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Brew Quest Coffee Basics 101: What Really is Strong Coffee?

Timothy Boyer Ph.D.'s picture
Strength in coffee is not what you may think.

Discover now how the correct use of two common coffee terms can further your understanding of coffee brewing and demonstrate to others that you can talk the talk while learning how to walk the walk.


Talk the Talk

As with any profession, job-specific lingo is one of the defining characteristics that separates the newbie or the poser from those who know what they are doing and talking about. Yes, it smacks of pretention, but it also gives our BS meters a detectable signal alerting us as to whether someone is providing us with accurate information or are faking it.

However, there is also a positive to job-specific lingo. It shortens communication to where even a single descriptive word can carry more impact and information than a long drawn out ramble or PowerPoint presentation. With lingo, brevity rules; But you have to know the coffee-speak.

In the world of serious coffee drinkers and brewers, two descriptive words used to evaluate a cup of coffee are its “Strength” and its “Yield.”

The Yin and Yang of Coffee

“Strength” seems easy enough. However, many people mistake the strength of a coffee based on a preconceived notion that it has to do with the immediate impact of taste likened to a slap to the senses; or, that it has to do with just how caffeinated the beverage is toward providing a caffeine rush.

“Yield” on other hand is a little more esoteric. However, it generally is associated with the understanding that it answers the question, “What do you get back, after putting something in? And thus it is with coffee, in this sense and meaning of the word.

What makes “Strength” and “Yield” especially relevant together is that you can think of the two words as the Yin and Yang of coffee—that which together brings balance to a coffee’s taste.

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The Strength of Your Coffee

Technically, “strength” in the coffee world is a measure of the total dissolved coffee solutes (TDCS) in your brewed coffee. The components that flow over your tongue that gives you the sensation of the body a beverage possesses. An apt example is to imagine the difference in feel over your tongue when you take a sip of skim milk followed by a sip of whole milk or even cream. Either can be pleasurable to the tongue, but each is distinctly different in how it “feels.”

With coffee, one brew that has more TDCS than another will taste stronger. Whereas the brew with fewer TDCS will taste weaker. And of course, this is a matter of personal preference; however, it turns out that for most of us, the distinction between the two falls within a mathematical difference between 1 and 2 percent. That’s right. Our tongues can detect the difference between 1 and 2 percent TDCS from a sip and be classified as either being weak or strong respectively. Not so surprising though when you realize that you can tell the difference between skim and 2% milk in a taste test.

But strength alone cannot successfully carry the flavor of a cup of coffee. It also needs some help from the other half of coffee’s yin and yang—its yield.

The Yield of Your Coffee

Yield is a measure of the extraction of the soluble components of coffee, some of which (but not all) that gives “strength” its body that you feel on your tongue.

Remember earlier, we learned that the longer a grind is exposed to hot water, the more the grind becomes extracted. And, that if you extract too much, the coffee is bitter. This is why brewing is reliant on time as you are coaxing what you want out of the bean and into your cup—in other words, its yield.

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Physically extracting out as much solubles as possible out of a coffee bean comes to about 30% of what makes a bean a bean. However, this is the high side of over-extraction. The number brewers typically shoot for is an extraction of 18 to 22 percent.

Depending on the bean source, an extract of 18% can typically taste under-extracted and thus be less flavorful, and possibly sour. Whereas, with the same source of bean, an extract of 22% typically can taste over-extracted and be bitter or astringent.

The Right Balance

What this boils down to is that for a brew to be successful, there has to be a yield that releases just enough of the taste components (which are not released equally from the bean) so that a balance is achieved between a narrow window of under-extraction and over-extraction, while at the same time providing the strength the tongue needs to sense that is pleasurable to individual preferences.

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Scientists have broken down strength and yield as falling between 1.15 and 1.35 percent for strength, and 18 to 22 percent for yield as the ranges that together appeal to taste buds in general quantifying as determinants of good coffee.

That said, it is possible to have overly strong coffee with weak yield (under-extracted), as it is to have a weak coffee with a high yield (over-extracted), depending on the bean and your brewing technique and method.

I like to visualize this as a taste meter device with two side by side needles swinging in opposite directions that cross over one another when just the right strength and yield combination produce the best taste from a grind.

The point here is that with an industry standard understanding of some of the coffee lingo used, you will have also added to your understanding of what it takes to create a great cup of coffee.

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In a future Brew Quest 101 article, we will learn how you can influence both strength and yield by experimenting and controlling the factors that coax the soluble components out of your grind.

Coffee Talk

Coffee Talk is meant to encourage discourse between you and someone you are having coffee with, as well as for the comments section below. If you agree or disagree with the topic and what is said, or have something you would like to share, Coffee Talk is there for you.

Since the Yin and Yang metaphor seemed apt when discussing how that strength and yield are so important toward achieving balance in your coffee, here is one post by a healthcare provider who gives her view on how coffee fits in with Traditional Chinese Medicine.

Timothy Boyer has a Ph.D. in Molecular and Cellular Biology from the University of Arizona. For 20+ years he has been employed as a freelance health and science writer. Timothy continues writing about science with a focus on the connection between coffee and healthy living. For continual updates about the benefits of coffee on your health, you can also follow Timothy on Twitter at TimBoyerWrites.

Image Source: Photo by John Schnobrich on Unsplash

Reference: “Coffee Benefits and Risks” by Dr. Caitlin Gordon, D.Ac., C.M.F.P., a functional medicine clinician, board-certified doctor of acupuncture, and transformative health coach based in Boulder, Colorado and owner of Amaluna Wellness.