (ethanol and lactic acid oxidizing, acetic acid overoxidizing, acid tolerant, and moderately heat tolerant), during the natural cocoa bean fermentation process. For instance, it turned out that the capacity to use citric acid, which was exhibited by L. fermentum 222, is of the utmost importance. Also, the formation of mannitol was dependent not only on the LAB strain but also on environmental conditions. A mixture of L. plantarum 80, L. fermentum 222, and A. pasteurianus 386B can now be considered a mixed-strain starter culture for better controlled and more reliable cocoa bean fermentation processes.

scholarly journals Comparative Simulation Study on Synchronous Generators Sudden Short Circuits

2009 ◽  
Vol 2009 ◽  
pp. 1-11 ◽  
Author(s):  
Lucian Lupşa-Tătaru
Keyword(s):  
Mathematical Model ◽  
Time Domain ◽  
Short Circuit ◽  
Structural Equations ◽  
Process Models ◽  
State Variables ◽  
Synchronous Generators ◽  
State Equations ◽  
Starting Point ◽  
Short Circuits

Although of a great extent in time, the research works directed at studying transients in synchronous generators have not yet provided fully sufficient comparative studies in respect to sudden short circuits of the machine. The present paper puts forward novel and comprehensive process models for dynamic simulation of short circuit faults of initially unloaded synchronous generators, using the generalizedd-q-0 mathematical model as starting point in derivation. Distinct from the time-domain analysis, the technique proposed here allows an effective comparative overview by employing a specialized procedure to perform repeated time-domain simulations accompanied by peak values recording for the various circumstances. The time consuming matrix numerical inversion at each step of integration, usually performed when selecting currents as state variables, is eliminated by advancing the process models in a convenient split matrix form that allows the symbolic processing. Also, the computational efficiency is being increased by introducing a set of auxiliary variables common to different state equations. The models derivation is carried out without altering the structural equations of the generalizedd-q-0 mathematical model of synchronous generators whilst the simulation results are both compared and discussed in detail.

Sign in / Sign up

Export Citation Format

Share Document