The only post you will ever need to read to understand coffee brewing

by Joseph Trichilo

Ok, maybe not the only one, but for those that are trying to refine their knowledge of coffee brewing, this post will help tie everything together.

As simple as it may seem to brew a cup of delicious black coffee, understanding the nuances of the quality of your brew can be overwhelming. The idea behind this post is to compliment your understanding of coffee by explaining the coffee brewing control chart published by the SCAA.

In a previous blog post written on Medium – GETTING THE BEST OUT OF YOUR ROASTED COFFEE BEANS – I discuss a blueprint on how we can optimize the flavours of our favourite roasted coffee beans. The blog post examined brewing using a single coffee-to-water ratio, which did not go into detail about making delicious coffee at various concentrations using multiple ratios. We are not constrained to a single dose of coffee per volume of water, and, in my opinion, understanding this idea is the key to grasping the complete nature of coffee brewing – I say this because it allows you to focus on the big picture of coffee brewing and not on a single aspect of it.   

The Specialty Coffee Association of America has published the following coffee brewing control chart:

This graph charts a variety of coffee doses per liter of water used in the brewing process, with resulting strengths and extraction yields, as well as suggesting an optimum balance. The ideal range after brewing is between 18% - 22% extraction, with strength between 1.15% - 1.35%. Extraction is the percentage of the dry coffee dose that finds its way into the final beverage, while the strength is the concentration of the dissolved coffee in the mixture. Extraction is the result of the variables controlled during the brewing process, such as the coffee-to-water ratio; quality and size of ground coffee; and the temperature and quality of your brewing water, to name a few. Extraction affects brew time, and vice-versa, which is a very important indicator of the quality of your brew. The concentration will influence your perception of the final cup profile.

Before we dive into manipulating the control chart, a quick example will help you understand how the chart is used. Consider the following brew:

  • A coffee-to-water ratio of 60 grams per liter is used, as shown in the brewing control chart
  • We achieve 19% extraction, meaning that 19% x 60 grams = 11.4 grams of coffee finds its way into the final mixture
  • After losing water to spent coffee grounds, plus some evaporation, and adding the extracted coffee solids, we are left with approximately 900 grams of coffee
  • The strength of the final beverage is 11.4/900 = 0.0127 or 1.27%

Holding the 60 grams per liter ratio as a constant, you can manipulate the extraction percentage by manipulating some of the other variables explained earlier, for example, the grind size. This manipulation will allow you to move along any brewing ratio line, which will not only alter the extraction percentage, it will also affect the strength of your beverage, and ultimately your experience of a particular coffee.

Let us take this concept one step further and look at the brewing chart in a slightly different way:

The Coffee Brewing Control Chart is an overview of all possible profiles for your delicious bag of roasted coffee. Each area will manifest slightly different perceived characteristics within the cup. The intensity at which you perceive these profiles depends on the starting coffee-to-water ratio and the extraction. We want to stay away from the under and over extracted areas of the chart, which is done by controlling the time of your brew – see GETTING THE BEST OUT OF YOUR ROASTED COFFEE BEANS.

Directly above and below the area of optimum balance shows ideal extraction, however, it is probable that you view these areas as being too strong or too weak. Unless you enjoy a stronger beverage as I do, you can dilute coffee that falls in the area directly above the optimum balance, allowing you to obtain your desired strength – this is the point. We define this as a bypass, as you are bypassing extraction and only affecting the strength of your beverage. The concept of a bypass is valuable as it empowers brewers with knowledge of the entire scope of coffee brewing. We are not limited to a single recipe, and this knowledge allows us to brew with purpose. As one of many examples, this knowledge allows you to craft larger batches on your equipment, by creating a highly concentrated beverage and using a bypass.

As a final example, I typically use a starting ratio of 16.5 grams of coffee to 250 grams of quality brewing water. This starting ratio falls on the coffee-to-water ratio line of 66 grams per liter. With ideal extraction, we are looking at an area of high strength. For customers that are more sensitive to the strength of the beverage, adding the desired amount of hot water to the coffee will create the desired balance without altering the flavours of the beverage, just the perception of these flavours. Effectively, the bypass will achieve the same extraction at a weaker dose.

Some Added Perspective:

How do we obtain ideal extraction without owning a fancy refractometer?

  1. By understanding the inner workings of your brewing set-up
  2. By understanding the taste of your brews
  3. Most importantly, by tracking brew time and recording the time that gives you your ideal profile preference – I would recommend you stay consistent with your system of brewing and only change the grind setting to alter the brew time, or in other words, the extraction.

Let’s take the following set-up:

Ratio: 16.5 grams of coffee to 250 grams of quality brewing water

Method: Hario V60 Pour-Over

Filter: White Paper

With the above set-up and my brewing technique, I usually find, on average, that I enjoy my brews most when they end at 2 minutes and 45 seconds. If you know your brew is going to run longer than your ideal time, you can stop your brew prematurely at your ideal time and use a bypass to return to optimal strength.

The ratio is very important, and it is very useful to use the control chart when developing your coffee recipes. Most importantly, as coffee brewers, I believe that if we view brewing from a bird’s-eye view, it will facilitate in understanding the interactions within our system. I believe that it is then that we can truly master the art of brewing great coffee.

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