Why Does Milk Curdle in Coffee? And How to Prevent It


Why does milk curdle in coffee? Is it because of the brewing method used, the ph of the milk, or it because of the coffee creamer?

The curdling process and what causes it is something that needs to be determined before we can remedy the situation.

pouring oat milk as creamer
pouring oat milk as creamer

If you experiment, you’ll notice that in iced coffee and room temperature coffee, milk doesn’t curdle as readily.

What Causes Milk to Curdle in Coffee?

The acidity of the coffee and temperature of the coffee are the two most frequent factors that cause curdling. This is the case whether you’re using cow’s milk or non-dairy milk, from the scientific perspective lactic acid plays a role.  

Using a highly acidic coffee bean can cause the milk in your coffee to curdle.  The acid from the coffee combined with the acid from the milk itself creates a fair amount of acid which can result in a chemical reaction that causes curdling. Using low-acid coffee can be a good solution for avoiding curdling.

And waiting a bit for your coffee to cool slightly rather than drinking piping hot coffee can also help to avoid this problem.

What Kinds of Milk Curdle in Coffee?

Whether you’re someone who likes to consume plant milk or you might prefer dairy milk options, both types have the potential to curdle in coffee if you’re not careful.

A dairy-free alternative such as cold almond milk is a good option. Coconut milk and other alternative milks can work well, especially if you’re already accustomed to their flavor.

pouring creamer
pouring creamer

There are many good plant-based milk alternatives on the market. But if you’re afraid of soy milk curdling or you’re wondering if using oat milk will cause oat milk curdle, we’ll be frank with you and let you know that in some cases it will.

Let’s face it, curdled oat milk or any milk that has curdled is not ideal to be floating in your delicious cup of coffee.

What Kinds of Coffee Cause Milk to Curdle?

Coffee that has high acidity matters, such as African coffees that tend to cause curdling. Acidity of coffee matters and it’s something to take into consideration to help avoid unwanted curdling.

Lighter roasts tend to be a better option if you’re someone who appreciates a good dose of milk as creamer in your coffee mug.

Along with the acidity of your coffee, the temperature of the coffee matters. Coffee drinkers care about the temperature of their beverage, but letting it cool slightly before adding creamer can help prevent the unwanted curdling.

What’s the Best Kind of Milk to Use in Coffee?

You can use a variety of milk in coffee, depending on your dietary restrictions. Coffee shops generally have some plant-based options available as well as your favorite dairy products. Just ask the barista.

coffee creamer
coffee creamer

If you’re thinking of trying a non-dairy product, consider using fresh oat milk. It’s a good option and will help prevent unintentional curdling.

Just use caution when adding your milk to your coffee when the coffee is at a higher temperature. It’s better to wait until the coffee is at a lower temperature and has had the chance to cool slightly.

Frequently Asked Questions

Following are frequently asked questions that relate to why does milk curdle in coffee. If you have a question that’s not answered here, feel free to drop it to use in the comments box below and we’ll be happy to respond.

Is it okay to drink curdled milk in coffee?

If you suspect that the reason for the curdled milk in your coffee is because the milk has expired, then you’ll not want to drink it. It should be thrown away instead.

Is it safe to consume curdled milk?

We don’t recommend consuming curdled milk. Milk that has curdled by itself usually indicates it has gone bad. Consuming food that has spoiled can be dangerous and has the potential to cause food poisoning.  

coffee creamer
coffee creamer

How do you keep dairy free milk from curdling in coffee?

The best way to help keep your dairy free milk from curdling in coffee is to allow the coffee to cool slightly before adding the milk. If you don’t have time to let the coffee cool, you might try slowly adding the coffee to the milk instead of vice versa.

Why does my creamer curdle in my coffee?

The main factors that cause milk to curdle in coffee are acidity and temperature. The combination of a high coffee temperature and the cool milk along with the acidity of both can cause the milk to curdle when it’s added to the coffee.

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Sarah is known for her extra fancy yeast breads, melt in your mouth pies, and everything salads. She has won awards as a home cook, and is passionate about helping others feel smarter in the kitchen. Sarah is the cooking genius of the sister duo.

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