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The Truth about Acid in Coffee

The Truth about Acid in Coffee

Posted by Stephen Berke on Sep 10th 2020

What’s the real deal on coffee acidity?

Ever heard of a non-coffee drinker saying they would drink coffee but for the “bitter” taste? In certain professional circles, coffee also takes a lot of heat for being branded as an “acidic” drink, bringing about stomach maladies for those with gastrointestinal problems.

TRUTH BE TOLD: facts explicitly suggest that coffee—having a pH rating of 5—is below common drinks such as soda, beer, and even orange juice! When we study the chemistry of coffee, we can quickly see a complex array of compounds that shed light on why this wildly popular beverage is unfairly maligned.


When you hear the word “acidity,” it’s almost a reflex to think of sour, tangy, bitter, sharp. But in the world of coffee, the term is used in at least three ways:

  • Coffee aficionados identify acidity as the dry, “bright”, and sparkling sensation that defines a high-quality, high-altitude coffee apart from the mundane, lower-grown beans. In other words, highly-prized coffees that sometimes cost $50 a cup are grown at plateaus atop the world’s mountain ranges. They are characterized by their acidity.
  • If you’re into deeper science, you’ll figure out that acidity is something to be measured on the pH scale, which uses 7.0 as an indicator of neutrality. Numbers under 7 are more acidic while numbers above are less acidic. For instance, lemon juice registers at around 2.0; milk at 6.5. Your typical coffee clocks at around 5.5 to 6.5.
  • But for the casual coffee fans, acidity is the property of food that makes their tummies hurt—and unpleasant quality that can break their whole day, sometimes an entire week.

Admittedly, each coffee type unravels perceived bitterness in its own way. The bitterness of a coffee is usually being correlated to its level of acidity. So here again, common misconceptions can mislead the casual coffee drinker into thinking that coffee is a strong, “full of acid” drink.

Let’s look at some of these “acids” that can be found in our favorite morning brew.


As we dig deeper for the truly curious, we see various types of acid in our daily cup of Joe.

Chlorogenic Acids

One of the main groups of acids present in coffee is chlorogenic acids, which also happen to be an important group of antioxidants. While the overall effect of antioxidants in coffee is still in the research stage, some people are very excited about the very large concentration of chlorogenic acid in green coffee beans compared to other plants. In its purest state, green coffee contains a lot of different acids – some good and some not so well. Most of the bad ones disappear during the roasting process or are transformed into a less aggressive state, but it may also reduce the antioxidant levels of the coffee. The green versus roasted coffee debate rages on, but that article must wait for another day.

The chlorogenic acids are a group that contributes to perceived bitterness. They break down, however, during the roasting process, which is why coffee expert James Hoffman writes, "the longer and darker that a coffee is roasted, the lower the perceived acidity tends to be when that coffee is brewed and tasted."

An actual graph of different coffee roasting levels shows us darker roasts present lower levels of chlorogenic acid. Therefore, the lighter roasted coffees, which are popular today, have a more pronounced acidity in their flavor profile. Keep in mind, Arabica types have a lower concentration than Robusta.

Quinic Acids

As coffee is roasted, the chlorogenic acids degrade to form quinic acids. This acid group plays a very important role in overall coffee taste. They affect the astringency of a beverage (think of sampling a green banana). Dark roasted coffees are high in quinic acid but low in some of the other acids responsible for flavor. This why darker roasts can cause that hollow, sour sensation in the tummy. If this is you, a lighter roast may serve you better or savor your dark roast in smaller amounts.


Christopher Bean Coffee always serve the freshest coffee around! Our roast-to-order coffees are never stale, keeping harmful acidity levels in check for even the most sensitive stomachs.

Better yet, try Christopher Bean’s low-acid coffees. With their mild pH levels, you can still enjoy a good cup of Joe without that gut-wrenching trip to your doctor.

Lastly, don’t let your coffee sit for too long, as chemical reactions will come about. Drink your cup while it’s hot and freshly brewed.

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