How Different Brew Methods Affect Caffeine Extraction

Australia's very own Crema Coffee Garage, in partnership with the University of Newcastle, undertook a study to examine how various brew methods affect caffeine extraction. As a testament of accuracy and precision, the researchers used the KRUVE Sifter to achieve reliable and replicable measurements.

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As the specialty coffee market becomes more mainstream, our desire to understand even the smallest details about coffee and brewing grows. Across the industry and the market, we are having more conversations and debates regarding flavour profiles, roast types, origin, bean and grind uniformity, and so on.

An area of particular interest to coffee scientists, researchers, coffee professionals and enthusiasts are the factors that influence caffeine extraction. We already know how the various intersecting elements of coffee brewing – temperature, method, grind, bean type – impact on the flavour and perceived “strength” of a coffee, but to what degree does this affect caffeine extraction? This is what we wanted to find out at Crema Coffee Garage, so we sought help from some pretty incredible individuals at The University of Newcastle, NSW and KRUVE.

WHY INVESTIGATE CAFFEINE CONTENT?

There were several reasons we decided to pursue this project, but there are two distinct reasons for us. First, many Australians experience digestion or stomach issues with caffeinated beverages, and we wanted to further educate our market to make more informed decisions about their caffeine consumption. Second, when we tried to source this information we couldn’t find any consistency in information regarding caffeine content in coffee – no raw data to interpret, no context as to how the drinks were being made or consumed. We wanted to make the information we were looking for widely available to the market with the data and with context, and so we began our project. We chose the most commonly consumed coffee brews and coffee bean origin in the Australian market – a Colombian Excelso brewed as a standard espresso, stovetop, cold brew, pour over and French press – and compared the caffeine content of each. Results are below:

The daily recommended intake by the Australian government is about 400mg of caffeine, below our results show how many of each brew method (in a small, single or 1 cup serve) customers can consume within a 400mg limit:

However, the results of the caffeine content alone doesn’t tell the whole story. The results above don’t tell you why one method produces more caffeine than another, so we looked at the variables of each method and how they intersect to affect caffeine extraction. This is where the KRUVE Sifter became a critical tool for our project, as it allowed us to sort the nitty from the gritty and look at how grind size and particle distribution potentially impacts caffeine extraction as one intersecting factor. 

HOW WE USED THE KRUVE SIFTER

Our purpose in using the KRUVE Sifter was to ascertain a true metric range and particle size distribution of each grind setting, i.e., provide a definitive measurement and check the consistency of each grind setting. To determine this, we manipulated 50g of each grind setting used in the project using each micron range provided by KRUVE from 200-1600+ microns. Results are below:

This is where the KRUVE Sifter became a critical tool for our project, as it allowed us to sort the nitty from the gritty and look at how grind size and particle distribution potentially impacts caffeine extraction as one intersecting factor.

This allowed us to more deeply consider how grind size potentially impacts caffeine extraction in conjunction with other variables, such as temperature, brewing time, etc. In doing this, we discovered some interesting results regarding not only caffeine extraction, but also standard grind settings for the Australian market. 

GRIND SIZE, CAFFEINE EXTRACTION & OTHER FACTORS

Since analyzing grind size as a determining factor in caffeine extraction was not the objective of our project, our results don’t include definitive conclusions regarding this; however, the data does show interesting correlations between extraction factors, including grind size, and caffeine content in different brew methods.

For example, the Espresso method extracted almost twice the amount of caffeine compared to Stovetop espresso, approximately 47% more caffeine than Cold Brew, and more than 80% more caffeine than French Press and Pour Over methods. When we consider why this is, we have to look at the primary variables that influence caffeine extraction – temperature, brew time and grind size:

• Temperature: the temperature used in a commercial or home coffee machine to produce espresso is not higher than you would use in any other brew method. So although temperature is probably the most significant factor in caffeine extraction, it is unlikely to influence caffeine extraction in this instance since it is not outside the temperature range used in other brew methods.
• Brew Time: a longer brew time can often lead to increased caffeine extraction, but a 30 mL shot should take on average between 18-25 seconds and a 60 mL shot on average between 28-35 seconds. It is the shortest brew time out of all the methods. Some argue the pressure from the machine aids in this extraction, however, the amount of pressure required to affect caffeine extraction in this way is not possible in an espresso machine.
• Grind Size: The primary variable then is grind size! Espresso uses a very fine grind size, which creates overall more surface area for extraction and restricts water flow, creating a unique environment for optimal caffeine extraction.

This project has been immensely rewarding and everyone here at Crema Coffee Garage is grateful for the input, knowledge and contributions of the KRUVE team in completing it. For any coffee researcher, Q Grader, or anyone just really in love with coffee, who wants to know all the tiniest details that affect extraction or flavour profiles, the KRUVE Sifter is a must have in your tool kit. As a tool for research, it provided us with invaluable insights and established avenues for further research in the future.

Full Research Findings available for download here.

About Crema Coffee Garage

Crema Coffee Garage is headquartered in Newcastle, Australia and has a second location in Brisbane, Australia. With a roaster, showroom and espresso bar, their mission is to share their passion for coffee by bringing their customers the latest and greatest in coffee innovations. Crema's objective is to make everyone love coffee as much as they do, and they do this by delivering an extensive range of products and coffee-specific services. 

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