Tree-to-bar basics

Recently I finally visited the small factory of the Chocolatemakers in Amsterdam, where delicious chocolate bars are handmade from bean to bar. Funny enough I had seen the facilities in the US (Mast Brothers in Brooklyn, NYC and Taza near Boston), but never the one closest to where I live. Naturally, I wanted to post something about my impressions at the Chocolatemakers as well, but suddenly realized that I never spend a single minute on explaining what ‘bean-to-bar’ actually means… do you know how chocolate is made?

Where does the magic happen in the making of chocolate? Where does the magic happen in the making of chocolate?

Making chocolate is pretty fascinating thing, but the complexity of the process demands a lot of devotion (if you want to make good chocolate) and quite a number of machines and know-how. The second is especially true if you want to scale things up to make them more efficient and in the end: cheaper. The combination of both is probably the reason while there is a frightening low number of actual chocolate producers out there. Currently the biggest chocolate producer is Barry Callebaut which meanwhile processes more than 30% of the world’s chocolate1 (they also deliver for example Nestlé and Hershey, but also hundreds of smaller producers where many people would expect more artisan-like production methods…).
Fortunately, recent years brought an opposing trend in the high-quality chocolate sector: bean-to-bar. This litterally means that a producer starts from dried chocolate beans to finally produce his own chocolate. For the producer this has the huge advantage of having much more control over the final flavor and texture of the chocolate. While very few traditional chocolate makers have produced their own chocolates for decades2 , the number of small-scale bean-to-bar chocolate makers increased notably over the past few years. But what does that mean?

Illustration infographic of the chocolate making process
Illustration showing the chocolate making process. Click image to enlarge.

First back to the basics. Cocoa beans are in principle the seeds of the fruit from cocoa trees (theobroma cacao) which grow in tropical regions not too far from the equator. Much of what most would consider being chocolate flavors only starts to develop during fermentation of the beans. The cocoa beans are surrounded by the pulp which among others contains sugar. To ferment the cocoa beans they are simply left together with the pulp for several days. Some people describe fermentation as controlled rotting which sounds little appetizing, but is in essence correct. Fermentation is a very complex process and involves the presence of microorganisms such as yeasts and bacteria. The unreasoned fear of ‘microorganisms’ in general and the need of precise control in industrial mass production led to a severe decline of fermentation processes in our daily food3. This is clearly a pitty, since fermentation is maybe THE source of some of the most complex flavor profiles we know of. Think of wine, beer, cheese, many teas, traditional bread… and yes: chocolate! The moistness and sugar content of the pulp makes sure that certain microorganisms proliferate which in the end leads to a very complex alteration of the initial product4.
The oversimplified basic scheme is that first yeasts convert the sugar of the pulp into alcohol which is then converted by bacteria into acid. This is very analogous to making first wine and later vinegar out of grapes. The acid produced in the pulp penetrates, and thereby biologically ‘kills’, the beans and triggers very complex biochemical reactions that create many of the cocoa flavor precursors and strongly lower the concentration of other chemical compounds. Here, complex also means that the reaction is absolutely not yet understood in full details!5 What is clear though, is that the beans lose a lot of their bitterness and astringency and brownish6. Further a part of the cocoa proteins is converted into free amino acids which together with sugar molecules form the chemical basis of a lot of flavor development steps the most pronounced of which probably is the Maillard reactions during later roasting. The variety and growth conditions of the beans together with their fermenting is arguably the biggest contribution to the beans’ potential to develop a certain flavor profile.
A lot of the magic happens during cocoa fermentation
Fermentation is than stopped when beans are dried, which also makes the beans ready for storage and transport7 . Unless for those in fear of heated food, roasting the dried beans represents the second key step after fermentation to develop the complex chocolate flavors. Roasting converts many compounds that were created during fermentation (which is why people speak of ‘flavor precursors’) into a wide range of typical cocoa flavors8. In total more than 600 different aroma components have been found in chocolate which already gives a good feel for where the very complex flavor profile of high-quality chocolate comes from.
Roasting is certainly the key step for many bean-to-bar chocolate makers because the way of roasting has a lot of influence on the final flavor profile. In general, roasting can create a lot of flavors but does so in two different ways. On the one hand roasting enhances what is sometimes called the cocoa flavors, but on the other hand the process also produces distinct roast flavors that can become very dominating after heavy roasting. Roasting also reduces the chocolate’s acidity. Hence in most cases, mild roasting leads to a more acidic chocolate with only mild roast flavors, while intense roasting shifts the balance more towards the roasting flavors9 that also tend to have less acidity.
Roasting is followed by a series of mostly mechanical steps. The beans are broken and the shell is removed. The remaining cocoa ‘nibs’ contain about 50% cocoa butter and 50% cocoa solids and are ground until they release the cocoa butter and form a homogeneous mass (cocoa mass or chocolate liquor). The degree to which the cocoa mass is ground is very important for the resulting texture. The cocoa solids in the mass remain perceivable if they remain in average larger than about 25µm, which gives a grainy texture10. Sometimes grinding is divided in separate rough grinding and refining steps. Either during grinding or in-between grinding and refining sugar, and for milk chocolate milk powder, is added. Fairly often, a small amount of extra cocoa butter and/or lecithin is added to achieve a smoother, creamier texture.
In practically all cases the refined cocoa mass with added sugar (and milk powder for milk chocolate) is conched. During conching the liquid chocolate is stirred at elevated temperatures typically between 50 and 80°C. Conching has two main effects. First, the mixing which is done in a way that locally induces high sheer forces, has a severe effect on the chocolate texture. During the typically 6 to 72 hour long process, cocoa flavors are partially transferred from the cocoa solids and the cocoa butter to the sugar surface. This clearly changes the flavor perception. Conched chocolate also has a smoother and creamier texture. The second effect of conching is a change of the flavor composition. The temperature is typically too low to drive strong chemical reactions as in the case of roasting. But since the chocolate is kept warm and mixed for a long time, a substantial fraction of the more volatile flavor compounds leaves the chocolate. In many cases this is a desired effect because some of these volatile flavors are considered ‘off-flavors’ (such as acetic acid which is one of causes of the astringency of chocolate). However, this also remains a question of what desired chocolate flavors are. The common dogma in the chocolate world is that conching is a MUST for a ‘correct’ chocolate flavor. Yet some chocolate makers have even started to skip conching altogether. You should definitely taste one of these chocolates made by Claudio Corallo. Yes, their flavor profile is quite different compared to ‘correct’ chocolate. But instead of suffering from all those ‘off-flavors’ I was totally thrilled by its rich and complex fruitiness. Corallo’s chocolate is hence carrying a very clear message: There are a lot of things worth questioning in chocolate making!

And after conching? Still reading? We’re nearly done… After conching (or if you are Corallo one step earlier), the chocolate flavor is ready. It only needs to be tempered which is a procedure to make sure that the cocoa butter becomes solid in the right way. Finally, the tempered chocolate is poured into molds where the chocolate becomes a shiny solid and ready to eat… cheers.

A lot of the magic happens during cocoa fermentation

Written resources

  • Stephen T. Beckett “The Science of Chocolate”, 2nd edition, 2008.
  • Stephen T. Beckett “Industrial Chocolate Manufacture and Use”, 4th edition, 2009.
  • Harold McGee, “On Food and Cooking: The Science and Lore of the Kitchen”
  • Sandor Katz “The Art of Fermentation”
  1. As described for example here. []
  2. Such as Bonnat (very old) or Michel Cluizel (somewhat old). Most of the now established high-end bean-to-bar makers are not older than 10-15 years. []
  3. See Sandor Katz’ making a case for a revival of fermented foods! []
  4. Typically the pulp contains around 85% water with 10-15% sugar [Beckett, 2009]. []
  5. To get some more insight, you can also have a look at [Beckett, 2009]. []
  6. An overly bitter dark chocolate can hence be a sign of an incomplete fermentation process as sometimes the case for cheaper chocolate. []
  7. Beans are often dried in sun dried down to 7-8% water content which prevents molds from growing and makes the beans stable for a long time… actually some of the bulk chocolate beans lie around for years before usage []
  8. One important class are Amadori compounds which are a made of sugar and an amino acid during fermentation. []
  9. For me, one of the best examples to taste this are many of the chocolates from ‘Prallus’ which are often heavily roasted. []
  10. Which very few manufacturers even prefer, such as Taza. []

- - - - Comments - - - - - - -

  1. Ben McMahon | commented on 30. September 2016 , 17:04

    Thank you for this. Great information.
    I have shared your process image on our new website while we create our own – Please let me know if there’s any problems.

    • sweetmatterphysicist | commented on 18. October 2016 , 11:10

      Hey Ben,
      as long as the source is somehow state somewhere: no problem!

  2. Suzi Pijnenburg | commented on 31. October 2016 , 13:08

    I’m currently writing my BSc Food Science thesis on cacao. I found your illustration lovely; is it okay if I use it in my proposal? I added your site as the source, of course. Please let me know if you’d prefer me not to use it, and I’ll immediately remove it :)

    • sweetmatterphysicist | commented on 31. October 2016 , 15:40

      Hi Suzi,
      thanks for asking! You can of course use the illustration if you mention the source. I’m glad you liked it!
      Good luck with your thesis.

  3. Anjaneya | commented on 7. November 2016 , 08:54

    Thank you for sharing this Bean to Bar chocolate making process.
    Can u also help in setting up a Chocolate making production unit?


  4. Cindy | commented on 6. May 2017 , 22:32

    We are a small chocolate maker in Canada. We make a bean to bar chocolate and I was wondering if we could use your diagram (with credit given) to help children understand the process. You have done a wonderful job explaining the process. Thank you for considering

  5. Alyssa Cho | commented on 12. July 2017 , 04:08

    I would like to use your image (cacao bean to bar) for an educational outreach event at a farm fair (I will cite the source). Please let me know if this is ok!

    Thank you,

  6. Rachel | commented on 15. March 2018 , 17:58


    I’m writing from The Week Junior, a children’s current affairs and fact filled magazine based in the UK.

    We run a feature every week called ‘All About’ and this week’s subject is ‘Chocolate’

    I’ve come across your amazing infographic on how chocolate is made, and I was wondering if we could use this in the magazine please?

    Please let me know, we can of course offer a repro fee.

    Thank you,

  7. Ana Carolina | commented on 14. September 2018 , 19:57

    Hello! I am also studying chocolate in my masters and I’d like your permission to use this infographic in my research (mentioning the source). Thanks a lot!!!

    • sweetmatterphysicist | commented on 14. September 2018 , 21:46

      Sure! As long as the source is mentioned somehow that’s fine for me. Good luck with your research.

  8. Hannah Kuo | commented on 24. July 2019 , 09:42

    Hi!I’m writing an article to talk about chocolate production for a fair-trade company called “Better Foody” in Taiwan. I really like your clear and cute images, may I put them into my article please? The article will be in Chinese but I’ll keep the original images without edit, and they will all be sited and linked to this page as well.

    • sweetmatterphysicist | commented on 26. July 2019 , 13:53

      Sure. Thanks for asking and proper citing!

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