I look forward to getting up out of bed and starting my day by brewing the perfect cup of fresh coffee. But if you’ve ever brewed a cup to find yourself disappointed upon the first sip, chances are your coffee might be too bitter.
A slightly bitter cup of coffee can sometimes be great, as coffee is naturally bitter. But when your coffee tastes too bitter, it can completely ruin the cup. Often, bitterness in coffee is caused by specific compounds that emerge during the brewing process. Here’s what you need to know about the causes of bitter coffee and how to prevent this occurrence.
What causes bitter coffee?
“Bitterness is inherent in coffee”, says Ben Angelo, Director of Coffee at City Bean Roasters. “It can be balanced out by other characteristics (e.g., sweetness, brightness) through careful roasting and brewing. But it can also be enhanced during those processes. Bitter coffee is caused by caffeine, chlorogenic acids converting to caffeic and quinic acids, and tannins during the brewing process,” he shares.
Why a touch of bitterness isn’t bad
Chlorogenic acids and phenylindoles are natural byproducts of heat breaking down acids and sugars in the beans. While a tiny bit of these compounds in your cup adds some pleasant complexity, too much can cause your coffee to taste too harsh. Per Maria Soler, Area Manager at Crema Gourmet, a little bit of bitterness in your coffee can make your coffee taste good, just like how with dark chocolate, a touch of bitterness adds depth and contrast. Bitterness in coffee can balance sweetness and create a unique flavor — but there’s a fine line between a little and too much.
“Since it is an inherent attribute of coffee, bitterness is a key component of what makes up the ‘coffee’ flavor profile,” says Soler. “Much like wine, beer, or chocolate. It’s the balance of bitterness with other pleasant flavor characteristics that makes for a delicious coffee. How much bitterness is desirable is subjective to the taster,” she shares.
How roast level and bean type influence bitterness
Experts also say the type of coffee beans you use for your brew can also impact the bitterness of your cup. “Robusta beans have higher caffeine content (twice as much), so they have more bitterness. Arabica has higher natural sugar content as well, so the perception of bitterness is generally more balanced. Recent improvements in varietal selection and processing have led to specialty grade Robustas with increased sugars and balance,” says Angelo.
The roast level of your coffee bean also plays a critical role in how bitter your cup tastes. “There is a point at which the sugars pass caramelization and begin to burn. This and increased melanoidins in darker roasts can contribute to increased bitterness levels,” Soler says. Coffee beans sourced from Central and South America are typically considered sweeter and less bitter, but how you brew also matters a great deal.
Brewing bitter coffee
“When you brew coffee, water extracts flavors from the grounds. If water stays in contact with coffee too long or the grind size is too fine, it pulls out everything — including bitter compounds that come out last. This overextraction can lead to a bitter, dry aftertaste,” says Soler.
To minimize bitterness in your cup of joe, she recommends selecting methods that allow precise control of variables in brewing, such as time and temperature. Brewing your coffee with methods like pour-over, AeroPress, or Chemex brew can produce smoother cups with less bitterness. “Cold brew is also known for its lower bitterness since it extracts at a cooler temperature over a long time.”
Water temperature & grind size
When brewing with filter methods, using a heavier filter paper can also help minimize bitterness in your brew. Additionally, don’t ignore your water temperature when trying to remedy bitter coffee. Water that is too hot or brewing that takes too long can draw out too many bitter compounds and change the flavor of your cup.
Selecting the right grind size for your brewing method can also change how bitter your coffee tastes. “To fine a grind can cause over-extract, and hard or highly mineralized water can emphasize bitterness,” she shares. To combat this, she recommends using balanced water or filtered water to help create a smoother flavor for your brew.
Reducing bitterness when brewing coffee at home
Experimentation and changing variables in your brew can help you get to the bottom of what’s causing a bitter cup of coffee. If you’ve found your coffee to taste a tad too bitter, start by:
- Using fresh, high-quality coffee beans, as stale coffee can taste harsher
- Grind coffee just before brewing for optimal freshness
- Watch the temperature of your water to avoid overheating
- Keep your brewing time consistent and use the correct grind size for your brewing type
- Try a slightly coarser grind if your coffee tastes bitter
- Clean your coffee maker regularly, as old coffee oils can also contribute to bitterness
