While coffee is naturally bitter, excessive bitterness may result in an undesirable overall drinking experience. It is important to note that while this bitterness is an undesirable effect, astringency in coffee is merely a result of the interaction of some coffee compounds and salivary proteins.
However, if your coffee is unnaturally bitter, or you’re looking for ways to counter the natural bitterness of coffee, read on.
Reasons Why Your Coffee is Bitter
Using The Wrong Type Of Coffee
The most common species of coffee are Arabica and Robusta. Robusta coffee is naturally more bitter than Arabica varieties due to higher caffeine and chlorogenic acid (CGA) content.
Flavor profile on the other hand is usually determined by factors like growing regions and altitude. However, growing conditions can also affect CGA levels in plants. Meaning environmental impact, plant stress, and other external factors increase CGA levels. This explains why Robusta coffee, which is grown in harsh conditions, contains higher levels of CGA.
- Arabica coffee contains 0.9 – 1.2% caffeine and 5.5 – 8.0% CGA.
- Robusta contains 1.6 – 2.4 % caffeine and 7.0 – 10.0 % CGA (1).
As you can see, caffeine accounts for some of the bitterness but CGA is primarily the cause of astringency in coffee.
Arabica coffee has lower caffeine content and less CGA and with it, a naturally sweeter taste, albeit more acidic.
Consider going with a naturally sweeter Arabica variety if Robusta is too bitter for you. You can further reduce the level of bitterness by opting for a decaffeinated option as well.
Using The Wrong Roast
Dark roasted coffee beans have a stronger “roasted” quality in their flavor profile. With that comes a noticeable bitterness or burnt quality. Dark roasted beans actually contain less caffeine than light but are more bold because the quinic and caffeic acids have developed. Quinic acid results in a bitter, astringent taste.
As we mentioned above, both beans contain Chlorogenic acid which is bitter to start with. You’re then dark roasting the bean which makes them even more bitter as the quinic acid develops. Then as you brew the coffee and let it sit on the hot plate it continues to develop the quinic taste.
The chemical composition of medium and dark roasted coffee differs a lot. Dark roasted coffee is bitter due to the lower acid content, higher soluble solids, and weaker aroma. Medium roasted coffee has a higher acid content, stronger aroma, and smaller amount of soluble solids.
On the opposite end of the spectrum, a light roast is a mild coffee variety. Lighter roasts are often noted for having floral and fruity/sweet notes with a mild body.
Choosing The Wrong Grind Size
The overwhelming bitterness may be a result of using the incorrect grind size.
While the brewing technique you use does matter, using grinds that are too large/coarse will normally result in a lighter, weaker cup of coffee. This is because of interaction between the water and the ground coffee.
A coarse grind can result in under-extraction as the water runs over the coffee.
On the other hand, using finely ground coffee can offer a relatively bitter cup as the coffee can be over-extracted.
Here’s a quick guide of grind sizes to use for the more popular brewing methods:
- Moka Pot
- Turkish Coffee (Extra fine)
- Drip Coffee
- V60 (Medium Fine)
- Chemex (Medium Coarse)
- French Press
Using The Wrong Type of Water
A cup of coffee is 98% water. Needless to say, the type of water you use and the temperature of that water is important. If you’re noticing that your coffee is bitter or astringent, then there may be a chance your water is the culprit.
Water from your tap often contains more than just water. There are a large amount of solubles and solids; For instance minerals and other organic substances.
The Specialty Coffee Association of America (SCAA) has a detailed breakdown of water standards for superior extraction of coffee solids. They are the following:
Magnesium is noted for being able to extract sharper, fruitier flavors. Calcium is noted for being able to extract heavier, creamier flavor notes. The carbonate in the water is able to soak up acid and acts as a regulator and stabilizes acid levels.
So as we can see, these minerals in water are important. This is why you should avoid distilled water because it lacks the necessary mineral content to extract the flavors from the coffee. Instead you should invest in a filter that’s able to filter for the desired ppm levels specified above.
It is also important to ensure that the water heats up to an adequate temperature. Colder water results in flat, under-extracted coffee. While water that’s too hot can result in poor coffee due to loss in quality.
The SCAA recommends a range between 195 and 205 degrees Fahrenheit. If you don’t have a thermometer, simply let the water come to a boil (212 degrees Fahrenheit). Then take off the heat and allow to stand for 30 seconds. Then use the water for brewing.
Using The Wrong Brewing Method
The brewing method used also influences the resulting taste of your coffee. It has been scientifically proven that the compounds in coffee, which contribute to the resulting taste of each cup, are extracted at different rates, some faster than others, during the brewing process. Over extraction of these compounds, especially soluble solids, results in an overpoweringly bitter brew.
To reduce the bitterness of your coffee, consider using brewing methods that reduce the likelihood of over extraction. This might mean using coarser grinds, or a drip system instead of a French press.
You should also use the right coffee to water ratio. The “golden ratio” of one to two tablespoons of ground coffee to every six ounces of water is standard.
Using The Wrong Type of Milk
A variety of coffee beverages require the addition of milk; These include macchiattos, cappuccinos, and lattes.
It’s important to consider how the flavors in soymilk, dairy milk, coconut milk, and almond milk interact with the coffee beans you are using. This is because some milk flavors may be too weak or overpowering.
Take the time to find out how well different types of milk go with specific coffee beverages.
Most people don’t know the average lifespan of roasted coffee beans. It’s generally recommended that the coffee beans be used six weeks after being roasted. If you use stale beans you are likely to end up with bitter coffee.
When purchasing coffee you should opt for whole bean instead of pre-ground. Pre-ground coffee is more apt to stale faster as the oxidation process is accelerated. The beans should also be roasted 1-2 weeks prior to purchase. You should also determine how much coffee you drink in a 4-6 week span and only buy what you need.
You should store coffee beans in an air tight container (preferably with a CO2 release valve), in a cool dry place, and away from sunlight. This ensures the beans stay fresher, longer.
It’s also recommended that you buy whole beans and put off grinding until you’re ready to brew coffee.
If your coffee is too bitter, any of the above reasons might be to blame. Remember though, coffee is known to be naturally flavorful as well as slightly bitter.
- Rivera, J. A. (2015, April 23). Chlorogenic Acid. Retrieved from https://www.coffeechemistry.com/chemistry/acids/chlorogenic-acid.