Brewing an exceptional cup of coffee is a craft. It’s equal parts art and science. Just like cooking, it requires large doses of curiosity and experimentation, as well as the ability to master a couple of tools and techniques.
As with every craft, there are many variables that go into creating a great end product.
With coffee of course, it all starts with the beans.
Then there’s the brewing method- French press, pour-over, electric drip or espresso machine?
But what use are great beans if we don’t know how to extract the best flavours out of them?
In this article, we’ll cover the 7 essential elements you will need to consider when brewing coffee at home.
After reading, you’ll be perfectly equipped to get the best out of your beans- no matter your brewing method of choice.
Brew ratio
The first concept to wrap our heads around is the concept of brew ratio.
Very simply, brew ratio refers to the volume of liquid (water) in relation to the quantity of solids (coffee) in our preparation.
With the exception of espresso, which uses a very unique recipe, most other methods can be prepared with a relatively similar brew ratio.
This includes filter preparation methods like pour-overs or electric drip brewers, as well as immersion methods like French press, clever dripper or even cupping.
The main idea to focus on when it comes to brew ratio is the idea of concentration/ dilution. Think about a clear glass of water. Now imagine adding ground coffee particles by the spoonful. Adding more will result in a murkier, more concentrated preparation. On the contrary, adding only one spoonful will give us a more diluted, clearer mixture.
Now, this will somewhat vary between coffee types and preparation methods, but most experts have agreed on an ideal brew ratio. It’s somewhere between 1:12 to 1:20, or 1 gram of coffee for 12 to 20 grams of water (where 1g of water equals 1ml). So for example, with 250ml of water, a 1:12 ratio would require 21 grams of coffee; while the 1:20 ratio would call for 12.5 grams.
The “Gold Cup Standard” proposed by the SCA (Speciality Coffee Association) is 55 grams (+/- 10%) of coffee per litre of water. This equals a brew ratio of between 1:16 and 1:20.
So to sum up our main idea here- the lower the number, the more concentrated our brew.
This becomes very apparent with the espresso recipe, which calls for a brew ratio of 1:2, so 1 part of coffee (typically 17g) is extracted into only 2 parts (34g) of water.
Grind Size
With grind profiles, we’re introduced to another key aspect of coffee making- extraction.
Arguably the most important concept to grasp when brewing coffee, extraction is simply defined as what is taken away from the ground coffee as it comes into contact with hot water. In other words- hot water dissolves compounds that are present in the coffee grounds. And that’s where all the flavour comes from.
These compounds are made up of, among others: caffeine, acids (lending or taking away acidity), lipids (which add or subtract viscosity) and sugars (responsible for your preparation’s sweetness, or lack thereof). But we can’t just drown a handful of coffee beans in hot water and expect a nice brew to come out! Coffee beans have a pretty sturdy constitution, making it hard for water to penetrate their surface. This is why we have to grind them.
The grind size will be the decisive factor in your brew’s overall flavour and texture.
A finer grind increases the coffee’s surface area, making it easier for water to penetrate to its core and extract more compounds. But this can lead to the coffee being over-extracted- as we will explain further in the following section.
Conversely, a coarser ground offers less contact surface, thus making it harder for water to extract the necessary compounds. So if enough extraction time is not given, it may result in under-extracted coffee.
Brewing Time
This variable is intimately linked to the one above. We just spoke about the different chemical compounds that are contained in roasted coffee beans. Well, it turns out not all of these compounds are extracted from the coffee at exactly the same time.
Acids, along with caffeine, are the simplest compounds, meaning they’ll be dissolved first. These are your sour, slightly salty, and of course- acidic notes. Then come the oils and fats, which are responsible for the preparation’s overall body (a.k.a. viscosity), as well as some of its more subtle fruity and aromatic notes. Sugars are next. As they are a more complex compound, water will take longer to dissolve them.
These lend coffee its sweet aspect. Once the hot water has worked its way through acids, lipids and sugars, it will inevitably start breaking down the plant fibers that make up the coffee bean.
This is largely responsible for the bitterness in your brew. If the beans are very finely ground, this means that hot water will take less time to dissolve the 3 initial compounds, as smaller particles offer less resistance, reaching that “bitter end” quicker. They will therefore need less contact time with the hot water. On the other hand, grind them too coarsely, and water will take longer to work its way through the flavour compounds. This means more contact time is needed with the ground coffee.
If we make the time variable fixed (let’s say, 4 minutes) what would then happen to coffee that’s been ground finely versus coarser grounds? The finely ground coffee might end up being over-extracted, resulting in an overly bitter and somewhat “flat” brew. The coarser coffee on the contrary might be under-extracted, and will likely taste acidic, sour, watery and weak.
Now, there isn’t an ideal brewing time, as these will vary greatly from coffee to coffee, and between different brewing methods. There will usually be recommendations from your roaster however, so look out for those on the package. But ultimately it’s up to you, with what you’ve learned so far, to experiment and find your own ideal brewing times. Have fun!
Water Temperature
An often overlooked aspect of coffee brewing, water temperature is however very important because it affects the speed of extraction.
In general terms- the higher the temperature, the quicker the extraction.
Most expert bodies believe the ideal brewing temperature to be around 93°C. The National Coffee Association (US) goes a little further, proposing a range going from 90°C to 96°C. This range works because it makes it possible to accommodate for slight variations in your roasting profile, as well as your grind size and preparation method.
With darker roasts, it is recommended to use a lower water temperature, closer to the 90°C mark. This is because dark roasts boast bolder, deeper tasting notes. If our water is too hot, we’ll end up over-extracting, resulting in an overpowering, bitter brew.
In contrast, the lighter roasts are suitable for higher water temperatures towards those 96°C, as it helps speed up the extraction process. This also allows the water to unlock the more complex, interesting tasting notes hidden within these lighter roasts.
Using what we’ve learned from the previous two sections (grind profile and brewing time), it’s easy to see how the three are correlated.
Water Quality
Another aspect that often goes under the radar, the quality of the water we use to prepare our cup is a legitimate contender for the title of “single most important element” in coffee brewing. If our end product is made up of roughly 98-99% water, then we’d better make sure we get some of the good stuff!
Think of water as a canvas in which the different flavours that make up our coffee will develop. Without getting too technical, our ideal water will need certain minerals- but too much of the wrong ones is detrimental. Particularly in London, tap water is too hard for coffee brewing. It has a high content of both calcium and magnesium. This isn’t necessarily a bad thing, as calcium helps highlight the creamier, heavier notes in coffee; while magnesium brings out the sharp, fruity aspects of it. But tap water also contains elements such as chlorine, copper or even iron from old piping that do not interact well with the compounds contained in our coffee grounds. So a good option for our brew is filtered water, which helps to get rid of some of the undesired elements in our water. Another viable option is certain bottled waters. Own-brand supermarket waters for example, particularly from Tesco or Waitrose, have given good results. Volvic and Acqua Panna are two brands whose mineral profiles interact well with coffee. However, there is of course the issue of sustainability and cost when it comes to bottled waters.
Some specialty coffee shops have started to use what they call “formulated water”. Formulating water is a treatment that starts with reverse osmosis. This is a filtering process that gets rid of all the unwanted total dissolved solids (TDS) in your water. It then re-introduces only those elements that are beneficial for brewing. But this is getting way too geeky! To summarise- our water shouldn’t be too hard. To fix this, we can filter regular tap water. Even with something like a Brita filter. This is already significantly better than unfiltered. Or, we can use bottled water, but have to keep in mind sustainability and cost.
Turbulence
Remember we said in our intro that brewing was both an art and a science? Up until now, it’s mostly been about the science to be honest. Well, this is the time in which we can start to show off our barista training!
Turbulence is not about measuring, weighing, counting and you know- math. It’s about manual skills you can develop with practice. This is where the art of the barista truly comes in. “The Hand”.
Turbulence happens when we introduce water in a chaotic movement so as to “shake up” our ground coffee. It helps us with two things: it promotes an even extraction, and accelerates the extraction process. There are a couple of techniques to achieve this. The most common one is simply stirring. We can stir our grounds after pre-wetting in a pour-over preparation, or in a French press before plunging.
We can also achieve agitation by pouring the water in a particular way. Swirling is a method of pouring water in a spiraling motion so as to distribute the grounds more evenly. Lastly, we can pour around the edges of our filter in a “flushing” motion. This way, we bring in all those coffee particles that might have been missed out by our previous pour, thus staying “high and dry”.
Filter Medium
The last variable to consider when brewing at home is the type of filter we will use.
Most of the time, that choice is made for us. It’s dictated by the type of coffee maker we have at hand. For example, a French press does not allow us to choose a filter, as it comes with its distinctive metal mesh by default. But in those coffee makers that allow us to choose- pour-overs, Chemex, electric drip brewer- the type of filter used will also have a big impact on the final product.
One thing to consider right off the bat is the grind size we use for our preparation. As we’ve seen throughout this post, this will largely depend on our chosen type of coffee and its roasting profile. Generally speaking, paper filters will be more suited to finer grounds. At the other end of the spectrum are metal filters, which are better matched with coarsely ground coffees.
Paper filters are tightly woven and absorbent, meaning they leave out some of the coffee’s essential oils, as well as the micro-grounds. This results in a clean, bright cup with a strong perceived acidity. Metal filters, on the other hand, allow the oils and some of the micro-grounds to sieve through. Our brew will be bolder, richer, and more full-bodied as a result. Finally, there are cloth filters. These lay somewhere halfway between paper and metal, allowing the oils through but leaving the micro-grounds behind. The result is a full-flavoured cup with decent viscosity but a light body. Cloth filters are, however, hard to come by and even harder to maintain; so this should also be kept in mind when considering your ideal filter medium.
There they are! Those are the seven essential elements of coffee brewing. We hope you’ve enjoyed this article, and above all- hope that it gave you the inspiration, the knowledge and most importantly the confidence for you to go out there and get some tasty beans to start experimenting.
As we said, once you’ve assimilated these basic concepts is where the fun part begins! Now it’s your turn to have a go and start discovering what works for you. Remember these are mere guidelines. What’s really important is that you develop your own personal preferences and find your own unique taste. The main takeaway here is to understand how all of these variables are inter connected. With a little bit of practice, you’ll begin to understand how altering one affects the other, and you’ll start to see the bigger picture.
PS ...
As a closing thought, and for a little bit of fun, we’d like to introduce the following idea. Imagine coffee as music. The type of beans you choose represent the kind of music you’re in the mood to listen to right now: Ethio-jazz, cumbia or bossa nova? You place the record on your turntable. Now, that record will come with its own unique blend of sounds, from the instruments used to how it was produced. But imagine how much more is possible with a great amplifier, a decent mixer and a lovely set of speakers.
Now it’s your job to extract the best possible notes out of that record, while staying true to its original sound. Play on!
By
Mauro Buzzurro
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