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This is more of a vague feeling than something I'm sure of, but from the many cups I've drunk, I have a feeling that when prepared in a french press, my coffee tastes a little more sour/acidic, compared to a turkish brew. Is this a documented phenomenon, or is it just me?

Of course, assume the same coffee is used both times, which by the way is some home-ground (blade grinder) arabica.

  • 1
    A friend and I tried to test this ourselves (using perceived acidity rather than pH acidity). We tried drip, French press, and espresso. Drip was the least acidic, French press was marginally more acidic, and espresso was the most acidic by a relatively large margin. I have no idea whether it's a documented phenomenon though. – Alex A. Feb 6 '15 at 16:06
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This is a perfect follow up to the "What coffees are the least acidic?" question!

As always, Lets answer it with some data! My company uses machine learning, data science, and sensory science to build flavor profiling and quality control tools for the craft beverage industry.

TL;DR: Yes. Preparation has a significant affect on the flavor profile of coffee - including the level of acidity.


Distribution of Acidity by Brewing Method

Boxplot of Sour & Acidity by brewing method

If I may present to you... the distribution of acidity in coffee by brewing method! Clearly and without surprise, Espresso (coffee extracted under pressure) is the most acidic preparation method, on average. French Press (full immersion brewing) is the least acidic, and V60 (a type of pour-over) has the widest range.

But is there something else going on here? What if there exists a conflating factor such as green processing, roast level, or growing environment? Some of these questions we're already answered in the link above, so lets focused on the remaining question - how does the origin of the coffee effect the perceived acidity of the coffee by brewing method?


Acidity by Brewing Method Controlling for Continent of Origin

Acidity by brewing method controlling for continent

So is the effect of brewing method consistent? No. What we're seeing here is that each continent tends towards a different green processing technique, and thus a different optimal level of roast - all of which exert as much influence over the resulting level of acidity in the flavor profile of the coffee.


Please just save me from exogenous variables

Oh... you should have just said so....

Inference Tree of Acidity in Coffee

This is a conditional inference tree mapping the distribution of acidity scores to a series of categorical variables.

Where:
C is Country 
P is Preparation 
G is Green Processing
and the bar plot shows the distribution of acidity

Country is clearly the most used variable in creating this tree, and interestingly, Green Processing is only used as a splitting rule when a country has a variety of green processing methods in common use.


Please leave a comment if you'd like me to add a variable or further analysis to this answer!

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    Great answer, as always! However, am I missing something, or is turkish brew missing from your preparation methods? Being the one I wondered about in the question, I am curious of how it stocks up to the others. Also, I'm ...trying to wrap my head around that last "exogenous variables" graph. I'll succeed in some few minutes. Great addition to the answer ;) – Ludwik Feb 17 '15 at 21:12
  • Thanks! Currently, I don't have enough reviews to analyze Turkish coffee as a preparation method... and I'm not sure it makes sense to do so, as Turkish Coffee usually has sugar added to it (which increases the acidity)! Turkish coffee would most closely fit with French Press in this analysis. – JayCo Feb 17 '15 at 22:24
  • Sugar, ey? Got to try that. But yeah, this sure answers my question. – Ludwik Feb 18 '15 at 12:34
  • @JayCo There is no direct relation of Turkish coffee with sugar. It is just a brewing methodology. Adding sugar is just an option just as the next brewed coffee type on these charts. – MTSan Jan 1 '16 at 23:34
  • @MTSan There is a strong "direct relationship" between Turkish coffee and sugar - the method of preparation calls for boiling or simmering the ground coffee and water with the sugar, and letting those all settle down together. It is possible to make Turkish or Greek coffee without sugar, but that's like drinking a cafe Cubano without sugar - possible, but not common, and the method has been optimized for it's inclusion. Anyway, because of how common sugar is with Turkish coffee, good flavor profile data is hard to come by. – JayCo Jan 1 '16 at 23:47

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