Does Coffee Get More Acidic The Longer It Sits?

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I drink a lot of coffee throughout the day. Depending on how I brewed it, I might get fresh cups as the day progress, however, there are times when I have to drink from a big batch that was left out for hours. This made me wonder: Does Coffee Get More Acidic The Longer It Sits?

When coffee sits out for longer periods of time, it has a longer time to react with oxygen. This oxidation changes the flavor profile of the coffee, making it taste more bitter, or stale. The oxidation process raises the pH level of the coffee, making it taste less fresh.

Fresh coffee is the best coffee. In my opinion, you should drink your coffee within 30 minutes. And, a great coffee should have a balance of sweetness, acidity, and bitterness.

But, let’s dive into this topic in more detail as there is often confusion between acid or pH levels in coffee versus coffee acidity (taste profile).

Here we go…

Acid vs Acidity in Coffee

In scientific terms, the pH level of a compound is what determines if it is acidic or basic.

Coffee tends to be in the slightly acid range with typic pH levels hovering around 5 (7 is neutral).

But, let’s stop talking about science,

and start talking about flavors, taste, body, etc…  

It is important to note that acidity in coffee is not referring to the scientific quality of pH levels. Instead, acidity is used as part of a taste profile to rate coffee and it is a trait that many find desirable.

Acidity is a key term to assess a coffee’s flavor. The confusion comes into play because contrary to what people think, a coffee with more acidity will not wreak havoc with your stomach.

Coffee connoisseurs describe a coffee’s taste with the term acidity. Many say that coffee with more acidity tends to present more with wine-like flavors, dry with sweet fruit and floral nuances like citrus or berries. 

So, a particular brand of coffee could have a scientific pH level of being acid yet from a tasting perspective, its acidity is quite good!

Are you interested in trying high-quality coffees with more acidity?

Look into coffees from the east side of Africa, grown in high altitudes with a light-medium roast. They can be found from countries like:

  • Kenya
  • Tanzania
  • Yemen (Mattari, Hirazi)
  • Zambia
  • Zimbabwe
image source: wikipedia

Coffee Acidity By Roast Type

Generally speaking, the level of acidity decreases as the roast gets darker.  Therefore, darker roasts have lower acidity. For example, an espresso will be lower in acidity than a typical American roast.

Coffee with higher acidity tends to be lighter roasts and tastes great when drinking black. As the roast gets darker, the acidity level decreases but the bitterness may increase. Think of the perfect Italian espresso. That is a dark roast that has lower acidity, a full body with a bit of bitterness.

Can Brewing Methods Impact Coffee Acidity?

Your brewing method can impact your coffee’s acidity. The most notable difference can be the distinction between hot brewing versus cold-brewed coffee.  

Cold-brewed coffee (coffee that is steeped in cold water vs hot water) has lower acidity.  Many coffee drinkers love cold-brewed coffee because it is smooth and less is bitter.

Additionally, brew times and the coarseness of the coffee bean grind can impact the acidity levels as well. Coffee beans that are ground too coarsely and brood too quickly will result in a coffee that has poor acidity.

When brewing hot coffee, there are many brew options to choose from. Below is a list of brewing methods, ranked from best tasting to least best tasting, in my opinion:

  • AeroPress – This is a method of coffee brewing that was invented in 2005. It uses a plunger to force the steeped coffee to pass through a filter. The recommended steeping time is less than 50 seconds. The resulting coffee is a full, smooth, and less bitter tasting coffee.
  • Pour Over – This is what it sounds like. A filter is placed above the coffee cup. The filter contains the ground coffee beans. Then hot water is manually poured over the coffee beans. The trick is to pour the water in a slow methodical method. When done correctly, a pour-over is a wonderfully flavored, cup of coffee.
  • Moka Pot – This is a pressure styled coffee maker. A Moka pot is a stove-top, double-decker device. The bottom level holds the water. The upper level holds the coffee grounds. As the water boils, the steam forces the water up through the upper level. 
  • French Press – This is a manual method of brewing coffee with a plunger device. It does not use paper filters. The ground coffee is placed in the press, along with hot water. The coffee steeps for approximately 5 minutes and then you press down on the plunger to extract the filtered coffee. 
  • Drip Machine – This is the traditional coffee machine that most people are familiar with. It uses a filter to hold the ground coffee and hot water is dripped into the coffee grinds. Gravity does the job of letting the water drip through the coffee grind and falls into a pot.  

Does Where Coffee Beans Grown Impact Acidity?

The short answer is yes, absolutely!

Coffee beans that are grown in high altitudes have a higher acidity from a taste profile perspective. That is, they have a more complex taste. This is not as much to do with the altitude but more to do with the temperature of the environment they are grown in.

Higher altitude plants tend to grow in cooler temperatures and they grow at a slower rate.  

Coffee Taste Profile & Countries by Altitude

AltitudeTaste ProfileCoffee
Very High (5,000+ ft)Floral, Fruit, Berry, Wine, SpiceEthiopia, Columbia, Guatemala, Kenya, Papua New Guinea, Sulawesi
High (4,000 ft)Chocolate, Nut, Vanilla, CitrusCosta Rica, Java, Sumatra, Nicaragua, Mexico Altura
Medium (3,000 ft)Sweet, Smooth, Low AcidityBrazil, Bouma, Santos
Low (2,000 ft)Subtle, Soft, Bland, Simple, Mild, EarthyHawaiian Kona

The lower elevation coffee beans grow faster and produce higher yields, making them great for mass production and higher profits for coffee manufacturers. But, these beans are not good for darker roasts.

The high elevation beans grow slower, allowing them to develop a richer, more complex flavor profile. These beans are also able to retain their flavor in storage for a longer time.

Try this as a taste comparison and experience the difference yourself! Drink a Sumantran coffee and compare it to a high-quality Kenyan coffee. I think that find that the Keynan coffee to be brighter, cleaner, and crisper.

Do the taste test and let me know!

Does coffee get more acidic with time
Brett Bio

Hey there, I'm Brett Lewis, the self-proclaimed brew master behind Brew Dog Metrics. I am a long time coffee, tea, and beer drinker and have begun brewing my own beverages at home since 2001 to get the best tasting drinks for me & my family. I began this website to help others learn more about brewing coffee, tea and beer at home to improve the quality of their daily lives. I'm thrilled at how much Brew Dog Metrics has grown and I look forward to expanding this site and sharing more at home brewing solutions and information with you. Cheers & happy brewing!

Brett Bio

Brett Lewis

What started out as the desire to brew the perfect cup 'o joe, turned into an obsession in brewing coffee, tea, and beer at home. This has turned into a mission to share my experience and research with as many beverage drinkers as possible. :)