What Affects the Taste of your Coffee Brew?

Learn how to get that barista-crafted flavor from your home brew

It’s the most frustrating part of the journey to better coffee. You purchase a bag of coffee from your favorite local roaster (hopefully), grind it up, brew it, and… it’s just not the same. Did they sell you the wrong beans? Is your equipment not fancy enough? Is the barista a wizard? All of these very valid questions arise as you try to figure out where you went wrong.

Fortunately, there are other possible reasons for your less-than-stellar brew. Coffee is one of the most chemically complex foods that we consume, and the process from farm to cup isn’t much different. By the time you purchase your bag of coffee, the farmer, roaster, and barista have all done their part. Now, it’s up to you, the consumer, to do yours.

Don’t worry! It doesn’t have to be hard to get great coffee at home! Your home cup can be improved by paying attention to a few variables: water, beans, grind, and ratio.

Bean Freshness

The first way to improve coffee quality, if you change nothing else, is to improve your beans. Coffee is just like any other food – it can and does go bad. And contrary to popular belief, coffee doesn’t have a very long shelf life.

As coffee is roasted, gases are formed inside of the bean. The majority of carbon dioxide and other gases leave the beans over the course of the first few days following a roast. After this window, which varies from batch to batch, the coffee enters its optimal time to be brewed.

Brewing coffee too soon often results in an uneven extraction because CO2 escapes rapidly from the bean, pushing water away instead of in contact with the beans (this is why coffee bubbles or “blooms” on initial contact with water). On the other hand, waiting too long to brew or pre grinding your beans exposes them to oxygen, speeding up the oxidation process. Oxidation causes foods to spoil. It’s the same reason apples become brown when exposed to oxygen.

Your best bet: treat your coffee as you would any other perishable grocery and buy only what you will use over the course of about a week.

Should you buy oily or dry coffee beans? Find out what the oiliness means for your coffee brew.

Grind size

In addition to the timing of your grind, grind size also plays a major role in your cup of coffee. When we brew coffee, what we are aiming to do is extract coffee from the beans. The rate of this extraction depends on the surface area of coffee grounds.

Finer grinds expose more surface area and allow for more rapid extraction and thus a quicker brew time. Conversely, more coarse grinds result in a slower extraction and thus needs a longer brew time. If your brew method involves water passing through and spending less time in contact with coffee grounds, such as espresso or a pour over, a finer grind is preferable. If using a full immersion method, such as a french press, where coffee is in constant contact with water, a coarser grind should be used.

A good rule of thumb for troubled brews: if your coffee is too far on the bitter side, it is over extracted and a coarser grind should be used. If it’s too sour, weak, or watery, it is likely under extracted and can be corrected by using a finer grind.

By far the most accurate way to ensure a consistent grind size is to invest in a burr grinder. Blade grinders (grinders with two spinning blades, like a blender or food processor) don’t allow for a reliable, uniform grind.


Bad water makes bad coffee. It’s as simple as that. A cup of coffee is 98% water, so if you wouldn’t drink it, you probably don’t want to brew with it. The water you use should be clean and free from any strong odor or taste, such as chlorine. Use filtered or bottled water whenever possible to ensure a better water for your coffee.

Time, Turbulence, and Temperature: The 3 T’s of Coffee Brewing


Time is one of the most important variables when brewing coffee. The longer your coffee is in contact with water, the more extraction occurs. Ideal time for brewing varies depending on grind size and brew method. Full immersion methods and coarser grinds usually require longer brew times. Conversely, drip methods and finer grinds will call for a shorter brew time.


Put simply, turbulence refers to water passing through and over coffee, allowing them to mix. Different brew methods require different types and rates of turbulence — fast or slow pour, stirring the grounds, etc. Usually, you want to ensure that all of your grounds are immersed in water while keeping your turbulence to a minimum, as too much turbulence makes recipes difficult to repeat from brew to brew.


The water temperature is extremely important to brewing coffee. If your water is too hot, you run the risk of over extraction. Water that’s too cold will result in an under extracted cup. According to the SCAA Coffee Brewing Handbook, Your water should be between 195F and 205F (91-94 C).


Almost everyone uses recipes for cooking but for some reason most people skip any kind of recipe or directions when brewing coffee. Now that you’ve learned all about the variables the affect coffee above, you can probably guess that this is a big mistake.

When brewing coffee, your ratio is simply the amount of ground coffee to the amount of water used. Knowing your coffee to water ratio ensures a consistent cup every single time.

The most efficient way to measure your coffee and water is by weight using a scale. A lot of people measure their coffee by the scoop. This is deeply flawed and inconsistent because coffee beans vary in size and density. Investing in a cheap, small kitchen scale is one of the easiest ways to improve your home brews.

A Final Tip

If you’re aiming to get a consistent cup every time, log your brew. Grab a small notebook or use your phone to write down the specifics of each step of your brewing process. This allows you to change one of the above variables at a time until you discover what works best for you. This can involve changing your grind size, water temperature, origin of your beans, etc.

There are many variables that affect your brewed coffee. Now, of course, the best coffee to drink is the one you enjoy. But if you’re going to be spending money on quality coffee, now you have a better idea of how to make it worth it.