How to make oat milk—with science

You're a pill away from the perfect oat milk.

Plant-based beverages have become a go-to solution for those who can’t (or won’t) drink cow’s milk, but still want to, say, enjoy a latte from time to time. Of all the alternatives, oat milk is one of the easiest to make at home: just blend some oats and water, strain, and you’re good to go. 

But the result of that technique will only be good for cold drinks and smoothies. If you dare heat it up, your oat milk will acquire a flan-like consistency. That’s not necessarily a bad thing (especially if you’re into bouncy desserts), but there’s no dispute—you can’t drink that. 

This is where science comes to the rescue. Adding enzymes to the mix will render oat milk that’s not only less slimy when heated, but also more sweet. 

If you just want the recipe, you can click here and jump right to it, but understanding the science will definitely improve the result.

Why oat milk gets slimy

When you make oatmeal, you’ll notice that after a few minutes of soaking in hot water, oats swell and a gel-like substance starts to appear. This is gelatinization, and it happens when you combine water, oat starch, and high temperatures. 

The key to this reaction is starch, which in the case of oats, is made of two kinds of sugars: amylose and amylopectin

[Related: Not all oats are gluten free—here’s how to be sure you’re safe]

The latter absorbs water and can swell up to 10 times its size. Amylose, on the other hand, is hydrosoluble, meaning that it starts to break down in water, explains Shuang Qiu, who researches protein chemistry at Cornell University. When this happens, amylose leaches out of the starch granule. 

But once amylose is free, just like people who befriend each other after being kicked out of the same club, it starts bonding with other amylose molecules. This results in a gel-like consistency that’s great for making porridge, but not right at all for coffee.  

Enzymes, the key to non-slimy oat milk

There are many things in nature that border on magical, and enzymes are one of them. These proteins’ biggest trick is their ability to break down substances, which is why we use them to help us get rid of horrid smells and stains

There are many types of enzymes, but the one that will help us make delicious non-slimy oat milk is called amylase. (Yes, it’s one letter away from amylose, the goop-making sugar we mentioned above, so don’t get them confused.) You can find this particular protein in a variety of foods, including honey, mangos, avocados, ripe bananas, and papayas. 

As you probably already guessed, amylase is particularly good at breaking down the components in oat starch. This enzyme will turn amylose’s long sugar chain, and amylopectin’s branching structure, into much smaller chains of glucose, preventing your beverage from turning into slime. As a bonus, these new liberated sugars will sweeten your milk, making it naturally more tasty. 

This may sound like a complicated lab experiment, but because most grocery stores have aisles filled to the brim with vitamins and nutritional supplements, amylase is easy to get. 

[Related: We made pancakes with substituted ingredients so you don’t have to]

But perhaps the wildest place you’ll find amylase is in your own saliva. Your body creates this enzyme naturally to break down starches and turn them into simple sugars during the first stage of digestion that takes place in your mouth every time you chew your food. (And for the sake of all that is good in this world, do not spit into the mixture or use pre-chewed oats. That’s nasty.)

How to make oat milk

Now that you’re fully equipped with scientific know-how, let’s get those homemade oat milk lattes coming. We consulted with Olga Padilla-Zakour, a food science professor at Cornell, who helped us nail down the ultimate oat milk recipe.  

Stats

  • Time: 30 minutes
  • Cost: $1.50 per 34 fluid ounces (that’s about a quart)
  • Difficulty: easy

Materials

  • 4 cups of cold water
  • 1 cup of old-fashioned oats
  • 16.7 milligrams of amylase

Tools

  • Measuring cup
  • Large bowl 
  • Blender 
  • Colander
  • Cheesecloth (or nut milk bag)
  • (Optional) Pot 
  • (Optional) Microwave (or stovetop)
  • (Optional) Food thermometer
  • (Optional) Mortar and pestle (or pill grinder)

Instructions

1. Blend the oats and water together for 30 to 60 seconds. How long you churn will depend on the power of your blender. The less blending time, the better—you want to keep the spinning blades from heating your mixture.

Note: You may be wondering why we’re not soaking and washing the oats before blending. Many oat milk recipes suggest this as a way to reduce the amount of starch. But there are two reasons why you shouldn’t. 

[Related: The almond milk craze could be bad news for bees]

First, if you’re not using enzymes, there will be starch no matter how much you wash the oats, so there’s no way to escape the oat slime. The second reason is nutrition—rinsing can decrease the amount of vitamins and other water-soluble nutrients in the oats, Padilla-Zakour says.

2. Add the amylase, stir, and let the mix sit for 10 minutes. The way you add the amylase will depend on the digestive enzymes you bought and how they are packaged. 

When you buy your enzymes, look at the nutritional facts on the label and pay special attention to the amount of amylase per serving. Calculate how much of it is in each pill or capsule by dividing the amount per serving by the serving size. For example, for a bottle where the amount of amylase per serving is 50 milligrams and the serving size is three pills, each pill has 16.7 milligrams of the protein. Use this information to calculate how many pills you’ll need to add to your blended oats. 

Packaging also matters. Powders are the easiest—weigh the amount you need, add, stir, and you’re golden. Capsules are a close second—open them up, pour the powder into your mix, and stir. 

If you buy pills, make sure to pulverize them well before you add them. You can use a mortar and pestle or a pill grinder, but a large spoon and a paper towel will also do the trick. Place the pill between two paper towels and press down gently with the back of a spoon. 

3. Pour the mix into a colander over a large bowl to remove large particles. Discard anything left in the colander.

Filter the mix again using a cheesecloth or a nut milk bag over a large bowl. Squeeze the wet sack softly with your hands to get as much liquid out as possible. Congratulations—you now have oat milk.

  • Pro tip: You see that oat-mush in your cheesecloth or nut milk bag? Don’t throw it away. We’ve got suggestions for that below.

4. (Optional) Pasteurize your milk. Heat your beverage to 194 degrees Fahrenheit. You can use a pot, or your microwave in 30-second increments. Use a food thermometer to keep tabs on the temperature. 

Pasteurization will kill all remaining enzymes in your milk. This will prevent them from  breaking down even more starch while your milk is in storage, which may change the flavor. If you plan on consuming your oat milk within a day or two, pasteurizing might not be necessary. 

“The beverage has a nice consistency and good flavor,” says Padilla-Zakour, who came up with this recipe after some thorough kitchen experimentation. “But It will separate over time, so it still needs to be shaken before using it.”

And because we’re a waste-not kind of publication, we have some recommendations when it comes to that leftover blended oat mush you have now. You can let it dry and use it to bake cookies, you can immediately add more water and make some porridge, or you can slather your face with it as-is and do a brightening oat face mask. I chose the last option because although glow comes from the inside, we need to give our skin a little help.

Correction, May 5th at 4:44 p.m.: This story has been updated to more accurately reflect the correct amount of amylase needed for this recipe. The original version asked for 16.7 grams of amylase. It’s 16.7 milligrams.

Sandra Gutierrez G.

Sandra Gutierrez G.is a Chilean journalist and the assistant DIY editor at PopSci. She has previously worked as an editor for MSN.cl, and a reporter for Rolling Stone magazine. When she's not putting baking soda on things, she's walking her 10-year-old beagle, Lucas. Contact the author here.