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Freshly Baked Science

Food Archaeology: Chocolate

by Dr Alicia Colson

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15th April 2019

Popping to the corner shop to buy a bar of chocolate or catching up with friends over a hot chocolate at a coffee shop is one of those simple pleasures in life. In some parts of the world, like Mexico, they will even use chocolate as an ingredient in savoury dishes, such as ‘mole poblano’. This may sound like an odd concept to some, but for you chocoholics out there, check out Elizabeth Lambert Ortiz’s cookbooks for some chocolatey inspiration or even our Triple Hot Choc Bun recipe!


The process of chocolate making begins with the beans of a cocoa pod. Each pod will contain roughly 20-50 beans. The trees they grow on (Theobroma cacao) like hot, rainy, tropical conditions with lush vegetation to provide them with the shade that they need.

But how does this bean turn into a bar?!

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Cacao pods of the Theobroma cacao taken by Sadie Whitelocks at the KulKul plantation on Karkar island, Papua New Guinea

Well, turning a bean into chocolate is a multi-step process. When the beans are removed from the pod, they are fermented, dried and then roasted. At this point, the shell and ‘meat’ of the beans are separated. The shells, known as ‘cocoa hulls’, can be ground up and used as an ingredient high in antioxidants and as a garden fertiliser. The ‘meat’ is ground into a bitter, sticky paste called chocolate liquor. This chocolate liquor contains both cocoa butter and cocoa solids, so a hydraulic press (invented by Coenradd Johannes van Houten in 1828) is used to extract the cocoa butter. From this point, different proportions of ingredients can be added to make specific types of chocolate. For example, milk chocolate can be made by adding milk, sugar, cocoa butter and optional extras to cocoa liquor.


Next, the mixture is ‘conched’, which uses a scraping mixer to evenly distribute all the ingredients and develop the flavour. Before the chocolate can be poured into a mould, it must be tempered, which involved heating, cooling and reheating the chocolate to thicken it and give it a shinier finish. The cooling is done at a fixed rate to protect the delicate flavour.


The resultant chocolate bar is so popular that cocoa beans have to be grown globally to meet the demand. Due to the specific growing conditions needed, cacao trees can’t be grown in Europe, so we rely on import from other countries, closer to the equator. The first time cocoa beans were bought into Europe, by Christopher Columbus between 1502 and 1504, their worth wasn’t immediately realised as he’d also bought back other items of more obvious value.  It wasn’t until a conquistador, Hernán Cortés, tried a cocoa drink in Mexico, which the Aztecs called ‘chocolatl’, that the commercial value was realised. He bought the recipe back to Spain, where sweetener, vanilla, cinnamon and black pepper were added to improve the flavour.


So, how long have humans been consuming chocolate?


The simple answer is, a long, long time! In order to accurately answer this question, many smaller questions must be posed; where did the cocoa tree originate? How and when was the tree domesticated? When was the cocoa bean first harvested? These questions have puzzled archaeologists, ethnohistorians, ethnobotanists, historians, linguists, archaeobotanists and geneticists for years.


The wild relatives of domesticated Theobroma have been found to be native to northern Amazonian South America. This was discovered through the analysis of the Theobroma cacao genome, which revealed that the greatest diversity is found in the upper Amazon region of northwest South America, suggesting this is where it originated. This claim was supported by cacao starch grains, theobromine residues and ancient DNA which was dated from approximately 5,300 years ago, from an archaeological site called Santa Ana-La Florida in southeast Ecuador.


Residues extracted from pottery vessels from Puerto Escondido, now in Honduras (Central America), underwent chemical analyses of the residues, which showed that cacao drinks were being made there before 1000 B.C., 500 years earlier than indicated by previous findings. This remains the earliest evidence of cacao being prepared for consumption.


Rather than using the beans to make chocolate, as we know it today, Native South Americans used the fruity pulp surrounding the beans to make a liquid which was fermented to produce an alcoholic drink called ‘chicha’. Evidence of ‘chicha’ and other cacao beverages goes way back into the Precolumbian period in Mesoamerica and comes in the form of texts, depictions and beverage residues. Cacao beverages featured prominently in the Olmec and Maya cultures of Mesoamerica as, much like modern society, it became an important part of the social and ritual lives of people who lived there.


The cacao beverages they would have been drinking all those thousands of years ago would be very different to what we now know as hot chocolate. If you were to try the chocolatl or chicha, you’d probably find it far too bitter. Likewise, wouldn’t it be amazing to let the Aztecs try our modern chocolate? The sweetness would definitely give them a shock!


Wolf, Bonny May 4, 200512:00 AM ET Mole Poblano de Guajolote: Turkey Mole Puebla Style. NPR.Org. https://www.npr.org/templates/story/story.php?storyId=4629176, accessed March 31, 2019.

Kew Science, Plants of the World Online Theobroma http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30005713-2 accessed March 31, 2019

Cocoa Market Update Compiled by the World Cocao Foundation from Published Reports and Resources March 2012. World Cocoa Foundation.

About Van Houten – 180 Years  of History http://www.vanhoutendrinks.com/en/history, accessed March 31, 2019.

Anderson, Jerry 2015 A Short History of Chocolate, and Montezuma’s Golden Goblet. History Spaces...out of the Past, December 13. http://www.historyspaces.com/food-and-candy/a-short-history-of-chocolate-and-montezumas-gold-goblet/, accessed March 31, 2019.

Zarrillo, Sonia, Nilesh Gaikwad, Claire Lanaud, et al. 2018

The Use and Domestication of Theobroma Cacao during the Mid-Holocene in the Upper Amazon. Nature Ecology & Evolution 2: 1879–1888.

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