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
Cocoa beans are the raw
material of chocolate production
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%
Key unit operations in the cocoa supply chain.
Beans in a Pod
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
Fermentation is essential for
cocoa bean quality, chocolate
aroma and flavour
1. Hydrolysis of pulp
2. Metabolic end-products, enzymes diffuse into
bean
3. Physico-chemical changes cause bean
death. Activate endogenous degradation of
bean constituents.
4. Produces precursors of chocolate flavour
which develops during roasting
5. NO fermentation; NO chocolate flavour
Fermentation is a traditional,
uncontrolled process
Inefficient ; beans of inconsistent quality
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.
Fruit flies, insects, animals, birds
7.
Natural origin (totally organic!!)
The microbial ecology of cocoa bean
fermentations—100 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
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
The challenge of industrialized
fermentations
• Define microbial starter cultures
• Design of fermentation vessel --- to allow
uniform mixing, control of aeration,
temperature, pH, cleaning etc
Impact of yeasts on cocoa bean
quality and chocolate character
Innisfail,
Queensland
Cocoa Bean Plantations in
Queensland
South Johnstone
South Johnstone
after cyclone (April 2006)
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)
Pilot Scale Cocoa Bean
Fermentations
Box
Heap
Barrel
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
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
Yeast growth during fermentation of Australian
Cocoa - BARREL
10
log cfu
8
6
4
2
0
0
1
2
3
Time elapsed (Days)
Hanseniaspora spp.
Saccharomyces cerevisiae
5
Issatchenkia orientalis
Yeast growth during fermentation of Australian
Cocoa - BOX
Yeast growth during fermentation of Australian
Cocoa - HEAP
10
8
6
4
2
0
10
8
log cfu
log cfu
4
6
4
2
0
1
2
3
Time elapsed (Days)
Hanseniaspora spp.
Saccharomyces cerevisiae
4
Issatchenkia orientalis
5
0
0
1
2
3
Time elapsed (Days)
Hanseniaspora spp.
Saccharomyces cerevisiae
4
Issatchenkia orientalis
5
log cfu/g wet bean
Bacterial growth in fermenting Australian cocoa June 2005 - Box
2 (Control)
10
9
8
7
6
5
4
3
2
1
0
0
1
2
3
Time elapsed (Days)
4
Lactobacillus plantarum
Asaia spp.
Acetobacter pasterianus
Leuconostoc spp.
5
6
Bacterial growth in fermenting Australian cocoa June 2005 - Box
3 (Increased Mixing)
10
log cfu/g wet bean
9
8
7
6
5
4
3
2
1
0
0
1
2
3
Time elapsed (Days)
Lactobacillus plantarum
Acetobacter pasteurianus
4
Asaia spp.
Leuconostoc spp.
5
6
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
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)
1 cocoa pods
2 at the beginning of fermentation
5 drying
4 end of
fermentation
3 fermenter box
YEAST 1
STARTER CULTURE
DEVELOPMENT PROCESS
Spontaneous fermentation
Screening of isolates
Mass culture
YEAST 2
YEAST 1
Lab fermentation
Pilot-fermentation
Further screening
Pilot Scale Fermentations
Control - no added starter
Hanseniaspora spp.
Pichia spp.
Saccharomyces
cerevisiae
Acetic acid bacteria
Lactic acid bacteria
Starter mixture 1
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
> 30
70
80
5.5 - 6.0
5.6
6.0
5.0
6.9
8.1
Cocoa bean pH
Flavour score
Quantitative sensory profiling
•
•
Profiled using trained panel
and GC-MS
Starter directly affect
sensory profile of beans and
chocolate
Control
Starter
Ghana
Accelerated proteolysis
•
Vicilin class
proteins
•
Enzymatic
breakdown leads
to chocolate
flavour precursors
•
Orange arrows:
faster proteolysis
with starters
• Shorter
fermentation
possible
Start (0 h)
Middle (48 h)
End (120 or 96 h)
Functional properties
Increased retention of
polyphenols during
fermentation
Inhibition of
mould growth
during drying
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
Acknowledgements
• Cadbury—Schweppes
• Queensland Government
Team Cocoa
Chemical Changes during
Fermentation
PULP
BEAN
Before
Citric acid 2.4%
After
1%
Before
1%
After
0.5%
Lactic acid 0.03%
0.6%
0.01%
0.2%
Acetic acid 0.04%
1%
0.09%
2.0%
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
Chemical Changes during
Fermentation
PULP
Before
BEAN
After
Before
After
0.1%
0.4%
Fructose
6%
1%
Glucose
5%
0.5%
Sucrose
3%
0%
Ethanol
0.1%  6%  1%
1%
0.05% 0.01%
2%
0%
0.1%  3% 
Predominant Yeasts in Cocoa Beans
of Different Countries
INDONESIA Saccharomyces cerevisiae; Candida
tropicalis; Kloeckera apis
BRAZIL
MALAYSIA
GHANA
IVORY
COAST
Saccharomyces cerevisiae; Kloeckera
apiculata; Kluyveromyces marxianus;
Candida spp.
Saccharomyces, Kloeckera, Pichia,
Candida, Debaryomyces
Saccharyomyces, Kloeckera, Pichia,
Candida, Schizosaccharomyces
Saccharomyces chevalieri, Kloeckera
Pilot-Scale Fermentations
of Cocoa Beans
• Box, Heap, Barrel
• Barrel; with nutrient
supplementation
• Box; with increased turning
and mixing
• Box; increased fermentation
time