Why Does Coffee Tastes Like Alcohol Point to Extraction?

A cup that tastes sharp, sour and thin usually signals under-extraction, with little sweetness, a salty edge and a short finish. Coffee that tastes bitter, dry or hollow points to over-extraction. If coffee tastes like alcohol or fermented notes appear alongside these signals, the brew is out of balance and the grind, time and ratio need correction.

Extraction is simply water dissolving substances out of coffee grounds. About 28 percent of a roasted bean's weight is water-soluble, so that is the ceiling for what can be extracted; the rest is cellulose and structural plant material. Insoluble fine particles stay suspended and shape mouthfeel but do not count toward extraction yield, which is why flavor and texture must be read together when diagnosing a cup.

Extraction is the most central yet most easily misunderstood part of coffee brewing. Starting from flavor and mouthfeel, this article systematically sorts out the typical signals of under-extraction and over-extraction, helping you quickly judge the state of a cup of pour-over coffee and adjust parameters accordingly. Under-extraction often shows up as sharp sourness, a lack of sweetness, saltiness, and a short finish; over-extraction brings bitterness, dryness, and a hollow feeling. Once you understand these clues, you can correct grind, time, and ratio with more direction, bringing the coffee back to a balanced, delicious place. The article also retains product recommendation information related to Front Street Coffee for easy reference in daily practice.

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Among all the steps in coffee brewing, extraction is probably the most critical, yet also the part that quite a few baristas understand least thoroughly. It could be said that extraction determines everything. Without the extraction step, you simply would not be able to drink a cup of coffee at all.

To summarize it in the simplest, though not one hundred percent rigorous, way: extraction is the process by which water dissolves substances out of coffee grounds.

It sounds like something that can be explained in one sentence, but truly understanding it and using it skillfully is far from this simple.

When coffee grounds come into contact with water, a series of changes takes place in the system. Water dissolves a large number of flavor components from the coffee, and these dissolved substances make up almost all of the taste experience you perceive when drinking coffee. What remains is the insoluble portion, mainly extremely fine coffee particles, which affect mouthfeel. However, these insoluble substances cannot be counted into the extraction yield, because they are merely suspended in the liquid.

About 28% by weight of roasted coffee beans consists of water-soluble substances. In other words, at most you can extract flavor components equivalent to 28% of the coffee bean's weight; the rest is basically cellulose and other plant materials that make up the bean's structure.

Water is very good at dissolving these soluble chemical substances, but it also needs some "assistance." To help water work better, you need to increase the surface area of the coffee beans, opening up the "channels" for water to pass through, so that flavor substances are more easily carried out. Doing this requires only a grinder: grind the coffee beans to multiply the surface area, and water can then do its job more fully.

The ideal situation would be to grind the coffee beans into extremely fine particles, let water contact them, and dissolve out all the good flavors within. Unfortunately, what you often end up with is a bitter, undrinkable cup of terrible coffee. The reason is that not all flavor substances in coffee are pleasant, and during brewing you must control the amount of flavor substances dissolved out in order to get a cup of coffee that "tastes good."

Trying to avoid the bad flavors caused by over-extraction by increasing the dose and taking only the early part of the extraction will not work. Under-extracted coffee tastes just as bad.

Many people understand extraction as a two-way road connecting "over" and "under." On this road, everyone tries to keep the coffee in the middle zone, avoiding over-extraction or under-extraction as much as possible.

Under-extracted Coffee

Under-extraction means that not enough flavor substances have been dissolved out of the coffee grounds, and a large amount of material still remains in the grounds, material that could originally have balanced out the bad flavors.

Think back to an Espresso you have had with too short an extraction time, for example a Ristretto made with beans roasted at the currently popular specialty coffee espresso roast level. It often has sharp acidity, lacks sweetness, has a strange saltiness, and a disappointingly short finish—these four characteristics are the most obvious signs of under-extraction.

Sourness

Sourness is a very subtle thing, especially when we are always pursuing good acidity in coffee. Many people ask: "Aren't sourness and acidity the same thing?" This question is actually quite natural, because in many languages "sourness" and "acidity" share the same word—"sour." As you can imagine, this creates some inconvenience for multilingual cupping.

To distinguish them, "sourness" is usually defined as a negative sensation. Sourness comes very quickly and intensely. It triggers a bodily reaction almost immediately: you pucker your lips, and a strong, sharp sensation appears on both sides of your tongue. Sourness is an unpleasant, bad taste.

Whenever acidity is discussed, it may be good or bad. More precisely, it is a flavor category that includes both positive and negative attributes. For example, "That coffee's acidity is delightful" and "That coffee's acidity is very sour" are both statements that, in my view, hold true. Acidity includes many things such as sour, juicy, bright, and tart.

Lacking Sweetness

One of the most important aspects of coffee flavor is its "sweetness." Sweetness is the essence. Have you ever heard someone complain, "This espresso is too sweet"? You can think about that carefully. Under-extraction has no sweetness and is far from it. Under-extraction always leaves some emptiness that makes you feel unsatisfied, and after drinking a cup you feel "far from enough." One benefit of lacking sweetness is that it makes sourness more obvious, thereby making under-extraction easier to identify.

Salty

Many people may not agree with this view, but under-extracted coffee is salty. This saltiness is not the kind of "sorry, I accidentally added salt" saltiness; under-extracted coffee always brings a salty tactile sensation/taste. In terms of mouthfeel, this saltiness is very similar to the slippery sensation brought by alkaline solvents. (Please do not try drinking ammonia water just to verify this. Just trust me.)

Quick Finish

The finish of a properly extracted cup of coffee lasts for several minutes (or even several hours, if you are lucky enough). This finish is just like when you have just eaten a piece of brown sugar, or just eaten a piece of toffee—very delicious!

A cup of under-extracted coffee cannot provide these finishes. When you swallow it, everything disappears at once, and you will not feel much pleasant finish. That abrupt, lingering-but-unsatisfied experience after drinking coffee is really not so delicious.

There are some other flavor expressions that also suggest under-extraction, but the above four aspects are the most prominent. When you taste these four flavor expressions, you can be sure that your coffee is under-extracted.

Over-extracted Coffee

Over-extraction means that too many soluble flavor substances have been dissolved out. This extraction state brings some bad flavors.

Try to recall again an Espresso made with beans roasted at the currently popular specialty coffee roast level, with an extraction time of 40-50 seconds. Such an Espresso is bitter, drying, and hollow—these three flavors are also the three most obvious characteristics of over-extraction.

Bitter

Everyone knows coffee is bitter. Over-extracted coffee is extremely bitter. Unless you are drinking Campari (a bitter liqueur based on strong alcohol), you really do not want to taste so much bitterness. The bitterness in coffee mainly comes from caffeine, but many other chemical substances also affect bitterness. The chemical changes in dark-roasted beans have already entered the dry distillation stage and contain more bitter chemical substances.

Drying

Coffee with a drying sensation is extremely bad, because dryness is a very intense feeling and lasts a long time. This sensation is also called "astringency," and it is also experienced in unsweetened black tea, young red wine, or white wine that has been stored too long. In wine, astringency is mainly caused by polyphenolic substances (widely present in plants, seeds, bark, and so on). Similar chemical substances exist in coffee and can also cause astringency.

Polyphenolic substances are bitter and will bind with proteins in saliva. Simply put, this binding reduces the lubricity of the tongue surface, creating a rough, dry sensation in your mouth (this sensation should not be confused with "crisp" and "dry" in wine—these two words in wine mean bright acidity and low sweetness, not mouthfeel).

Hollow and Empty

Over-extracted coffee tastes very hollow and lifeless, as if you pressed and squeezed out everything with force, but in the process destroyed everything as well.

Properly extracted coffee fills your mouth with a sense of body; it is tasty, smooth, and more importantly, rich. Under-extracted coffee, on the other hand, is hollow, bland, rough, and hard to swallow, so lacking in flavor and character (not referring specifically to any particular flavor).

The above are the typical flavor characteristics of over-extracted coffee. Of course, the flavor characteristics of over-extracted coffee are not limited to these, but these are the easiest to identify. With this understanding, when you drink a cup of over-extracted coffee, you should be able to recognize it immediately!

The above content is compiled by CoffeeHunters, a coffee news website.