Millions of people enjoy iced coffee every morning, as a cool and refreshing way to wake up and get that energy boost necessary to start the day. Yet one persistent problem plagues people who prefer their coffee cold in the morning: bitterness.
Coffee can grow bitter after it has been made and left to sit too long. It's a solvable problem, but you need to understand the reason it happens in order to find a solution. Luckily, we have a few possible solutions for you.
Why Coffee Gets Bitter
Coffee gets bitter for one reason: oxidization. Oxidization can happen at any stage of the coffee process, and a certain amount of it is nearly unavoidable.
Coffee cherries are picked roughly once a year, though, in some areas, conditions are right for two harvests each year. They are picked when they're ripe, though, on larger and more mechanized fields, entire trees can be stripped of their cherries, regardless of whether they're ripe or not. The best coffees are hand-picked, which is a huge boost to quality, but also extremely labor-intensive.
Once the cherries are picked, they're processed. The flesh of the cherry isn't used, but if it's left in place, it can rot and spoil the batch.
- Dry coffee preparation spreads the coffee cherries out to dry in the sun, covering them at night or in the rain to protect them from more moisture, until they're down to a fraction of their original moisture content.
- Wet coffee preparation pulps and removes the flesh from the cherries, then ferment the beans to remove the residual mucilage from them. They are then sorted, rinsed, and dried.
- Honey processed coffee is similar to wet-processed, except the final fermentation step isn't used. Instead, some of the pulp is left on the beans, and it is fermented as it is, changing the flavors of the coffee.
The beans are then dried if processed wet. This drying in the sun can begin the oxidation process, but since the beans are still whole, it's largely inhibited. Beans are then milled to remove their hulls and fragments of residual mucilage and pulp, and then they are shipped out.
At this point, the beans begin to oxidize in earnest, though it's still just the outside of the beans that are exposed to the air. If you buy fresh beans and grind them yourself, the resulting coffee is a lot less bitter than buying pre-ground coffee or even grinding beans at the store to use at home.
When beans are ground, all of their oils and aromatic compounds are exposed to oxygen and begin to break down. Initially, they are rich and flavorful, almost fruity. As oxygen breaks down those compounds, they become bitter and the coffee loses a lot of its flavor.
When you make iced coffee, you brew a pot of coffee and pour it over ice. You might cold brew, you might hot brew and chill; there are many preparations.
There's one common problem amongst iced coffee drinkers, and that's oxidation overnight. Many people who make large batches of iced coffee love how they taste on the first day, but by the second day, they start to taste stale and bitter.
The culprit, of course, is oxygen. Grinding coffee begins to oxidize the compounds, and brewing it temporarily halts that oxidation. However, the brew itself is those compounds carried forward in the water, with the coffee grounds discarded. That brew, when exposed to air, continues to oxidize.
There are six ways that coffee can be exposed to oxygen and grow bitter.
- The coffee is old. Time is the main culprit and is why good coffee one day can be bitter the next.
- The coffee is hot. Too much heat can also break down the compounds in the coffee, leading to bitterness.
- The coffee is of poor quality. Low-quality beans or pre-ground coffee can be exposed to air a lot before you ever buy it, and that means it's well on its way to bitterness already.
- The coffee is too packed. Too much coffee and not enough water means more air interacts with the coffee and leads to bitterness.
- The coffee is too finely ground. Course ground coffee has less surface area to be exposed to air and thus keeps from oxidizing as quickly.
- The mechanism you use to brew is dirty. Old coffee still clinging to machines has had time to oxidize and infuses new brews with bitterness.
There's a lot more nuance to it than just time and exposure to air, of course, but getting into the specific chemistry of coffee compounds is a bit beyond the scope of this article. What we're concerned with are ways to prevent that bitterness, or counteract it. We've put together five different methods you can use, depending on your preferences and preparation.
1. Add Sugar or Cream
The first option is to add sugar or creamer to your coffee. This doesn't prevent the coffee from oxidizing, but it does help drown out the bitterness of the coffee with sweeter flavors. You might have a nice, delicious brew of coffee one day, but the next day it's a bitter cold brew; adding in your creamer or your sugar (or a sugar replacement, or creamer alternative) will help make it more palatable in the mornings.
Now, this is a good alternative if you're after the flavor and the caffeine, but it's not a good option if you're concerned about losing weight and you don't want to consume a bunch of calories and sugar in the mornings. There are a few sugar alternatives that are healthier for you, like Stevia or Xylitol, but some people really don't like the artificial sugar flavors. Creamers tend to have a ton of calories as well. We wrote a post on creamer alternatives, which you can check out if you want.
To be clear, while this is a good option for masking the flavor of coffee, it has a lot of drawbacks. It doesn't actually do anything to halt or change the bitterness of coffee, and if bitter flavors stand out to you, coffee will still be bitter in the background of the cream and sugar. It's also, you know, sugar; it's high calorie and turns your nice skinny morning beverage into a meal replacement.
2. Add a Pinch
Another alternative is to do something to alter or halt the bitterness of the coffee itself. There are two primary options you can use here.
If you've already brewed your cold coffee and you're on day two and want to salvage it, consider adding a teaspoon of lemon juice. That small amount of lemon juice won't make your coffee sour, but it will interact with the compounds that taste bitter and can counteract them. Sour flavors and bitter flavors counteract each other. This can make your coffee beverage taste sweeter and calmer, but it might taste a little weird to you if you've never tried it before. Some people love it! Others find it a little off-putting.
The other option is to add a pinch of salt to your coffee. You can do this to try to "revive" a stale cup of coffee or to try to revitalize your coffee the second or third day you're drinking it. You can also include the salt when you brew the coffee, to enhance the flavor and help it keep longer.
Salt helps to counteract the oxygen that causes your coffee to become more bitter. It also helps to enhance the actual flavor of the coffee. Salt – just a small pinch per cup – operates as a flavor enhancer, and you won't taste the salt at all. If you DO taste salt, you've probably added too much.
3. Start Better
There are a lot of different factors that can lead to your coffee ending up bitter before you're ready to discard it. Many of those factors can be counteracted by starting with better base ingredients. We have several tips for you on this front.
Buy higher quality beans. Higher-quality beans are hand-picked. They're processed well, and they're packaged carefully before they're shipped. They're roasted lightly, rather than dark, because a dark roast destroys flavors but makes coffee more consistent in its bitterness. A higher-quality starting bean means higher-quality coffee once you brew it.
Don't grind until you're ready. One of the worst things you can do for coffee is purchase pre-ground coffee. Even grinding the beans at the store isn't great. When you grind the coffee, more and more of the compounds inside it are exposed to air and start to oxidize. Buying your own coffee grinder and grinding your beans immediately before using them is the best idea. Also, don't grind your coffee too finely; more surface area means more oxidation.
Brew cold, not hot. Heat is the enemy of flavor. Cold-brew coffee keeps the coffee in suspension and helps suppress chemical reactions. Cold-brew coffee stays flavorful for longer than hot brew coffee, even if you then chill the hot coffee. You can try freezing it to help stop the reactions, but you need to use it before too long if you do.
4. Seal Your Coffee
Oxygen is the enemy, so if you minimize how much oxygen is able to access your coffee, you'll have a better chance of having a nice, fresh cup in the morning. The trick is to store your cold-brewed coffee (or chilled coffee) in an air-tight container. Storing it in a simple glass jug or an open-topped carafe lets a lot of oxygen in, whereas storing it in a sealed container with as little space as possible is ideal.
The trouble here is that each day, you pour some coffee out, and the remainder of your coffee has more air in the container. There are a lot of different kinds of containers you can use to try to circumvent this, but you'll need to find the one that works best for the amount you drink and the time you store your coffee.
Ideally, you will brew coffee more frequently and in smaller batches, so it doesn't last as long and doesn't have as much time to oxidize. We recommend brewing every few days instead of once a week unless you're explicitly brewing coffee to freeze and store.
5. Buy a Coffee Mix
Our best recommendation is to skip all of the above and don't even worry about brewing the coffee yourself. Sure, if you like the ritual of brewing coffee and preparing a beverage every morning, that's one thing. If you just want coffee and don't care about the ritual, why not try something like our skinny iced coffee mix?
"But how does this keep from being oxidized?" you might ask. Instant coffee like what we use in our coffee mix is pre-brewed and then crystallized. This process essentially halts the chemical reactions that occur in coffee, freezing it in a delicious, pre-oxidized state. That, along with additives like a non-dairy creamer and a few supplements like L-carnitine, help keep the coffee flavorful and avoid that bitterness.
Your Recipes
Everyone who brews coffee has their own secrets, and if you're anything like us, you probably love sharing them. So, we'd love to hear them! If you have a secret for keeping your coffee from getting bitter on day two or three, let us know in the comments. If you've been searching for a solution, try out one of ours, and let us know how it goes!
Don't forget, there are other flavor options as well, beyond just sugar and cream. Consider adding spices to your coffee, like cinnamon, nutmeg, or turmeric. Kick the flavor up with a bit of fresh vanilla or vanilla extract. You can even go for a full-on beverage and mix coffee and green tea together. You have the entire wide world of spices and supplements to add to your coffee, so feel free to explore and report your findings.
