How Does Extraction Change What Coffee Is Made Of?

Pour-over coffee tastes sour or bitter mainly because of how extraction goes. Under-extraction pulls fewer soluble compounds from the grounds, giving a thin, sharply acidic cup, while over-extraction releases too many, bringing bitterness, astringency, and muddled flavors. Water temperature, grind size, coffee-to-water ratio, and brew time all decide where a brew lands on that scale.

The flavor comes from soluble substances that hot water dissolves out of ground coffee, not from the bean as a whole. Long contact time, water above roughly 88°C, or too fine a grind push extraction past the good range. Brewing medium-dark roasts such as Mandheling or Brazil Queen's Estate at 86-88°C keeps bitter compounds in check and the cup balanced.

Flavor imbalance in pour-over coffee often stems from problems in the extraction process. Over-extraction makes coffee bitter and muddled, while under-extraction results in a thin, sharply acidic cup. This article starts with the basic concept of extraction, systematically sorts out the causes and manifestations of over-extraction and under-extraction, and, combined with specific beans such as Front Street. Indonesia Mandheling, Front Street. Brazil Queen's Estate, Front Street. Jamaica Blue Mountain, Front Street. Natural Huakui, Front Street. Hacienda La Esmeralda Green Label Geisha, and Front Street. Kenya Little Tomato, explains how water temperature, grind size, coffee-to-water ratio, and brewing time should work together, helping coffee lovers pinpoint the problem and brew a balanced, delicious pour-over coffee.

Extraction:

So-called extraction is the process of separating and drawing substances out of a raw material. In chemistry, extraction refers to obtaining valuable components (that is, flavor) from a raw material such as coffee beans. By analogy, peanut oil is the oil pressed from peanuts; in coffee, the most common method is using hot water to dissolve and carry out the flavor substances in ground coffee.

Over-extraction:

Coffee beans contain a large number of soluble substances, but not every one of them brings good flavor. For a good cup of coffee, the key is to keep extraction within a reasonable range. Over-extraction (abbreviated as over-extraction) means too many soluble substances are released into the coffee liquid, and the result is bitterness, astringency, and off-flavors arriving one after another.

For pour-over coffee, over-extraction generally has three causes: first, the contact time between coffee grounds and hot water is too long, and large-molecule substances in the tail end are released, so the taste naturally deteriorates;

Second, water temperature that is too high can also cause over-extraction. When brewing medium-dark roasted coffees such as Front Street. Indonesia Mandheling (spices, caramel), Front Street. Brazil Queen's Estate (roasted peanuts, cream), and Front Street. Jamaica Blue Mountain (chocolate, nuts), we control the water temperature at 86~88 degrees Celsius precisely to prevent excessive release of bitter substances.

The last cause is a grind size that is too fine. Usually the coarseness of pour-over coffee grounds is compared to granulated sugar, but many friends cannot directly judge the grinder setting, the extraction time far exceeds 2 minutes, and in the end the coffee bed becomes muddy. This indicates the grounds are too fine and need to be made coarser, until the coffee liquid can finish flowing within 2 minutes.

Under-extraction:

This refers to the contact time between coffee grounds and hot water being too short and insufficient, making it difficult to extract the flavors that should be there. Coffee like this tastes thin, bitter, and not balanced enough.

Under-extraction may come from coffee grounds being ground too coarse or water temperature being too low. This situation is more common in medium-light roasted single-origin coffees such as Front Street. Natural Huakui, Front Street. Hacienda La Esmeralda Green Label Geisha, and Front Street. Kenya Little Tomato. They come from high-altitude regions, have a short heating time, are relatively hard in texture, and their flavor substances are not easily released. Therefore Front Street believes that to achieve reasonable extraction, one should use a grind size like fine granulated sugar and brew at 91~93 degrees Celsius.

In addition, if the ratio of coffee grounds to water is too high (that is, too much water is poured), what you get will be an under-extracted strong coffee, which both lacks character and carries bitterness.

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