How Much Pressure Should Be Applied When Tamping Espresso? Espresso Extraction Ratio, Grind Size, and Parameters

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In the process of extracting espresso, we all perform an important procedure - tamping. So what exactly is the purpose of tamping?

Tamping refers to using a tamper to compact the coffee grounds in the portafilter, forming a puck-like shape. Is this tamping step necessary? And what is the purpose of tamping? FrontStreet Coffee will first demonstrate through a comparative brewing experiment.

FrontStreet Coffee extracted two sets of espresso, with the only difference being whether tamping was performed. One group was tamped as the control group, while the other was not tamped as the experimental group. All other parameters were kept the same. Coffee grounds weighed 20 grams, extracting 40 grams of coffee liquid.

The normally tamped espresso extracted normally with a stable flow rate, with a final extraction time of 27 seconds. The non-tamped group immediately ejected coffee liquid at the beginning of extraction, with an overall fast flow rate, watery consistency, and unstable flow. The entire extraction time was 8 seconds faster compared to the normal control group, and the taste was also more watery and bland compared to the normal group.

The Purpose of Tamping

In the process of making espresso, the first step is grinding coffee beans and evenly distributing them into the portafilter. The purpose of distribution is to evenly spread the loose coffee grounds in the portafilter. At this point, the coffee grounds are still in a loose state, with gaps of varying sizes between the coffee particles. If extraction is performed without tamping at this time, under the high pressure of 9 bars from the coffee machine, water will quickly pass through the coffee grounds. Because of the loose state, the coffee grounds will be directly scattered by the water flow, and the water will seek easy paths to flow through. These easily passing parts will be over-extracted, commonly known as channeling.

So we know that the purpose of tamping coffee grounds is to compact them, reduce the gaps between coffee particles, and provide enough resistance against the water flow during extraction, allowing the water to evenly extract the coffee grounds.

What to Pay Attention to When Tamping

So what should you pay attention to when tamping?

First, you should choose a tamper that matches the diameter of your portafilter. A mismatched diameter might lead to inability to press down or gaps with the portafilter edge, making tamping meaningless.

Tamping posture varies from person to person, but the general principle is that the tamper handle should be perpendicular to the portafilter, and the force applied to the tamper should be evenly distributed. Press down on the portafilter to make the coffee layer smooth and even. If the force is uneven and causes tilting, the high-temperature, high-pressure hot water from the group head will seek the path of least resistance, causing uneven extraction.

The tamping pressure also varies from person to person. Around 2000, when La Marzocco was designing the Swift automatic filling device, they conducted extraction experiments with forces ranging from 2 pounds to 30 pounds (approximately 15kg). They found that regardless of how much force was applied, almost no force was transmitted to the bottom of the puck. Therefore, the tamping pressure has little impact on espresso extraction, as long as the grounds are compacted firmly. You can also "feel" the compression changes of the puck during tamping. There's no need to press too tightly - if the puck is compacted too tightly, its resistance becomes too strong, and the time required for water to penetrate the puck becomes longer, resulting in coffee that is thick and bitter in taste.

After tamping, there may be small amounts of fine powder particles sticking to the tamper or the surface of the portafilter. At this time, you just need to gently rotate the tamper before removing it.

FrontStreet Coffee's Espresso Beans

What coffee beans does FrontStreet Coffee use to make espresso?

Those who have visited FrontStreet Coffee's stores to drink espresso-based coffee often ask what coffee beans are used, finding them quite special! FrontStreet Coffee uses its own blended Sunflower Warm Sunshine Blend coffee beans. This consists of 70% Honduras Sherry coffee beans and 30% Ethiopia Yirgacheffe Red Cherry Project G1. Both of these coffee beans are of the highest quality grade in their respective coffee-producing countries. The 70% Honduras Sherry barrel-aged coffee beans provide flavor and body to this espresso blend, while the 30% natural processed Yirgacheffe contributes more aroma and acidity.

FrontStreet Coffee's Espresso Extraction Parameters

• Grinder: Feima 900N
• Grind size: 1.6
• Pressure: 9 bar±2
• Temperature: 90.5~96°C
• Time: 25~30 s
• Dose: 20g (double shot espresso)
• Yield: 40ml

Espresso Flavor Profile

Espresso flavor: Smooth mouthfeel, medium body, with distinct fruit acidity upon entry accompanied by subtle berry aromas, whiskey fragrance, rich chocolate flavor, and a noticeable aftertaste.

For more specialty coffee beans, please add FrontStreet Coffee on private WeChat: ID: kaixinguoguo0925

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473