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The Detailed Version of Brewing Coffee at Home
Posted on December 23 2023,
This guide is not intended to be the definite guide on brewing coffee. Its purpose is to provide some principles and guidelines explaining how to brew 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 contained in this guide is my current understanding and may change as I am always learning more.
One simply can’t discuss coffee brewing without using the term extraction. In relation to brewing coffee, extraction is the act of the water pulling out 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 not enough or too much 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 that ideal amount of extraction and troubleshoot your coffee when you don’t.
Whether you are on city water or well water, most of us probably don’t have a lot of control over the water we use for brewing 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.
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 pull more out of the coffee than colder water. Hotter water increases extraction.
If you have control over the temperature of the water you are brewing with, use 200 °F as a starting point. You will need to decrease this temperature by 2 degrees for every 1,000 feet above sea level you are. So, if you are 2,000 feet above sea level, your starting temp would be 196 °F. If you don’t have control over water temp, then that is one less parameter you can tinker with to dial in your brew. Depending on your personality type, this could be a good or bad thing.
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 have different grading scales) with a Q score of 85 or higher. The grade has to do with 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 on many factors and end up with a score. Anything above 80 is considered “specialty” coffee grade. Anything above 90 is rarer and more expensive.
Freshness and Storage
After roasting, coffee needs to rest for at least 3 days. I prefer 5, but 3 is the minimum. Carbon dioxide is trapped in the coffee after roasting, preventing extraction. A few days is needed for the CO2 to off gas. It is true that there is about an 8 to 24 hour window after roasting for you to taste the coffee, but you will only get coffee that fresh if you are roasting your own. Look at the roast date on the bag and ensure it has been a few days since then.
After letting the coffee rest for 3 days, you have about 3 weeks until the flavor of the coffee deteriorates. Exposure to air is what decreases the flavor of the coffee. Given that coffee is good for about 3 weeks, there is no need to store the coffee in the fridge or freezer. The only way to slow the aging of the coffee 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 smells that are in 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.
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 weight of the water 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.
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 will allow you to change the grind size. This will enable you to troubleshoot your cup of coffee and grind for various brewing methods you might use. This will be discussed later.
It is preferred not to use a chopper-style grinder because the particle size will not be consistent, and that can lead to poor extraction. Not only will it produce everything from fine to coarse particles, but each time it is used, you will have a different grind when compared to the previous time.
Coffee Particle Size
Particle size matters. The size of the coffee particle is determined by the amount of time the water is in contact with the coffee. Just remember that the longer the brew time, the coarser the grind. Or said the other way, the quicker the time, the finer the grind, e.g., cold brew and French press have longer brew times, so they require a coarser grind. Espresso is a shorter time and needs a finer grind. This is because quicker brewing methods need more surface area caused by the 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).
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.
Signs that your coffee is over-extracted are a bitter or woody flavor, it leaves your mouth dry or has a hollow or empty flavor. To fix over-extracted coffee, you can decrease the water temperature, shorten the brew time, or grind slightly coarser.
Too Weak of Coffee
Increase the amount of coffee and go a little finer on the grind.
Too Strong of Coffee
Decrease the amount of coffee and go a little coarser on the grind.
For a lot of coffee drinkers, the only thing you will be able to adjust is the dose of coffee 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.