Instant coffee is famous worldwide for its convenience and low price. Whether rushing out the door or staying in a hotel room, you’ve likely found a reason to brew instant coffee. But you might wonder why your instant coffee keeps turning out bitter.

Instant coffee can taste bitter because of the way you made the brew. The type of bean, drying process, and roast level can all cause a bitter taste. It could also be a user error. The type and temperature of the water and the ratio used can make coffee more bitter. 

In this article, I’ll discuss the different reasons your coffee may turn out bitter and quick fixes to try for your next cup. I’ll also give you tips on making a cup of bitter coffee taste better, so be sure to read until the very end! 

1. Your Instant Coffee Contains Bitter Tasting Robusta Beans

Even though instant coffee is a fine powder, by the time it gets to your cup, that substance starts as coffee beans. Most likely, Robusta beans. 

The wide varieties of coffee boil down to four types of beans:

• Robusta
• Arabica
• Excelsa
• Liberica

Of these four types, Robusta and Arabica are the most popular and therefore are the most common in regular coffee. 

Compared to Arabica, Robusta beans are much easier to grow and are cheaper to produce. The name “Robusta” actually stems from how robust the bean is because Robusta beans can withstand harsh growing conditions. This variety also contains twice as much caffeine as its Arabica counterpart, leading to a sharper and more bitter flavor. 

These factors make the Robusta bean an excellent choice for instant coffee manufacturers. However, this can also lead to a more bitter coffee for the consumer. 

If you’ve tried everything and your coffee tastes bitter, it may be the beans. Try an instant coffee made from Arabica beans and see if that improves your morning cup.

2. The Drying Process Affects Your Instant Coffee Flavor

Another reason your instant coffee may taste bitter is the drying process. 

The following procedure can briefly outline the manufacturing process for instant coffee:

1. Whole beans are placed into an oven and roasted to the desired color.
2. The beans then go through a grinder to be coarsely chopped into grounds.
3. The coffee makers then brew the coffee to make a liquid coffee concentrate of the desired strength.
4. The coffee concentrate is then dried, evaporating all the coffee’s water. 

This last step, the drying process, is what we are interested in when it comes to bitter-tasting coffee. 

Coffee makers employ two drying methods when making instant coffee: freeze-drying and spray-drying. 

The Freeze-Drying Process

1. The makers place the coffee grounds at an extremely low temperature (-50°C or -58°F). This process ensures that they lock the coffee flavor and aroma.
2. They then grind up the frozen coffee sheets to produce fine coffee granules. This process creates the fine powder texture you find in instant coffee. 
3. They heat the granules under vacuum conditions. The pressure of the vacuum chamber allows the remaining ice to evaporate without becoming liquid water, leaving behind a dry powdered coffee. 

For more information about how this freeze-drying method works, you can check out this YouTube video on the Free Documentary channel:

While freeze-drying is the preferred method for most coffee drinkers because it traps the flavor and aroma in the powder, it is a more expensive and time-consuming method. Therefore, some manufacturers prefer the spray-drying process. 

The Spray Drying Process

The spray-drying method is the opposite of freeze-drying in that it uses heat to dry the coffee grounds. The coffee makers mist the liquid coffee into a large chamber full of swirling hot air that can reach several hundred degrees. These high temperatures cause the water to evaporate quickly, leaving dried coffee grounds ready to be powdered. 

While this process is faster and cheaper for manufacturers, placing the coffee grounds under such high temperatures can alter the chemistry of the coffee, causing a bitter taste. 

If your instant coffee seems slightly bitter, you may be drinking a spray-dried coffee. Try a freeze-dried coffee and see if that better suits your taste. 

3. Your Coffee Is Bitter Because Your Roast Is Too Dark

Aside from the manufacturing process, there could also be some taste preferences or user error that is causing your coffee to come out bitter. For example, you may be drinking a roast that is too dark for you. 

Darker roasts tend to have a more bitter flavor than lighter roasts. Darker coffee is roasted longer, leading to less acidity and more bitter compounds developed during the process.

As mentioned before, the higher temperatures cause more bitter-tasting coffee, so it would make sense that coffee beans roasted at higher temperatures for extended periods taste more bitter than their lighter roast counterparts. 

Therefore, if your coffee is too bitter for your taste, you may prefer a lighter roast. A lighter roast instant coffee will taste milder than a darker roast coffee.  Starbucks Premium Instant Blond Roast (available on Amazon) is a light roast a favorite for instant.

4. Your Coffee to Water Ratio Is Off

So you have a freeze-dried, light roast, Arabica instant coffee that is still too bitter. What gives? Well, you may want to check your water-to-coffee ratio. 

The more coffee concentrated your cup is, the more bitter it will taste. According to the Specialty Coffee Association, the standard brew ratio is 55 g (1.94 oz) of coffee per 1 kg (2.2 lb) of water. That is about 3 tablespoons (37.5 g) per about 4 cups (946 ml) of coffee. If you make your single cup (236.6 ml) of instant coffee, you likely need a little less than 1 tablespoon (14.78 oz) to get the perfect brew. 

Try adding more water or not adding as many grounds and see if that helps with your coffee’s bitterness.  Mount Hagan Organic Instant Coffee (available on Amazon) is a medium roast Arabica coffee that is smooth and consistent.

5. Your Brew Is Bitter Because Your Water Is Too Hot

If your coffee-to-water ratio is spot on, it may be that your coffee is too hot. 

You know by now that high temperatures bring out a bitter taste in coffee. But how are you supposed to avoid that with instant coffee? To make instant coffee, add boiling water to the grounds for a perfect cup. 

Water starts to boil at 212°F (100°C). However, according to the National Coffee Association, the ideal water temperature for coffee brewing is only 195°F – 200°F (90.5°C – 93.3°C). Temperatures higher than that range can result in bitter-tasting coffee. 

Try making your coffee using warm to hot water instead of boiling water, shooting for that ideal range for the best-tasting cup. 

6. Your Coffee Is Bitter Because Your Water Is Too Alkaline

In addition to water temperature, water pH can also affect the flavor of your coffee. Water too high in alkaline can extract bitter compounds from your coffee, leading to a more bitter cup. The ideal pH for brewing coffee is between 6.5 and 7.5. 

If you’re brewing at the right temperature, you may want to try using a different water source and see if that improves your cup of coffee.   

7. Your Cup Might Be Dirty

If you are a habitual coffee drinker, you may make more than one cup of coffee in a row. Many people will reuse and refill the same cup with their second drink. However, residual coffee in your cup can make your next cup taste bitter.

To avoid this, be sure to rinse your cup between coffees and wash it thoroughly when finished with it. 

Ways To Fix a Bitter Cup of Coffee

So you know how to fix your coffee—but what about the cup you made that is bitter? You don’t want to waste a precious cup of coffee, or you may not have any more instant coffee mix to create a new cup. In those cases, saving your bitter cup may be your only option. 

Here are a few ways you can make a cup of coffee less bitter after you’ve already brewed it:

• Sweetener: Adding a sweetener such as a sugar or sugar alternative can help mask the bitter taste with a sweeter taste. This additive is an excellent option if you don’t mind a sweeter coffee. 
• Butter: In recent years, butter coffee has become more popular. While it may sound odd if you’ve never tried it, a small amount of butter will give your coffee a smooth and silky texture while also cutting the bitterness of the drink. 
• Milk or Creamer: Simply adding milk or creamer to your coffee can lessen the bitter taste. You can also try a flavored creamer if you want a sweeter flavor without adding sugar—vanilla is an excellent option! 
• Spices: Simple spices such as cinnamon or cocoa can also cut the bitterness of your cup while giving your coffee a delicious and subtle flavor. 
• Citrus: While it may not be as common as creamer or sugar, citrus is also a great additive to a bitter cup of coffee. Adding a squeeze of lemon or orange to your coffee can help the brew’s flavor. 

You’ve probably seen that instant coffee dissolve completely. But do you know the reason? I’ve written an in-depth guide to describe the difference between instant coffee and regular coffee beans, why instant coffee dissolves and why some instant coffees don’t. [Is Instant Coffee Supposed to Completely Dissolve?]