You may have seen ‘koji’ mentioned around Crate; most noticeably in our gin, lemon and koji soda cocktail. But what actually is it? And why are we so into it?

Let us break it down.

Koji explained

Koji is a traditional Japanese ferment that’s made by growing a specific mould (Aspergillus oryzae) on grains like rice, barley or soybeans. It has been used for over a thousand years in Japanese cooking and is the backbone of some of the world’s most recognised fermented foods and drinks - think miso, soy sauce, mirin and sake.

What makes koji special is its ability to unlock flavour. During fermentation, it releases enzymes that break down starches and proteins into sugars and amino acids. This process results in natural sweetness, savoury depth (umami), and a rounded complexity.

Put simply, koji makes things taste better.

Why we use it

At Crate, we use rice-grown shio koji to lift and balance the flavours in our gin, lemon and koji soda cocktail. It adds a subtle salinity to the drink, which helps bring out the flavours and botanicals of the gin. This delivers a more balanced finish, and brings a unique spin to a familiar drink combination; the gin/lemon. 

Koji can play a key role in the kitchen, too. It was a staple on the menu at Silo restaurant, featuring in their umami-rich mains like the koji porridge, and also their infamous koji quaver. Beyond the fine-dining applications, it’s a simple way to level up at-home cooking; be it tenderising meats, or adding depth to marinades and dressings.

Made in Hackney Wick

Our koji is grown right here in East London by our friends at Flux Fermentation, who are based just down the road from our Hackney Wick taproom.

Flux produce tonnes of koji each month in their fermentation factory. The space runs like a lab; think high-spec equipment, tightly controlled processes, and a carefully managed warm, humid environment where the koji can thrive. It’s precise work, and while it’s highly technical, there’s plenty of thought and attention poured into everything produced.

A key part of Flux’s work revolves around rethinking how traditionally imported products can be made locally and more sustainably. They have used their koji to create a London-grown, zero-soy soy sauce - showcasing just one of many ways koji can be used.

Fermentation, flavour and the bigger picture

Koji is a way for us to add depth and originality to what we serve at the bar, while supporting local producers. This unique microbe also showcases how culinary innovation can come from revisiting ancient techniques and applying them in new contexts.

If you’re curious, come try koji in our gin, lemon and koji soda cocktail at Crate; or explore what Flux are doing over at fluxfermentation.com.