Crema Coffee Garage's Caffeine Content Study

Caffeine in Coffee: A Comparison of Espresso, Stovetop, Pour Over, Cold Brew & French Press


French Press Coffee


Do you know how much caffeine is in your cup?

A new study in collaboration with the Chemistry Staff in the University of Newcastle examines caffeine content across Australia's favourite brewing methods.



Overview

When it comes to the caffeine content found in a cup of coffee there are resources everywhere… but there is a lot of inconsistency between results with little explanation for the discrepancies. We wanted to find out exactly how much caffeine was in each kind and size of brew most commonly consumed in Australia.

To work this out we chose five common brewing methods in Australia: 

  •     - Espresso - run-of-the-mill barista-made coffee
  •     - Pour Over - brew poured through a paper or metal filter
  •     - Stovetop Espresso - boiled on a regular home stove
  •     - Cold Brew - brewed by replacing heat with time, typically overnight (8-12 hours)
  •     - French Press - also known as a plunger or a coffee press

To make the experiment as uniform as possible, we used the same Colombian washed beans for each brew and made each brew five times before combining them to ensure we'd accounted for any variables.

What's the most efficient cup of coffee?

Espresso was found to be the most efficient for consumers, extracting two to six times the amount of caffeine of the other brews in a shorter amount of time, using the same amount of beans.

Coffee culture is on the rise in Australia with cities like Melbourne treating espresso as if it’s forty-year-old scotch and the notion of being literally unable to function before your morning brew is now socially acceptable. This growth in coffee culture has prompted consumers to learn more about their daily caffeine fix. Some key findings from the study were:

  •     - Espresso used a similar amount of grind, but extracted the most caffeine and had the shortest brew time
  •     - Cold Brew extracted the second highest amount of caffeine but requires 8-12 hours to brew
  •     - French Press and Pour Over methods extracted the smallest amount of caffeine, each producing less than a quarter of espresso's caffeine content

The full results of the study can be found in the table below, which compares how much caffeine is in a litre of each brew; 30mL of each brew; a small, medium and large recommended serve of each brew; and the normal serving size Australian consumers are making for themselves.

Crema Coffee Garage Caffeine Content Results

Is Your Daily Caffeine Fix Too Much?

Do you know the recommended caffeine content in your mug of coffee? What about your daily intake limit or when you've hit it? Most Australians don't and when it comes to resources on the topic, they're far and few between for the Australian market.

While there are inconsistencies across government health websites suggesting differing caffeine contents in products, one thing is consistent - they all tell us that research suggests we consume no more than 400mg of caffeine in a day. 

Caffeine Intake Inforgraphic

           

Through serving the home coffee market, countless conversations with coffee lovers, and developing our brew method guides, we have observed that Australian consumers tend to ignore or are unaware of recommended serving sizes, particularly with methods like French Press and Stovetop. For example, it is the habit of most Australian consumers to drink the entire contents of a 3 Cup French Press or a 2 Cup/3 Cup Stovetop brew as a single serving. For this reason, we have included a 'Normal Serving Size' section in our findings, as it reflects more accurately what we understand (anecdotally) to be the amount of coffee/caffeine Australians are potentially consuming.

Another interesting discovery from this study was how close in caffeine content a ‘mug’ size of each brew method was. In the table below, we have compared a mug size of each brew method; an average ‘mug’ size is between 8-12 oz (236-355 mL) and the caffeine content for each brew method is based off the normal serving sizes. As you can see, the methods produced very similar amounts of caffeine in a typical sized serving, with most producing differences of less than 50 mg.

Normal Serving Sizes in the Australian Market

How to Get More Caffeine In Your Cup

Espresso extracted a much larger portion of caffeine compared to every other method examined. 

Considering all factors, we found there were a number of reasons leading to espresso milking the most caffeine from the bean.

The biggest effect came from grind size. Espresso uses an extremely fine grind which creates more surface area for the caffeine to be extracted from.

Other significant factors that came into play when it came to extracting caffeine were the temperature and brewing time.

Caffeine per litre

Citations:

http://www.health.nsw.gov.au/aod/resources/Pages/caffeine.aspx
https://healthfinder.gov/FindServices/SearchContext.aspx?topic=133
https://www.healthdirect.gov.au/caffeine
http://www.foodstandards.gov.au/consumer/generalissues/Pages/Caffeine.aspx
http://www.nutritionaustralia.org/sites/default/files/Caffeine%20and%20Energy%20Drinks.pdf
https://www.betterhealth.vic.gov.au/health/healthyliving/caffeine

Full Study:

Sent upon request to [email protected]

Cite This Page:

Crema Coffee Garage. "Caffeine in Coffee: A Comparison of Espresso, Stovetop, Pour Over, Cold Brew & French Press" 25 September, 2018. <https:cremacoffeegarage.com.au/caffeine-study>


Methodology Excerpts

A variety of methods were used to prepare the coffee samples - from bean selection and brewing to sample production - and to perform the caffeine analysis.

Coffee Bean Selection

The coffee bean selection was an important foundation for the project, as we wanted to know our results were as consistent and comparable as possible, but knew the bean would have to be commonly consumed in the Australian market as well. Head Roaster at Crema Coffee Garage, Douglas Thew, selected a Colombian Excelso Fully Washed from the Tolima region, which was chosen for its well-known uniformity in size, shape, colour and flavour that results in an even roast and makes the results of our brews far more predictable.

“Excelso” is a quality grade term used primarily in Colombia. Excelso coffee beans are large, but slightly smaller than Supremo coffee beans, and pass through Grade 16 (16/64" diameter) sieve perforations, but are too large to pass through Grade 14 (14/64" diameter) sieve perforations. We roasted this bean to a finishing temperature of 215°C, classified as a medium roast, and the beans were rested for seven days before used for samples. Waiting seven days from the roast date for brewing is our standard recommendation for use, as this allows for the beans to degas and for flavour development. The average cupping score of the Colombian Excelso was 83.13pt. 

Coffee Grind & Sorting Process

The grind sizes for each of the brew methods was based on standard recipes that are widely used by the Australian market, both commercially and domestically. We ground all our coffee used for sample brewing in the same DK-40 batch coffee grinder, using our standard grind measurements - the same grind settings we use when grinding customer coffee – which is on a scale from 1-8 (see the table below). 

Espresso Grind Settings DK40 Batch Grinder

It is common knowledge within the coffee industry that when grinding coffee, the particle sizes do vary and include quantities of fine particles and large particles that fall outside the specified grind setting. The quality of the coffee grinder can reduce the variability to some degree, but it is impossible to eliminate entirely. In approaching this part of the project we wanted to achieve two things:


1) better understand what the particle size range of each grind setting contains in a scientific measurement (microns), and;
2) ensure consistency throughout our brew methods.

This is where the KRUVE sifter was an extremely useful instrument. The KRUVE is a three-tiered sifter that uses sieves designed with round holes (rather than square holes) measured in microns. These sieves sort coffee particles into more consistently “true size” ranges for different grind settings by eliminating particles that are too coarse or fine. At the time of the project, the full set came with sieves ranging from 200 micron all the way up to 1100 micron. When we discovered this range was not wide enough to include French Press grind, Mr Adam Krupa, CEO of KRUVE, posted a set of sieves with a larger 1200-1600 micron range suitable for Australian standard French Press grind which is now available for purchase. The result is a metric particle size guide (micron, μm) for coffee grind, rather than using words like ‘salt’ or ‘sand’ to describe grind size, and it is important to note that the metric result is a micron range.

Coffee Brew Methods

The brew methods we chose for their popularity among Australian coffee drinkers. This was determined anecdotally by Crema Coffee Garage staff based on best-selling products at our stores and brew methods that consumers most frequently ask questions about. For more information, check out the brewing method guides below:

Espresso Guide

Stovetop Brewing Guide

Pour Over Brewing Guide

Toddy Cold Brew Brewing Guide

French Press Brewing Guide

You can also review sample production methods in section 3.4 of the paper.

Caffeine Analysis Method

The method used for the analysis of caffeine content was high performance liquid chromatography (HPLC), which allows for the accurate analysis of soluble compounds (in this case caffeine) from a liquid. Read more about this method in section 3.5 of the paper.

Caffeine Content Results

The following results are the detectable caffeine concentrations of brews supplied by Crema Coffee Garage. Run September–October, 2017, by Students in CHEM2201 (Medicinal and Analytical Chemistry), University of Newcastle. Read more about the results in sections 4 and 5 of the paper.


University of Newcastle Caffeine Results

Full Study:

Sent upon request to [email protected]

Cite This Page:

Crema Coffee Garage. "Caffeine in Coffee: A Comparison of Espresso, Stovetop, Pour Over, Cold Brew & French Press" 25 September, 2018. <https:cremacoffeegarage.com.au/caffeine-study>