CACAO fermentation

Source code can be found on this GitHub repo

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See the Credits section for and other info. The Source Code for the presentation is available on GitHub.


Tree to Bean to Bar
the Process of Making Chocolate

Making cocoa: a complex & multistep process

cacao to cocoa

Volatile compound profiles in beans vs chocolates

more than 600 volatile compounds in cocoa flavor


Fermentation defined


Fermentation in Cacao

What is the process of fermentation in cacao?

How does fermentation contribute to the flavor of chocolate?

What factors influence the fermentation process?

The Cacao Bean

The Seed

Cacao Pulp
a rich medium for microbial growth

The Pulp

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Cacao Fermentation
the key step in the formation of aroma precursors

Why is fermentation important &
what are the microbes doing?

  • Unfermented beans do not produce cocoa flavor on roasting.
  • Produces acids, alcohols, & heat that penetrate the testae.
  • Metabolic activity stops. Kills the embryo.
  • Allows the diffusion of metabolites in & out of seed.
  • Which triggers complex biochemical reactions in the cotyledon.
  • Initiates chemical reactions that will form the precursors.
  • No evidence that microbial enzymes penetrate testae.
  • Rather enzymes inside the beans are activated by microbial metabolites.
  • Exact role of microbes in final product is not understood.


fermentation process


fermented beans

pre and post testae

Fermentation Dynamics
What factors influence community formation & growth kinetics?


Where do the microbes come from?

Do we know?

Seeds within the ripe pod are microbiologically sterile.

When the pod is opened with a knife, the pulp becomes contaminated with a variety of microorganisms many of which contribute to the subsequent fermentation.

Organisms come mainly from the hands of workers, knives, unwashed baskets used for transport of seeds, and dried mucilage left on the walls of boxes from previous fermentations.

from Schwan RF & Wheals AE (2004) The microbiology of cocoa fermentation & its role in chocolate quality. Critical Reviews in Food Science & Nutrition, 44: 205–221


Credits & Resources

Photo, image, & graphic credits

Plesse note that unless otherwise stated, I created all figures and take full responsibility for their content.

Credits continue on the next slide

Credits continued

Images on the History of fermentation slidecome from the following references:

Creating a chemical collage

Here is the recipe I used to make the chemical collage.

Getting the chemical structures

  1. Get a list of compound names, e.g., from a paper.
  2. Put the names into a single column text file, say compounds.txt.
  3. Upload the file to PubChem Identifier Exchange Service. Under Input ID List select Synonyms from the drop-down menu and the Choose File radio button. Upload the file. Under Operator Type select Same CID from the drop down. For Output IDs select CIDs and for Output Method choose the two column option. Then hit Submit Job.
  4. Download the resulting file. This will have the CID to Compound name. Delete the compound name so there is a single column of CIDs. Save a new file with the csv file extension.
  5. Upload file to the PubChem Download Service. Select PubChem Compound, under Choose a format select Image then hit the Download button. You should get a directory of .png image files, one for each CID.

Putting the pieces together

  1. Once I had .png files for all of the compounds I did some cropping in Gimp.
  2. Then I used an online tool called Photo Collage to put all the images together and Inkscape to add text and finalize the image. Finally I used this tool to compress the image.

Packages used in this presentation