How is oat milk made? Why "no added sugar" oat milk still tastes lightly sweet

From oat grain to glass: four steps

Whether it's made at home or in a factory, oat milk goes through four basic steps:

1. Mix oats with water. Usually a lot of water compared with the grain. Oat milk is mostly water.
2. Blend it smooth. The grain breaks apart, and starch, fat, protein and some fiber move into the water.
3. Strain out the pulp. The coarse fiber stays in the sieve, and the cloudy liquid passes through. That's the milk.
4. Finish it. It depends who's making it: a pinch of salt, a little oil for creaminess, then cooking or sterilizing so it keeps longer.

At industrial scale, there's one more important step between steps 2 and 3. That step creates the signature taste of many cartons on the shelf.

The secret of the gentle sweetness: starch gets "snipped"

Oats are packed with starch. Starch is made of long chains of glucose, and on its own it barely tastes sweet.

Many manufacturers add enzymes, tiny biological "scissors" similar to the enzymes in your saliva. The enzymes cut long starch chains into short pieces, including maltose, a double sugar. Maltose tastes lightly sweet.

That's why many cartons say "no added sugar" yet still taste gently sweet. Nobody poured sugar in. But part of the oats' own starch has turned into sugar.

We mention this so you can read labels correctly: "no added sugar" doesn't mean "no sugar". Look at the carb line and the sugar line in the nutrition panel. For more on reading labels, see the "sugar free" and "no added sugar" labels.

Why does homemade oat milk turn slimy?

Anyone who's tried making oat milk at home has probably met this: a thick, gloopy glass, sticky like paste, nothing like the café version.

There are two culprits:

• Starch meets heat. Once the temperature reaches about 60°C or higher, starch granules soak up water and swell, just like tapioca starch does when you cook chè (Vietnamese sweet soup). The warmer the blending water, the thicker the milk.
• Beta-glucan. This is the soluble fiber in oats, and it loves to form a gel. Blend too long or squeeze the pulp too hard and you pull lots of beta-glucan into the milk. We have a whole article on beta-glucan in oats.

Home tips for clean, smooth milk:

1. Use cold water, even a few ice cubes.
2. Blend briefly, about 20 to 30 seconds is enough.
3. Strain through a fine cloth, and let it drip on its own. Don't squeeze hard.
4. Don't boil the milk after straining. If you want it hot, just warm it gently.

What's in 100ml of oat milk?

Every brand has its own recipe, so the numbers vary quite a bit. Unsweetened oat milk on the market usually has, per 100ml:

A 250ml glass comes to about 120 kcal and about 2g of protein. Light and easy to drink, but not a protein source.

What about calcium, vitamin D and vitamin B12? Oats don't naturally have much. Many big brands add them. If the label doesn't say fortified, don't assume it replaces cow's milk on that front. The detailed comparison is in oat milk vs cow's milk.

Why does plant milk curdle in coffee?

Pour plant milk into hot coffee and sometimes you see little lumps, as if the milk went off. It didn't.

Coffee is acidic and very hot. Acid plus heat makes the protein and other parts of plant milk clump together. Soy milk does it most often.

"Barista" versions made for cafés are usually adjusted to handle acid and heat, and are a bit richer so they foam nicely. At home, the easy fix is to let the coffee cool a little, or pour the milk first and the coffee second.

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