The Industrialization of Cocoa Bean Fermentations

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The Industrialization of Cocoa Bean Fermentations

• Hugh Dircks and Graham Fleet
• Food Science Group
• School of Chemical Sciences and Engineering
• University of New South Wales
• Sydney, Australia

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Cocoa beans are the raw material of
chocolate production
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Cocoa Statistics

• Chocolate industry 70 billion, globally
• Cocoa beans 3000/ tonne
• Major producers of cocoa beans
• West Africa-- -- 70
• Asia Pacific--- 20
• South/Central Americas--- 10

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Key unit operations in the cocoa supply chain.
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Beans in a Pod
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Cocoa Bean Processing
Harvest pods from trees Storage, transport of
pods to fermentary Remove beans and pulp from
pod Fermentation (3-6 days) Drying, roasting
of beans Processing to cocoa butter, cocoa
powder
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Fermentation is essential for cocoa bean
quality, chocolate aroma and flavour

• 1. Hydrolysis of pulp
• 2. Metabolic end-products, enzymes diffuse into
  bean
• Physico-chemical changes cause bean death.
  Activate endogenous degradation of bean
  constituents.
• Produces precursors of chocolate flavour which
  develops during roasting
• 5. NO fermentation NO chocolate flavour

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Fermentation is a traditional, uncontrolled
process
Inefficient beans of inconsistent quality
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Origin of Microorganisms
1. Beans aseptically extracted from pods are
sterile 2. Implements for breaking pods and
extracting beans hands of workers 3. Containers
for transport 4. Fermentation vessels 5. Air 6. Fr
uit flies, insects, animals, birds 7. Natural
origin (totally organic!!)
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The microbial ecology of cocoa bean
fermentations100 years of research

• Yeasts Hanseniaspora guilliermondii
  Saccharomyces cerevisiae Pichia membranifaciens,
  P. fermentans Issatchenkia orientalis Candida
  spp
• Lactic acid bacteria Lactobacillus plantarum, L.
  fermentum Leuconostoc spp Pediococcus
  acidilactici
• Acetic acid bacteria Acetobacter pasteurianus
  Gluconobacter oxydans
• Bacillus spp
• Fungal species

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Complex microbial ecology

• Which species are essential ???
• How do individual species impact on cocoa bean
  quality and chocolate character???
• Controlled Fermentation Studies
• Sanchez J. et al (1985)--- S. cerevisiae
• Schwan R. (1998)--- S. cerevisiae

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The challenge of industrialized fermentations

• Define microbial starter cultures
• Design of fermentation vessel --- to allow
  uniform mixing, control of aeration, temperature,
  pH, cleaning etc

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Impact of yeasts on cocoa bean quality and
chocolate character
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Cocoa Bean Plantations in Queensland
South Johnstone
South Johnstoneafter cyclone (April 2006)
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Experimental Strategy

• Pilot scale fermentations (50-100kg beans) in
  North Queensland (Department Primary Industry,
  Queensland).
• Monitor

• Microbiology (yeasts, fungi, bacteria)
• Chemistry of pulp and cotyledon (sugars, acids,
  ethanol, pH)
• Temperature (fermentation profile)
• Quality (beans, chocolate)

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Pilot Scale Cocoa Bean Fermentations
Box
Heap
Barrel
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Microbiological Analyses

• ISOLATION
• Yeasts and moulds. MEA DRBC
• Lactic acid bacteria. MRS
• Acetic acid bacteria. WL-Nutrient
• Other bacteria. TSA
• IDENTIFICATION
• Base morphology, biochemistry, DNA sequencing
• DGGE
• KVL University, Denmark

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Microbiology of Fermentation

• Yeasts Hanseniaspora uvarum,H. guillermondii,
  Issatchenkia orientalis, Saccharomyces
  cerevisiae, Pichia spp., Kluyveryomyces marxianus
• Lactic acid bacteria Lactobacillus plantarum,
  Pediococcus acidilactici
• Acetic acid bacteria Acetobacter pasteurianus

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Yeast starter culture fermentations

• Various mixtures S.cerevisiae I.orientalis
  H.guilliermondii P. membranifaciens K.
  marxianus
• Monitor
• Fermentation kinetics
• Criteria of cocoa bean quality
• Cocoa bean chemistry
• Chocolate character

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Experimental Strategy

• Controlled micro-scale fermentations (5 kg beans)
  at UNSW (Sydney)
• Monitor

• Microbiology (yeasts, fungi, bacteria)
• Chemistry (GC-MS, aroma volatiles of beans)
• Quality (beans, chocolate)

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1 cocoa pods
2 at the beginning of fermentation
5 drying
4 end of fermentation
3 fermenter box
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STARTER CULTURE DEVELOPMENT PROCESS
YEAST 1
Spontaneous fermentation
Mass culture
Screening of isolates
YEAST 2
YEAST 1
Lab fermentation
Further screening
Pilot-fermentation
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Pilot Scale Fermentations
Control - no added starter
Starter mixture 1
Pichia spp.
Hanseniaspora spp.
Saccharomycescerevisiae
Acetic acid bacteria
Lactic acid bacteria
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Starter yeast affects chemistry of
fermentation
faster ferment,more EtOH,less acids
Enhanced quality and sensory
outcomes
Criteria Industry standard Control With Starter
Fermentation index gt 30 70 80
Cocoa bean pH 5.5 - 6.0 5.6 6.0
Flavour score 5.0 6.9 8.1
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Quantitative sensory profiling

• Profiled using trained paneland GC-MS
• Starter directly affect sensory profile of beans
  and chocolate

Control
Starter
Ghana
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Accelerated proteolysis

• Vicilin class proteins
• Enzymatic breakdown leads to chocolate flavour
  precursors
• Orange arrowsfaster proteolysis with starters
• Shorter fermentation possible

Start (0 h)
Middle (48 h)
End (120 or 96 h)
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Functional properties

• Increased retention of polyphenols during
  fermentation

Inhibition of mould growth during drying
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Conclusions

• Fermentations in barrels with added cultures of
  yeasts gave commercially acceptable cocoa beans
  and chocolate
• Faster fermentations ( 4-5 days)
• Chocolate flavour varied according to yeast
  species used
• Some improved functional qualities
• PLATFORM TO INDUSTRIALIZED PROCESS

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Acknowledgements

• CadburySchweppes
• Queensland Government

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Team Cocoa
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Chemical Changes during Fermentation
Beans Lipid 45-55 lipases? Protein 1-7
proteases free amino acid content increases 4-5
fold formation of flavour specific
peptides Glycosidases -- active Polyphenoloxidases
-- active
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Chemical Changes during Fermentation
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Predominant Yeasts in Cocoa Beans of
Different Countries
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Pilot-Scale Fermentations of Cocoa Beans

• Box, Heap, Barrel
• Barrel with nutrient supplementation
• Box with increased turning and mixing
• Box increased fermentation time