Coffee extraction is basically making the coffee grounds soluble in water. But there is more to it than that. Many factors affect the result of coffee extractions like the roast type of coffee ground, amount of water, the temperature of the water, and quantity of coffee grounds.
Coffee is notorious for its caffeine. This world-famous beverage is widely known around the globe. People rely on it more than they like to admit. Even right now, I’m sipping coffee as I write this blog.
So, anybody who drinks coffee whether they get it from a coffee shop or brew it at home does coffee extraction. For the coffee shop, the coffee maker does it for you and at home, you do it yourself. But what is coffee extraction?
Let’s find out together as I found out some really interesting information on this topic.
What Is Coffee Extraction?
The process of getting coffee dissolved into water is coffee extraction. But many factors are taken into consideration for achieving the desired result like the roast, type of coffee ground, amount of water, the temperature of the water, and quantity of coffee grounds.
Have you ever realized how much coffee do you actually drink in a day? No? It’s okay, just asking. Well, if you drink plenty then you do coffee extraction every day. Confused? Don’t be.
Coffee extraction is basically the process of getting coffee solvents mixed in the water. That’s it. Though it’s not as simple as I put previously, the basics are this only. It is the process of dissolving coffee solvents into water. Many factors come into play when we talk about coffee extractions.
Water is a universal solvent. Two positive charged hydrogen atoms plus one negative charged oxygen atom. This polar arrangement attracts a lot of variety of soluble easily. This molecular composition helps to dissolve coffee compounds a lot better than any other liquid.
The water-soluble coffee compounds that would be in the extracted coffee would be:
In other words, how much of the dry coffee ground got dissolved in the water is your extracted coffee. So, for example, you used 15 grams of coffee grounds, and only 5 grams made their way into the water.
So the extraction yield percentage would be 25% (5gm/15gm). Plus, the water used for extracting coffee isn’t the same. For example, you used 250 grams of water and after the brewing, you have 200 grams of coffee in the cup. This is the outcome of coffee extraction.
You can have a look at this amazing video that I found on coffee extraction.
What Is The Best Way To Extract Coffee?
There is no correct way to extract coffee because every method results in a different tasting and smelling coffee. It all depends on what you like and want to achieve with the coffee extraction. But an average good quality cup has about 18% to 22% TDS.
As mentioned earlier, coffee is a very complex drink. And this complexity can be seen all around the world. Every region has its own way of making coffee.
I mean how can the same ingredients taste different? But that’s the quality of coffee. It is customizable and can have a variety of flavors, aromas, and tastes.
Therefore, there is no right way or measured way of getting that ‘perfect’ cup of coffee. It all depends upon what you are looking for from the coffee cup.
You want a sweet-tasting coffee; you want a slightly bitter coffee or do you just want a power-packed espresso shot. You see, every method of extraction or brewing as we say is result-oriented. But there is a measurable way to determine whether your extraction has been successful. It’s called the TDS.
TDS stands for Total Dissolved Solids. Now the TDS is always counted in percentages. Also, you cannot measure the TDS of an extracted coffee manually.
You need a refractometer to measure the quality of extracted coffee. Different types of coffee’s TDS range between 1% to 12%. But keep in mind, the higher the TDS, the stronger and bitter the taste.
This TDS method has stemmed from the research of Prof E.E. Lockhart by Coffee Brewing Institute done in the 1950s. The ideal percentage should be between 18% to 22% according to this scale. With under 18 % being under-extracted. Which means that its, thin, sour, and weak. And over-extracted if the number is above 22%, with bitter to burned notes.
But the extraction process is also affected by many factors like the grind of coffee, the roast, the type of coffee, the temperature of the water, the uniformity of coffee grounds, and the amount of water added.
In addition to all this, the ideal temperature of the water should be just below boiling which is 195 to 205 F (90 C to 96 C). Above this will extract coffee quicker and below this will slow down the extraction process.
I’ve summarized a table for you to let you the taste, method, and caffeine content of each yielded cup of coffee.
|Method||Caffeine Content||Ideal Coffee Taste|
|Drip (pour over)||150 to 175 mg||Savory and Full-Bodied|
|Immersion||100 to 110 mg||Balanced and Clean|
|Espresso||50 – 70 mg||Strong and Bitter|
|Boiling||40 – 50 mg||Bittersweet and Rich|
What Is Coffee Over Extraction?
In the extraction process when the coffee ends up tasting bitter and burned, it is called over-extracted coffee. Also, if we were to talk about it in TDS, anything above 22% is over-extracted.
By now you must be clear about the coffee extraction. So, let’s talk about over-extracted coffee. Well, according to popular belief, there is no such thing as over-extracted coffee. Why? Because for every kind of coffee there is someone who enjoys it that way.
Some people drink sweet creamy coffee while others enjoy right in the face bitter coffee. But the coffee connoisseurs agree that there is an over-extracted coffee.
Essentially, if we take into consideration the TDS scale, anything above 22% is over-extracted. This means, that two much of the dry coffee has gotten into the water thus making it taste burnt and bitter. This result can be due to various reasons.
They’re as follows:
- Incorrect ground size
- Temperature of the water being too high
- No uniformity in the coffee grounds
- Amount of water
- Brewing time
Incorrect ground size like too fine or too coarse can make an over-extracted coffee. Likewise, if the temp of the water was extremely hot, it can burn the grounds and produce burned coffee.
Temperature is actually one of the most important aspects of making coffee. You can read about that here where I discuss how temperature affects your cup of joe.
So, in conclusion, you need to control each element in order to produce the ‘perfect cup of coffee.
Coffee Extraction Methods
There are four main extraction methods. They’re decoction, infusion, gravitational feed, and pressurized percolation.
Coffee can be extracted in numerous ways. This means that it can the different brewing methods can be categorized into four groups. And these groups are based on how water is added to the coffee grounds. So, let’s jump deep into each of them.
This is one of the easiest ways to make coffee. This type of coffee gets prepared within 5 to 10 minutes total. On the stove, water is added to the heat, and sugar is also stirred in while the water is boiling.
Once it starts bubbling heavily, finely ground coffee is added and cooked over medium heat for another 3 to 4 minutes. This method of coffee extraction is popular in India and the Middle East.
You must be familiar with Turkish coffee, right? Turkish coffee is a product of boiling coffee with water.
In this extraction method, the coffee grounds get steeped in water, whether hot or cold. This extraction method lets the coffee grounds in water for long periods of time.
In measured coffee grounds, hot or cold water is added. Then left for several hours, depending on what is the desired end product. Usually, cold brew is made by this extraction.
This is a long process if done manually. But a French press makes it easy and delivers your ideal coffee within minutes
Gravitational Feed (drip or pour over)
As the name suggests, gravity plays an important role in yielding this extraction method. In this method, coffee grounds are placed on a filter over a large vessel.
Then water is slowly and constantly dripped or poured over it. Then coffee which drops down due to gravity in the bottom of the vessel is the extracted coffee. Hence the name.
Pressurized Percolation (espresso)
Simply put, the word percolation means to ooze through a permeable substance, and pressure means to put force. Putting both of these words together means coffee which is made by forceful oozing. The best example of this is espresso.
Have you ever seen the barista in a coffee shop making a shot of espresso? Did you hear the sound that comes from it when the barista removes the pod? The sound is of the gas releasing which is built up in this process. The coffee grounds are leveled and tamped in the chamber.
Then the water is passed through at the set temperature for a set time along with the pressure. This yields a much strong and colder cup of coffee, and in this case espresso.
My Final Verdict
Coffee extraction isn’t just about water and the coffee grounds. There’s a whole lot of science that goes behind in making that ideal cup of coffee.
Though the definition of the perfect cup of coffee differs from person to person, to measure the quality of extract there is a method called the TDS.
But what if it doesn’t go well? You will end up with an under-extracted coffee or an over-extracted cup. Over extracted cup has a burnt and bitter taste.
But most people believe there is no such thing as over-extracted coffee. It all depends upon the liking. Whatever it might be, you can enjoy your chockers however you want.