Beginner's Tutorial: Coffee Extraction Basics

Regardless of the extraction method used, the coffee needs to be dissolved.

Water is one of the best solvents in nature and has a strong solubility for hydrophilic substances.

In order to better extract the molecules inside the coffee beans, we need to create a larger area for the coffee to contact with water. This is the main reason why we grind coffee into powder. So the next question is: how much coffee powder should be used?

If we use Arabica instead of Robusta, we need more powder. Arabica grows at higher altitudes, has a denser texture, and is less soluble than Robusta. Arabica also requires a higher extraction temperature, usually between 88-94°C, which is the standard water temperature used by most coffee machines.

After setting the ideal water-powder ratio and temperature, we can adjust the next variable: time . If the coffee made by our recipe tastes bland or sour, it means that the coffee is not fully extracted; if it is too bitter or astringent, it means that it is over-extracted.

We can use a device called a "refractometer" to measure the total amount of soluble matter in coffee . The ideal extraction degree for drip coffee is 18-22%, and for espresso it is 18-21%. Below 18%, the coffee is under-extracted; above 22%, the coffee is over-extracted.

The refractometer is a good measuring tool, but we can't just rely on numbers, our taste buds are the final checkpoint . Sometimes the extraction ratio is not within this range, but the coffee still tastes good. We can't generalize based on numbers.

About the cup volume

The amount of coffee in a cup is the total weight of the liquid in the cup. The amount of coffee in a cup is the key for baristas to improve coffee quality and service level. Regarding the amount of coffee in a cup, we should not only pay attention to the extraction time, because the length of time depends on our recipe.

Simply put, the amount of liquid in the cup is the amount of liquid in the cup. A high amount of liquid means a heavier taste, a simpler flavor, and a more bitter taste; a low amount of liquid means a fuller flavor, but a stronger sour taste. Mastering this principle will help us master the balance of coffee flavors.

The standard cup size should be 2 cups of powder. For example, if we use 20g of coffee powder, the cup size should be 40g. Once we find the right cup size, we can let the coffee machine remember this data to ensure that the cup size is stable and accurate. It needs to be explained here that caffeine will not increase with the increase of cup size. More than 70% of caffeine has been fully extracted in the first few seconds of coffee extraction.

Sometimes we always complain about the unsatisfactory results, but in fact it is our operation in each link that determines the final quality of the coffee. We must ensure that the coffee powder particles are of accurate size and uniform texture, the amount of coffee powder in the filter bowl is accurate, the pressure of the powder is appropriate, and the handle does not hit the head group when installing, and there should be no diversion.

After understanding the amount of coffee, we can start to adjust the overall taste balance of coffee according to the type and origin of coffee. For a truly balanced coffee, the sweetness, acidity and taste must be harmoniously unified.

Acids and fats are the first to be extracted, followed by sugars and finally bitter substances. The taste depends on the brewing ratio we use.

Brewing ratio

The brewing ratio is the ratio between coffee powder and water. Water also affects the taste of coffee. Too little water means we cannot extract all the flavors in the coffee; too much water means some negative flavors will be extracted. The standard ratio for espresso is 1:2; for drip coffee, it is 1:16, that is, 1g of coffee powder should be matched with 16g of water.

author

Edoardo

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