April 30, 2019

How Origin Affects Coffee Chemistry & The Impact on Traceability


What is your preferred coffee origin? Brazil, Kenya, Ethiopia? And why should you care which country coffee comes from? One reason it may matter is because the same variety of coffee can have different chemical components depending on where it’s grown. These chemical differences not only impact flavour and profile, but can help us better identify coffee.

Read on to understand more about how origin can impact chemistry and what that means for transparency.

Lee este artículo en español Cómo el Origen Incide en la Química Del Café y la Trazabilidad

Making notes on coffee chemistry. Credit: Nathan Colton

The Relationship Between Region & Chemistry

Lots of factors affect the chemistry of coffee. Producers control a large number of variables, including which variety they grow, when they harvest the plant, and how the coffee is processed. They also make choices about the environment that the coffee is grown in, including how much fertilizer is used and shade levels. The combination of these factors, as well as the natural environmental conditions of the region and specific plot, contribute to the unique flavours of each coffee.

We have long grouped coffees into flavour profiles based on origin. We talk about fruity, high-acidity African coffees, or full-bodied Central American ones. Flavour is a result of the unique chemistry of the coffee, so we can conclude that regional flavors are the result of similar chemical features in coffees from each region.

But what are these chemical differences? And could we use chemical markers to reveal or confirm a coffee’s origin?

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Coffee being brewed using a Kalita Wave. Credit: Miguel Regalado

Using Chemical Markers to Identify Coffee

Through nuclear magnetic resonance spectroscopy (better known as NMR fingerprinting), scientists have found markers that can identify coffee from Colombia and the same technique has been used to identify Robusta in coffee blends. This is useful when there is suspicion that Arabica blends have been adulterated by cheaper Robusta.

Researchers have also looked at phenolic and methylxanthine compounds to identify coffees. Both of these groups of compounds are present in all coffees.

Methylxanthines include caffeine, theobromine, and theophylline. Phenolic compounds include organic and chlorogenic acids, such as ferulic acid, quinic acid, caffeic acid, and the compounds formed from combinations of quinic acid and caffeic acids known as caffeoylquinic acids (CQAs). Phenolic compounds create much of the aroma and flavour of coffee.

Both of these groups of compounds have been shown to be incredibly sensitive to the changing environment of the coffee plant. It’s thought that they are involved in how coffee plants adapt to their environment.

Researchers from the European Commission of Health and Consumer Protection have used analysis of methylxanthines and phenolic compounds to classify coffee by continent of origin with at least 90% accuracy. Although impressive, the placement of coffee to its continent is still too broad to have a practical application.

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Coffee beans on a map of the world. Credit: Nathan Colton

Country-Specific Chemical Differences

My own company, Sci-Fi Foods, is focused on determining chemical differences related to national or regional origins. We’ve observed that there’s a large variation in the levels of caffeine and phenolic compounds, such as diverse CQAs, among different coffees. For example, coffees from El Salvador and Venezuela have extraordinarily low levels of caffeine and CQAs, whereas Kenyan coffees are known for their high CQA levels. Our research also suggests a significant and characteristic difference in levels of trigonelline and acetic acid within South American and Central American coffees.

We’re working on finding further consistent regional variations within the chemistry of coffees with the goal of being able to identify region by concentrations of key molecules. We hope that in the near future we’ll be able to predict the origins of unknown samples and to differentiate among green coffees by origin.

Understanding chemical differences and their effects on profile might help to maintain or even intensify the specific characteristics of each region. If we’re able to better understand which factors make each region’s flavour unique, we could experiment with new conditions to intensify or modify flavour characteristics.

Coffee cherries and beans. Credit: Miguel Regalado

Why The Relationship Between Chemistry & Origin Matters

Understanding how chemistry relates to flavour in both green and roasted coffee is important for roasters, buyers, and consumers. It can inform what kind of beans we buy – if we know that a bean is high in a compound that produces a flavour we enjoy, that may be a more accurate way of finding beans we like than reading subjective flavour notes. Better understanding of chemistry could also help us develop roasting and brewing methods.

The relationship between chemistry and origin could have a similar impact, allowing producers to choose the varieties best suited to their farm and to influence profile by agricultural choices. For example, if they know that a certain environmental condition produces a chemical related to a desirable flavour, they can choose to focus on creating that environment.

Coffee being poured into a cup. Credit: Fernando Pocasangre

If we can identify region by chemistry, we may be able to register coffees as protected denomination of origin. Better identification can also improve transparency and ensure traceability throughout the supply chain.

Why does traceability matter? Because the traditional coffee supply chain involves a lot of actors and it’s easy to lose track of exactly where a coffee is from and what processes it has undergone. If we can use chemical analysis to confirm origin and other factors, we can better trust the supply chain and have increased accountability. This, in turn, can improve market access and potentially raise prices for small-scale producers of quality coffee.

Chemical analysis may also have a benefit in reducing fraud and misrepresentation, such as in the example of finding Robusta mixed with Arabica blends.

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Ripe coffee cherries at El Águila, a coffee farm in El Salvador. Credit: Miguel Regalado

Barriers to Further Chemical Analysis

One of the main problems in fully understanding the relationship between origin and chemistry is that there isn’t much chemical data about green coffee specified by origin. Understanding the chemistry of coffee connected to region requires the analysis of a lot of coffee samples from every major coffee region, over several harvest seasons.

Considering that coffee production is spread over several continents, with many producing nations, this would be a daunting task for any single research team or company. To undertake such a large scale piece of research, we need a collective effort.

More focus has been given to the relationship between coffee chemistry and flavours. Various institutes, companies, and enthusiasts have created a network to share data and ideas on the topic. This result is a systematic recording of data, as more teams are informed as to which data points are still lacking. This should be an example to researchers looking to find out more about the connection between coffee chemistry and origin.

Cup of and Ethiopian coffee brewed as a pourover. Credit: Julio Guevara

There’s much to be gained from better understanding the relationship between origin and chemistry in green coffee. Increased knowledge could inform farming practices, allowing producers to select the best variety and better tailor their methods to the region.

As well as providing better understanding of how profile is created, chemical analysis could allow us to improve transparency and traceability within the supply chain.

If researchers and producers across the industry are able to collaborate and track data on a large scale, there’s huge potential to more fully understand the coffee plant.

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