You Are Making These 5 Coffee Extraction Mistakes

Published July 26, 2024

Introduction

Making coffee is an art form as well as a science. Getting the optimal extraction plays a critical role in what experience you will ultimately have with that coffee bean. If your coffee is not tasting as nice as it could, you are likely making some very common mistakes when brewing coffee with your home coffee machine. Whether you are a seasoned barista, or a home taught barista, this guide will help shine some light on rooms for improvement in your process and get you on the road for a fantastic coffee journey ahead.

1. Using the Wrong Grind Size

A typical mistake that beginners will make is grinding the beans too fine or too course. This leads to clumping in the group head or uneven extractions causing water to be either too restricted or too free to pass through the puck. Inevitably, this causes an extremely unpleasent tasting brew with sour or bitter notes.

To resolve this issue there are a few things to consider. At the beginning of any new coffee bean purchase, you should first experiment with what grind size works best with that coffee bean on your machine. This means that you should have multiple attempts of extracting coffee with each grind size, adjusting as you get closer to your target and taking note of the extraction time, quantity of output and the taste.

2. Incorrect Brewing Time

Typically your home machine will be preset with its own brewing timer. This should be adjusted to suit your targetted coffee extraction. Using the programmable buttons on your machine, you have many options to create various types of espresso. Too long or too short of a brew time will create an extremely bitter or acidic tasting coffee.

Too long brew time: Creates an over-extracted and bitter coffee.
Too short brew time: Creates an under-extracted and weak coffee.

Your typical extraction for common drinks such as lattes or cappucinos should be targetting around the 28-30 second mark, for a 1:2 ratio yield.
For example, if you are using 18g of ground coffee, you should target a 36g of coffee yield between 28-30 seconds.

Pro tip: A good way to identify overextractions is if your puck is watery when you remove the portafilter from the group head.

3. Tamping Unevenly and Too Hard

Tamping your coffee correctly is essential to optimising the flow of water through the puck. A common issue with this is slanted tamping and tamping too hard.

When a coffee puck is tamped unevenly, e.g. slightly leaning to left or right, it causes the water to flow toward the elevated side first, leading to an uneven extraction and bitter flavours in your cup.

If the puck is tamped using too much pressure, it will compress the coffee inside the portafilter to a point where water will struggle to get through the bed and ultimately cause channeling to occur. This will lead to an over-extracted and bitter coffee.

To tamp correctly, ensure that you are using a flat surface, preferably a rubber tamping mat. Ensure the ground coffee is evenly distributed across the bed and angle your arm at 90 degrees, applying pressure from your elbow to ensure it is tamped perfectly straight. Wipe off any excess coffee on the sides and you’re good to go!

4. Using Old or Stale Coffee Beans

Using old or stale coffee beans significantly decreases the quality of output in your cup. Coffee is subject to many external factors that have an impact on the taste. For instance, coffee older than a month wont taste the same as fresh coffee that has just finished the de-gassing process. Coffee that has not been properly stored in an air tight container will go stale extremely quickly.

For the best results, always purchase coffee in smaller quantities and always buy freshly roasted coffee. If you want the ultimate experience, I highly reccomend using specialty coffee beans. These are picture perfect beans that will grant you the ultimate coffee tasting experience.

At The Coffee Conservatory, we roast fresh multiple times per week and ensure only the freshest specialty coffee ends up in your cup. We believe that this has everything to do with the spectacular experience our customers have with our beans.

5. Poor Equipment Maintenance

Lastly, a commonly neglected step in the process of any coffee connoisseur is equipment maintenance. Most people forget that without taking care of your machine, it wont take care of you!

It is absolutely essential to perform simple cleanliness techniques after each use of your machine to ensure its longevity and enable it to deliver high quality results for you, every single time. Here are some techniques you may want to adopt in your current process.

1. Perform a flush prior to each use of your machine. Ideally you want to keep the portafilter in the group head to warm it up.
2. After each extraction, immediately perform a flush to clean the inside of the machine of any coffee residue which can become corrosive.
3. Ensure the water tank is kept clean and topped up. Replace the water as required and stay on top of filter changes every 2 months.
4. Before and after steaming milk, ensure that the steam wand is properly purged to remove any excess milk stuck inside the wand.
5. From time to time, your machine will require a descale. This is a thorough internal cleaning process. Most machines will let you know when the time has come for this by flashing the descale option on the screen. Ensure you are properly equipped with descaling liquid or tablets for this.
6. Every few months, it is good practice to take the hopper completely off your machine and thoroughly clean the inside. Unground coffee beans can get stuck in the mechanisms and cause issues with grinds in the future.
7. Always ensure that your machine is kept clean and tidy, and the drip tray is regularly emptied.

Conclusion

Perfecting your coffee involves paying attention to all of these details. By perfecting your grind size, measuring your coffee and water accurately, monitoring your brewing time, and keeping your equipment clean, you’ll be well on your way to enjoying a consistently great cup of coffee. Happy brewing!