Why Your Cold Brew Coffee Tastes Bitter + How to Fix It

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Recently I made the decision to start making my own cold-brew coffee. But when I finished my first brew and tried it, it tasted much more bitter than the cold brews I'd ordered from coffee shops in the past. Which made me wonder why my cold brew tastes so bitter and how to fix it.

A cold brew coffee will taste bitter if it's been over extracted and a large amount of bitter tasting tannic acids have come out of the beans and into the water. Overextraction can result from too fine a bean grind and also from soaking the beans in water for too long. Some coffee beans will also create more of a bitter flavor in cold brew than others.

In this article, I’ll not only share with you exactly why your cold brew coffee tastes bitter, but I’ll also give you a few different things you can do to fix it. Let’s get into it!

Why Your Cold Brew Coffee Tastes Bitter

If your cold brew coffee tastes really bitter, the most likely reason why is that it’s over-extracted.

What’s extraction you ask? It’s basically how much flavor is pulled out of the coffee beans during brewing and dissolved into the water to make coffee.

No matter the method of brewing coffee, the level of bean extraction (after water quality) is the biggest influence on the drink's flavor. A perfectly extracted cup of coffee will pull enough of the flavor from the coffee beans to create a sweet, ripe, acidic, and smooth cup of cold brew.

If a coffee bean is under-extracted during brewing and not enough of the flavors end up in the drink, the cold brew will taste sour, thin, watery, and sometimes salty.

And if a coffee bean is over-extracted during brewing and too many of its compounds end up in the drink, the cold brew will taste really bitter, dry, and bland.

The bitter taste in an over-extracted cup of cold brew comes from a compound known as tannic acid. Tannic acid usually only appears in coffee in small quantities. However, if too much of the coffee bean is extracted, extra tannic acid will end up in the drink and make it more bitter tasting than usual.

So what causes a batch of cold brew to end up over-extracted and bitter? Two things:

1. The beans were ground too finely

2. The beans were soaked in the water for too long

Too finely ground beans means more surface area is in contact with the water and the flavors and compounds are extracted from the beans much quicker and easier, leaving extra tannic acids in the cold brew and making it taste bitter.

And soaking the beans too long leads to over-extraction because obviously the longer the beans are soaked, the more time there is for the flavor to be extracted from them.

How to Make Your Cold Brew Coffee Taste Less Bitter

So now you know why your cold brew is tasting bitter, but how can you fix it?

Well if you already made a full batch and don’t want to let it go to waste you can try diluting the cold brew with water to make the concentrated bitter taste more palatable. You can also use milk or creamer to lighten the flavor up and make it easier to drink.

To prevent future cold brews from tasting too bitter, below are 4 adjustments you can make to your brewing process. I recommend only changing 1 variable in your recipe at a time so that you can know what improves the flavor and what doesn’t. If you change all 4 at once and it tastes a little less bitter you won’t know why.

1. Grind Your Beans Coarser
One quick adjustment you can make to help keep your cold brew from becoming over-extracted and bitter is to grind your beans coarser. Ideally, they should be ground to a size similar to sea salt. This coarse grind will reduce the surface area of the coffee beans and lead to a slower extraction.

If you can, use a burr grinder instead of a blade grinder to grind your beans since burr grinders will create an equal uniform grind that will allow all the beans to get extracted evenly and make it easier to create a consistent, nonbitter taste.

2 Soak the Ground Beans for Less Time
The best adjustment you can do to make your cold brew less bitter is to just soak the ground beans in the water for less time.

Generally, people recommend you leave the coffee beans in water for 12-24 hours when making cold brew. So if you’ve been soaking them for 18-24 hours, ending the brew at around 14-16 hours might help balance out the extraction.

The best way I can think of to find the optimal brewing time for your cold brew is to just taste test it every few hours and end the brew when it's reached a balance of flavor between the sourness of under-extraction and the bitterness of over-extraction that you like.

3. Try a Different Brand or Origin of Coffee Bean
If you’ve changed the grind of your beans and brewed your cold brew for less time and it’s still tasting bitter, the next step is to try using a different brand or origin of coffee bean.

It could just be that the type of coffee you’ve been using has a more bitter flavor profile, and changing the beans you use could completely fix the bitter taste you're finding in your cold brew.

4. Make Sure You’re Using the Right Ratio of Coffee to Water
One really important part of making a good cold brew is using the correct ratio of coffee to water. If you’re using too much coffee or too little water, there's more opportunity for tannic acids to leave the beans and enter the water, making your cold brew bitter.

The general rule for cold brew is to use 1 cup of coffee beans for every 4 cups of water. If you’re having a problem with over extraction you could even use a little less coffee or a little more water, just don’t go too far away from the 1:4 ratio or else you may overcorrect and start making sour, under extracted cold brew.

What if I want my Cold Brew Strong but Not Bitter?

So what if you’re trying to make your cold brew taste really strong and concentrated, but you don’t want to over extract the beans to the point where it tastes bitter? Well, theres a few things you can do to make your cold brew stronger while limiting the amount of bitterness it develops.

1. Use a Darker Roasted Bean
Darker roasted coffee beans will naturally have a more concentrated, stronger flavor and will be able to give that flavor to your cold brew without needing to be over-extracted.

2. Use a Robusta Coffee Bean
There are 2 types of coffee beans: Arabica and Robusta.

Arabica is much more common to use and has a smooth, sweet flavor, while Robusta beans are known for being much stronger and harsher tasting and have almost twice the caffeine.

By using robusta beans for your cold brew you’ll be able to create a strong, concentrated, caffeinated drink without needing to over-extract the beans.

3. Use Fresh Coffee Beans
Old or stale coffee beans will have a much less sweet, more bitter and pungent taste to them than coffee beans that are freshly roasted, which makes using fresh coffee beans (roasted no more than 7-10 days ago) a great way to avoid bitterness in your cold brew.

Final Thoughts

If a cup of cold brew coffee is tasting extremely bitter, it’s likely due to the coffee being over extracted. Over extraction can result from too fine of a grind and/or from too long of a brew.

To fix a bitter cold brew, grind your beans coarsely, end the soaking before the cold brew gets bitter, and use beans that don’t have an intensely bitter flavor profile.

I hope this article was helpful! If you’d like to learn more about cold brew and coffee, be sure to check out the rest of my website!


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