the industrialization of cocoa bean fermentations

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