Is coffee acidic? What you need to know

The word acidic sounds negative, but in fact acid is an essential ingredient in high quality coffee. If you've ever wondered how much acid there is in coffee, or how to reduce the levels of acidity, then read on to find out more.

How much acid is in black coffee?

Coffee contains hundreds of natural compounds and several major acids, but it's not as acidic as you might think. Beer, fruit juice, fizzy drinks, and wine all contain more acid than coffee.

To put this in context, the average cup of coffee measures 5 on the pH scale. Anything under 7 is considered acidic.

Red wine and tomato juice usually sit around 4 on the scale, while apple juice and some fizzy drinks have a pH level of 3.

When coffee drinkers talk about acidity, what they are actually referring to is a flavour note, which might also be described as a bright, fresh crispness. Acidity sounds undesirable but without it, your coffee would taste flat.

The key is getting the balance right – too much acidity can be unpleasant, and can lead to a confusion between something that is bitter and coffee that is sour.

The two main acids in coffee

Coffee beans in their purest form contain lots of different acids, good and bad. Some disappear, or reduce, during the roasting and brewing process, and others remain.

The biggest contributors to the taste of coffee are chlorogenic and quinic acids.

1. Chlorogenic acid

Chlorogenic acid is a type of dietary polyphenol that is found in coffee and some other plant compounds. It's thought that it may have an antioxidant effect, which is why some people believe that coffee is good for you.

This type of acid breaks down during the roasting process, so it stands to reason that the darker the roast, the less acid it has.

Arabica coffee beans have lower levels of chlorogenic acid than Robusta beans.

2. Quinic acids

Quinic is a type of acid found in some species of plant, and it's responsible for the 'sour' taste you get when coffee has been stood for too long. As chlorogenic acids degrade in the roasting process, they transform into quinic acids.

So, conversely, dark roasted coffee actually contains more quinic acid and less of the other acids responsible for some flavour notes.

What affects acidity levels in coffee?

Not all coffee has the same levels of acid, and this is predominantly down to four things: the roasting level, the brewing method, grind size, and the origin of the coffee beans.

Roasting

The longer it takes to roast the beans, the less acidity will end up in your coffee. For this reason, darker roasts typically contain less acid and lighter roasted coffee has a brighter, crisper flavour.

Brewing

The brewing method also affects the acidity of coffee, and studies have shown that cold-brewed coffee is significantly lower in acid. The time it takes to brew your coffee has an impact as well – in this case, the shorter the brew time, the more acidic it is.

Grind size

Acidity is often a side effect of under-extracted coffee, which often happens when the grind size is too coarse. Coffee that is ground too finely can also lead to high levels of acid, and it can be hard to strike a balance.

Coffee origin

Coffee beans from different parts of the world have different flavour profiles, and some beans are naturally lower in acids than others. Arabica plants grown in Sumatra and Brazil tend to be less acidic than the fruitier varieties of coffee produced in Kenya.

Read more about what makes Sumatran coffee special and why it's low in acidity.

Growing coffee at high altitudes and in volcanic soil can both affect the levels of acidity in the finished product.

You're unlikely to find this information on the packet of standard shop-bought coffee, but a specialist coffee purveyor, like Pumphrey's Coffee, will be able to tell you where (and how) your coffee was produced.

How do you reduce the acidity in coffee?

If you like your cup of coffee with less acidity, then we recommend that you:

• try a cold-brewing method instead of hot
• brew your coffee at a lower temperature
• increase the brew time by using a different method, like a French Press
• experiment with the grind size of your beans
• choose dark roasts over light roasts

You might also benefit from adding milk or cream to your coffee, and some people even advocate putting in salt to neutralise the bitter taste and bring out its sweetness.

Add the salt to your grounds before brewing, but be careful – a little goes a long way!

If you like experimenting with your coffee, then try Arabica beans from different coffee growing regions around the world. Sampling different types of coffee is one of the best ways of pinning down the flavours you enjoy the most (and discounting the ones you don't).

Is acidic coffee bad for your health?

The majority of people drink coffee without having to worry about its side effects, but for some it causes heartburn and acid reflux.

If you suffer from something like gastroesophageal reflux disease (GERD), a gastric ulcer, or irritable bowel syndrome, then any type of acidic drink is likely to irritate your symptoms.

The acid content in coffee may not be the direct cause of the problem. Coffee can also stimulate the production of stomach acid, and caffeine is known to relax the muscles in the gastrointestinal tract which can cause reflux.

To combat this, try switching to decaffeinated coffee or limit how much coffee you drink in a day.

The key takeaway - is coffee acidic?

The average cup of black coffee contains no more acid than a lot of other drinks we consume on a daily basis. Acid is essential to a quality cup of coffee, and without this flavour note, it would taste flat. If you don't like the acidic taste of some coffees, then try using dark roasted Arabica coffee beans or experiment with your brewing method.