FAQ

The big one - Why do you pasteurise your miso and shoyu?

This is probably the question we get asked most, and it is a fair one.

Pasteurisation (and any other cooking process - like making miso soup) stops the microbes, but it doesn’t undo what fermentation already did. 

During fermentation microbes break down proteins and carbohydrates into amino acids, organic acids, peptides and other metabolites. Those compounds are often referred to as postbiotics, and they remain even after heating. Fermented foods (including miso) contain prebiotic fibres and other substrates that help feed the beneficial microbes already living in your gut. This is also where the deep savouriness, complexity and richness come from.

So whilst pasteurisation stops live cultures and makes the product more shelf stable, the majority of the nutritional and fermentation derived compounds are still there.

I cover a fair bit of this in my book The Science of Fermentation, but if you want to jump into some quick papers that cover the nature of pre & post biotics you can check these out:

https://www.nature.com/articles/s41575-021-00440-6?utm

https://www.nature.com/articles/s41575-020-00390-5

We pasteurise because it gives us a more stable product with a longer shelf life and more consistent quality. It also means our jars and bottles can sit happily on a shelf before opening, which matters when you are sending food out into shops, kitchens and homes across the country.

In short: pasteurisation stops the microbes, but it does not erase the good that they have done.

What is koji?

Koji is grain or another cooked ingredient that has been grown with a special mould called Aspergillus oryzae. 

That might sound unusual, but koji is one of the foundations of Japanese fermentation. It is used to make miso, soy sauce, saké, mirin and many other foods.

Koji produces enzymes that break down starches and proteins into sugars, amino acids and other flavour compounds. In plain terms: koji is what unlocks the deep savoury magic.

It’s worth noting that Koji is only one Japanese subset of a larger mould based fermentation family that stretches across Asia - including Chinese doubanjiang, Korean gochujang, and many, many others.

Are you in competition with Japanese miso?

No. Not at all.

We have a huge amount of respect for Japanese miso, shoyu and koji traditions. Slow Sauce exists because we love those traditions, not because we want to replace them.

What we are doing is localising the method. Instead of trying to imitate Japanese miso with imported soybeans and rice, we are asking what koji fermentation can look like here, using Scottish and British ingredients. 

Japanese miso will always be Japanese miso. Slow Sauce is our Scottish expression of the same craft.

Can it be called miso if it is made with oats & peas?

Yes, and we use the word carefully.

Miso is not one single fixed recipe. It is a broad family of fermented pastes made using koji, salt and a protein or carbohydrate-rich base. In Japan, miso is most commonly associated with soybeans and rice or barley koji, but there are many regional styles, ingredients and methods.

Our miso follows the same core logic: koji, salt, time and microbes. The difference is that we use organic oats and peas as the main ingredients, creating something that is rooted in the miso-making tradition but shaped by the grains, materials and culture around us.

We have the great honour of supplying miso to the Japanese Consulate of Scotland, so in our eyes, if they’re happy - we’re happy.

Why oats and peas specifically?

Because they make sense here.

We are based in Scotland, surrounded by brilliant grains, pulses and farmers. Oats are one of the great grains of this part of the world, Carlin and Flamingo peas are beautiful heritage pulses with deep flavour and a strong connection to British food history.

Using them lets us make something that is rooted in the place we are making it.

If it is like soy sauce, why is it whisky coloured?

Because not all shoyu is dark.

Most people in the UK are familiar with dark, all-purpose soy sauce, but Japanese shoyu is a much broader family than that. One of the traditions we look to is shiro shoyu, or white shoyu, a light, golden style traditionally made with a much higher proportion of wheat to soybeans. It is prized because it brings savoury depth and gentle, aromatic profile.

Is it gluten free?

Yes. We make everything without wheat, barley or rye.

Is it soy free?

Yes, everything is soy-free, which makes it a useful alternative for people avoiding both gluten and soy.

Is it vegan?

Yes. Our miso and shoyu are totally plant-based and vegan.

How should I use oat miso?

Use it anywhere you want deep savoury flavour.

Stir it into soups, broths, stews, sauces, dressings, marinades, butter, mayo, gravy or roasted vegetables. It is particularly good with mushrooms, potatoes, brassicas, beans, eggs, fish and anything smoky or charred.

A spoonful can do a lot, so start small and build from there.

How should I use oat shoyu?

Use it as you would use soy sauce, but expect a slightly different character.

It is salty, savoury and full of umami, but it has a lighter amber colour and a rounded, malty depth from the oats. 

Splash it over rice, noodles, eggs, greens, mushrooms, grilled meat, fish, tofu, dumplings or soups. It also works beautifully in dressings, glazes and marinades.

Because it is gluten-free and soy-free, it is especially handy when cooking for mixed dietary needs.

Do I need to keep it in the fridge?

Before opening, the jars and bottles are shelf stable. After opening, keep them in the fridge and use a clean spoon or pour carefully to keep them at their best. Cross contamination from other condiments can cause things to get a bit mouldy in a bad way!

Miso is naturally salty and robust, but good habits help preserve flavour, colour and quality.

Stable for 12 months after production.