Espresso Extraction Parameters Guide: How Much Coffee, Time, and Temperature for Perfect Espresso

Introduction

Just like pour-over coffee, extraction parameters significantly influence the flavor expression of espresso. Particularly with espresso, slight deviations in extraction parameters such as coffee grounds quantity, extraction time, and pressure can amplify certain flavors in the espresso, potentially leading to sharp acidity or bitterness. Therefore, understanding espresso extraction parameters is crucial! So what parameters should we pay attention to when extracting espresso?

Coffee Grounds Quantity

The amount of coffee grounds for espresso extraction is determined by the portafilter basket capacity. Currently, common portafilter basket capacities on the market include 7g, 9g (single shot), and 16g, 18g, 20g, 22g (double shot). The basket specification equals the recommended loading capacity, with a tolerance of ±1g for maximum and minimum amounts. For example, FrontStreet Coffee now uses a 20g basket with a minimum loading of 19g and a maximum of 21g.

Why is the tolerance ±1g? Because the amount of grounds affects the density of the coffee puck. When applying the same tamping pressure, insufficient grounds will make the puck density higher (looser), allowing water to pass through more quickly, resulting in under-extraction; excessive grounds will make the puck density lower (denser), slowing water flow and leading to over-extraction.

Grounds-to-Liquid Ratio

Unlike the commonly used grounds-to-water ratio in pour-over coffee, where a fixed amount of water is used for brewing, it's impossible to calculate how much water is used in espresso extraction. Therefore, we use the grounds-to-liquid ratio, which is the ratio of coffee grounds to coffee liquid. This ratio is influenced by two factors: the amount of coffee grounds and the amount of water injected. A lower ratio will result in a very rich, heavy-bodied coffee that can easily develop bitterness from over-extraction; while a higher ratio will produce a flat, dull coffee with sharp acidity from under-extraction.

When people first began to recognize the importance of the grounds-to-liquid ratio, they used X grams of grounds: X ml of coffee liquid, where the former is a weight unit and the latter is a volume unit. Due to different densities, these two units cannot be equated. Particularly in espresso extraction, there is a crema layer, which varies with the freshness of coffee beans or the degree of roasting. When calculated using volume units, the crema layer is often included, making this measurement method result in inconsistent production.

To ensure consistent espresso production, the grounds-to-liquid-weight ratio emerged, which is X grams of grounds: X grams of coffee liquid, measured by weighing the extracted coffee liquid with an electronic scale. Generally, the recommended grounds-to-liquid ratio for extraction is between 1:1.5 and 1:2.5, with 1:2 being commonly used. For example, FrontStreet Coffee's daily production uses 20g of coffee grounds to extract 40g of coffee liquid.

Extraction Pressure

Generally, semi-automatic espresso machines have an extraction pressure of around 9 bar, which is preset by the machine itself. When the extraction pressure becomes problematic, it's necessary to contact a professional for inspection. Of course, as more people research coffee, the pressure of around 9 bar can no longer satisfy everyone's "research needs." Now, some machines on the market offer variable pressure extraction functions, allowing for increased or decreased extraction pressure based on coffee bean characteristics, thereby changing the extraction efficiency.

Extraction Temperature

The water temperature for espresso extraction is generally between 90°C-94°C, which is also preset by the machine (of course, some machines do have adjustable extraction temperature functions). Water temperature that is too high can lead to over-extraction, causing bitterness in the coffee; water temperature that is too low can result in under-extraction, causing sharp acidity. If the extraction water temperature exceeds or falls below the set extraction temperature, it's necessary to contact a professional for inspection.

Extraction Time

Extraction time refers to the entire duration from attaching the portafilter and pressing the extraction button to the completion of extraction. FrontStreet Coffee suggests an extraction time of approximately 18-23 seconds for single-shot espresso and 25-30 seconds for double-shot espresso. When we notice abnormal extraction times, the first things we should check are the amount of coffee grounds and the grind size.

Excessive coffee grounds result in lower puck density, extending water flow time; insufficient coffee grounds lead to higher puck density, shortening water flow time. Grind size that is too coarse creates larger channels between coffee particles, increasing water flow speed; grind size that is too fine creates smaller channels between particles, slowing water flow speed.

Extraction Flow Rate

The flow rate is the speed at which coffee liquid flows down. Normally, espresso should begin dripping the first drop of coffee liquid around five seconds after pressing the extraction button, with a relatively uniform subsequent flow rate.

If many seconds pass without the first drop of coffee liquid, it means the puck density is too low; if the first drop begins within two to three seconds of pressing the extraction button, it means the puck density is too high, creating more channeling effects for water flow.

Important Notice :

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FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

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