Achieving the Perfect Sweet Spot in your Espresso: Striking the Right Balance Between Over and Under Extraction

The art of finding the balance in espresso shot extraction

This post is a follow on from my previous post about how to get the best from your commercial coffee blend. This can only be achieved by ensuring your espresso extraction is on point, so lets delve deeper into what that actually means...

Achieving the perfect espresso shot is a fine balance of science and art. One of the key elements in this process is extraction—the method by which water passes through the coffee grounds to pull out flavours, oils, and aromas. However, if this process isn’t just right, you can end up with either over-extracted or under-extracted espresso, leading to less-than-ideal flavors in your cup.

In this blog, we’ll break down what happens when espresso is over-extracted or under-extracted, what causes these issues, and how to fix them for a well-balanced and flavorful shot.

What is Extraction in Espresso?

Extraction refers to how much of the coffee’s soluble compounds are dissolved into the water during brewing. The goal is to extract just the right amount—typically around 18-22% of the coffee’s mass—to achieve a balanced shot with rich flavors, pleasant acidity, and a smooth finish.

When the extraction process goes wrong, your espresso will either be over-extracted (too much is pulled out) or under-extracted (too little is pulled out).

What is Over-Extraction?

Over-extraction occurs when too much of the coffee’s soluble compounds are pulled out, leading to a bitter and unpleasant taste. This happens because the water extracts too many bitter compounds after it has already drawn out the desirable flavours.

Signs of Over-Extracted Espresso:

• Bitter, harsh flavours

• Dry, astringent aftertaste

• Dark, almost burnt notes

• Thin, weak body with little crema

Causes of Over-Extraction & How to Fix It:

1. Grind Too Fine: A very fine grind increases surface area and slows down water flow, leading to over-extraction.

• Fix: Use a slightly coarser grind.

2. Brew Time Too Long: If water takes too long to pass through the coffee puck, it extracts too many compounds.

• Fix: Aim for a shot time of 25-30 seconds for a double espresso.

3. Too Much Coffee in the Portafilter: Overloading the portafilter can slow down extraction and overwork the coffee.

• Fix: Stick to a standard dose (e.g., 18g for a double shot).

4. Water Temperature Too High: Water that’s too hot (above 96°C/205°F) can extract unwanted bitter flavors.

• Fix: Ensure your machine is using water in the ideal range (90-96°C / 195- 205°F).

What is Under-Extraction?

Under-extraction happens when too few of the coffee’s soluble compounds are dissolved, resulting in a sour and weak espresso. This is because the first compounds to be extracted are acidic and fruity, but without enough extraction time, the sweetness and body never fully develop.

Signs of Under-Extracted Espresso:

• Sour, sharp acidity

• Lack of sweetness and depth

• Weak or watery body

• Pale crema with large bubbles

Causes of Under-Extraction & How to Fix It:

1. Grind Too Coarse: A coarse grind allows water to pass too quickly, leading to under-extraction.

• Fix: Use a finer grind to slow extraction.

2. Brew Time Too Short: If the shot pulls in less than 20 seconds, it won’t extract enough flavors.

• Fix: Adjust grind size and tamping pressure to aim for 25-30 seconds.

3. Too Little Coffee in the Portafilter: If there’s not enough coffee, water passes through too fast without fully extracting.

• Fix: Use the proper dose (e.g., 18g for a double shot).

4. Water Temperature Too Low: Water below 90°C (195°F) won’t dissolve enough coffee solids, leading to weak and sour flavors.

• Fix: Make sure your machine’s temperature is in the correct range.

Finding the Perfect Balance

The key to a well-extracted espresso is balance—a harmony between acidity, sweetness, and bitterness. A properly extracted shot will have:

• A rich and smooth body

• A pleasant, rounded acidity

• A balance of sweetness and bitterness

• A golden, even crema

By fine-tuning your grind size, brew time, dose, and temperature, you can consistently achieve a great-tasting espresso.

Final Thoughts

Understanding the difference between over and under-extraction is crucial for making consistently great espresso. If your shots taste bitter and harsh, you may be over-extracting. If they taste sour and weak, under-extraction is likely the issue. With practice and small adjustments, you’ll be able to dial in the perfect espresso shot every time.

Are you struggling with extraction issues? Let us know in the comments, and we’ll help troubleshoot your espresso game!