Key Points of Espresso Extraction, Extraction Time for Americano, and Taste Characteristics of Iced Americano

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You've excitedly extracted a shot of espresso, only to discover upon tasting that its acidity is surprisingly sharp!!! Or, the taste is extremely bitter!!!

Friends who frequently make espresso at home will immediately understand: this espresso adjustment battle is going to be quite challenging! Just yesterday it tasted perfectly fine, so why does it have such a frustrating taste today? What methods can quickly correct the espresso's flavor while minimizing coffee bean waste?

Why Do Coffee Beans Change Flavor?

This is no exaggeration~ The reason why extracted espresso tastes different from day to day is precisely because its extraction is influenced by three factors: the condition of the coffee beans, air temperature, and humidity!

From the moment coffee beans complete roasting, they continuously release carbon dioxide. This CO2 creates resistance during extraction, but as the gas dissipates, the resistance gradually decreases, ultimately leading to parameter changes.

For example: On day one, you might use 19g of coffee grounds to extract 38ml of liquid in 30 seconds. However, because the coffee beans continue to release gas overnight, with less resistance, on day two you might only need 26-28 seconds to extract 38ml of liquid with the same 19g of coffee grounds.

Additionally, changes in humidity and air pressure! When indoor humidity is higher, there are more water molecules in the air! This can cause coffee beans in dry environments to absorb numerous water molecules, affecting stable extraction. Fluctuations in air pressure can also subtly affect the strength of the espresso machine's extraction pressure.

Therefore, when using yesterday's parameters to extract today's beans, it's difficult to replicate yesterday's flavor. This is why the first thing baristas do every morning is to calibrate the espresso flavor - primarily to ensure that daily coffee maintains a consistent taste.

How to Calibrate Espresso?

First, don't touch the grind size! Grind adjustment is a last resort. Each adjustment at least wastes one dose of coffee as "sacrificial grounds" because it contains remnants from the previous grind setting. The extraction data from these grounds cannot be used for reference and must be discarded.

When the parameters are roughly the same as yesterday (for example, yesterday was 18g of grounds extracting 36ml in 30 seconds, while today is 18g extracting 36ml in 28 seconds), we can start by adjusting the extraction ratio.

Espresso Extraction Ratio

In the coffee world, pour-over coffee has a certified "golden extraction ratio" of 1:16. However, for espresso, there's no precise standard. Everyone generally defaults to an extraction ratio of 1:2, meaning 1g of coffee grounds extracts 2ml of liquid.

The reason there's no precise standard is that espresso extraction is influenced by many factors, making it impossible to directly apply templates like pour-over coffee to achieve desired results.

So, when the espresso has a sharp, acidic taste, it's likely under-extracted. We can extend the extraction, increasing from 18g of grounds extracting 36ml to 38ml, increasing by 2ml increments each time. If you can clearly perceive the sharpness of the acidity decreasing, it indicates you're adjusting in the right direction.

However, if a bitter flavor appears, it indicates that the extraction amount has exceeded the extractable aromatic compounds, resulting in over-extraction. In this case, we need to adjust downward and reduce extraction!

Coffee Ground Amount

Besides the extraction ratio, we can also adjust extraction strength by increasing or decreasing the amount of coffee grounds. Just 0.2g of grounds is enough to significantly change the coffee's flavor, so when adjusting ground amounts, we increase (or decrease) by 0.2g increments.

For example, if you're using 19g of grounds to extract 38ml of liquid in 30 seconds, but you still feel the extraction is insufficient with some sharp acidity (or over-extracted and bitter), then without changing the extracted liquid weight, you can appropriately reduce the ground amount, adjusting by 0.2g increments each time.

Grind Size

When your ground amount has reached the limit of the portafilter basket—for example, using 20g of grounds in a 20g basket—but extraction is very fast, completing 38-40ml in 24 seconds and tasting very acidic! This phenomenon indicates the grind is too coarse, with excessive gaps, preventing grounds from fully contacting hot water, resulting in ineffective extraction. This is when you need to adjust the grind!

Rotate the grinder setting one notch toward smaller numbers, discard the first batch of grounds, then use the same amount to extract the same liquid volume. You'll find the extraction time is longer than before and the flavor is fuller. Then you can make fine adjustments using the two methods mentioned above!

Conversely, with the same 20g of grounds, if it takes more than 40 seconds to extract 38ml of liquid, and assuming it's not light to medium roast coffee beans, the extracted coffee is likely over-extracted.

At this point, we need to adjust the grind toward larger numbers, where larger numbers mean coarser grinding, to increase the gap size for water to pass through, reducing extraction strength. Finally, using the first two methods for fine-tuning will yield properly extracted espresso!

Once you've mastered these adjustment techniques, you can quickly find the appropriate correction method. Sharp acidity, bitterness, and weakness will all be manageable! However, if you're just satisfying your own daily coffee craving at home without needing to serve others, then it doesn't need to be so complicated! The most important thing is finding a comfortable method that works for you~

Important Notice :

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