the industrialization of cocoa bean fermentations
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
The Industrialization of Cocoa Bean Fermentations
Hugh Dircks and Graham FleetFood Science Group
School of Chemical Sciences and Engineering
University of New South WalesSydney, 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 pulp2. Metabolic end-products, enzymes
diffuse into bean3. 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 Microorganisms1. 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 Johnstoneafter cyclone (April 2006)
South Johnstone
Experimental Strategy
• Pilot scale fermentations (50-100kg beans) in North Queensland (Department Primary Industry, Queensland).
Monitor :
• MicrobiologyMicrobiology (yeasts, fungi, bacteria) (yeasts, fungi, bacteria)• ChemistryChemistry of pulp and cotyledon (sugars, of pulp and cotyledon (sugars,
acids, ethanol, pH)acids, ethanol, pH)• TemperatureTemperature (fermentation profile) (fermentation profile)• QualityQuality (beans, chocolate) (beans, chocolate)
Pilot Scale Cocoa Bean Fermentations
BoxBox
BarrelBarrel
HeapHeap
Microbiological AnalysesISOLATION
• Yeasts and moulds. MEA; DRBC• Lactic acid bacteria. MRS• Acetic acid bacteria. WL-Nutrient• Other bacteria. TSA
IDENTIFICATION• Base morphology, biochemistry, DNA
sequencing
DGGEKVL 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
0
2
4
6
8
10
0 1 2 3 4 5Time elapsed (Days)
log c
fu
Hanseniaspora spp. Issatchenkia orientalis
Saccharomyces cerevisiae
Yeast growth during fermentation of Australian Cocoa - BOX
024
68
10
0 1 2 3 4 5
Time elapsed (Days)
log c
fu
Hanseniaspora spp. Issatchenkia orientalisSaccharomyces cerevisiae
Yeast growth during fermentation of Australian Cocoa - HEAP
0
2
4
6
8
10
0 1 2 3 4 5Time elapsed (Days)
log c
fu
Hanseniaspora spp. Issatchenkia orientalis
Saccharomyces cerevisiae
Bacterial growth in fermenting Australian cocoa J une 2005 - Box 2 (Control)
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4 5 6Time elapsed (Days)
log c
fu/g
wet
bea
n
Lactobacillus plantarum Asaia spp.
Acetobacter pasterianus Leuconostoc spp.
Bacterial growth in fermenting Australian cocoa J une 2005 - Box 3 (Increased Mixing)
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4 5 6Time elapsed (Days)
log c
fu/g
wet
bea
n
Lactobacillus plantarum Asaia spp.Acetobacter pasteurianus Leuconostoc spp.
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 :
•MicrobiologyMicrobiology (yeasts, fungi, bacteria) (yeasts, fungi, bacteria)•ChemistryChemistry (GC-MS, aroma volatiles of (GC-MS, aroma volatiles of
beans)beans)•QualityQuality (beans, chocolate) (beans, chocolate)
1 cocoa pods 2 at the beginning of fermentation
3 fermenter box
4 end of fermentation
5 drying
YEAST 1
YEAST 2
STARTER CULTURE DEVELOPMENT PROCESSSpontaneous fermentation Screening of isolates
YEAST 1
Lab fermentation
Further screeningPilot-fermentation
Mass culture
Pilot Scale Fermentations
Control - no added starter Starter mixture 1
Pichia spp.Hanseniaspora spp.
Acetic acid bacteria
Lactic acid bacteria
Saccharomycescerevisiae
Criteria Industry standard
Control With Starter
Fermentation index > 30 70 80
Cocoa bean pH 5.5 - 6.0 5.6 6.0
Flavour score 5.0 6.9 8.1
Enhanced quality and sensory outcomes
Starter yeast affects chemistry of fermentation
faster ferment,more EtOH,less acids
Quantitative sensory profiling• Profiled using trained panel
and GC-MS• Starter directly affect
sensory profile of beans and chocolate
Ghana
Starter
Control
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
Citric acid
Lactic acid
Acetic acid
2.4% 1% 1%0.5%
0.03% 0.6% 0.01%0.2%
0.04% 1% 0.09%2.0%
BeforeAfter BeforeAfter
PULPPULP BEANBEAN
Beans: Lipid 45-55%; lipases?Protein 1-7%; proteases; free amino acidcontent increases 4-5 fold; formation of flavour specific peptides
Glycosidases -- activePolyphenoloxidases -- active
Chemical Changes during Fermentation
Fructose
Glucose
Sucrose
Ethanol
6% 1% 0.1%0.4%
5% 0.5% 0.05%0.01%
3% 0% 2%0%
BeforeAfter BeforeAfter
PULP BEAN
0.1% 6% 1% 0.1% 3% 1%
Predominant Yeasts in Cocoa Beans of Different Countries
INDONESIAINDONESIA
BRAZILBRAZIL
MALAYSIAMALAYSIA
GHANAGHANA
IVORY IVORY COASTCOAST
Saccharomyces cerevisiae; Candida tropicalis; Kloeckera apis
Saccharomyces cerevisiae; Kloeckera apiculata; Kluyveromyces marxianus; Candida spp.
Saccharomyces, Kloeckera, Pichia, Candida, Debaryomyces
Saccharyomyces, Kloeckera, Pichia, Candida, Schizosaccharomyces
Saccharomyces chevalieri, Kloeckera apiculata, Candida spp.
Pilot-Scale Fermentations of
Cocoa Beans• Box, Heap, Barrel
• Barrel; with nutrient supplementation
• Box; with increased turning and mixing
• Box; increased fermentation time