Coffee Brewing Basics

This guide is not intended to be the definitive guide on brewing coffee. Its purpose is to provide principles and guidelines for brewing a good cup of coffee. A primer on coffee brewing, if you will. There is a lot that can be and has been said by coffee lovers who know much more than I do. The information in this guide reflects my current understanding and may change as I continue to learn.

The Basics

One simply can’t discuss coffee brewing without using the term extraction. In brewing coffee, extraction is the process by which water pulls soluble compounds from the coffee beans. Extraction also describes what we end up with in our cups. It’s the totality of everything, all the compounds and chemicals removed from the coffee. There is an ideal amount of extraction, and there is neither too much nor too little extraction. Not enough extraction is called under-extraction. Meaning the water didn’t pull out enough soluble compounds. Too much extraction is called over-extraction. You guessed it, the water pulled out too many compounds. If you have a bad-tasting cup of coffee, it may not be the coffee beans. It could be that the coffee was either under- or over-extracted.

There are many variables that affect extraction, and our goal is to provide you with the knowledge to hit the ideal extraction and troubleshoot your coffee when you don’t.

The Water

Quality

Whether you are on city water or well water, most of us probably don’t have much control over the water we use to brew our coffee. Just realize that the quality and chemistry (hardness, pH, and other nerdy stuff) will affect how your coffee tastes. If you are having difficulty getting your coffee to taste good, maybe you should try some filtered water. Carbon-filtered water would be the minimum.

Temperature

The temperature of the water affects extraction. Think back to your high school chemistry class. What does heat do? It speeds up processes. If all other variables are the same, hotter water will extract more from the coffee than colder water. Hotter water increases extraction.

If you can control the water temperature you are brewing with, use 200 °F as a starting point. If you don’t have control over water temperature, then that is one less parameter you can't tinker with to dial in your brew. Depending on your personality type, this could be a good or bad thing.

The Coffee

Quality

It goes without saying, but coffee quality matters. Coffee comes in a wide range of qualities. Research the company you are buying coffee from. Here at Wacker Coffee Co., we only purchase coffee that is Grade 1 or equivalent (different origins use different grading scales) and has a Q score of 85 or higher. The grade reflects the physical qualities of the coffee. For example, how many defects are there in a sample size? What elevations was it grown at? What size are the beans? A Q score is generated by a qualified tester. They judge the coffee based on many factors and arrive at a score. Anything above 80 is considered a “specialty” coffee grade. Anything above 90 is rarer and more expensive.

Freshness and Storage

After roasting, coffee needs to rest for at least three days. I prefer 5, but 3 is the minimum. Carbon dioxide is trapped in the coffee after roasting, preventing extraction. A few days are needed for the CO2 to off-gas. It is true that there is an 8- to 24-hour window after roasting to taste the coffee, but you will only get fresh coffee if you are roasting your own. Check the roast date on the bag and ensure it's been a few days since then.

After letting the coffee rest for three days, you have about four weeks before the coffee's flavor deteriorates. Exposure to air reduces the flavor of the coffee. Given that coffee is good for about three weeks, there is no need to store the coffee in the fridge or freezer. The only way to slow coffee's aging is to store it at -10 °F. I doubt your freezer goes that low. In addition, coffee is porous and, if not sealed properly, will absorb odors from the fridge or freezer. If you don’t consume 1 pound of coffee in 3 weeks, you should consider your life choices. It’s time to up your consumption.

Store coffee in the bag it came with. After you get what you need to brew, push the air out of the bag and then seal it back up. Remember that air is coffee’s enemy.

Weighing

I would suggest getting a scale with grams and a resolution of .1g if you don’t already have one. Weighing your coffee and water will ensure consistent cups of good coffee and allow you to troubleshoot subpar cups. A measuring scoop is inconsistent, and the weight of the coffee will vary by roast degree. Darker roasts contain less moisture. Therefore, a ½ cup of dark roast coffee will weigh less than a ½ cup of light roast coffee.

Use a ratio of 1g of coffee to 17g of water as a starting point. To calculate this ratio, you must know how much water in grams your brewing method uses. Do not go by how many “cups” the equipment is, and then figure out how many grams of water that equals. For some reason, a coffee cup is typically 5 ounces, not 8. Anyways, divide the water's weight by 17, and the result is how many grams of coffee to use. Weigh the whole beans and then grind. This way, you only grind what you need.

The Grind

Burr Grinder

It is preferred that you grind your coffee with a burr grinder right before you brew. Why? There are a few reasons. First, whole-bean coffee stays fresher for longer. Ground coffee exposes more surface area of the coffee to the air, and air is the…….anyone? Anyone? Air is the enemy of coffee. More of the coffee exposed to air means it loses its flavor faster. Second, a burr grinder produces a more consistent particle size than a chopper-style grinder. This is important because it will result in more even extraction. Different-sized coffee particles yield different amounts of soluble compounds being extracted. A coffee bean ground into a smaller particle will yield a higher extraction than a larger particle because more of the surface area of that bean is exposed to the water. Third, having your own grinder lets you adjust the grind size. This will enable you to troubleshoot your coffee cup and grind for various brewing methods you might use. This will be discussed later.

It is preferable not to use a chopper-style grinder because particle size will not be consistent, which can lead to poor extraction. Not only will it produce everything from fine to coarse particles, but each time you use it, you will have a different grind compared to the previous time.

Coffee Particle Size

Particle size matters. The size of the coffee particles is determined by how long the water is in contact with the coffee. Just remember that the longer the brew time, the coarser the grind. Or, put another way, the shorter the brew time, the finer the grind; e.g., cold brew and French press have longer brew times, so they require a coarser grind. Espresso takes less time and requires a finer grind. This is because quicker brewing methods require more surface area, provided by a finer grind, to extract the proper amount of coffee for a good cup of Joe. During longer brew times, water spends more time in contact with the coffee. Therefore, proper extraction requires a coarser grind (less surface area).

Troubleshooting

Under extracted

Signs of under-extracted coffee are an unpleasant sourness or tang, a lack of flavor, and saltiness. To fix an under-extracted coffee, you can increase the water temperature, increase the brew time, or grind slightly finer.

Over extracted

Signs that your coffee is over-extracted include a bitter or woody flavor, a dry mouth, or a hollow, empty flavor. To fix over-extracted coffee, you can decrease the water temperature, shorten the brew time, or grind slightly coarser.

Too Weak

Increase the amount of coffee and go a little finer on the grind.

Too Strong

Decrease the amount of coffee and go a little coarser on the grind.

For a lot of coffee drinkers, the only things you can adjust are the coffee dose and maybe the grind size. That’s okay. Adjust what you can and have fun tinkering. There are three things in life a person needs to be picky about: the person you marry, the beer you drink, and the coffee you drink. I can’t help you with the first two, but I hope this guide and the coffee we roast help you with the third.