Is Coffee Acidic? pH Levels, Taste, and Brewing

Coffee is acidic. The pH of coffee falls between 4.85 and 5.4 on a 0–14 scale, according to a 2018 study in Scientific Reports, though values vary. Roasting temperature, brewing temperature, and type of coffee bean are factors that affect the pH of coffee. Coffee “acidity” refers to the bright, tangy, or crisp taste you perceive, not its pH. Coffee tastes acidic because it contains natural acids, like citric acid, malic acid, quinic acid, and a few others.

Dark roast coffee is less acidic than light or medium roasts due to the extended roasting process. The least acidic coffee is a dark roast Robusta blend from low-altitude regions like Brazil, Sumatra, and Bali. The best place to get low acid coffee is specialty coffee shops, online retailers, or health food stores. Different types of coffee like decaf, cold brew, mushroom coffee, and espresso do not have the same acidity or pH levels. After brewing, used coffee grounds become nearly neutral and are safe for most soils.

What is pH?

The term “pH” refers to the measure of how acidic or basic (alkaline) a substance is on a scale from 0 to 14. The pH is described by Hopkins and Sharma in "Physiology, Acid Base Balance" as critical for assessing acid-base balance in bodily fluids. A pH of 7 is neutral, below 7 is acidic, and above 7 is basic or alkaline.

The pH scale is logarithmic, meaning each number represents a tenfold change. For example, a substance with a pH of 4 is ten times more acidic than one with a pH of 5. A lower pH indicates more hydrogen ions and higher acidity, while a higher pH indicates fewer hydrogen ions and higher alkalinity.

pH has no units because it is defined as the negative logarithm of hydrogen ion activity. Since logarithms are dimensionless, the resulting pH value is also unitless. This allows pH to express acidity or basicity on a comparative scale without referencing physical units.

The term pH means "potential" or "power of hydrogen," with the "p" likely from French "puissance," German "Potenz," or Danish "potens," all meaning "power." Danish chemist Søren Sørensen introduced the concept of pH in 1909.

What is the pH of Coffee?

The pH of black coffee typically ranges from 4.85 to 5.4, making it mildly acidic. The pH balance of coffee is acidic due to natural organic acids like chlorogenic acid. This acidity can irritate the stomach lining and trigger acid reflux or heartburn in sensitive individuals. Low-acid coffees have a pH of 5.5 or higher and are recommended for those with digestive issues.

The pH value of coffee is determined by bean type, roast level, brewing method, water quality, and grind size. Lighter roasts and Arabica beans typically have lower pH (more acidic). Cold brewing and darker roasts raises pH, while hot brewing lowers it. For comparison, lemon juice has a pH of 2.0–2.6, making it much more acidic than coffee.

Some studies report the actual pH value of coffee can reach up to 5.6 or higher, depending on coffee species and brewing style. For example, a 2018 study published in Scientific Reports by Niny Z Rao of Thomas Jefferson University showed hot black coffee has a pH of 4.85 to 5.13, while cold brew is less acidic with a pH of 5.40 to 5.63. Mineral content and water temperature also impact the final acidity.

The pH balance of black coffee changes depending on how it is brewed. A 2013 study published in European Food Research and Technology by Alexia N. Gloess found pH values of coffee ranged from 5.5 to 5.9 across several brewing methods. French press coffee had the highest pH, while single-serve capsules had the lowest.

The following table summarizes measured pH ranges for different hot and cold brewed coffees, instant coffee, milk-based coffee drinks, and teas.

How Does pH of Coffee Compare to Other Beverages?

Coffee has a pH of 4.85 to 5.4, making it moderately acidic. Soda is far more acidic with a pH around 2.5. Black tea is similar to coffee with a pH of 4.9 to 5.5. Lemon juice (pH ~2.0), apple juice (pH 3.3–4.0), and energy drinks (pH 3.0–4.0) are more acidic than coffee. Chai tea is usually slightly less acidic than coffee, depending on how it's made. The following table compares the approximate pH ranges and relative acidity of common beverages.

What Factors Affect the pH of Coffee?

Factors that affect the pH of coffee are the elements that influence how acidic or basic it is. Key factors include bean type, roast level, coffee to water ratio, water quality, and brewing method. These factors can lower or raise the pH, changing the coffee’s taste and acidity level.

1. Coffee Bean Type
2. Roast Level
3. Coffee to Water Ratio
4. Water Quality
5. Grind Size

1. Coffee Bean Type

Coffee bean type refers to the variety of coffee, such as Arabica or Robusta, which plays a role in how acidic coffee is and its pH level. Arabica beans typically produce a less acidic coffee with higher pH than Robusta. A 2007 study published in the Journal of the Science of Food and Agriculture by Susana Andueza found that Arabica coffees tended to have lower pH values (5.2 to 5.8), indicating higher acidity, compared to Robusta blends when brewed as espresso under same conditions.

2. Roast Level

Roast level refers to how long coffee beans are roasted, which affects coffee's pH. Darker roasts result in lower acidity and a higher pH, while lighter roasts retain more acidic compounds and have a lower pH. A 2009 study from University of California found that roasting coffee above 200°C reduces acidity, brightness, and body while increasing pH. Green beans contain 61–86 mg/g of chlorogenic acids, but roasting at 230°C for 12 minutes cuts them in half, and 250°C for 21 minutes nearly eliminates them. As acids break down, pH rises from 4.9 in light roasts to 5.3 in dark roasts.

3. Coffee to Water Ratio

The coffee to water ratio refers to the amount of ground coffee used relative to the amount of water during brewing. A higher coffee-to-water ratio increases acidity and lowers pH. A 2013 study published in European Food Research and Technology by Alexia N. Gloess found that coffee lungo brews had a pH of 5.1. The same 2013 study found that ristretto brews had a pH of 4.8. The study confirmed that more water increases pH by diluting hydrogen ions.

4. Water Quality

Water quality refers to the mineral content and chemical composition of the water used. A 2021 study published in Food Chemistry by Córdoba et al. shows water quality affects coffee pH. The study finds brewing methods change coffee pH and shows that water mineral content, including calcium and magnesium, causes pH variation. It concludes water with higher mineral content increases coffee pH, making it less acidic. High bicarbonate levels raise pH by neutralizing acidity, while soft or low-buffer water lets more acidity pass into the cup.

5. Grind Size

Grind size affects the pH of coffee by controlling the rate of extraction. Finer grinds produce a lower pH by extracting more acids. Coarser grinds produce a higher pH by extracting fewer compounds. A 2024 study titled "Impact of Coffee Roasting and Grind Size on Acidity and Bitterness" found that finer grind size significantly increased measured acidity intensity (via electronic-tongue) compared with coarser grinds. This supports the idea that grind size affects acid extraction and perceived acidity.

What is Coffee Acidity?

Coffee acidity refers to the bright, tangy, or crisp flavor notes in coffee, not its pH level. Coffee acidity means sensory acidity that describes the citrus-like flavor in premium coffee. In contrast, acidic coffee as a chemical acidity measures hydrogen ion concentration in brewed coffee. One is a flavor experience; the other is a scientific property. Coffee acidity is a key factor in evaluating coffee. Coffee acidity serves as a primary metric used by experts and judges to score quality.

The acidity of coffee is caused by natural acids extracted from the beans. A 1985 study published in Zeitschrift für Lebensmittel-Untersuchung und Forschung reported that 22 different acids influence coffee acidity. The study identified citric acid as the primary acid at 12.2%, acetic acid as a major acid at 11.2%, and chlorogenic acids as significant at 9% in roasted coffee.

What Determines Acidity in Coffee?

Coffee acid level is influenced by bean variety, altitude, soil quality, climate, processing method, and roast level. Arabica beans grown at high altitudes in volcanic soil tend to produce higher acidity. A 2018 study by Mohammed Worku published in Food Research International showed that sensory acidity scores increase with altitude in Arabica coffee. The study showed that sensory acidity rises by approximately 0.22 cupping points for every 100 meters of elevation.

The perceived acidity of low-altitude Robusta coffees, such as those from Brazil and Indonesia, is lower. A 2019 study by Brizio di Donfrancesco in Food Research International found that Robusta coffees score lower in sensory sourness and brightness compared to Arabica. The study found that Robusta coffees have heavier body, stronger bitterness, and lack the crisp acidity of Arabica.

Processing methods affect acidity in coffee. Wet processing produces clean, bright cups with higher acidity. Wet hulling yields fuller-bodied, earthier brews with lower acidity. A 2019 study titled "Effect of methods of processing on raw and intrinsic quality of Sidama and YirgaCheffee coffee types" showed that wet-processed coffees have higher acidity, while natural and sun-dried coffees have more body but lower acidity.

What Makes Coffee Acidic?

Coffee is acidic because it contains organic acids like citric, malic, quinic, acetic, formic, lactic, chlorogenic (CGAs), and tartaric acid. These compounds collectively contribute to the enhanced acidic profile observed in caffeinated and decaffeinated coffee. The following list shows which acids in coffee make it more or less acidic.

1. Citric Acid
2. Malic Acid
3. Chlorogenic Acids
4. Quinic Acid
5. Acetic Acid
6. Formic Acid
7. Lactic Acid
8. Phosphoric Acid
9. Tartaric Acid

1. Citric Acid

Citric acid is a weak organic acid found naturally in citrus fruits like lemons and limes. Citric acid gives coffee a bright, citrus-like acidity and enhances perceived freshness. In green coffee beans, citric acid is the most abundant acid at about 1.3%. A 2019 study in Royal Society of Chemistry found green Arabica can reach up to 1.3 g/kg of citric acid. Citric acid declines during roasting. The decline reduces sharpness in flavor. Light roasts retain more citric acid, which contributes to fruity or vibrant taste notes.

2. Malic Acid

Malic acid in coffee is a type of organic acid that creates tart, fruity flavors similar to green apples. A 1999 study in Chemistry and Environmental Science identifies malic acid as a key contributor to this tartness. Malic acid occurs naturally in green coffee beans and is preserved or altered through roasting. Green Arabica coffee contains 1.2 g/kg of malic acid, but roasting lowers it to under 0.5 g/kg. Malic acid contributes to coffee’s perceived brightness and acidity, especially in lightly roasted, high-altitude beans.

3. Chlorogenic Acids

Chlorogenic acid in coffee is a powerful antioxidant and the most abundant polyphenol found in green coffee beans. Chlorogenic acid affects coffee acidity by contributing sour and astringent notes in green beans, mild bitterness in light roasts, and strong, lingering bitterness in dark roasts. A 2014 study by Josiane Alessandra Vignoli published in Food Research International reported chlorogenic acids (CGAs) changes during roasting. The acid breaks down into lactones and phenylindanes, which are responsible for the coffee’s bitter and metallic flavors.

4. Quinic Acid

Quinic acid is a naturally occurring cyclic polyol found in many plants, especially in coffee beans and cinchona bark. Quinic acid affects coffee taste by adding bitterness, sourness, and astringency. It creates a sharp, tonic-like flavor, especially in dark roasts. A 2023 study published in Current Research in Food Science by Christina J.Birke Rune confirmed that quinic acid is a dominant acid in brewed coffee and increases bitterness and acidity as roasting intensifies. In moderate amounts, Quinic acid enhances complexity and mouthfeel. In excess, Quinic acid causes an overly sour or harsh taste, particularly in stale or over-roasted coffee.

5. Acetic Acid

Acetic acid refers to a colorless organic compound with the chemical formula CH₃COOH. Acetic acid affects the taste of coffee by adding brightness and sharpness at low concentrations, similar to citrus or wine notes. At high concentrations, acetic acid produces a vinegar-like taste and smell, often linked to over-fermentation or dark roasting. Dark roasted Robusta coffee contains up to 10 times more acetic acid than green Arabica coffee, according to a 2000 study by Michael Ginz in European Food Research and Technology. The study shows that acetic acid concentrations can exceed 2.0 g/kg.

6. Formic Acid

Formic acid is a naturally occurring colorless organic acid that adds a sharp, pungent sourness to coffee, as noted by Pam Hartwig in a 2006 study published in the Journal of Food Science. Formic acid levels are notably higher in Robusta coffee, particularly after roasting, with dark roasts containing up to 0.5 g/kg. This acid forms primarily through the degradation of sugars and other organic compounds during high-temperature roasting.

7. Lactic Acid

Lactic acid occurs naturally in coffee beans and is less reduced by roasting than other acids. A 1995 study in the Journal of Food Science titled "Flavor Characteristics of Lactic, Malic, Citric, and Acetic Acids at Various pH Levels" found it maintains stable levels, adding smoothness and mild acidity to brewed coffee. In green and roasted Arabica coffee, lactic acid remains stable at 0.3 to 0.4 g/kg. USDA researchers note this consistency helps balance acidity and mouthfeel, making it essential to coffee’s flavor profile.

8. Phosphoric Acid

Phosphoric acid refers to a colorless, odorless, and non-volatile mineral acid. Phosphoric acid gives coffee a sparkling, tingling sensation similar to carbonated drinks. It enhances fruity flavors like grapefruit, mango, blackberry, and currant. While it sweetens the cup, it can also add slight bitterness depending on concentration and origin, especially in coffees from Kenya.

9. Tartaric Acid

Tartaric acid is a naturally occurring organic acid present in many fruits. Tartaric acid is present in coffee in lower concentrations. Tartaric acid adds a sour taste and enhances fruit flavors in coffee, according to experts at The Good Scents Company Information System. Tartaric acid occurs at 0.2 g/kg in green Robusta coffee and decreases slightly after roasting, according to a 1999 study in Chemistry and Environmental Science.

What Health Effects Does Coffee Acidity Have?

Coffee acidity has both positive and negative health effects. On the positive side, natural acids like chlorogenic acid provide antioxidants that may reduce inflammation and protect cells. A 2023 study published in International Journal of Molecular Sciences by Giuliana La Rosa showed that chlorogenic acid is a strong antioxidant that lowers harmful molecules (ROS and MDA) inside cells.

Coffee acidity also reduces inflammation by blocking signals like IL-1β and TNF-α, which helps keep cells healthy. On the downside, high coffee acidity can irritate the stomach, worsen acid reflux, and harm dental health. For those with gastritis, reflux, or IBS, brewed coffee’s acidity may cause discomfort and health problems.

Does Coffee Make Your Body Acidic?

No, coffee does not make your body acidic. Although coffee has a low pH, it does not cause acidosis or disrupt your pH balance. Your body maintains a tightly regulated blood pH between 7.35 and 7.45 through buffering systems. The acids in coffee do not significantly alter your body's overall pH balance or cause systemic acidity. While coffee can make your urine a little more acidic, this effect is small and temporary. The body regulates urine pH through kidney function, so coffee alone is unlikely to cause significant or harmful acidity in urine.

Is Dark Roast Coffee Less Acidic?

Yes, dark roast coffee is less acidic than light or medium roasts. The extended roasting process breaks down many of the naturally occurring acids in the coffee bean. A 2022 study titled “Impact of the Roast Level on Chemical Composition of Coffee from Colombia” found that darker coffee roasts contain lower acid levels and higher pH values due to a steady decrease in volatile organic acids as roast level increases. This results in a smoother taste and a higher pH, making dark roast coffee easier on the stomach for people sensitive to acid.

Is Light Roast Coffee More Acidic?

Yes, light roast coffee is more acidic than dark roast due to its shorter roasting time, which preserves more of the original organic acids. A 2023 study titled "Acids in brewed coffees: Chemical composition and sensory threshold" showed that lighter-roasted coffees contain higher levels of citric, malic, and chlorogenic acids and exhibit stronger perceived acidity than darker roasts. The researchers confirmed that prolonged roasting lowers acidity by causing thermal degradation, which creates the smooth, low-acid flavor of dark roast coffee.

Light roast coffee is also more acidic than medium roast, according to a 2024 study published in Chemosensors by Masaaki Habara. The study measured acidity across roast levels using an electronic-tongue system. The researchers found lighter roasts produced higher acidity than medium roasts under identical brewing conditions. The study showed that roast level amplifies perceived acidity by changing extraction behavior and creating roast-derived compounds.

What is the Least Acidic Coffee?

The least acidic coffee is a dark roast Robusta blend. Robusta beans have fewer organic acids than Arabica. Dark roasting (Full City or darker) lowers acidity by breaking down chlorogenic acids. Low-altitude beans are also less acidic. Natural processing and older roast dates further mellow the acidity for a smoother cup.

The least acidic coffee typically comes from regions like Brazil, Sumatra, and other parts of Indonesia. These coffees grow at low elevations and have fuller bodies with muted acidity. Brazilian and Sumatran beans offer smooth, earthy flavors and naturally low acidity. Look for specialty coffee brands like Colipse that roast these beans to a medium-dark level and deliver them fresh to ensure you get a consistently low-acid, rich cup every time.

Where to Buy the Least Acidic Coffee Beans?

You can buy the least acidic coffee beans at specialty coffee shops, online retailers like Amazon, or even health food stores like Whole Foods. The prime example is Colipse Coffee, an online store offering low acid coffee blends and single-origin options like Sumatra, Brazil, and Bali, starting from from $22.50 USD for 12 oz bag. Choose from decaf, espresso, and cold brew roasts available in whole bean or ground form in coarse, medium and fine suitable for many brewing methods. At Colipse Coffee, we provide free U.S. shipping, multi-bag discounts, and flexible subscriptions.

What are the Best Low Acid Coffee Brands?

The best low acid coffee brands are listed below.

• Colipse Italian Espresso Blend
• Folgers Simply Smooth Ground Coffee
• Purity Coffee EASE Dark Roast Low Acid Organic Coffee
• Puroast Dark French Roast
• Volcanica Low Acid Coffee
• HealthWise Low-Acid K-Cup Coffee
• Alex's Low Acid French Roast Coffee
• Lifeboost Coffee
• Simpatico Low Acid Coffee
• Java Planet Low Acid Coffee
• Fabula Low Acid Coffee

What Does Acidic Coffee Taste Like?

Acidic coffee tastes bright, tangy, and citrusy, with notes like lemon, green apple, or berries. The bright feeling is called perceived acidity and comes from the acids and flavors in coffee, not its pH. How acidic coffee tastes depends on the total amount of acid in it (titratable acidity) and the kinds of acids pulled out, which change based on how you brew and what equipment you use. More total acid makes coffee taste brighter, while less acid makes it taste smoother.

Does Coffee Become More Acidic as it Sits?

Yes, coffee becomes more acidic as it sits due to chemical changes. Chlorogenic acid breaks down into quinic and caffeic acids, increasing bitterness and sourness. Oxidation of oils also contributes to this effect, especially when coffee is kept warm. For best flavor, drink coffee shortly after brewing.

How to Make Coffee Less Acidic?

To make coffee less acidic, start by using cold brew methods, choosing dark roasts, or adding alkaline ingredients like baking soda or milk. Use alkaline or hard water, paper filters, and coarser grinds to reduce acid extraction. To reduce coffee acidity, avoid overheating brewed coffee and regularly clean your coffee maker.

Is Decaf Coffee More Acidic?

No, decaf coffee is mildly acidic, with a pH between 5.0 and 5.8, making it less acidic than regular coffee. The decaffeination process removes some organic acids, and darker roasts or cold brew methods can reduce acidity further, benefiting those with acid sensitivity.

Is Cold Brew Less Acidic than Hot Coffee?

Yes, cold brew is less acidic than hot coffee because cold water extracts fewer acidic compounds during brewing. Although the pH may be similar, cold brew has lower titratable acidity, making it gentler on the stomach and better tolerated by people with acid reflux or sensitivity.

Is Mushroom Coffee Less Acidic?

Yes, mushroom coffee is less acidic than regular coffee due to the alkalizing properties of functional mushrooms like chaga and reishi. These mushrooms in coffee, combined with gentler roasting methods or cold brewing, lower the beverage’s acidity, making it a stomach-friendly option for people with acid reflux or sensitivity to acidic drinks.

Is Espresso Acidic or Alkaline?

Espresso is acidic, with a pH typically between 5.0 and 5.5. This makes it less acidic than orange juice (pH 3.3–4.2) but more acidic than water (pH 7). Espresso’s acidity can vary based on roast level, bean origin, and brewing method, especially compared to cold brew.

Are Used Coffee Grounds Acidic?

Used coffee grounds are only mildly acidic to nearly neutral, with a typical pH of 6.5–6.8 after brewing. While fresh coffee grounds are more acidic, used grounds do not significantly acidify soil and their effect on soil pH is minimal and temporary. Therefore, used coffee grounds are not acidic enough to meaningfully alter soil pH for most plants.

How to Test Coffee pH?

The pH of coffee is measured using litmus paper, pH test strips or a digital pH meter. The process involves brewing the coffee, allowing it to cool to room temperature, and then dipping the strip or inserting the meter into the liquid. The resulting pH value is compared to a pH scale.