Coffee is the most highly consumed beverage in the world, after water. It’s become synonymous with killing some time (Let’s go grab a coffee) and first dates (Would you like to have a coffee some time?); and it’s often one of the first things we offer our guests at home.
So why is it that the cup of coffee doesn’t always taste good? The ability to extract the right flavours in the right quantities, so your cup of coffee tastes just perfect, requires the knowledge of proper extraction techniques and an understanding of the science behind them. It goes without saying that everyone should know how to make a good cup of coffee; it’s an essential life skill, whether you drink it or not. While there are countless ways, ranging in complexity, to prepare that delicious bean juice; there are a few tried and true rules that apply in pretty much all circumstances.
It’s all about the coffee beans. It may sound cliché, but no fancy machine, or advanced barista skills, will save you if you’re using inferior beans. Don’t settle for the pre-packaged crap from your grocery shelf. Find a specialty shop, or better yet, a local roaster, and prepare to be blown away by the difference fresh beans can make. You’ll finally understand all those snooty sounding adjectives like fruity, citrusy, and earthy which you’ve never tasted, but definitely heard before.
A single mature coffee bean is composed of, on average, 4.5 million living cells. However, when the bean is roasted each cell fills up with carbon dioxide gas, causing the bean to inflate. Confined within the cell walls are the soluble flavours we all crave. The four main categories of soluble compounds and flavours they produce in the cup are shown in the following table.
|Compounds||Flavour they Impart|
|Caffeine & Fruit Acids||Light fruity flavour|
|Fats||Nutty, Vanilla & Chocolate|
|Melanoidins||Nutty, Vanilla & Chocolate|
|Fiber & Carbohydrats.||Earthy sweet tones|
The fruity acids along with caffeine are the easiest ones to dissolve out of the bean. Next come the oils and fats, which don’t technically dissolve out of the bean, but rather are removed by the hot water as a liquid suspension. Brewing methods that make use of filter papers trap a vast majority of these lipids within them preventing them from going into the cup. Whereas brewing methods like French Press or espresso, which use metal filters with larger pores allow them to pass through providing “body” or “mouth-feel” to the beverage. Meanwhile melanoidin compounds are responsible for giving the beans and the liquid beverage their characteristic qualities. The largest compounds are carbohydrates and they make up roughly half of dry bean’s mass; however not all of the carbs are soluble.
When hot water interacts with the coffee grounds, it starts to dissolve the soluble compounds trapped in the cells walls and carries them to the cup. Only thirty per-cent of the coffee bean is made up of soluble compounds and out of these ten per-cent are horrible tasting and thus, bad soluble components. Twenty per-cent are the good soluble components and it is these twenty per-cent that we want to extract into the cup. The majority of the bean, roughly seventy per-cent, is composed of insoluble fibres and carbohydrates. The good news is that the undesirable components are not very quick to extract, as they take a long time to dissolve. By controlling the amount of time water has to work its magic on the grounds, the bad soluble compounds can be kept out of the cup.
Deciding on a Roast Level
I know. You can admit it. When it comes to roast levels, you pretty much just pick something at random and pray for the best. I know, because I used to do exactly the same when faced with the office machine. Believe it or not, there is a difference to all the different roasts beyond smart marketing.
Light roasts are roasted for the shortest amount of time and keep more of the characteristics of the actual coffee bean. It’s actually beautiful when you think about the fact that you’re tasting the environment and conditions that coffee bean grew up in. Light roasts are the one you’ll hear described as citrusy earthy, fruity, floral, fresh. If you’ve ever rolled your eyes at someone describing a coffee as having “undertones of jasmine and walnuts, with a hint of grassyness”; they were drinking a light roast. Light roasts are all about enjoying all the subtle little flavors they reveal. If you’re a fan of light roasts, getting high quality coffee becomes even more important as defects in the coffee cannot be covered up in the roasting process.
Dark Roasts, in contrast are roasted for the longest amount of time, and reach the highest temperatures. The beans will be much darker, and in the later stages will start to have a slight shine as the essential oils of the beans spill out and coat the exterior. Dark roasts sacrifice the natural characteristics of the coffee bean in favor of infusing them with the intoxicating flavors of the roast itself. I like to think of it as cooking out the old flavors and baking in some new ones. These coffees tend to be described as smokey, woody, or even as having hints of tobacco. They are typically more full bodied than their lighter brothers and tend to produce a stronger coffee.
Medium roasts, as the name implies, fall somewhere in the middle of the two, and tends to be the most favored variant in America. You can read any of the links above to read about the nuances of each roast type in detail.
Just like we said about beans earlier, if you’re using poor ingredients, you’ll end up with a poor final product. Water quality plays a huge factor in the chemistry of coffee. Many coffee snobs will insist you only use fresh spring water bought from some fancy sounding bottler who will sell it you at several times the price of gasoline. I don’t think that’s necessary. I typically like to run some tap water through my Brita water filter and use that without giving it much extra thought. I’ve tried bottled water in the past and honestly, it just didn’t make any perceptible difference at all. What you don’t want to do however is use soft or distilled water. These are missing minerals which are needed during the brewing process.
Now that you’ve picked your beans and brought them home, we need some pointers on preparing them. If you follow just a few simple rules your guests will be raving about how you make the best cup of coffee around. The first thing you need to know about is water temperature. Most amateur brewers will simply dump the grounds into their machine of choice, and boil the heck out of it for as long as they think is necessary. All wrong! First of all, there is an ideal temperature for brewing coffee which ranges from 195 °F (91 °C) to 205 °F (96 °C). The hotter end of the range will usually produce the best results. Using boiling water tends to burn the coffee grounds while a temperature lower than 195 degrees will not extract the flavours properly. With that said, if you’re getting premium coffee it will likely state the ideal brewing temperature and length somewhere on the package.
There is likewise, an ideal serving temperature for coffee. We’re all terrified of serving coffee too hot thanks to a very high-profile lawsuit and that one episode of Seinfeld. On the other hand, there’s nothing quite as disgusting as a luke warm cup of coffee is there? We’ll put your fears to rest by sharing that the Ideal service temperature for most people ranges from 155 °F (68 °C) to 175 °F (79 °C). Closer to 175 tends to be most popular.
We can’t really understand why temperature is so important without understanding the brewing process. What’s actually going on inside that coffee machine or French press; and what can we do to optimize the final product? Firstly, we’ll need to understand the difference between Percolation and Maceration.
This is the one you’ll be most familiar with. Percolation has its origins in the Latin word “percolare” which means “to strain through”. Like when the coffee is strained through the coffee filter. This is perhaps the best known method of coffee brewing which takes place whether you’re using a filter in a drip machine, or whether you’re using the coffee itself as a filter as with Espressos. The term percolation has become synonymous with brewing coffee but it’s not the only way.
Maceration is a word you may not have heard before but it’s a process you will recognize immediately. Maceration simply means that the coffee is left within the hot water so that the water absorbs the flavors of the coffee. This is also known as “Steeping” and it’s something you’ll be familiar with if you’ve ever made a cup of tea; which is another example of maceration. With Maceration comes a higher risk of burning your coffee as it’s up to you to decide when the grounds should be removed from the water (usually 4-5 minutes). While maceration is not as widely used as percolation, it is still quite popular, and delicious, as any owner of a French Press can tell you.
We’ve covered the major points, and now we’re getting into the finer nuances of brewing a delicious cup of coffee. Grind size, an often overlooked aspect that can make the difference between good, and excellent. The art of brewing coffee is a fine balancing act. There are a multitude of compounds found in coffee grounds, many of them are desirable; but others aren’t. Coffee brewing can therefore be thought of a balancing act between leaching out those good compounds while leaving the bad ones within the bean. You want to make sure your grind is not too fine for the same reason you want to make sure your water temperature isn’t too hot, or that you don’t steep for too long. Doing this, allows for those undesirable compounds to be released into your cup, creating a bitter, acidic tasting cup of coffee. Far from excellent…
So coarse grind is best then? Not exactly. Again, it’s a balancing act. Course grinds are more forgiving but are also much more inefficient. Imagine dropping a solid coffee bean into a French press. How long would it take for the water to absorb that? Much longer of course. When the coffee bean is ground into smaller sizes, greater numbers of cells are exposed which the water can come in contact with. When water has more cells it can come in contact with, it can remove the desired soluble particles faster. As the individual coffee crystals get smaller and smaller the brewing process becomes more efficient as the water has more surface area to work on rather than struggling to break down one massive block in one shot. In other words, grind size and time are inversely proportional. When one is increased the other has to be decreased. Hence, to get a good extraction, a balance has to be achieved between time and grind size. This also explains why grind size must be consistent. A mixture of sizes means that the smaller particles will have all of the flavourful components dissolved out of them before the larger sizes ones, leading to uneven extraction.
Ultimately, there is no right or wrong answer when it comes to grind size, it’s really more of a matter of preference. This will rely heavily on personality traits such as whether you’re attentive and detail oriented, or like to play things a little looser and more light hearted. This is one where you’ll get to have some fun experimenting on your own to develop your own brewing style.
Water to Coffee Ratio (Strength):
The proportion of coffee used in a given quantity of water is another major factor that affects extraction and eventually the flavour of the drink. If there is too little coffee, the drink will seem flavourless and weak. There are a number of ways to deal with this problem. Increasing brew time will counter this, another option is to use finer grounds or decrease the amount of water.
If excessive amounts of coffee grounds are used, it will lead to something that is very bitter and heavy. The way to rectify this wold be to use coffee grounds that are coarser, shorten brew time, or finally, add water to get the right balance. The SCAA (Specialty Coffee Association of America) recommends a ratio of one part coffee to 16 or 18 parts water. So, for every one gram of coffee grounds, sixteen to eighteen ml of water should be used.
In terms of coffee, “rate” refers to the quantity of particles that should be extracted from the coffee grounds. The longer water is allowed to interact with the grounds, the greater the quantity of soluble compounds that will end up in the cup. However, according to the Specialty Coffee Association of America (SCAA) guidelines, best tasting coffee is produced when only 18 – 22% of the soluble components are removed from the grounds and the rest are left behind. This means that if we take the weight of the coffee grounds being brewed, 18 – 22% of that weight should dissolve and make its way into the cup. The amount of time water is allowed to interact needs to be controlled so only the ideal amount of flavours have the opportunity to dissolve in the water. Longer interaction time will yield a cup of coffee that is bitter, while insufficient interaction time will yield a cup of coffee that is sour, a little salty and lacks sweetness.
Now that you know the basics of making a great cup of coffee, get ready to dive into the diverse world of coffee brewing! Coffee is enjoyed on every continent, and each culture brings its own unique twist on how to prepare the perfect cup! Many of them are fascinating and you’re sure to find a new favorite technique from some far off land if you jus take the time to do some research. (I’ve been trying to perfect my Vietnamese coffee lately which is no small feat!) Check out the links below for helpful step by step guides that will help you navigate all the different brewing methods!
How to Make French Press Coffee (Coming Soon)
How To Make Strong Coffee (Coming Soon)