You know the feeling: you walk into a coffee shop and order an espresso, only to find that it tastes like dirt. We've all been there. But what exactly happened? Why did your coffee not taste good? If you guessed "coffee extraction," then you're right! Understanding how coffee extraction works is essential for getting the perfect brew at home or in your cafe. Coffee extraction refers to the process of extracting flavour from roasted beans by forcing hot water through them, which can be done in three ways: grinding, brewing and ratio. The goal is always a high-quality cup of joe with a balanced taste profile--not too bitter, not too sour...but just right!
What is coffee extraction?
Put it simply, extraction is everything that the water takes from the coffee. It is arguably the most important and least understood aspect of coffee brewing. When you mix coffee and hot water, a series of chemical reactions occur that end up with the delicious brown liquid we all know and love. What dissolves a lot of the coffee flavours that end up in your cup.
Roasted coffee beans are around 30% soluble in water - which means that when brewing coffee you can extract less than 1/3 of its components. Why not crush the beans extremely fine until it reaches a powder texture and soak it in water to extract more? Well, that would result in a terribly bitter cup that is not enjoyable at all. Not all coffee flavours taste good and controlling how much you extract makes the difference between a good cup and a great cup.
Coffee extraction can generally be described as either being under-extracted or over-extracted: too much water will result in an under-extraction, while too little water will result in an over-extraction.
What is under-extracted coffee
Under-extraction occurs when you haven’t taken enough flavour out of the coffee grinds when brewing. There’s still a lot left behind that could balance out less enjoyable elements such as sourness, saltiness, lack of sweetness, and short finish. The resulting coffee can be unbalanced and one-dimensional.
If you're tasting these undesirable flavours chances are your barista under-extracted your espresso shot. When buying specialty coffee from your favourite Toronto coffee roaster or online coffee store you'd want to avoid under-extracting in order to make the most of your home-brewed coffee.
What is over-extracted coffee
Over-extraction describes the opposite problem: you've taken too much flavour out of the coffee grinds, resulting in a bitter, drying and hollow brew that's difficult to enjoy. Over-extracted espresso and other brewing methods also present no pleasant aftertaste.
If your barista over-extracted your shot they most likely went over the usual brew time range although other factors influence and can result in over-extracted coffee. The quality of the beans, coffee to water ratio, coffee grind size, and coffee brewing time are some we'll cover. But first, let's talk about coffee strength.
Understanding coffee strength
It's common for people to describe their coffee as strong or weak. But what exactly is coffee strength? Contrary to popular belief, strength does not refer to how much caffeine you get in your cup. It actually pertains to the ratio of coffee to water in your brew.
The more ground coffee you use, the stronger your cup will be. This is a general rule that can also apply when making drip or filtered coffee with a French Press or Chemex. Using less ground coffee results in a weaker quality and using more produces an over-extracted flavour profile that tastes bitter and lacks sweetness from sugars such as sucrose and glucose present inside roasted beans' cells walls.
Coffee strength is closely related to coffee extraction. If you decrease the amount of water you use to improve the flavour of your coffee, it becomes more difficult for the water to extract all of the essential tastes.
Now that we've covered what extraction is and how it affects flavour...let's talk about why adjusting grind size, brewing time, and ratios are important to get just right!
Grind size is directly related to how water will extract flavours from your coffee. If you use coarse ground coffee, the water will take longer to extract all of its flavours, and you risk resulting in an under-extracted espresso. Finer grounds will extract faster, presenting you the risk of resulting in over-extracted coffee that tastes bitter.
The best way to avoid an under or over-extraction when using coffee grinds is by adjusting the coarseness of your ground beans: if you're aiming at a milder flavour use coarser grounds; for a stronger taste, finer grounds will do the trick!
Large coffee chains or grocery store coffee usually has a one-size-fits-all approach to grind size (yikes!). That's why it is important to grind your own coffee at home if you have access to a grinder or shop at reputable local coffee roasters that can professionally grind your coffee for your preferred brewing method.
Once you find the best grind size for your personal taste, it's time to adjust your coffee to water ratio.
Coffee to water ratio
The coffee to water ratio refers to the amount of coffee and water you choose for a single cup or batch. Too much or too little can affect your brew's strength and flavour profile!
The most commonly recommended ratio by coffee professionals is 16:1, water grams to coffee grams. That means if you’re brewing a standard 8oz cup which is around 240ml you should use 15g of ground coffee to be in the good brew ballpark.
When choosing how much coffee and water to use consider all these factors as well as personal taste: some people like their cups stronger while others prefer weaker ones; if you're unsure about where to start you can check the coffee to water ratio guide. All our coffees have recommended ratios you can use as starting points to find what works best for your palate.
Coffee brew time is the amount of time the water takes to pass through your ground coffee. The longer it stays in contact, and more surface area is exposed (remember: finer grounds will increase exposure) you risk over-extracting your batch resulting in a bitter taste.
You can adjust your contact time in a variety of ways, but the two most basic are as follows: your recipe and your grind size, which we've already discussed. Because the more coffee you have in your filter, the longer it will take your water to go through and out of it, extracting coffee material along the way. Obviously, less coffee implies that water can move through the grounds faster, resulting in less extraction.
Now that you understand more about coffee extraction, brush up your tasting skills with our guide to tasting coffee like a barista and let's get brewing!