In the coffee industry, mastering espresso is essential for any barista, and to achieve this, there are key parameters every barista should know. These parameters are crucial for controlling and refining the espresso-making process. Below, you’ll find a rundown of some of the most commonly discussed factors, along with the specific terms used in the industry.

Key Parameters Every Barista Should Know

1. Dose (Dry Dose / Input)

• Definition: The weight of the dry coffee grounds used to brew the espresso.
• Measurement: Grams (g).
• Typical Range: Usually between 16-22 grams, depending on the desired strength and style.

2. Yield (Brewed Coffee / Output)

• Definition: The final weight of the liquid espresso extracted, also referred to as the “extraction weight.”
• Measurement: Grams (g).
• Typical Range: For a standard double espresso, a yield might range from 30 to 50 grams, but this can vary widely depending on the recipe.

3. Brew Ratio (Dose-to-Yield Ratio)

• Definition: The ratio of the dose (coffee grounds) to the yield (extracted espresso). It defines the strength and concentration of the espresso.
• Formula: Brew Ratio = Yield (g) / Dose (g).
• Typical Ratios:
  • Ristretto: 1:1 to 1:1.5 – more concentrated, intense flavour used for medium/dark blends.
  • Standard Espresso: 1:2 – balanced flavour.
  • Lungo: 1:3 to 1:4 – longer extraction, balanced lighter flavour commonly used with a light/medium roast.

4. Extraction Time (Brew Time / Contact Time)

• Definition: The time it takes for the espresso to be extracted from start to finish.
• Measurement: Seconds (s).
• Typical Range: Arguably nowadays there is no typical range as I have extracted beautiful coffee at 12 seconds and also beyond 30 seconds. Usually it is between 25-35 seconds, though it can vary depending on the coffee and desired flavor profile.
• Relevance: This impacts the flavour development; shorter times may lead to under-extraction (sour notes), and longer times may lead to over-extraction (bitter notes).

5. Grind Size

• Definition: The fineness or coarseness of the coffee grounds, which affects how water passes through them during extraction.
• Measurement: No standard measurement; described as fine, medium-fine, or coarse in espresso contexts.
• Relevance: A finer grind leads to slower water flow and longer extraction times, while a coarser grind speeds up the flow and shortens extraction time.

6. TDS (Total Dissolved Solids)

• Definition: The concentration of dissolved coffee solids in the extracted espresso.
• Measurement: Percentage (%).
• Relevance: Indicates the strength of the coffee; measured with a refractometer. A higher TDS means a more concentrated espresso.

7. Extraction Yield (Percentage Extraction)

• Definition: The percentage of the coffee grounds that have been dissolved into the water during brewing.
• Measurement: Percentage (%).
• Relevance: Commonly ranges between 18-22%. If it’s too low, the coffee may be under-extracted (sour); if too high, it may be over-extracted (bitter).
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8. Extraction Time & Temperature

• Brew Temperature: The temperature of the water passing through the coffee puck, typically between 90-96°C (194-205°F).
• Brew Pressure: The pressure applied to push water through the grounds, typically around 9 bars (though some recipes may vary).

Mastering espresso requires a deep understanding of these key parameters that every barista should know, from the dose to extraction time. I caution against following conventional wisdom and out the importance of Evolving Espresso Brewing Techniques when it comes to extraction. Coffee brewing, especially espresso, has evolved significantly over the years. Traditional parameters—such as a 1:2 brew ratio, 25-30 second extraction time, and a focus on balanced flavour—are now being challenged and adapted, thanks to a deeper understanding of coffee chemistry, shifting consumer preferences, and new technology. While these parameters play a significant role in recipes, dialing in processes, and cupping notes, they are no longer the only path to achieving the desired espresso flavour profile and balance.

Experimentation leads to new discoveries, so don’t be afraid to think outside the box and explore different approaches and technologies.