Acid in Coffee

For some coffee drinkers, the acid reflux and heartburn they get after drinking coffee can turn it into an uncomfortable experience. 

While some of these side-effects can be attributed to the acid in the coffee itself, we've already listed why acid in coffee isn't the only cause of discomfort. Caffeine and a range of other compounds in coffee can also trigger unwanted side-effects. 

However in this post we focus on the acid in coffee and why it can be problematic for some coffee drinkers. 

Does Coffee Contain Acid?

Yes, but to understand this more fully, it's worth exploring the science behind the bean a little better.

There are technically two different ways to analyze the acid profile of coffee: coffee acidity and coffee acid.

Coffee Acidity

The acidity of coffee is its actual pH value (potential of hydrogen).

Everything has a pH value that's typically charted on a scale of 0-14, though the range can be greater or smaller. Values below 7 (neutral) denote acidic substances versus alkalis (or bases), which rank upwards of 7 on the chart. 

This scale helps measure the activity of hydrogen ions in the substance. In food, it refers to the food's residual pH left in your body as the substance gets digested. 

While our bodies have a pH value of 7.4 (around neutral), tap water 6.5-8.5, coffee is typically around pH 4.3-5, which is mildly acidic.

Typically any food or beverage more acidic than our own body chemistry can trigger digestive discomfort, inflammation and "burning" side-effects like acid reflux or heartburn.

The level of acidity in coffee depends on two factors: the elevation of the coffee and how the coffee has been roasted. 

Coffee Elevation

Coffee plants grown at elevations lower than 4,500 ft or in non-volcanic soils contain less acid than plants grown at higher elevations.

However as coffee becomes less acidic, so the fruitier expressions in the coffee bean also decrease.

As a result many highly-prized artisanal coffees with spicier, fruiter coffee cupping notes will have been harvested at higher, harder to reach elevations. 

Coffee Roasting

Roasting also affects a coffee bean's acidity.

As a rule of thumb, the more you roast a coffee bean ("bold", "French" or "dark" roasts) the less acidic it becomes. 

However this also allows more of the volatile flavor compounds to evaporate from the bean, resulting in less nuanced and range of flavor. This is why we choose to roast Cultured Coffee on a light-medium, or "city roast" setting. 

Is Cold Brew Coffee Less Acidic?

Some preparation methods can also mitigate the level of acidity in your cup. One popular alternative for heartburn and acid reflux sufferers, for example, is to drink cold brew. 

The acidity of cold brew coffee is tied to the lower level of coffee solids suspended in the water to make the brew. 

Since cold brew coffee doesn't get heated, less of the volatile compounds in the beans, which require heat to be extracted, end up in the surrounding liquid. However less of the coffee flavor is extracted too.

To complicate matters, cold brew is often mixed with other ingredients that can increase the acidity again.  

Coffee Acid

Outside of the actual pH value of coffee, coffee also contains a range of organic biochemical compounds known as "acids." 

Each of these acids is naturally produced by the coffee plant and have been associated with a host of potential health benefits.

However some of these acids can be harder to digest, which triggers discomfort for some people. These acids also send signals to your stomach cells to produce acid, which can lead to heartburn.  

Acid Taste

While it's possible to detect the taste of these acids, they tend to break down very easily through roasting, which is also why darker roast coffees also taste less acidic. 

Chlorogenic Acid

An ester, or chemical compound made from an acid where at least one hydroxyl group (oxygen bonded to hydrogen) has been replaced by an alkyl (hydrogen and carbon) group.

Chlorogenic acid is naturally found in many plants including eggplants, peaches and prunes. Scientists are currently researching its potential effect on reducing inflammation and blood pressure.

Arabica coffee, the type of coffee we prefer to work with for Cultured Coffee, is naturally lower in this type of acid.  

Quinic Acid

A crystalline acid discovered in the 19th century, quinic acid is tied to the perceived acidity and astringency of coffee.

Unlike its counterpart, this acid is naturally produced from chlorogenic acid when you roast coffee beans.

Interestingly, it is now also used as a starter for the commercial development of the flu vaccine. 

Caffeic Acid

Coffee beans contain a modest amount (0.03mg / 100ml) of this organic compound technically classed as phytochemical (produced by the plant) hydroxycinnamic acid, which plays a role in enabling the coffee plant to absorb energy from sunlight.  

This acid is found in higher concentrations in other edible plants, seeds and mushrooms. Despite the name, it's not associated with caffeine, and is being investigated for its potential effects on inhibiting cancer.

Cultured Coffee: Reduced Acidity and Troublesome Acids

Naturally occurring acids are reduced in Cultured Coffee by culturing our beans before we roast.

By fermenting our coffee beans, natural reactions start to take place to convert less digestible acids into a form that's more easily absorbed by the body. 

At the same time, while the acidity of the coffee bean isn't changed by fermentation, the mix of microbes we use to ferment the coffee beans before roasting have an alkalizing effect on the chemistry of the bean. This means the coffee is likely to disrupt your body's pH balance when you drink it. 

As a result of the different acids and acidity, Cultured Coffee coffee becomes easier to digest resulting in less discomfort and potential for acid reflux or heartburn.  

We hope this post has provided a helpful overview of the acid and acidity in coffee and how to reduce your consumption if it causes problems for you. Happy brewing!

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Continue your journey exploring the world of fermented coffee and fermentation science in our blog. 

If you'd like to taste the benefits for yourself, stock up on the health benefits of Cultured Coffee today!