difference between strength and extraction

One of the best things about making coffee is that you can do it in the comfort of your own home. But, brewing your own coffee can be a real challenge, particularly if you are new to black coffee as I was.

While there are plenty of pod espresso or drip coffee machines that will produce a drinkable cup of coffee, if you don’t want to settle, take the time to really understand coffee and learn how to make the best possible coffee suited exactly to you taste.  

Before we get to that point though, there are some general brewing principles you should explore.

This guide will explain how coffee brewing works from start to finish with fundamental extraction principles and the tastes that you should familiarize yourself with to better identify under and over extracted coffee. 

Let’s dive in.

Extraction v. Strength - What’s the difference?

We’ve all been there. You take the time to buy the best beans from your local roaster who romances you with talk of chocolate undertones and a creamy mouthfeel. You take the time to brew it carefully not understanding why the first sip tastes no better than the instant stuff you used to drink.

If you are new to coffee-making, it may be hard to discern whether your coffee is simply too strong or if there are some extraction issues going on.

There is actually a lot of science behind the brewing process, so let’s break it down into smaller parts, starting with strength.

Among the many things you will eventually be able to manipulate in your brewing process, coffee strength is fortunately both the easiest element to recognize and the quickest to correct. 

Here’s the secret.

Weak coffee will have a tea-like consistency and will be much more watery and transparent, where strong coffee can be muddy and feel thick in the mouth. If your brew is too weak you will know to add more coffee next time. If it’s too strong, add some hot water!

While this may sound simple enough, strength actually goes much deeper than just the water volume in the cup.

Strength = the Amount of Dissolved Compound in the Brewed Cup

It is a common mistake that when people talk or hear about the strength of coffee, they think it is referring to the caffeine level of the drink. But, when we talk about strength we are really talking about the ratio of ground coffee to the amount of water it is being brewed with.

Let’s take two common brew types and compare them.

Espresso

Espresso is a highly concentrated form of coffee. In fact, it is made up of “7-12% dissolved compounds to 88-93% water.”

Filtered coffee

Compared to espresso, filtered coffee is far less concentrated at roughly “1-2% dissolved coffee compounds to 98-99% water.”

When we talk about coffee, strength is simply the ratio of ground coffee to water.

If you don’t use enough water, your coffee will feel swampy in your mouth and the flavour will be extremely overpowering. If you use too much water, the coffee will feel exactly that, watery.


There is a Relationship between Strength and Extraction

While it is easy to discuss strength and extraction separately, don’t underestimate their relationship. The amount of water you use to produce your desired cup will determine how easily your brew will ‘extract’ the flavors of your coffee. The less water you use the harder it is to extract the best parts of the grind and the less likely you’ll be able taste the distinct taste profile of your chosen roast. . 

While extraction is a little more difficult to understand than strength, there are some tips you can put into practice now to turn your tastebuds into extraction detectives.

Understanding Extraction

Fortunately, no matter your chosen method of preparing coffee, the general steps remain the same. Your chosen roasted beans are ground and water is added. As soon as the water is filtered through the ground coffee, the flavour compounds begin to be extracted. No matter what brewing method you use, the flavour compounds will always extract in the following order producing the taste qualities we’ll explore in more depth later.

Fats and Acids

Flavour profile: Sour/Oily

When the water that you pour into your grounds begins to pass through as coffee it is beginning the process of extraction. Acids and fats are the first compounds to be extracted from the coffee. It is these acids that provide sour undertones. Water is easily able to dissolve these simple molecular compounds and as a result, will always extract these first. It is these oils and fats that add the body to the cup but if the brewing process is stopped too soon, or the coffee is under-extracted, it is these sour flavours that will overpower the taste of your cup.  

Sugars

Flavour profile: Sweet/Syrupy

The next stage is the extraction of those rich sugars. Even the most simple of sugar structures have more of a molecular complexity than those of acids. The water needs more time to pass through this stage to extract more than just the initial fats which can leave coffee sour. These sugars are what gives a well-extracted coffee that characteristic sweetness.

Plant Fibres

Flavour profile: Bitter/Thin

The final stage of the extraction process involves the breakdown of the plant fibers that hold the coffee together. Just like any other plant material, think of those strings in celery, these strands can taste bitter and a bit dry and chalky in the mouth. This bitterness is characteristic of an over-extracted coffee and is also referred to as a burnt flavor. 


Extraction is the most essential yet most difficult part of the coffee brewing process

Let’s take a look at some of the different tastes you will experience across the varied landscape of extraction.

 

Tongue position and taste

Though the tongue map you’ll see on many coffee blogs has actually been debunked, taste and extraction are still very closely related as you can see in the above flavor map. Here are some flavor profiles to hunt for in your next cup:

Under-extraction

If your brew is under-extracted you should be able to detect sourness, a really quick finish, saltiness or notice that it is lacking any sweetness. This is because the fats and acids are the first compounds to be extracted and will be the reigning flavor if your extraction process ends too quickly.

Over-extraction

Over extraction can be characterized by bitterness and a severeness in the taste. It may even feel dry to the tongue or seem burnt. This is because the plant materials and their associated flavors will linger when the extraction is allowed to run on too long.

Ideal Extraction

You'll know you've found the extraction sweet spot when, you guessed it, it's slightly sweet, smooth in your mouth and leaves no undesirable after taste. The extraction time will have moved the process through the initial sour notes of acids and fats and stopped before reaching the bitterness of overcooked plant matter.


Manipulating Extraction: Brew Ratio, Time, Grind and Temperature

Now that you understand how extraction works and the various taste profiles that appear during different stages of the process, let’s take a look at how you can manipulate your brew at home to improve the texture, taste and strength.

When it comes to making coffee, regardless of your brewing method, there are only four variables that you can directly influence; your brew ratio, how long your brew for, the time you brew for and the temperature of the water that you are using.

Pro-Tip: As with any experiment, only ever alter one variable at a time, keeping all else equal. This way you can clearly see the results of any manipulation in isolation rather than messing with everything at once and not really knowing which change most impacted your result.

Extraction Variable 1: Exploring Brew Ratio

As we mentioned above, extraction is simply the process that happens when you add hot water to ground coffee. But how much water vs. how much coffee should you use for the optimum brew?

Here at Coffee Geek, our general guide for starting out is to use the 1:17 ratio.

But what does this actually mean?

A 1:17 ratio simply states that for every 1 gram of coffee you use, you will need to use 17 grams of water. We have found that this ratio is optimal for both manual and automatic pour over methods.

 

To explore brew ratio at home you’ll need to invest in a set of scales made especially for coffee. We recommend the heavy-duty, precise and inexpensive………...

For those without a scale, you can just as easily use tablespoons and ounces to measure your coffee and water use. Outlined perfectly by Counter Culture Coffee, simply follow the ratio of 1:4. “1 tablespoon of coffee for every 4 ounces of water.”

When you feel confident enough to start manipulating your brew time, alter your ratio in small amounts and note down on paper or in a coffee tasting app such as Angel’s Cup any differences in flavors and aromas.

Maybe even try starting with a 1:15 ratio and then alter it up or down based on your taste.

Don’t be afraid to get a little crazy with it. You might enjoy it and if not you will at least learn a lot about your personal tastes and how mixing your ingredients at different rations can yield a whole variety of flavours.

Extraction Variable 2: Playing with Grind Size

While brew ratio is one of the easier concepts to get your head around, grind size is one of the most difficult. ‘Why?’ you might ask. The are actually two parts to the answer.

The first part has to do with the ground material. When you grind anything, including coffee, there is no way to ensure that all of the particles grind at the same rate or end up the same size. We can’t quantify grind with any kind of number or ratio as each ground piece of coffee bean is so small to measure each individually.

The second part to this answer has a lot to do with the grinder itself. Across the variety of grinders available for at-home and professional use, there is no way to ensure that the grinders all grind the same way. Even within the same brands, not all machines are calibrated the same way, making it impossible to establish a numerical standard or system.

For this reason we most often characterise grind by the setting on your grinder and the look and feel of the grounds. Could you tell your coffee grind size just by looking at it?

Here are some clues to help you:

A Very Fine (Espresso) grind can be likened to the look and feel of refined sugar.

Fine is almost the equivalent of ground table salt.

Medium is closer to sand and can even feel quite gritty rather than soft.

Coarse would be closer to a cracked pepper type look and feel.

So what is coarseness exactly and how does it impact your brew?

Coarseness refers to the ease or difficulty for water to pass between the ground coffee particles. A finer grind makes it more difficult for the water to pass through and generally speaking can result in a stronger brew. This, however, is also impacted by the amount of time you brew the coffee for. Usually, a finer grind will require less time to extract the best brew, where a coarse grind, which allows the water to pass more quickly, may need longer to really extract all the particular roast has to offer.

Investing in a good grinder will be extremely helpful in your journey to better understand grind size. Get used to using it. Explore the tactile joy of feeling ground coffee between your fingers. Once you get to know your grinder and the different textures it can produce you’ll be better able to dial in your brew and enjoy a wide variety of tastes without altering any other part of your brewing process.

Extraction Variable 3: Calculating Brew Time

Now that we’ve covered the impact of the brew ratio and grind size on your final cup, let’s take some time to look at, well, time.

How do we measure brew time?

It’s quite simple actually. Your brew time started the very second that your hot (or cold) water first touched that ground coffee until all of the extracted coffee has drained and no liquid remains in the brew bed.

You will find that no matter which method you use, coffee with a brew time between 2 and 6 minutes yields the best results.

This brew time includes two separate stages; the bloom and the main brew.

Quick definition: The bloom is when a small amount of water is first added to the ground coffee to wet the grinds and release gases, such as CO2. This is when the brew commences.

The main brew is when more water is added based on your brew ratio and grind size.

You can alter your brew time as you begin to understand how your grind and the amount of water you use influences what ends up in your cup and ultimately, on your tongue.

Extraction Variable 4: Understanding Temperature

The temperature of your water is easy to measure particularly if you’re using a purpose-built jug like …………………. You can also use a kitchen thermometer or try this brewing thermometer specifically designed for at home coffee-making.

The ideal water temperature will vary depending on your chosen brewing method. Cold brew will obviously have different parameters than that of your inversion aeropress brew. However, one rule is always true. Say it with me:

Coffee boiled is coffee spoiled.

No matter your brewing method your water temperature should never reach 100 degrees celsius.


Summary

Coffee brewing can get very technical and complicated very quickly. The better you want your coffee to be the more technical and detail-oriented you will also have to become.

Extraction is the turning point of the spinning coffee world. When you’ve mastered the basic flavour profiles you’ll be be better placed to understand the variables that impact it.

You know now that there are four variables when it comes to altering your extraction; brew ratio, brew time, temperature and grind size. Spend a little time experimenting with these to see which different flavours most appeal to you and the best way to achieve them.

Don’t be afraid to just get stuck in and try.

A lot of these concepts may seem a little intimidating to begin with, but over time with practice and patience they’ll make you the best coffee maker you can possible be.