5 Top Reasons For Bitter Iced Coffee: And How To Fix It


5 Top Reasons For Bitter Iced Coffee header image

Got some iced coffee but after the first sip you notice it’s way more bitter than you like? What went wrong and how can you fix it? Here’s what you want to know. 

Excessive bitterness in iced coffee is usually the result of using beans with a very dark roast or stale, low quality beans. Over extraction can also cause a harsh bitterness which can be reduced by using a coarser grind, cooler water and shorter bloom time. 

Let’s go through all the top reasons why iced coffee can be too bitter and what to do about it. 

Reasons Iced Coffee Tastes Bitter

There can be a few reasons why iced coffee tastes bitter. Let’s go over what those reasons are and then we can figure out how to fix them. 

To be clear, we’re talking about iced coffee, not cold brew coffee here. There are differences. 

1. Taste Buds And Temperature

The taste buds perceive tastes differently at different temperatures. For each of the tastes, there is an ‘ideal’ temperature where you can taste a certain taste (sweet, bitter, bitter, sweet, umami), the best. Everyone knows that foods and drinks taste differently the further they warm up/cool down. 

However, in most cases colder temperatures, especially in an iced drink, the bitterness is less noticeable. What can happen though is that other tastes are subdued. Usually this leads to a more sour taste and not bitter. But that of course depends on the original taste of the coffee you began with. Some coffees have more acidity, some have more bitterness. 

Sweetness is going to be quite subdued in iced drinks. And there is actually quite a bit of sweetness in coffee. It’s not sweetness like sugar or honey but it does provide a lot of taste notes to coffee. By reducing the intensity of this sweetness, the bitterness is going to come out more. However, that implies a lack of acidity as well. That means that likely a really dark roast is used or the coffee is over extracted, more on that later. 

Man tasting coffee

2. Stale Coffee

If you bought your iced coffee from a coffee shop (or made it at home), there is a chance the coffee is stale. Depending on the coffeeshop, they might brew a big batch at the beginning of the day and pour from that batch until it runs out. If you come later in the day, it can get stale. 

The compounds in coffee start oxidizing and this degrades the taste. If the coffee is kept hot this oxidation happens very quickly. In that case you’ll taste a significant difference in an hour. Depending on the coffee, this can lead to more sourness or bitterness. 

If kept cool in an airtight container, the staling process will be a bit slower but after a few hours brewed coffee will still taste significantly different. And if left cold but in an open container, it definitely will go stale. 

It doesn’t really matter if this is at a coffee shop or at home, coffee oxidizes over time whatever the location.  Also, even if the coffee is brewed fresh but the used grounds were stale, you get similar results.

Suggested: Why does homemade coffee taste different?

3. Coffee Roast Level

If a coffee bean is roasted light, you have a higher chance at a sour cup of coffee. If it’s roasted dark, it’s more likely to be bitter. That is because with a light roast there is more acidity (origin taste) left in the beans to begin with. Acidity or bitterness in coffee is not a bad thing. It can provide a wonderful fruity, bright taste or that punchy flavor that wakes you up. 

Suggested: Which type of beans is good for iced coffee?

Roasting can be seen as caramelizing, it’s the same chemical process. The darker you make a caramel, the heavier and more bitter the taste becomes. The same is the case for coffee beans. The darker a coffee is roasted, the less acidity there is but more bitterness. 

Also, the darker beans are roasted, the more porous they become. That means the water can penetrate into the grounds easier and faster which means that the grounds are extracted faster. So it’s easier to extract too much from dark roasted beans which leads to bitterness. 

If you buy coffee at the supermarket, there is likely no roast indication. In that case, there is probably a ‘strength’ indicator. In that case, a higher strength usually means a darker roast. 

Coffee beans of different roast levels from green to very dark.
Coffee beans of different roast levels from green to very dark.

4. Type Of Beans Used

There is an unbelievable amount of coffee beans and they all taste different. While a really harsh bitterness is usually not the fault of the coffee used, it can be a contributing factor. What is a nice level of bitterness for some people is unpleasantly bitter for the next person. 

Where beans come from, where they’re grown, what height they’re grown at, where they are on a specific farm, how they’re treated after picking and more all has an impact on the taste of your cup of coffee. You especially notice this with specialty coffee but there are variation in ‘normal’ coffees as well. Looking at the tasting notes on the bag can help. 

Lower quality beans tend to be roasted darker because that gets rid of sourness. In good beans that sourness is wanted because it tastes good but if the taste of that acidity is bad, roasting darker is an option. However, lower quality beans often also have a harsh bitterness. Roasting darker only makes that problem worse. Many people like the bitterness of coffee but there is always a limit. 

What I’m trying to say, sometimes it’s just the taste of the coffee beans you don’t like. You can influence the taste by brew method and technique but if the beans are bad, there is no way to get good tastes out of it. 

5. Over extraction

If the iced coffee is brewed fresh and with the right beans, you can still have a situation where the brewing method is the cause of the bitterness. 

To brew coffee you want the soluble material in the grounds to get into your water. However, you don’t want ALL of the soluble material, you want the right amount. If you dissolve too much, this is called over extraction. If you dissolve too little, it’s called under extraction. 

In general, if the coffee is bitter, the grounds are over extracted. If the coffee is bitter, the grounds are under extracted. So in this case, we’re worried about bitterness and there can be a good reason for this. 

The best way to brew iced coffee is to replace a part of the brew water with ice. You put the ice in the pitcher under the filter and the hot coffee drips on it, melting it and diluting the coffee. However, by reducing the brew water, there is less extraction going on. To counteract this, you should do three things; Use a smaller grind size, use a longer bloom time and use hotter water. 

If you go too far with one or more of those factors, you risk over extracting the grounds and therefore getting bitter coffee. 

How To Fix Bitter Iced Coffee

Here are some things you can do to make your coffee less bitter by changing the beans, brewing process and a tip you can use to make your coffee less bitter after you’ve brewed it. 

1. Fresh Beans

Using fresh beans is always important. Without having high quality fresh beans, it gets pretty hard to brew really good coffee. Even if you use pre-ground coffee, make sure you don’t let it go stale. 

Buy a new bag and see if your coffee improves. Then get an airtight container to store your beans. Properly storing your beans will increase their lifespan. 

You can freeze part of the bag in an airtight container and those beans/grounds will stay fresh. Then just defrost the amount of beans you need for the week. Try to avoid opening the container too many times. So smaller containers are better than large ones. 

Leaving a big bag open for a few weeks is a guarantee you’ll have stale coffee at the end of it. 

Fresh coffee being picked

2. Right Beans

Freshness is one thing but the type and roast level of beans is another. A lot of this is down to taste which is obviously different for everyone. 

However, if bitterness is an issue for you, there are two ways you can change your coffee beans; Choose a lighter roast level or a type of bean that has more ‘bright’ taste notes on it. 

A lighter roast does two things; 1. Lighter roasted beans are less porous and therefore harder to extract. This will reduce bitterness in itself. 2. Lighter roasts have more sour/fruity notes and fewer bitter notes. 

Another thing you can do is to pay attention to the tasting words on the packaging. Usually people look at those words and don’t recognize any of those words in the taste of the coffee once they brew it. 

Forget the literal taste of those descriptors. Look at them to get an idea of the overall experience. If you see things like; fruity, citrus, lemon, grapefruit, floral, apple, that implies a fruity acidity which usually means less bitterness. Avoid words like; caramel, black tea, nutty, honey, chocolate, syrup, etc. those are ‘darker’ tastes which usually imply bitterness although they are also related to sweetness. 

Also, use high quality beans. Higher quality beans will have a more pleasant, subdued bitterness instead of harsh bitterness. 

3. Brew Fresh

Always aim to drink coffee that’s brewed just before you drink it. It doesn’t matter whether you’re doing it yourself or buying it at a coffee shop. 

In case you brew at home, this is pretty easy, in a coffee shop, you might have to ask. Possibly even shop around at a few different coffee shops to find what you are looking for. 

4. Fix Extraction

Once you’ve got the right beans and it’s still way too bitter, it’s time to fix the extraction. There are a few factors you can change to decrease the extraction and get fewer of those bitter compounds into your cup. 

To brew iced coffee, use about 1/3 of the amount of coffee you want to brew and replace it with ice. That will get the coffee cold (not icy cold) and leaves enough water to brew with. However, there is still less brew water so you need to do increase the extraction other ways;

  • Grind a bit larger: Grind your beans a touch smaller than you would for a regular pour over. This increases surface area and therefore extraction. Going too small can cause over extraction. 
  • Use slightly cooler water: Hotter water extracts faster. Use water that’s about 30 seconds off the boil. Especially with a dark roast. With lighter roasts using very hot water is usually not the problem. 
  • Use a 45 second bloom time: The bloom time can help ‘loosen’ some of the solubles. Add enough water to soak all the grounds and then let it sit for about 45 seconds before pouring. 30 seconds is normal for hot coffee but for iced coffee 45 seconds is usually optimal. Don’t go much longer than that. 
  • Pour a little faster: Add water to the filter a little bit at a time. Less water in the filter means less pressure and a slower flow which results in more contact time. Fill a little more water at a time and let the water flow faster. 

5. Add Sweet/Dairy

If you already have your coffee ready and it’s bitter. The only thing you can do is to add in something that balances out the taste. This is going to be something sweet or creamy since those are the best at counteracting bitterness. 

That means adding things like, dairy or dairy alternatives, sugar, honey, chocolate syrup, etc. 

6. Add Salt

Salt is a pretty amazing secret weapon against bitter coffee. It doesn’t matter what kind of coffee it is. Salt increases the perception of sweetness which then reduces the perception of the bitterness. It kind of confuses the brain into thinking the coffee tastes less bitter. 

If you’re interested, you can find a full explanation here. 

Go very light on the salt. Add a very small pinch to begin with. A little goes a long way. Once you overdo it, the coffee will just taste salty although some people actually like that. 

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