The chemistry of chocolate's past

The porous nature of ceramics means that vessels can trap and preserve residues from the foods and drinks they once held. These residues can be extracted and identified by molecular analysis using chromatography and mass spectrometry. Some compounds act as biomarkers for specific ingredients – for example, theobromine is a biomarker for cacao. Previous studies have identified theobromine in vessels from Guatemala, Honduras, Belize, Mexico and the US – including vessels from the Olmec and Maya cultures.

This project will conduct the first organic residue analysis on vessels from El Salvador. It will also test pottery in the Museum collection from other parts of Mesoamerica, including the overlooked site of Isla de Sacrificios, Mexico.

Earlier research shows that the use of cacao in foods and drinks was elaborate and complex. Inscriptions and historical sources suggest that cacao-based drinks varied in flavour – from spicy to flowery – and involved different preparation techniques. Consumption also seemed to vary depending on the context, the people involved and the type of drink.

The role of Mesoamerica in the adoption of chocolate beverages and the diversity of cacao-based foods and drinks is little studied. This project seeks to go beyond the identification of cacao as present or absent in vessels. It aims to reconstruct the culinary complexity of cacao – how it was prepared as chocolate and consumed over time. 

This project aims to understand the emergence and diversity of cacao use in Mesoamerica. Using molecular fingerprinting methods such as liquid chromatography-mass spectrometry (LC-MS), the project aims to:

• Identify the presence of cacao and the recipe of chocolate in vessels from El Salvador and Mexico.
• Improve our understanding of relevant objects in the British Museum collection by determining if vessels – some of which have cacao-related iconography – also contained cacao-based drinks and/or foods.
• Explore methods to identify other ingredients added to the recipes.
• Compare the efficiency of different extraction and analysis methods to retrieve compounds associated with the preparation of chocolate drinks and cacao-based foods.

The project's research findings will be shared with: 

• University and museum-based scholars.
• Wider audiences in the UK, including museum visitors, schools and the general public. 
• Partners in El Salvador and Mexico through the support of the Santo Domingo Centre of Excellence for Latin American Research (SDCELAR).

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