The “science” of coffee: The imPRESSions study

the science of coffee imageIt might be said that I am a bit of a coffee snob. I like it black, I like it bold, and I like there to be swirls of oil on the top, indicating the oh-so-fresh goodness of newly roasted beans.

This love for the black magical elixir sparked at debate on my recent travels. I have been a French Presser for nearly a decade, but I met someone equally passionate about coffee who made some valid arguments for the AeroPress style of brewing.

When I turned to the internet for advice on whether or not I should try the new way, I soon discovered that there is a heated debate about Aero vs. French. In order to make an informed decision about how I choose to caffeinate, I decided to leave it up to science.

 Science of coffee: The ImPRESSions study

Background & objective:

The pursuit of the perfect cup of coffee is a noble one. Since Kaldi discovered the magical elixir, generations have been searching for the perfect technique to optimize the characteristics of this unique and cherished substance. While great strides have been made in the professional coffee world, there is a great deal of debate in the literature regarding the optimal home-brewing methodology. It is not clear how rigorously this debate has been studied, and if single-blinded methods have been used to conduct a comparison, using controlled conditions (same coffee beans, water, and cups). Further, the investigators hypothesize the differences between methods may not be as pronounced if the materials are held consistent between the two methods. We hypothesized that the aroma  would be quite similar, and primary differences will be found in body, mouthfeel, and finish. Finally, the objective is to declare one of the methods of coffee preparation to be superior, and the investigators expect that one method will be predinantly selected among participants as more desirable. This outcome has potential implications for at-home coffee making for many people.



  • French Press
  •  1 AeroPress
  • Kettle
  • 1/2 pound iDeal Coffee’s Princess of Darkness blend, finely ground (for Aero)
  • 1/2 pound iDeal Coffee’s Princess of Darkness blend, coarsely ground (for french)
  • Colour-coded coffee cups (2 per participant)



A mixed methods approach was adopted for this study. Top coffee experts (fellow and former grad students) were recruited from Ottawa to participate in the sensory experience. Participants signed this consent form: CONSENT TO PARTICIPATE – Science of coffee (see Appendix 1). Participants were blinded to the coffee brewing method, receiving coffee in colour-coded cups. Participants were asked to score each cup on four attributes (aroma, flavour, mouthfeel, aftertaste) as well as give an score for the overall impression. (See Appendix 2 for scoring tool).  Scores on the individual components will be compared to see where the methods most vary, and the overall impression score was used to determine which approach was superior. In addition to providing quantitative scores, participants were asked to provide notes of the the aroma and the overall impression. These were reviewed for themes.


Subtle differences between the brewing methods can be noted when comparing the individual characteristics. Perfect scores were achieved by the french press in aroma, flavour, and aftertaste (x2 participants). The AeroPress achieved perfect scores in aroma, mouthfeel, and aftertaste (x2).


Based on this analysis, there was no clear preference of one method over the other. Four participants preferred the French Press, and four participants preferred the AeroPress. If the overall impression score was summed across all participants, there was a slight preference for the French Press (32.7 points vs. 29.85 points).

overall impression score


The perfect scores (aroma, flavour, and aftertaste (x2) for French press and aroma, mouthfeel, and aftertaste (x2) for AeroPress) indicate that the French press performs slightly better in flavour, while AeroPress is preferred in terms of the mouthfeel. This is shown more clearly when the summary scores are compared. As you can see in the following table, the French press performed better on aroma, flavour, and aftertaste, but the AeroPress was ranked higher on mouthfeel.

summary score

Interestingly, a large difference noted in the aroma, which was surprising to the investigators, who had hypothesized that the aroma would be similar, since the beans are the same, just ground differently. However, as noted by one participant, the aroma of the French Press coffee was “tobacco-like” while the AeroPress smelled like “a Turkish lady, a fine woman.”

It appears while equal numbers chose the French press as did the AeroPress, it would appear that those who prefer the French Press tended to give the AeroPress much lower overall scores, while those who preferred the AeroPress still scored the French Press quite high on overall impression. This suggests that if you were to only select one method and wished to appeal to the most people, choosing the French Press would be recommended, as it was more acceptable to those who prefer the AeroPress than vice versa.

Difference in scores by participant
Positive scores represent the number of points the French press scored above the AeroPress (Participants 1,3,4,8 preferred the French Press). The negative scores show the participants who prefer the AeroPress.

While each participant expressed a clear preference for one method, one of the themes in the qualitative data was that there may be distinct purposes for each type of brewing. The bold, concentrated “espresso” from the AeroPress, combined with the swift preparation time may make it ideal for rushed mornings, while the smooth, consistent character of the coffee from the French Press may make it ideal to sip throughout the morning. One participant expressed it that the AeroPress is most suitable for “sipping while smoking a cigarette in the rain while writing [her] memoir – which nobody will ever read” while the French Press coffee is ideal for “sitting at my desk at the start of a work day.”

Further research is needed, with a larger, population based sample in order to determine more definitively the optimal home-brewing method. The investigator would like to include additional brewing methods in future studies, including Chemex method. Additional studies may wish to include additional brewing methods, like In future, more extensive demographic information should be collected in order to see what individual, demographic, or behavioural characteristics are linked to this preference. This understanding may allow hosts to better understand and predict guests preferences.

Conflict of interest:

The authors have not conflicts of interest to report.

Appendix 1: Participant consent form

Screen Shot 2014-10-19 at 7.31.55 PM

Appendix 2: Scoring tool

Screen Shot 2014-10-19 at 7.27.53 PM


Big thanks to my wonderful friends for making this research possible!





5 thoughts on “The “science” of coffee: The imPRESSions study

  1. I would like to know why I wasn’t invited to partake in this study. I can drink a hot beverage like the best of them. Also, why no drip or cowboy coffee methods?

    Liked by 1 person

    1. Well, my dear, you are always welcome to make the drive down to Ottawa and I will put the coffee on! As you can see in my “suggestions for further research” is that I think that other methods should be included, but introducing too many types may put participants at risk of extreme over-caffeination.


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