Where Does Coffee's Acidity Come From? Which Coffee Beans Are More Acidic - Is Acidic or Bitter Coffee Better?

For many coffee beginners, the acidity in coffee feels unacceptable at first — the combination of coffee flavor and acidity just seems strange.

Before processing, coffee beans look like this. They're commonly known as coffee cherries.

Recently, some fresh coffee fruit came back to the roastery, and the pulp inside is remarkably delicious. Whether you believe it or not, it really is. The green coffee beans suitable for roasting, of course, must be processed first — washed, natural, honey, semi-natural and so on. Only after processing do we get those vibrant green coffee beans, and only after proper roasting and brewing do we finally have a delicious cup.

The Chemistry of Coffee Acidity

Coffee beans contain acidic organic compounds that the plant can synthesize itself, including weak acidic aromatic substances containing carbon molecules.

These organic acids include chlorogenic acid, quinic acid, acetic acid, citric acid, malic acid and lactic acid.

These organic acids rise and fall before and after roasting.

That, however, is not the acidity we taste when drinking coffee. The acidity we perceive comes mainly from the changes that occur during roasting.

Typically, when green coffee is roasted, some components undergo chemical reactions that form new acids.

For example: during roasting, chlorogenic acid continuously degrades into quinic acid, and so on.

Roast Levels and Acidity

Medium-light roast - acidity is pronounced

Medium roast - moderate acidity

Medium-dark roast - relatively low acidity

Dark roast - almost no acidity, but bitterness is prominent

Each type of acid has a different intensity and concentration. The acidity components and proportions in coffee beans are also related to the composition of the green beans, and the choice of variety affects acid production to some extent as well.

Altitude and Acidity

Coffee grown at higher altitudes contains more aromatic acids but has a lower oil concentration than low-altitude coffee. Those two factors make high-altitude coffee more acidic. Documented records verify this in Guatemala's eight major producing regions, where Huehuetenango (in the northwest, bordering Mexico) and Santa Rosa (in the southeast, bordering El Salvador) at altitudes around 2000 meters show significantly higher acidity than the other six regions, including Antigua. Additionally, for every 100 meters of altitude increase, the temperature drops by 0.6°C. Research has also found that for every 300 meters of elevation increase, the sucrose content in coffee beans increases by 10%. In principle, higher aromatic acid and sucrose levels produce more aromatic, mellow coffee. This is because higher altitude, lower temperature and large day-night temperature differences slow coffee growth, allowing more nutrients to accumulate. Sucrose generates more aromatic acids during roasting, which is why high-altitude hard beans are significantly more aromatic and acidic than low-altitude soft beans. Altitude, variety, complex genetic traits and ecosystems all indirectly affect coffee flavor.

Understanding Coffee Acidity

Coffee acidity describes a lively, bright flavor expression, similar to terminology used in wine tasting. If coffee beans lack acidity, they lose their vitality, tasting hollow, bland and lacking depth and layers. Acidity has many different characteristics. Coffee from Yemen, Kenya and Ethiopia's Yirgacheffe and Sidamo regions, for example, has acidity marked by striking floral and fruit aromas, along with wine-like notes.

There is also a sharp, dull acidity — a "dead acid" without aroma. Drinking it is as unpleasant as swallowing vinegar.

Coffee fruit acidity is natural and reasonable, and it even represents the truly natural state of coffee. It is absolutely not spoilage or foul acidity.

Recommended Acidic Coffee Bean Brands

FrontStreet Coffee's acidic single origins include washed Yirgacheffe, Kenya AA and Panama Floral Butterfly, all of which are guaranteed in terms of brand and quality.

FrontStreet Coffee Recommendation

If you want to understand why acidity can be a virtue rather than a flaw, start with a clean washed coffee. FrontStreet Gutingding Cooperative, from Yirgacheffe's Woka area, is a textbook example: washed processing brings out jasmine florals with bright citrus and lemon acidity, and a light-medium roast adds green tea and honey notes — a clean, elegant cup. FrontStreet Kenya Cherry Tomato shows the other end of the spectrum, with cherry tomato and smoked plum acidity, pear and black plum through the middle, and a long finish of brown sugar and green tea. Both are vivid, layered coffees, and both are excellent as pour-over or cold brew.