Cold Brew Coffee Sucks: Yes or No? - Page 4

Coffee preparation techniques besides espresso like pourover.

Cold Brew Coffee Sucks

Yes
32
34%
No
44
47%
Don't care
18
19%
 
Total votes: 94

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another_jim
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#31: Post by another_jim » Sep 03, 2019, 10:55 pm

It's been standard knowledge in coffee science since the 1970s that the pH readings are misleading due to the buffering effect of other solubkes in the coffee. For instance, Robusta and Arabica have roughly the same pH. Turns out, your tongue is much more accurate than a test strip, since the titrable acidity corresponds very well with people's perceptions of acidity.

Cold brew is outselling regular brewed coffee, because unlike hobbyists and professionals, most coffee drinkers dislike acidity. If I wanted to be the next Starbucks, I'd sell only small lot, organic, peasant and animal friendly Robustas, these, of course, being far more deserving and discerning than mere agrobusiness Arabicas.
Jim Schulman
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Almico
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#32: Post by Almico » Sep 04, 2019, 8:10 am

If anything, I find most non-geeky coffee drinkers confuse bitterness with acidity. They ask for coffee with low acid, but what they really want is coffee without bitterness. When they say their tummy can't handle the acid, I ask if it can tolerate tomatoes, orange juice or vinaigrette dressing. If they say yes, then it is not acidity they are looking to avoid.

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another_jim
Team HB

#33: Post by another_jim » Sep 04, 2019, 9:56 am

I wonder if its a generational thing? With older people liking bitter-sweet and younger people sweet and sour.
Jim Schulman

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Jofari

#34: Post by Jofari » Sep 09, 2019, 11:42 am

baldheadracing wrote:From the source article abstract:

As I failed organic chemistry, I can only defer to the authors' interpretation of their results. I linked to Perger as he seemed to have dumb-downed the article, no doubt making errors of omission that I cannot grasp.
I'll try to clear up the findings from this study for those interested. The authors are using two metrics for measuring acidity of coffee - pH and 'Titratable Acidity'. pH is the standard way of measuring acidity and is a measure of the concentration of protons present in a solution (by definition, acids have protons that they break away from in solution). Titratable Acidity is a measure of the amount of NaOH that is needed to reach a desired pH. The authors cite other studies that indicate that Titratable Acidity is a better metrics for measuring sourness than pH, but this isn't their main reason for measuring it.

For an extreme example of how these two metrics can differ, consider two solutions: (i) acetic acid dissolved in a buffer and (ii) hydrochloric acid dissolved in the same buffer. Let's assume that the two solutions measure the same pH. If that's true, then we know that there must be very different concentrations of each acid in solutions (i) and (ii) due to differences in the amount of protons given off by the acids (i.e. the "strength" of the acid). If we add NaOH to each solution until we get to a given pH (say pH=6), the volume needed to reach this point will differ for the two solutions. This is a case where pH is the same, but Titratable Acidity is different.

The cited study finds that the pH of hot and cold brew coffee are the same, but the Titratable Acidities differ. From this, the authors conclude that there must be different acids present at different concentrations in hot and cold brew.
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baldheadracing
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#35: Post by baldheadracing » Sep 09, 2019, 12:29 pm

Thanks for the explanation!

To be honest, I don't understand acidity in and of itself being an issue - after all, our stomach juices are pretty acidic IIRC.

So, if I am understanding this all correctly, when someone says "cold brew has less acidity," they are wrong, as Alan has stated. However, if they say, "cold brew could cause less stomach upset because of different proportions of certain acids," they may well be right (with effect varying across individuals, etc.).

All I know is that I have been eating ridiculous amounts of fresh tomatoes lately, and my system hasn't complained :D .
What I'm interested in is my worst espresso being fantastic - James Hoffmann

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Jofari

#36: Post by Jofari » Sep 09, 2019, 12:49 pm

baldheadracing wrote:So, if I am understanding this all correctly, when someone says "cold brew has less acidity," they are wrong, as Alan has stated. However, if they say, "cold brew could cause less stomach upset because of different proportions of certain acids," they may well be right (with effect varying across individuals, etc.).

All I know is that I have been eating ridiculous amounts of fresh tomatoes lately, and my system hasn't complained .
I think that's a fair conclusion. It seems unlikely that the measured differences would make cold brew easier on your stomach than hot brew.

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homeburrero
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#37: Post by homeburrero » Sep 09, 2019, 1:09 pm

baldheadracing wrote:So, if I am understanding this all correctly, when someone says "cold brew has less acidity," they are wrong
If they said that cold brew has a lower pH, then I might say they were wrong. But if they say that it has less acidity they would be correct because of significant titratable acidity differences. And titratable acidity is related to the perception of acidity on the tongue.

Per Marco Wellinger, Samo Smrke, Chahan Yeretzian in chapter 16 of the "Craft and Science of Coffee"
Perception of acidity in coffee has been studied extensively (for an overview see
Gloess et al., 2013). The most commonly cited phenomenon is the correlation of
sensory perception of acidity with titrable acidity of coffee extracts (titration to a
pH of 6.6, which corresponds to mouth pH). From a chemical point of view this
would also make sense as stated by Clifford (1988): "In effect, the reaction of the
acid with the receptor is a titration, and thus very similar to the process used in
measuring titratable acidity."
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

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Almico
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#38: Post by Almico » Sep 09, 2019, 2:35 pm

My guess would be rancid oils from stale coffee would affect a sensitive tummy more than acidity in coffee.