How Coffee Extraction Works — A Guide to Brewing Your Perfect Cup

Every cup of coffee takes a long journey before it reaches your hands: from harvesting ripe cherries to processing, roasting, grinding, and finally, brewing. Each stage plays a vital role in shaping the final flavor. Extraction is the last step in this journey—and one of the most important.

In this guide, we’ll explore how coffee extraction works, the science behind it, and the key variables that influence flavor, so you can better understand (and control) the process of brewing coffee you truly enjoy.

What Is Coffee Extraction?

Coffee extraction is the process of dissolving soluble flavor compounds from ground coffee into a liquid. Because water is colorless, tasteless, and an excellent solvent, it is the most common medium for extraction.

When water comes into contact with coffee grounds, it draws out the soluble compounds that create aroma, taste, and body—transforming plain water into the beverage we recognize as coffee. 

What Compounds Are Extracted From Coffee?

During extraction, coffee grounds release a wide range of compounds, including caffeine, organic acids (such as citric, quinic, and malic acid), volatile aromatic molecules, lipids, soluble sugars, and polyphenols. Together, these substances shape the flavor, aroma, and body of the final cup. Although water is an excellent solvent, not everything dissolves—cellulose and other large molecules remain in the spent grounds rather than in the brewed coffee.

The composition of these compounds is influenced by many factors: the coffee’s variety, growing conditions, processing method, and roast level all play a role. And during extraction, variables such as water temperature, brew time, and grind size further determine how flavors are released.

How Coffee Extraction Progresses in Stages

Different compounds dissolve at different rates during extraction, which is why flavor evolves over the course of a brew. In the early stage, bright acids and volatile aromatics—responsible for floral and fruity notes—are extracted more quickly. As the process continues, more sugars and soluble compounds contribute to sweetness, roundness, and balance. In the later stage, a greater share of bitter and astringent compounds is released, which can dominate the cup if extraction goes too far.

How Extraction Affects Flavor

The taste of coffee is shaped not only by the quality of the green beans and the roast profile, but also by two key brewing metrics: extraction yield and strength (or concentration). Extraction yield refers to the percentage of soluble compounds drawn out of the coffee grounds, while strength describes the ratio of dissolved solids to water in the final beverage.

Starting with extraction yield: not all compounds in ground coffee dissolve into water, and the degree of extraction directly influences the cup’s aroma and taste.

The speed and extent of dissolution depend on several factors. If brew time is too short, the water temperature too low, or the grind too coarse, fewer acids, lipids, and sugars will be extracted, resulting in under-extraction. Conversely, if the brew time is too long, the water temperature too high, or the grind too fine, a higher proportion of bitter and astringent compounds will be released, leading to over-extraction.

In general, under-extracted coffee tastes overly acidic, thin, and watery. Over-extracted coffee, on the other hand, tends to taste harshly bitter and astringent, with muted aromas and a muddy finish. Still, these terms are descriptive rather than absolute judgments—each person has their own preferences, and some may actually enjoy a brighter or more intense cup.

On the other hand, the ratio of dissolved compounds to water determines the strength (or concentration) of the brew, which also influences the taste. Even if a large amount of solubles are extracted, using more water can still result in a cup that tastes weaker or less intense.

This article focuses mainly on extraction and extraction yield, but if you’d like to explore the relationship between strength and extraction yield in more detail, please refer to the Specialty Coffee Association’s Golden Cup Standard.

How to Control Coffee Extraction

At its core, coffee extraction is the interaction between water and ground coffee. Several factors influence how effectively compounds dissolve: the surface area of the grounds, the contact time, the flow of water through the coffee bed, and the quality of the water itself. The basic principles are:

• The larger the surface area (eg: finer grind), the more easily soluble compounds dissolve.

• The longer the contact time, the more compounds are extracted.

• The higher the water temperature, the faster molecules move, speeding up extraction.

• Stirring or agitation increases interaction between water and grounds, improving solubility.

• Water quality also affects both extraction efficiency and flavor clarity.

Once you understand these fundamentals, you can look more closely at the specific brewing variables that shape extraction in practice.

Brewing Variable: Grind Size

Grind size is one of the most important brewing—and extraction—variables, because it directly determines the surface area of the coffee and how quickly water dissolves soluble compounds.

With a coarser grind, there is less surface area, so extraction takes longer. With a finer grind, there is more surface area, meaning extraction happens more quickly. Managing grind size allows you to balance how much acidity, sweetness, and bitterness make it into the cup.

Further reading: How Grind Size Shapes Flavor and Brewing?

Extraction Variable: Brewing Method

The brewing method—and the equipment you use—has a major impact on extraction. Each technique creates different patterns of contact between coffee and water, influencing both time and flow.

• Filter methods
  Water is poured over coffee grounds in a filter and dripper, and the brewed coffee drains through immediately. Contact time, pouring consistency, and agitation all affect the outcome. Common examples include pour-over and drip brewing.
  

• Immersion methods
  Grounds are steeped directly in water, giving the solubles more time to dissolve. French press, AeroPress, and cold brew are typical immersion methods.
  

• Pressure methods
  Hot water is forced through a dense coffee bed under pressure, achieving high extraction efficiency in a short time. Espresso machines and moka pots both rely on pressure.
  

• Boiling methods
  Coffee and water are heated together until boiling, resulting in extended contact time. The cezve (ibrik), used for traditional Turkish coffee, is a classic example.
  

• Other methods
  A siphon brewer, for instance, uses vapor pressure and a cooling-induced vacuum to create unique patterns of contact and flow, producing distinctive results.

Brewing Variable: Technique

Beyond the choice of brewing method and equipment, the techniques you use during brewing can also influence extraction.

• Even distribution
  Ensuring the grounds are evenly distributed in the filter or vessel helps water pass through consistently, preventing localized under- or over-extraction and improving balance in the cup.
  

• Pre-wetting (blooming)
  Before the main pour or pressurized extraction, a small amount of hot water is poured onto the grounds and left to sit briefly. This releases trapped carbon dioxide, preventing uneven flow and promoting more stable extraction.
  

• Agitation
  Adjusting how you pour—such as spiraling the kettle, changing pour height, or altering flow rate—creates controlled agitation that improves contact between water and grounds. This is common in pour-over brewing but requires careful balance depending on the method.
  

• Stirring
  In immersion methods like French press or AeroPress, stirring can encourage full saturation and more efficient extraction. However, excessive stirring may lead to over-extraction and unbalanced flavors, so use it selectively depending on recipe and preference.

Brewing Variable: Water Temperature & Quality

Water temperature is another critical factor in extraction. The hotter the water, the more energy it carries, increasing molecular movement and speeding up dissolution. This is why cold brew, which extracts at a low temperature over many hours, produces a very different flavor profile.

Further reading: A Guide to Water Temperature for Brewing Coffee

Beyond temperature, the mineral content of the water also shapes flavor. Calcium and magnesium ions, in moderate amounts, can improve extraction efficiency, making acidity brighter and sweetness and aroma more pronounced. But too many minerals can throw off the balance, masking subtle notes. On the other hand, water with very low mineral content may produce coffee that tastes overly acidic, thin, and lacking in complexity.

Brewing Variable: Brew Time

Brew time is one of the most straightforward variables in extraction. The longer the coffee and water stay in contact, the more compounds will be extracted. A shorter contact time, on the other hand, limits how much can be dissolved into the brew.

Brewing Variable: Roast Level

Roast level also affects how easily compounds are extracted. Broadly speaking, coffee can be categorized as light, medium, or dark roast, depending on how long it is exposed to heat.

Light roasts, with shorter roast times, are less structurally damaged by heat, meaning the cell walls remain more intact. Because of their intact cell structure, light roasts generally require finer grinds or longer brew times to extract flavors effectively. Dark roasts, on the other hand, undergo extended roasting, which breaks down more of the bean’s cellular structure. This makes solubles easier to extract, but also increases the risk of over-extraction and excessive bitterness if brewing parameters are not carefully adjusted.

Further reading: A Guide to Coffee Roasting: Stages and Impact on Flavor

By understanding and combining these variables, you can experiment and fine-tune your brewing to create the flavors you enjoy most. For example, if your pour-over brew has a relatively short contact time, raising the water temperature slightly can improve extraction efficiency and reduce the risk of under-extraction.

Choosing the Right Coffee Grinder for Consistent Extraction

To achieve precise control over grind size and uniformity—both critical for consistent extraction and balanced flavor—a high-performance grinder is essential.

The Femobook A68 Electric Grinder features a conical burr design with over 300 fine-tuned adjustment settings, allowing precise calibration for espresso, pour-over, French press, or cold brew. This flexibility makes it easy to tailor grind size to different beans and personal taste preferences. The grinder is also designed for quick disassembly and reassembly, making cleaning simple and convenient.

Its wide adjustment range, supported by stainless steel ball positioning, helps prevent alignment shifts and ensures consistent grinding performance—even after disassembly and reassembly. In addition, Femobook’s short grind path minimizes retention, helping preserve the full flavor potential of every dose.

Whether you’re brewing on the go with the compact A2, dialing in home recipes with the versatile A5, or seeking professional-grade control with the A68, Femobook grinders cover every brewing scenario. Wherever you brew—outdoors, at home, or in a café—you can rely on Femobook for high-quality, consistent grinding.