Fermenting oats into oatmeal (or if you are outside the US, porridge) is a delicious way to enjoy a healthy breakfast. This article will explain why you should be fermenting your oats, show you how to do it, and answer the most common fermenting oats questions I receive.

Why ferment oats?

If you are a lover of oatmeal, fermenting your oats before cooking them will take your breakfast to a new level. Here’s why you should do it:

1. Fermented oats taste delicious!

A bowl of oatmeal is already creamy and satisfying but when you ferment your oats with a live starter, they also take on a zingy flavour. Everyone who I have shared this process with has told me that, once they’ve tried their oats fermented, they can’t go back to normal oatmeal!

2. Fermenting oats makes them easier to digest.

Soaking oats softens them and the fermentation process breaks down their complex carbohydrates. This means your digestion does not have to work so hard – less bloating and more energy for your body to do other things.

3. Fermenting oats makes them more nutritious.

All grains contain anti-nutrients that can block the absorption of minerals – by fermenting your oats the right way (using the method below) you will neutralise those therefore making your oats more nutritious.

How to make fermented oats:

Making fermented oats is very simple. Here’s how:

1. Measure your rolled oats (I use around 50-60g per person) into a bowl and cover them with ample water.

2. Add a tablespoon of ‘starter’ to the mixture. This can be anything that has live probiotics in it. Some examples are: sourdough starter, yoghurt, milk kefir, buttermilk, apple cider vinegar, sauerkraut juice or kombucha. It’s important that this starter is active. If you are buying it from the store, ensure that it hasn’t been pasteurised after production (the packaging should say ‘live bacteria’).

3. Stir this well then cover the bowl and leave it to stand at room temperature. The length of time you leave your oats to ferment depends on how tangy you would like your resulting oatmeal/porridge. The longer you leave it the more tart it will become. I usually leave my oats overnight (I mix them up before going to bed and then cook them up the following morning).

4. When you are ready to cook your oatmeal/porridge, pour the entire contents of the bowl into your saucepan, add more water/milk as necessary, cook and enjoy.

How to eat fermented oatmeal/porridge

Fermented oatmeal can be eaten in any way that we would eat normal oatmeal.

For many, that means topping with sweet things like fruit and honey in a combination with nuts/seeds.

I often eat my porridge savoury; I like to stir in miso just before serving and then add ground flaxseed and olive oil. Sometimes, for a protein-rich breakfast, a few minutes before they’re done I stir in a couple of eggs, topping the mix with cream. I also love the fermented oats served simply with butter and salt.

Ways of saving/storing fermented oats

Fermented oats can be kept – both before cooking and after they’ve been cooked.

To store your uncooked fermented oats:

You don’t need to cook your fermenting oats straightaway. If your plans change, or you have too many, put the bowl into the fridge. This will greaty slow down the fermentation. The oats can be stored this way for 4 to 5 days before cooking.

To store your cooked fermented oats:

If you don’t manage to eat all your cooked,fermented oatmeal, you can store it in the fridge. It can be reheated anytime over the following few days – add a little extra liquid when doing so. See the question section below for more ideas on how to use cooked fermented oats.

Fermented oats questions:

Can I ferment steel-cut oats?

Yes, you can use this same method to ferment steel-cut oats. Because they are thicker, they will need a longer cooking time.

How long should I ferment my oats?

This is up to you. I generally ferment my oats overnight, for 12 hours. This produces an oatmeal with a light, tangy flavour. If you want a less marked fermented flavour, ferment your oats for less time or put them in a cooler place. If you love the sour taste of fermented foods you can leave them longer – for 4 to 5 days. If you are leaving the fermentation longer than a day at room temperature, I would recommend stirring them once a day.

Can fermented oats go bad?

This has never happened to me – and I have fermented oats for as long as six or seven days. If you want to leave your oats at room temperature for longer than a day, do stir them every 24 hours.

If you have left the oats fermenting for many days and the smell is too strong for you, you can ‘dilute’ the flavour by adding more dry oats to the mix.

Can fermented oats be eaten raw?

Yes they can, but I prefer to cook mine. Historically, oats have been eaten cooked and heating fermented oats helps make them even more digestible.

Does fermenting oats reduce phytic acid?

Yes. Most oats, during the processing stage, lose their inherent phytase (the enzyme which can help deactivate phytic acid). We can create the conditions to aid the breakdown of phytic acid by fermenting our oats – an acidic environment plus live yeasts and bacteria (the live starter provides both of these). Using warm water, and/or keeping our fermenting oats warm, aids this process as does including a freshly-ground, high-phytase flour (like rye or buckwheat) in the mixture. See my article The Lowdown on Oats and Phytic Acid for more information.

Should I rinse my fermented oats before cooking them?

There is no need to rinse your fermented oats before cooking them. A lot of the goodness of the grain leaches into the water and it’s good to capture that in your final dish.

Doesn’t cooking destroy all the probiotics in my oats?

Cooking fermented produce does kill live probiotics. But the work that those enzymes have carried out on your fermented oats will have brought about many changes in the food which are beneficial. In addition scientists are currently researching the benefits of postbiotics and para-probiotics, the microbes that are left behind when fermented foods are cooked, all of which do incredible things for our immune systems. Cultures have traditionally used fermented foods both raw and cooked and a diet utilising fermented foods in many, varied ways is most advised.

Can I ferment my oats in just water?

It is possible to ferment oats using water alone. The grains will have native yeasts and bacteria on them and so will your home environment. I recommend, however, using a live starter – giving your preparation a kick-start of already strong live bacteria makes the process a lot easier and much more likely to succeed. There is however an ancestral legacy of fermenting oats just in water, the Scottish made an oat ferment called Sowans. If you like to have a go, you can find my video course on it here.

Fermented Oats & Sowans — Fermenting oats (middle) flaned by jars of Sowans, the Scottish oat ferment

Is it safe to ferment oats?

Fermentation is a very safe process. Cheese, chocolate, beer, wine, salami – they are all fermented food that have been made for thousands of years. And when you ferment in clean vessels with an already-strong starter, you are standing in the shoes of generations before you, worldwide, who’ve done just the same.

What if my house is too cold?

Oats will ferment in a cooler environment, they will just take longer. If your home is cool expect the process to take a day or more. If you’d like to speed it up, look for a warm spot – on a shelf above a radiator, on top of your fridge or in an airing cupboard. You can also utilise a ‘proofing’ area; read my article How to Create a DIY Proofing Box for more details.

Can I keep these oats?

Yes you can! If you are not ready to cook them, you can keep them in the fridge for 4 to 5 days. If you’ve already cooked them and have too many you can store them for later reheating (add a little extra liquid to the pan) in the fridge.

Is fermented oatmeal good for you?

Yes! Soaking and fermenting these oats makes them easier to digest and much more nutritious. They are especially nutrient dense if you add in a traditional fat – butter, cream or olive oil when you serve them.

I’ve got left over fermented oats, what can I do with them?

You can eat them the next day for breakfast. Reheat them with a little extra liquid before serving.
If you make bread, add in some leftover cooked fermented oats into your dough to bring more softness to the resulting bread’s crumb.
You can use them as a non-dairy soup thickener.
You can mix them with any type of flour and shape them into patties before frying.

I love fermented oats! What else can I make with them?

Fermented oats can be used for so many other things. Check out my recipe for fermented oat bake here – I’ve created a savoury version, but you could do the same with dried fruit and spices making it sweet.

Cook My Recipes

How to Make Fermented Oats