When brewing a new single-origin espresso, you might find that the extraction isn’t quite right. Should you tweak the dose, grind size, water temperature, or perhaps look at factors like pressure, water quality, or even pre-infusion? Espresso extraction plays a pivotal role in creating flavorful coffee, ensuring customer satisfaction, and driving sales for coffee shops. However, troubleshooting extraction and developing new recipes can often feel like solving a puzzle.
Understanding Espresso Extraction
Espresso extraction refers to the process of pulling flavors and compounds from ground coffee using pressurized water. Achieving the right balance ensures a cup that’s neither bitter nor weak. To understand how to optimize it, I spoke with Peter Garcia, Managing Director of VA Machinery, who shed light on key variables affecting espresso extraction.
Peter is also hosting The Victoria Arduino Experience at Caffè Culture 2019 in London, an event showcasing the science behind espresso extraction. Attendees will compete to identify brewing temperatures, water types, and grind speeds, learning how each factor influences flavor.
Building the Perfect Espresso Recipe
Creating a recipe begins with a solid starting point. Peter recommends starting with 18g of coffee, yielding 36g of espresso, extracted at 9 bar in 30 seconds.
“You can consult the roastery or coffee shop where you purchased the coffee for a recommended recipe,” he advises. “However, treat it as a baseline, not a definitive answer.” Factors like equipment, water quality, and personal preference all impact the extraction and taste.
Once you’ve established a base recipe, begin experimenting in a controlled way. Adjust one variable at a time and taste the results.
“If the coffee tastes sour and under-extracted, try lowering the dose or extending the beverage yield,” Peter suggests.
Considering Coffee Preparation
Think about how the espresso will be served. “In many cafés, milk-based drinks like cappuccinos and lattes account for 75–90% of espresso usage,” says Peter. A highly extracted espresso with low TDS (Total Dissolved Solids) might taste amazing on its own but lose complexity when paired with milk.
For black coffee enthusiasts, experimenting with water temperature and extraction time can help highlight the unique flavors of single-origin beans.
Key Factors That Influence Espresso Extraction
To optimize espresso extraction, it’s essential to understand and adjust the following variables:
1. Dosing
Dosing refers to the amount of coffee used in the portafilter. It significantly affects the strength and balance of the espresso. Aim for a TDS of 7–12% and an extraction yield of 18–22%, widely considered ideal.
Higher doses often result in a heavier body and richer flavors, while lower doses with a longer yield can emphasize sweetness and acidity.
2. Water Temperature
Temperature affects how flavors are extracted.
- For dark roasts, use lower temperatures to avoid harsh, burnt flavors.
- For light-medium roasts, higher temperatures help extract pleasant acidity and aromatics.
Acidic compounds extract first, followed by sweeter ones, and finally bitter compounds. Adjusting temperature allows you to control which flavors dominate.
3. Grind Size
A finer grind increases the surface area of the coffee, enhancing contact with water and promoting sweetness and body. However, grinding too fine can lead to bitterness. Conversely, a coarser grind highlights acidity but may result in under-extraction.
4. Pressure & Pre-Infusion
Espresso machines are typically set to 9 bar, but pressure can range from 2–16 bar depending on the pump. Lower pressures provide a gentler extraction and can reduce channelling, which occurs when water flows unevenly through the coffee puck.
Pre-infusion, where water is introduced at low pressure before full extraction, also helps minimize channelling and promotes even flavor extraction.
5. Extraction Time
While espresso can technically be extracted in 10 seconds, optimal results often require 20–30 seconds to balance acidity, sweetness, and bitterness. Faster extractions tend to emphasize acidity, while slower extractions enhance sweetness and body.
6. Water Quality
Water composition directly impacts both espresso flavor and machine performance.
- Soft water can result in sharp acidity and lack of body.
- Hard water often leads to flat, chalky-tasting espresso.
Filtered water with balanced calcium and magnesium levels is key to consistent results.
Final Thoughts
Perfecting espresso extraction requires attention to detail and experimentation. By understanding variables like dosing, water temperature, and grind size, you can adjust recipes to bring out the best in each coffee.
Remember to consider how the espresso will be consumed, whether as a standalone drink or in milk-based beverages. A logical, step-by-step approach will not only reduce wasted coffee but also help you craft a recipe that truly elevates the coffee’s natural characteristics.
Focus on fine-tuning your espresso extraction, and you’ll unlock a world of flavors in every cup
