Lab file · From the literature
Is cold brew actually less acidic?
Short answer
By pH, barely: within about half a unit of hot coffee. By titratable acidity, yes: lower in every coffee tested, in both studies.
- pH, hot and cold (six coffees)
- 4.85–5.13Source [1]
- Coffees with lower titratable acidity cold
- 6of 6Source [1]
- Cold brew titratable acidity (Colombia)
- 0.33–0.90mg/gSource [2]
- Hot brew titratable acidity (same coffees)
- 1.81–2.00mg/gSource [2]
The data
“Acidic” means two different things in a lab, and the answer depends on which one you ask about.
pH counts the hydrogen ions floating free in the cup right now. Titratable acidity (TA) counts all the acid that a base can neutralize, including acid molecules still holding on to their hydrogen. You measure it by adding a base until the coffee reaches a set pH and recording how much it took.
In 2018, Niny Rao and Megan Fuller brewed six light-roast coffees both ways at the same ratio: cold for 7 hours at room temperature, hot as a 6-minute French press. The pH values all fell between 4.85 and 5.13, and the authors found the hot and cold readings not distinguishable [1]. Their supplement is a little less tidy: by its own t-tests, cold brew’s pH came out slightly higher in three of the six coffees. Higher by less than two tenths of a unit.
- Hot
- Cold
Data table
| Hot | Cold | |
|---|---|---|
| Brazil | 5.10 | 5.04 |
| Ethiopia (Ardi) | 4.85 | 5.01 |
| Ethiopia (Yirgz) | 4.96 | 4.96 |
| Myanmar | 4.92 | 5.13 |
| Colombia | 4.99 | 5.00 |
| Mexico | 4.95 | 5.08 |
Re-plotted from values reported in Tables 2 and 4 of source [1]. The paper's supplement labels the two Ethiopian lots the other way round; values follow the main tables.
Titratable acidity is where the gap shows. It was lower in cold brew for all six coffees [1]. The authors read this as hot water pulling out more acid molecules that don’t give up their hydrogen at coffee’s pH. Those don’t move the pH meter, but a base finds them.
- Hot
- Cold
Data table
Values in mL 0.1 N NaOH
| Hot | Cold | |
|---|---|---|
| Brazil | 3.17 | 2.83 |
| Ethiopia (Ardi) | 3.62 | 2.55 |
| Ethiopia (Yirgz) | 3.83 | 2.58 |
| Myanmar | 3.18 | 2.52 |
| Colombia | 4.27 | 2.93 |
| Mexico | 3.58 | 2.13 |
Re-plotted from values reported in Tables 2 and 4 of source [1]. Titrated to pH 6.0, the endpoint earlier work linked to perceived sourness. The pH 8.0 values point the same way.
A 2019 study from Colombia found the same pattern with more contrast. Its cold brews ran pH 4.81 to 4.92 against 4.36 to 4.44 for the hot brews, a real difference that the authors found significant. Titratable acidity split much wider: 0.33 to 0.90 mg/g for cold, 1.81 to 2.00 for hot [2]. Weaker brews would explain some of that. Not all of it: the coarse-ground 22-hour cold brews extracted more of the coffee than the hot brews did and still had less than half their titratable acidity.
Does any of this taste different?
Probably, though the evidence is thinner than the chemistry. Earlier sensory research, cited in the 2018 paper, found that sourness tracks titratable acidity, especially to pH 6.0, better than it tracks pH [1]. Other work, cited in the 2017 paper, found no link between pH and perceived acidity at all [3]. The 2018 study itself ran no tasting.
The Colombian study did. Its three trained tasters scored acidity 3.0 for both hot brews and between 1.0 and 1.7 for every cold brew [2].
How they measured it
Rao and Fuller, 2018. Six pre-ground light roasts from Brazil, Colombia, Mexico, Myanmar and two Ethiopian regions. Cold: 35.0 g of coffee in 350 mL of filtered tap water, 7 hours at 21–25 °C, then through a paper filter. Hot: same ratio, water heated to boiling, 6 minutes in a French press, same filter. pH was read on a benchtop meter. TA was measured by titrating 40 mL of coffee with sodium hydroxide to pH 6.0 and to pH 8.0. Each coffee was brewed twice per method and sampled several times.
Cordoba and colleagues, 2019. Two Colombian coffees, medium roast, cold brewed at 20 °C for 14 or 22 hours at two grind sizes, and hot brewed in a French press at a similar ratio. TA was titrated to pH 6.5 and reported per gram of coffee, so its numbers can’t be compared directly with the 2018 study’s. Compare hot and cold within a study, not across the two.
Limits
- The six-coffee study ran no taste test. The link between titratable acidity and sourness comes from earlier sensory work it cites, not from its own data.
- The Colombian study's tasters did score acidity, but there were three of them, and they tasted cold brew at 19 °C and hot at 70 °C. Serving temperature can change how a drink tastes, so part of that gap may be temperature, not chemistry.
- Both studies brewed cold at room temperature. Fridge-steeped cold brew, which is what most people make, wasn't tested.
- The hot comparison was a French press both times. Drip and pour-over weren't measured.
- Light roasts in one study, medium in the other. We don't know how dark roasts behave.
- Both measured total acid, not which acids. Citric, malic, quinic, chlorogenic: we can't tell you which ones the hot water pulls out.
- Nobody measured stomach comfort. If you heard cold brew is easier on the stomach, these studies don't test that, and the pH numbers don't back it.
Takeaway
If hot coffee tastes too sharp to you, cold brew is a reasonable fix. Lower titratable acidity is the measured difference, and one trained panel scored it less acidic. Don't expect a different pH. Both studies brewed at roughly 1:10 to 1:12 and drank it undiluted.
Related gear and coffee
Illustration Equator Coffees · Beans
Cold Brew Blend, Fair Trade Organic
Illustration Stumptown Coffee Roasters · Beans
Ethiopia Mordecofe
Sources
- Rao, N. Z. & Fuller, M. (2018). Acidity and Antioxidant Activity of Cold Brew Coffee. Scientific Reports 8, 16030. doi:10.1038/s41598-018-34392-wPeer-reviewed
- Cordoba, N., Pataquiva, L., Osorio, C., Moreno Moreno, F. L. & Ruiz, R. Y. (2019). Effect of grinding, extraction time and type of coffee on the physicochemical and flavour characteristics of cold brew coffee. Scientific Reports 9, 8440. doi:10.1038/s41598-019-44886-wPeer-reviewed
- Fuller, M. & Rao, N. Z. (2017). The Effect of Time, Roasting Temperature, and Grind Size on Caffeine and Chlorogenic Acid Concentrations in Cold Brew Coffee. Scientific Reports 7, 17979. doi:10.1038/s41598-017-18247-4Peer-reviewed
Charts are re-plotted from numbers printed in the sources' text and tables, never traced from their figures. How we pick and handle sources: about the Lab.