In this guide we will walk through all the different methods of brewing coffee to give you an understanding of how coffee is brewed and how different tools and methods impact the coffee flavor and texture. Reading this page should give you what you need to know about the coffee brewing process as well as the impact of solubility.
How Coffee Brewing Works
Coffee has been around for a long time which means there’s been many different methods of turning coffee beans into drinkable beverages that have developed throughout the years.
Initially a straight forward decoction formed by heating up water and grounds, coffee has evolved and so too have the many appliances and machines that can be used to create different brews.
The Different Ways of Brewing Coffee
Despite the long and interesting history of different brewing methods they all fundamentally fall into four distinct categories:
Filter Or "Drip"
The filter coffee method works by pouring hot water over ground beans which are contained within a filter.
The filter can be made of any number of things from cloth to metal. Either way the intent is to have the hot water soak through the grounds and extract the coffee and it’s associated flavors and aromas before falling into a collection pot.
Drip / filter brew methods also come in different varieties, with some requiring more effort than others. Of course famously the automatic drip coffee maker is among the easiest of methods you can use to brew filtered coffee but it tends to be make for an inferior end result.
Fortunately specialty drip-brew methods exist, like the “pour over”, and are increasingly becoming popularized by Third Wave Coffee aficionados and roasters.
The coffee that gets brewed through the filter method will end up with fewer lipid than coffee prepared in other ways. This means that filtered coffee will, for instance, contain less oil than espresso.
The trade off is that a coffee with fewer oils tends to produce a crisper drinking experience but espresso style coffee that leaves more oils present makes for a more full and syrupy feel.
When brewing using the drip / filter method the coffee should be ground to the medium-fine level.
Another method of brewing that is popular in a variety of countries including Greece, Russia, and Africa is what is commonly referred to as “Turkish” coffee.
This method starts with placing water and added coffee grinds into a special pot and heating it up until it reaches a boil. The pot is removed once it hits the boiling temperature but placed back on the heat source to keep it warm while the coffee is extracted.
This technique requires a very fine level of coffee grinds. In fact the coffee used in this method needs to be more fine than that used for espresso. This level of grind is only achievable with the use of a Turkish hand coffee grinder (or in some cases a very high quality burr grinder).
This method brews coffee by using a coffee pot that’s heated from below until the water in the pot gets so hot is splased upward and is repeatedly forced to pass through the coffee grounds and ultimately seeps back down into the bottom of the pot as it cools down.
A danger with this method is that it’s very easy to over extract the coffee if the coffee becomes too hot or if the beans aren’t coarsely ground enough. Generally the coffee should percolate for only three minutes before it starts to develop a bitter taste.
Espresso is more of a principal than a specific brewing method - since there are different ways of brewing espresso. Those different methods all share one point though. Specifically they take hot water and force it through very fine coffee grounds with the goal of extracting a highly concentrated coffee infused liquid. This forms the basis of the “espresso shot”.
The grind level of the coffee beans can vary a little - with adjustments sometimes needing to be made to ensure the espresso shot isn’t over or under extracted. Espresso can be used with any type of roast, although it’s commonly associated with darker roasts often used in Italy and France.
The macchinetta is a common tool used to brew espresso. When using this appliance the coffee needs to be ground a little coarser than traditional espresso.
The French Press, also known as a “cafetière”, extracts coffee though steeping. Generally the coffee beans will be coarsely ground and placed in hot water and once they’ve brewed a plunger is pressed down to press the grounds under the filter.
It’s recommended that a high quality burr grinder be used to grind the coffee beans as more uneven grounds will tend to leave a good deal of sediment at the bottom of the press.
Because the coffee grounds are still submerged in the water it’s recommended that coffee made with a French press be consumed within 10 minutes or the coffee will continue to be extracted even after the initial plunge.
Cold water extraction is used in the “cold brew” brewing method. Extraction with cold water is much slower (usually up to 24 hrs) and produces a darker and more potent coffee beverage that is usually diluted further with additional water or milk.
The way this works is the coffee grounds and cold water are added to a container that’s equipped with a filter and a plug. It’s left too steep and after about 12 hrs the plug is removed and the coffee will pass through the filter into a pitcher to receive it.
Cold brew tends to produce a coffee with very low acidity as the oils and fatty acids that yield those qualities are only truly unlocked at warm temperatures.
Coffee beans need to be coarsely ground in to account for the very long amount of time it takes for the extraction to complete.
Wirecutter has produced a great video outlining different methods for brewing coffee here:
Solubility of Coffee
To really grasp the relationship between coffee extraction and flavor you need to have a firm understanding of solubility as a concept.
If you can understand the impact of solubility on coffee flavor you’ll find it easier to evaluate a coffee brew based on the flavors that are present and work backwards to make changes to your quantities and methods in order to realize a coffee beverage that achieves your objectives as far as taste and quality.
Total Dissolved Solids (TDS)
The first important concept to understand is the Total Dissolved Solids (TDS).
TDS is expressed as a percentage. The percentage represents the proportion of the beverage that is made up of dissolved coffee. Obviously this is a proxy for how “strong” the coffee is as well.
The ideal TDS for coffee is 75-250 ppm (parts per million), according to the Specialty Coffee Association of America (SCAA)1.
The average coffee will contain somewhere between 1.2% - 1.45% soluble coffee and the rest will be water.
Expresso, which is a more concentrated brew, tends to have a significantly higher TDS than average coffee alternatives.
Refractometers are used to gauge the percentage of coffee that’s present. Refractometers are instruments used for a variety of purposes (not just coffee) and they function by measuring light “refraction” in liquids.
A coffee refractometer (also known as “brew strength” meters) can be used to analyze the level of caffeine concentration in coffee.
How Refractometers are Used.
- A few drops of coffee are collected as a sample.
- The sample is placed in a “well” which will light up and visibly shine through the liquid.
- The refractometer will measure the angles and degrees of the light and provide the associated TDS (total amount of dissolved solids).
- Using the reading the refractometer provided you can extrapolate, based on the volume of your testing brew, what the TDS and Extraction Yield would look like for a full cup of coffee.
Coffee Concentration Levels
If the level is too high then that would indicate the coffee has been over extracted into the beverage.
When they are too low you can usually diagnose the issue as one of under extraction.
A single coffee bean is actually, in and of itself, roughly 30% soluble.
When we speak using the term “Extraction Yield” what we are referring to is the percentage of coffee that was stripped from the grounded coffee beans and infused into the drink.
Did You Know?
The brewing process works because of the concept of “soluble solids”. A soluble solid is a molecule that will actually bond with water, which means it won’t eventually separate.
For instance if you mix a small ratio of salt into a large cup of water the salt will eventually bond with the water and become a soluble solid.
The same process applies to brewing coffee, where the hot water will be your solvent and select molecules from the coffee will bond with it and create “the brew”. If left to sit for a while eventually the insoluble solids in the coffee will separate and settle at the bottom of the cup.
Can you just add water to ground coffee?
In theory, yes. This would still create some degree of soluble solids and produce a coffee not unlike those produced with other brewing methods, but the insoluble solids will remain in the liquid and many will just stay at the bottom which means you’ll need to filter the coffee more to remove the “left over” coffee grounds.
What is cowboy coffee?
Cowboy coffee is the practice of “brewing” coffee by heating up (usually) coarse grounds in water and then simply pouring it into a cup after the grounds have settled.