Coffee: Acidity and pH — Brewed Coffee vs Cold Brew
Brewed hot coffee has a pH of 4.85–5.10; cold brew measures 5.3–5.8. Perceived acidity is a positive flavor attribute in specialty coffee, distinct from measurable acid concentration.
| Measure | Value | Unit | Notes |
|---|---|---|---|
| Brewed hot coffee pH (drip / pour-over) | 4.85–5.10 | pH | Varies by bean origin, roast, and brew method |
| Espresso pH | 5.0–5.5 | pH | Slightly higher pH than drip due to shorter extraction and high TDS |
| Cold brew pH | 5.3–5.8 | pH | Consistently higher (less acidic) than hot brew; Mogren et al. |
| French press coffee pH | 4.9–5.2 | pH | Similar to drip; full immersion extracts more acidic compounds |
| Chlorogenic acid content in brewed coffee | 150–350 | mg per 240ml cup | Primary acid class; varies dramatically by roast level |
| Quinic acid in dark roast coffee | 1,600–4,500 | mg/L | Formed by CGA degradation during roasting; sour-astringent taste |
| Citric acid in brewed coffee | ~100 | mg/L | Fruity, bright sourness; more prominent in light roasts and high-altitude origins |
| Malic acid in brewed coffee | ~150 | mg/L | Apple-like; common in Ethiopian and Kenyan coffees |
Acidity in coffee exists on two levels that are frequently conflated: measured pH (a chemical property of the liquid) and perceived acidity (a sensory attribute describing brightness, liveliness, and fruit-like complexity). Specialty coffee professionals use “acidity” almost exclusively in the positive sensory sense. Consumer concern about “acidic coffee” typically refers to gastrointestinal effects or flavor harshness — phenomena that correlate imperfectly with pH.
Key Organic Acids in Coffee
Coffee’s acid profile is a complex mixture of organic acids formed both during fruit development and during roasting. These contribute distinct sensory qualities:
| Acid | Flavor Contribution | Primary Source | Notes |
|---|---|---|---|
| Chlorogenic acid (CGA) | Astringent, slightly bitter-sour | Bean itself | Most abundant acid class in green coffee; degrades during roasting |
| Quinic acid | Sharp, sour, astringent | CGA degradation (roasting) | Increases with roast level; can cause perceived harshness |
| Citric acid | Bright, fruity, lemon-like | Bean metabolism | Higher in high-altitude, light-roast, East African origins |
| Malic acid | Apple-like, smooth tartness | Bean metabolism | Prominent in Ethiopian and Kenyan washed coffees |
| Acetic acid | Vinegary (at low levels: wine-like) | Fermentation during processing | Present in natural/anaerobic processed coffees |
| Lactic acid | Creamy, rounded, mild | Fermentation | Contributes roundness; also forms during roasting |
| Phosphoric acid | Bright, juicy, mineral | Bean metabolism | Notable in some Kenyan and Rwandan coffees |
| Tartaric acid | Wine-like, tart | Bean metabolism | Minor presence; contributes to overall brightness |
pH by Brew Method
The measured acidity of coffee varies by method due to differences in water temperature, extraction yield, and the specific compound classes preferentially extracted.
| Brew Method | Serving Size | Approximate pH Range | Character |
|---|---|---|---|
| Espresso | 30ml | 5.0–5.5 | Concentrated but higher pH due to short extraction |
| Drip / filter | 240ml | 4.85–5.10 | Standard reference; most data collected here |
| Pour-over | 240ml | 4.90–5.10 | Similar to drip; depends on technique |
| French press | 240ml | 4.90–5.20 | Full immersion; slightly variable |
| Cold brew (RTD) | 300ml | 5.30–5.80 | Noticeably higher pH, lower perceived acidity |
| Cold brew concentrate | 60ml | 5.50–6.00 | Before dilution |
| AeroPress | 120–240ml | 5.00–5.30 | Variable; pressure reduces extraction variability |
| Moka pot | 60ml | 5.00–5.40 | Pressure-assisted; darker extraction character |
Roast Level and Acid Development
Roast level has a counterintuitive effect on acidity. While many assume darker roasts are more acidic (because they taste harsh), the measured reality is more nuanced:
- Light roasts: Higher chlorogenic acid content, higher citric and malic acids → pH typically 4.85–4.95; perceived as brightly acidic
- Medium roasts: CGAs partially degraded; pH 4.90–5.05; balanced acidity
- Dark roasts: CGAs largely degraded, but quinic acid accumulates from CGA pyrolysis; pH 5.00–5.20; less measured acidity but harsh, astringent perceived quality
Dark roast’s “harshness” is not high acid content — it is primarily quinic acid, chlorogenic acid lactones, and bitter Maillard products, which taste sharp and drying without being particularly sour.
Origin Influence on Acid Profile
Coffee origin strongly influences which acids dominate the profile:
| Origin | Dominant Acids | Typical Character |
|---|---|---|
| Ethiopian (washed) | Citric, malic, phosphoric | Jasmine, bergamot, lemon |
| Kenyan (washed) | Phosphoric, citric, malic | Blackcurrant, tomato, wine-like |
| Colombian | Malic, citric | Apple, caramel, clean |
| Brazilian (natural) | Lower total acidity; lactic | Chocolate, nuts, low brightness |
| Sumatran (wet-hulled) | Earthy; reduced volatiles | Herbal, full body, low brightness |
The interplay of brew method, roast level, water alkalinity (which buffers acids), and bean origin determines the final sensory acid profile — making it one of coffee’s most variable and nuanced dimensions.
Related Pages
Sources
- Rao S (2008) — The Professional Barista's Handbook. Scott Rao
- Mogren L et al. — pH differences between hot brew and cold brew coffee. Food Chemistry
- USDA FoodData Central — Coffee, brewed from grounds
- Farah A, Donangelo CM (2006) — Phenolic compounds in coffee. Braz J Plant Physiol
Frequently Asked Questions
Is coffee acidic? How does it compare to other beverages?
Yes, coffee is mildly acidic with a pH of approximately 4.85–5.10 for hot-brewed coffee. For comparison: orange juice is pH 3.5–4.0, lemonade is pH 2.5–3.0, and tomato juice is pH 4.0–4.5. Coffee is less acidic than most fruit juices. Cold brew, with a pH of 5.3–5.8, is closer to black tea (pH 4.9–5.5) in measured acidity.
Is 'acidity' in specialty coffee the same as acid reflux triggers?
Not necessarily. Specialty coffee terminology uses 'acidity' as a positive flavor descriptor — brightness, complexity, fruit-like character — which is primarily driven by organic acid concentration and balance (chlorogenic, citric, malic, tartaric acids). Gastrointestinal sensitivity to coffee involves multiple factors beyond just pH: caffeine's effect on lower esophageal sphincter relaxation, certain diterpenes, and individual gut responses. Cold brew's higher pH may benefit individuals with acid sensitivity, but the relationship is complex and individual.
Why does cold brew taste less acidic even though it also contains acids?
Cold brew's perceived reduction in acidity has two components: a measurably higher pH (5.3–5.8 vs 4.85–5.10 for hot brew), and a different acid profile. Cold water extracts organic acids less efficiently than hot water — particularly chlorogenic acids and their degradation products. Additionally, cold brew typically uses longer steep times but lower temperatures, which favors extraction of sweeter compounds (sugars, amino acids) relative to sour acids. The result is a beverage with lower total acid concentration and a flavor profile tilted toward sweetness and chocolate notes.