Essentials to making great coffee at home (Part Three - Brewing Process)

February 15, 2019

What about the brew process is most important?

(Did you miss parts one and two? Part one of this three part series discussed the importance of quality coffee. Part two discussed the importance of quality water.)

So you’ve procured great coffee and obtained water that is suitable for coffee brewing. Throw those together and great coffee happens, right? Right?

Brewing process must-dos

Not so fast my friend. The process of making coffee is the third piece of the quality coffee puzzle. I’m not talking about equipment or specific techniques. This post focuses only on the basics for combining coffee beans and water to brew coffee. These must-dos apply no matter what equipment you brew with.

Coffee is a solution; crushed coffee beans dissolve in water. (The entire bean isn't soluble. That's why we throw out the grounds.)  Dissolve too little or too much of the coffee in the water and the cup will taste off, imbalanced, or just plain awful. Coffee pros use the term extraction to discuss issues of solubility in coffee brewing.

The hallmarks of an under-extracted coffee include sourness and a watery or thin body. An over-extracted coffee tastes bitter and very, very strong (but not in a good way). An extraction between 18 to 22 percent is ideal, meaning around 20% of the coffee dissolved into the water. But, no easy way exists for you as a home coffee enthusiast to measure extraction directly. You can do certain things when brewing coffee to create a well-extracted brew.

Brew with hot but not boiling water.

Water temperature affects what components of the coffee bean dissolve in water and at what rate. The optimal brewing temperature is between 198 F and 208 F, give or take a degree or two. If the water is too cool, too little of the coffee bean will dissolve in the water. This results in an under-extracted brew. Water that is too hot will dissolve too much of the bean.  If you’ve ever boiled your coffee, you’ll taste the bitterness of over-extraction.

Thermometers and temperature-controlled kettles can heat water to a specific temperature. However, special gear isn't necessary to get water to the right temperature. Simply bring water to a boil, remove water from heat, and start using water about 30 seconds after. This method of using water “just off the boil” ensures the water isn't too cold or too hot. Even though we use an electric kettle at home, I've tested this method with a thermometer and use this method when camping. The coffee tastes as good as coffee brewed using a temperature-specific electric kettle.

Use coffee ground to the right size for your brew method.

Extraction depends on a combination of grind size, brew method, time of brew. If you’re grinding your own beans, start with the recommended grind setting for your brewing method. You can find this information for most grinders and brew methods with a simple online search. If the coffee tastes off, try a finer or courser setting depending on what you're tasting. Recommended total brew times for specific methods can inform grind size. If your brew is finishing too quickly, try a finer grind. If your brew is taking too long, grind on a coarser setting next time. Above all, trust what you taste and adjust from there.

(If you’re interested, Barista Hustle published this neat coffee compass where you find what tastes “off” and get some specific recommendations to fix it. Access it here.

Some coffee pros tweak the grind size based on the roast level, bean density, or humidity for perfect extraction. I don’t doubt the truth in this at all; it makes sense chemically. But personally, I find this level of dialing it in too much fuss. I’m not the kind of person who wants to ponder a grind of 13 versus 14 versus 15 for my full city Kenyan at 7:30 AM on a Tuesday. After finding a good setting for a given brew method, I just use that.

Above all, don't stress about it. A medium or medium-course grind setting works well for most coffees and brew methods.  Honestly, even if the coffee is a tad under- or over-extracted, most people will not notice.

ground coffee

Use coffee ground to a uniform size.

What do you think happens if your ground coffee is not uniform in size? Meaning, it contains powder, small pieces, large pieces, medium pieces all mishmashed together. Think about what we discussed about extraction in the previous section.

Your coffee has ALL the extractions! Super over-extracted coffee mixed with properly extracted coffee blended with under-extracted coffee. And unfortunately under-extracted + over-extracted coffee does not cancel each other out; it’s just twice as bad.

How can we avoid this horrible fate? Sorry to be the bearer of bad news: All blade grinders and most cheap burr grinders produce uneven grinds. If you grind your beans on a low-quality grinder, even just before brewing, your coffee is going to taste off.

Great coffee beans can't save it. Perfect water can't save it. Even an Instagram-worthy brewing technique can't save it.

A cheapo grinder assures that your coffee is going to always be inconsistent, yet consistently crappy at the same time.

A quality grinder is one piece of equipment that can make a huge improvement in the taste of coffee you brew at home. But good grinders aren't cheap; expect to pay at least $100-$150 for a decent burr grinder. If you aren’t ready to invest in a burr grinder, your best option is to buy ground coffee.

Yes, you read that right. I’m telling you to buy ground coffee.

You've likely heard horrible things about pre-ground coffee. And how important it is to grind your beans JUST before you brew them. But hear me out.

What I’m not telling you to do is buy pre-ground coffee off the grocery store shelf. Remember the discussion about coffee freshness? Buying close to the roast date and drinking it quickly? The “buy fresh coffee” rule still applies. Coffee from the grocery store is almost always not fresh. Lack of freshness is the bigger problem, not the fact it's ground coffee. Yes, ground coffee will lose freshness, and subtle flavors, quicker than whole beans. So don’t dilly-dally drinking it. Buy fresh and buy only what you can consume within a week, no more than two.

A pre-ground, fresh coffee will taste better than that same coffee ground on a sub-par grinder just before brewing .

Don’t believe me? People in the coffee community have actually run experiments to test this. Read about them here and here.

Many roasters don’t like to deal with grinding and some don't sell ground beans. At Slow Wave, we offer several grinding options for our customers because burr grinders are expensive and grind is important. I will admit it adds complication to our operation and it’s messy! We don’t want the fact you lack a piece of equipment to stop you from enjoying a better cup of coffee!

So until you’re ready to invest in a burr grinder of your very own, ask the roaster/cafe/store to grind the coffee for you on their boss-ass equipment.

Brew with the right ratio of coffee to water.

Another piece of the extraction puzzle is the ratio of water to ground coffee. Too much water and the coffee will taste over-extracted. Too little water and the coffee will taste under-extracted brew.

Common ratios include 1:15, 1:16, 1:17. The ratios written in this way refer to the proportion of coffee to water by weight. For example, to brew at a 1:15 ratio using 30 grams of coffee, use 450 grams of water. (Fun fact: 1 g = 1 mL of water).

Precision is less important here. For example, if brewing 30 grams of coffee, it will taste fine with 430 or 475 g of water. These ratios are guidelines to be used as a starting point to find the brew strength you enjoy for a given coffee. We personally brew at a 1:15 ratio.

Because many factors affect extraction, don’t be afraid to experiment with a higher or lower ratios to brew a cup you enjoy .


Aim for the right brew time.

By brew time, we mean time from when water touches coffee grounds to when the coffee is complete. Brew time is important because the length of time water and coffee contact affects extraction. Different equipment and methods have different target brew times. The brew time for the Aeropress is about a minute, whereas a Chemex is closer to 4 minutes.

For immersion brew methods, like French press or Aeropress, you have complete control over the brew time. Activate the plunger at a certain time to separate coffee grounds from the brewed coffee. Voila.

For pourover methods, water ratio, grind size, and pour rate affect brew time. Brew time is a diagnostic measure, giving you an idea of what to adjust to improve the taste of your cup. You'll need to adjust some or all these factors to change brew time.

For example, too fine a grind in a Chemex will extend brew time, leading to overextraction. The increased surface area of the finer grounds increases extraction. The water also moves slower through finer grounds, increasing the contact time between coffee and water.

For automatic brewers, like a Mr. Coffee, you won’t be able to control the dispense rate of the water. If you suspect an under- or over-extracted brew, adjust grind size or coffee to water ratios to try and improve it.

TL;DR: Some universal guidelines for brewing coffee apply no matter what equipment or brew method you're using. For quality extraction, pay attention to the water temperature, grind size and uniformity, coffee to water ratio, and brew time. If you like to tinker, use these guidelines as a starting point and tweak as needed to find your perfect cup!

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