The Science of Brewing: Coffee & Water A Party to Remember.

Welcome back to Bear Essentials, this time we are going to talk about brewing coffee, how to do it well and go into some detail as to what actually goes on when we make our favourite drink.

What has Gone Before

Ok so before we get into brewing, it’s important to acknowledge just what has already happened to your coffee beans. No need to go into too much detail, if you really do want to know more check out The Flavour Journey Parts: 1, 2, 3 & 4.

But in summary, those beans we are about to brew have been grown, harvested and roasted with extraordinary care. They represent the collective work of many dedicated hands, so my first piece of advice is to always remember that, like a good wine, or a beautiful ingredient, quality coffee should be treated with care and respect. 

Extraction: The Science of Brewing Coffee

Right, time for the science lesson, don’t worry I will make it as painless as possible (promise). Just what is actually happening when we brew our coffee?

Disclaimer: Right blunt time, it’s important as I discuss this type of science (and it is science) to be clear on what I am, and what I am not. I am an acknowledged “field expert”. I have years of experience in brewing, and I have read thousands of words, and exchanged thousands more, on the science of brewing coffee, and of extraction in general.

I am not a “lab expert” my experience is hands-on, my knowledge of brewing science comes from standing on the shoulders of giants. I have had the great privilege and pleasure of meeting and talking to many very smart people, and I have learned what I can. While I do know my way around a refractometer and a centrifuge, I tend to leave that stuff to the experts.

Prof. Bear. Schools in Session

Ok so let’s get to it…

The process of getting the drink you want from coffee beans is a matter of removing soluble materials, which carry flavours, from the bean. We do this through Osmosis, the scientific term for getting stuff out of other stuff, using handy extra stuff to seperate them from each other. In our case we are drawing out the desirable (more on this later) measures of specific soluble materials from the coffee beans, using (usually, thank you cold brew) heated water as a solvent.

When we extract coffee from roasted beans we get quite a few materials, but there are four specific ones that will most define our coffee’s final taste. These are; Acids, Salts, Complex Sugars, and Dry Distillates. To understand how the flavour of coffee comes about, we need to study each of these individually and then consider them as a whole. So let me help you do just that. But first we’ll start with the catalyst for our reaction.

The Magic of Hot Water

Hot water making great coffee, because… science!

Water is an exceptionally effective solvent, this comes down to it’s molecular makeup. Water is polarised, that is to say it has both positively (specifically hydrogen) and negatively (ditto oxygen) charged molecules. This balance is fantastic when it comes to breaking down a substance, the dual charge makes water attractive to a lot of different materials, so with a little care we can (in theory) extract what we want, and leave what we don’t behind.

Once we heat water its solvent properties are greatly enhanced, the application of heat causes agitation in the molecules, making them mix with everything that is submerged within the water and chemically attract materials (like different folks mingling at a party). This means that hot water is extremely good at breaking down our coffee beans (or tea leaves for that matter, if that’s your particular jam), all we need to do is control what it brings out. Time to look at those materials inside our beans, in a little detail.

Acids: “Party on dude!”

One of the first guests at the party to bond with our hot water (what? You thought that party metaphor was just an aside?) is Acid. Soluble acids in coffee bring with them intense citrus and fruit flavours. These tastes are often sharp or tart, often to a very unpleasant degree. They could be thought of as the gregarious, though sometimes over excited folks at the party who are always the first onto the dance floor. 

Salts: “I bring the Beats!”

Next onto the dance floor is salt, yes really, your coffee tastes of salt (you can even add salt to your drink to balance bitterness in over extracted coffee, but that’s a different subject). I probably don’t have to explain that salts taste… salty. But hey I guess I just did, score. Best described as that guest you almost forget is there, but who tends the mini bar or runs the music, and perhaps even watches the door for uninvited Dry Distillates (more on those guys in a bit). You may forget them once things get going, but if ever they aren’t there your party is liable to suck. 

Complex Sugars: “You want to dance… with me?!”

When we roast a coffee bean we cause a chemical reaction which results in the creation of complex sugars, this is called The Maillard Reaction, and is used in all forms of cooking to produce tasty results (it’s the reason meats taste better with some caramelisation). These sugars are the heart and soul of our coffee party, and once we can get them energised and onto the dance floor things can really kick off. Still and all, if they were the only guests we would probably have a very oversweet experience, they kind of need that social interaction to come to life. 

Dry Distillates: “Not exciting enough? Hold My Drink!”

Finally we have the guy in the kitchen with a cold beer who “doesn’t dance” (also known as me), dry distillates are the last part of the coffee bean to break down and bond with water molecules. The tastes associated with dry distillates are often viewed as unpleasant, being mostly ashy or burnt. But actually the early breakdown of dry distillates creates some very useful tobacco like, or pleasantly bitter notes, so we do want them at the party, just not so tanked up that the neighbours complain. Think of them as that person you love to see, but who needs keeping an eye on before they get rowdy. 

H2O Loves to bond with others!

Good Coffee: The Bittersweet Symphony

So now that we have met the party guests let’s talk about managing interaction. Each of the flavours above is very distinct, and if allowed to dominate can deeply unbalance our drink. There are two specific ways this tends to happen. 

Under Extraction: The Parents Come Home Early

If we don’t allow enough time for the solvent to break down the coffee grounds, we end up with a sour and flat tasting drink. This is because the acids and salts in our coffee have made it onto the dance floor, just in time for the music to stop. We call this type of result an under extracted coffee and it is one of the most unpleasant drinks I can imagine. 

Over Extraction: Oh Shit the Neighbours Called the Cops

If, on the other hand, we allow things to go on too long, those too cool for school dry distillates will take over, crank up the bass and get rowdy. This drives the acids and sugars off the dance floor and drowns everyone in bitter intense flavours, then at some point the neighbours call the authorities and its party over folks. This is what we refer to as over extraction, mostly the coffee tastes bitter and lifeless. It’s (arguably) less unpleasant than under extracted coffee, and frankly slightly over extracted coffee is drinkable, if a little unexciting.

“Excuse me. Is your name on the list?”

The Perfect Party

So what we actually want is to get everyone grooving to a lively beat and having fun. This is the art of coffee brewing, the talent that we baristas have spent years learning. The trick is to find that sweet spot in the extraction process where the complex sugars are spread nicely between dance partners, and it’s not easy. 

How do we control all this chaos? Well we use measurable variables, specifically Grind, Weight and Timing. So lets meet the “party planners”.

Grind: The one that did all the detailed shit

The very first and arguably most important variable we can control is the coarseness/fineness of grind. When we grind beans fresh we do so with a plan, this is based on the brewing process we are going to use. I am not going to even try to detail this here, my title is no joke, this can get very technical. We’ll leave the art of the “perfect grind” to another article.

Weight: The one at the door, that asks “Are you on The List?”

Brewing consistently (hell doing anything consistently) is a matter of keeping as much the same as possible. Our best tool for this in coffee is a good accurate set of scales, and we “pros” weigh things… A lot. We weigh the amounts of coffee grounds and water, then we weigh the final drink, sometimes we then do weird maths with that info, this allows us to very precisely control one of the core variables in brewing.

Time: The one that planned the music and brought the alcohol

Ah timings. How I love and loathe this metric in brewing. I love it because it is incredibly important, and I loathe it because people get so easily over focused on it to the exclusion of all else. Quite often you will find that coffee is supplied with a “recipe” usually something along the lines of a recommended brewer and weight of coffee, along with a time to aim for. This is great, except when it’s not.

So firstly having a brewing time to aim for is good, it allows you to have some idea of where you need to start from. 

Now I am going to ask you to read that sentence again. Got the import of the wording? A Place To Start, not a goddamn sacrosanct, must hit target, and that’s where I arrive at the loathe part. So often I have to spend a lot of effort in teaching new coffee brewers that they can break the rules, because they aren’t rules. They’re more like guidelines anyway (lovers of movie quotes, enjoy).

Seriously the key to great coffee for you, is to remember that it’s great coffee For You. Once you taste a coffee at the recommended brewing guidelines, decide if you like it, then if not, change the rules. Ok so how to do that? Well that’s a big question (bigger than this already long article) but I’ll hit up some common changes and provide a few tips on how to achieve them.

It’s too Fruity

If you are finding your brew is too fruity or acidic in taste, chances are you need a longer extraction. Best way to achieve that is to change up your grind, a finer grind will allow for a more complete extraction and bring out more intense flavours. 

But My Coffee is Pregound!

If you have pre ground coffee you can get a slightly longer extraction by brewing for longer (if you are using a cafetière or Aeropress) or adding some extra grounds to slow the flow rate (if you are using a V60 or drip brewer). This is not a perfect solution but in a pinch it can make a difference. 

Ugh Bitter! Bleh!

The face that comes with this taste is one of the most common I come across, many people find that the bitterness in coffee is unpleasant or just too much for them. Solution? Less extraction, as we discussed above the early part of extraction emphasises the fruit and acid notes in coffee and this will mellow out the bitterness. 

Bonus: Secret Extra Solution or Not

Add salt. No really, honest. This one is a useful but tricky hint. The addition of a little salt can counteract bitter flavours. So importantly we are really talking A Little Salt, like one tiny drop of a 20% saline solution (2:10) will have an immediate impact. I really don’t recommend this unless you have A: No better option and B: Access to an accurately measure saline solution.

Do not under any circumstances just bang some salt into your coffee, you can thank me later.

Signing Off

Ok folks, here endeth the lesson (more movie references anyone?). That’s my quick (ish) guide to the art of brewing. If you are interested in this stuff and want to learn more, please stick around, follow our social media and subscribe to this blog, you will get more articles and insight into the world of coffee. Also keep your eyes open for education events in the coming weeks and months, we have some big ideas. In fact, on that note…

If you have an interest in learning more about brewing coffee, please click here or on the picture above and book in to join us for a virtual brewing session with our partners at Cloudgate Coffee

About Bear Essentials Coffee

If you have enjoyed this or any of my writing please check out my Homepage to find out more about me and my work. Follow the blog and if you feel you can, drop a donation to support my work.

Thanks, – Bear

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