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Brew Quest Coffee Basics 101: Turning Water Into Coffee

Timothy Boyer Ph.D.'s picture
Turing water into coffee is a daily miracle of its own.

Discover the basics of what happens the moment hot water and ground coffee begin the miracle of transforming water into liquid bean.


If all coffee beans were the same, life would be dull. Fortunately, the physical and chemical variations of the coffee bean is what holds the promise that our next cup of coffee—whether at a coffee shop or at home—may provide a new drinking experience.

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It is this irregularity of coffee beans and the fact that beans age rather quickly, that this holds true whether the beans come from the same or different sources.

Another factor…out of many…is that of the brewer and how he or she chooses to essentially squeeze with a machine or gently coax with a pour over method, the hidden flavor and essence the coffee bean guards so jealously like dragon gold. Think that this is an exaggeration? Read on.


When hot water and ground coffee meet, extraction happens. Think of extraction as being like trying to get a skinflint to open his wallet and make a monetary contribution to a cause—it doesn’t always come easy, but you are reasonably assured there may be a few bills, some loose change, an expired coupon and maybe even cobwebs.

From ground coffee you can expect a variety of three important components (1) soluble and insoluble gases, (2) oils and (3) solids, that gives coffee its flavor and texture. Flavor we all have a good idea of what that is. But what do we mean by texture?

Texture is important. Basically, it’s that “feel” we experience when something passes over the tongue that can affect our perception of taste. One example is that of cereal from the bottom of the box. There’s a reason why many of us never completely empty the last bit of cereal out of the box into our bowl of milk. It’s because as kids we learned that there is something yucky about how that cereal dust tastes when we spoon it into our mouth. An unpalatable mush. Texture.

And regarding soluble and insoluble, basically what it comes to is whether something dissolves in water or not, respectively. If a component does not dissolve, it may exist as a free floating miniscule solid, a bubbling gas trying to break the bonds of cohesion at a liquid’s surface; or, a floating oil slick. All of which add to texture. Which, hence, affects taste and your coffee drinking experience.

A Breakdown of the Three and Why They are Important

Soluble and insoluble gases—when hot water meets ground coffee, chemical reactions occur and result in soluble and insoluble gases that give coffee its aroma. In fact, the temperature of water mixed with coffee and the amount of time passing are strong determinants of what aromas are released and detectable. If you take a whiff of coffee as it is brewing, and after it is poured into a cup, and once again after it has cooled some, you can expect to find that the aroma changes over temperature and time.

Insoluble oils—when hot water meets ground coffee, insoluble oils trapped within the bean are also released. If the coffee is brewed without a cloth or paper filter—but with a metal mesh screen of some sort to keep the grounds from passing into the brew collector or cup—the insoluble oils will float on the coffee’s surface like an oil slick over water. However, if a cloth or paper filter is used, typically the filter will trap the oils and prevent them from going into your cup.

The significance of this is that the oils impart both texture and taste that can be described as being somewhat buttery to the palate. Therefore, depending on your filter type, you can expect a difference in the resulting taste while brewing.

Insoluble solids—as mentioned earlier, solids that do not dissolve become free-floating agents that provide texture and some taste. At its worst, too much of this can make a coffee feel gritty as if some of the grounds made their way into the cup.

Soluble solids—are the most important of the components. They are the ones largely responsible for whether the coffee tastes sweet, salty, acidic, savory or any combination of the sensations, including other flavors that taste chocolatey, nutty, etc.

But There’s More…

When I discussed the irregularity of coffee beans earlier and how the hand of the brewer shapes the taste by enticing the bean to release its flavorings, it turns out that there is more than just the aforementioned three components when water meets bean and the flavors released: There’s also what was done to the bean before it is ground—the roast.

Roasting is best handled later in another article. For now, what you need to know and understand is that basically, how a bean is roasted determines what forms of the three main components become available for extraction.

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In particular, there is a caramelization process of sugars within the bean where heat transforms (i.e. breaks down) sugars into different types that not only causes a change in color, but also causes a wide range of transformed and unlocked flavors such as butter, butterscotch, nuts, malts, rum, etc.

These sugars give coffee its sweetness. But, if roasted too long and/or too hot enough, that sweetness disappears and imparts more of a bitter flavor such as that found in dark roasts and over-roasted coffees.

And, there’s one more important factor: Time and how well the extracted components dance together.

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As it turns out, not all of three component types are released equally or at the same time. And, while some may complement each other, others paired together are as abrupt as a dancing partner stepping on your toes. In other words, depending on the bean, the extraction process with respect to time needs to be worked out so that the complementing and non-complementing components reach a balance that is just right for your palate.

And how do achieve this? By carefully timing just how long the extraction process takes when water first meets ground bean, while discovering through tasting at what point your brew reaches the boundary between being under-extracted and over-extracted where you will find great taste.

What You Can Do In Your Kitchen

Now is the time to put into practice what you have learned thus far. Depending on what you already have in your home, the main point is to collect the brewed coffee in equal amounts sequentially as water passes through the ground coffee so that you can sample and compare the differences in taste with each stage of extraction.

My recommendation is to buy a Vietnamese Phin filter system. It is relatively inexpensive, simple to use, great for experimenting, easy to clean, and makes pretty good coffee without stressing over the process.

Here is a video I picked on how to use a phin that demonstrates the simplicity and steps toward getting it right. Please note my adjustments and advice after the video;

How to Use a Vietnamese Phin for Brewing Coffee

Adjustments to the Video Technique on Using a Phin

1. For your purpose of testing extraction at differing extraction stages, I would recommend using 4 identical small lab-style beakers because they have graduations already imprinted on the side to tell you when exactly to switch from the first extraction to the second to the third, etc. The drip rate will likely change as the extraction progresses. What you want to shoot for is that each extraction is exactly the same amount. Roughly, aim for about 30 seconds to a minute per extraction. You only need just enough for a sip or two from each extract stage.

2. Skip the added sweetened condensed milk for now, since this is really about taste comparing what you get with each sequential extract. The condensed milk will mask some of the flavor differences.

3. Preheat the beakers in a flat shallow tray to keep them and the extraction warm until you are ready to taste and compare. Simply transfer the phin from one beaker to the next when it is time. No need to worry about losing a drop or two.

4. Preheat the phin as well with hot water before adding the ground coffee.

5. You can try bagged pre-ground Vietnamese coffee since it should have the correct grind and recommended dosage for a phin, but it will also work with any whole beans as long as you grind the beans fine enough for the metal filter used in the Phin system. It may take a little practice to get it right, but is well worth the effort.

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6. Take notes, learn, and enjoy.

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.

Earlier, I had mentioned that I like books that trouble the mind. The ones you start with coffee, but end up drinking something stronger towards its bitter or bitter-sweet end. One example is “Burmese Days” by George Orwell.

What got me thinking about it lately was some essays I had been reading about “privileges” and what it means today. In particular, an essay that challenges the use of the word and how that it is more accurate and constructive to replace “privileges” with the word “advantages” when it comes to framing a conversation addressing race relations. You can find it in a reference link below.

My recommendation is to read the essay, and then Burmese Days, which although dated holds some uncanny semblance to what is happening today where we might be witnessing an end to a type of colonialism of our own making. And then ask yourself, Am I living a privileged life or an advantaged life? And what does it mean?

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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 thanks to Battlecreek Coffee Roasters for sharing their work on Unsplash.

Reference: “The Language of “Privilege” Doesn’t Work” by Stephen J. Aguilara, provost postdoctoral scholar for faculty diversity in informatics and digital knowledge at the Rossier School of Education at the University of Southern California. Nov. 2016.