
Welcome
Welcome to The Koji Fermenteria’s website and wonderful world of koji!
We are London-based small fermenterium specialised in traditional koji making. We make koji in small batch using Japanese koji-buta method (like picture shown above) which enable us to closely monitor its growth.
Lately koji is treated as a rising star among chefs and fermentation enthusiasts all over the world and various new innovative koji making methods are starting to emerge. Although every idea has its own merit and of course there is no right or wrong answer, we feel someone needs to strictly follow the tradition based on the understanding of how and why it has been developed. We would like to take this role and contribute to the further development of newly born global koji culture.
Let me introduce a little bit about koji. Koji is an intrinsic microbe which has been co-habited with Japanese for millenniums and, without doubt, contributed to the development of umami-based Japanese food culture (it indeed has done numerous amounts of miraculous works on it. Click here for more detail about koji).
Whereas koji is strongly associated with Japanese food, the principle of it can be applied to any types of cuisine. We believe koji can offer huge potential to open a new dimension to already accomplished many locale cuisines in the world. This is what we want to see and is our motivation to roll out our various activities.


Meet Haruko
Haruko learnt koji making from Nakaji, the author of the highly praised “Koji for Life” and is a certified koji specialist (accredited by Nakaji’s Koji Academy). She inherits Nakaji’s koji making philosophy and approach which is traditional yet flexible.
With aspiration of making koji as a global culture as well as contributing to boost community welfare with it, she is involved in a various forms of activities such as having a stall at farmer’s market, hosting online/offline workshops, participating educational events.
She majored in chemistry in university and was trained as a computer engineer before embarking her career as a koji professional. Although the fields are very different, the influence of her backgrounds are clearly evident in her analytical approach in koji making (the glimpse of it is shown in her Instagram posts). She values both scientific evidence as well as sensory experience and is always searching for new subjects of trials and experiments, while carrying out research on new findings and journals. Her curious and inquisitive nature helped her to develop many connections with leading koji/brewing experts in Japan.
Haruko is also a professional translator and translated “Koji for Life” into English

Our activities
In order to accomplish our aspiration and mission, we are actively involved in various form of activities, such as having a stall at Stroud Green farmers market and selling homemade koji condiments, participating in educational events and providing consultation to restaurants.
However, our main focus is hosting in-depth koji workshops both online and offline which spans over days to weeks. Our approach toward workshops are known to be very experiential and gains high-level of satisfaction. Whereas koji is an extremely powerful tool as a cooking element, it is something that you need to build up the experiences and engrain then into your five sense. It is definitely not something you can learn by sitting, watching and listening. It also requires certain knowledge to make the most out of it. We design our workshops in a way you can gain confidence to deal with koji and optimise your setting on your own at the end of the class. We have a pride in providing such a course by deploying IT technology as best as we can.
Shops
We supply following products in order to support your koji and miso making needs.

Koji for Life
A bilingual book written by Nakaji, fully packed with valuable and indispensable information of koji making. It also gives deep insight about koji and Japanese history and culture as well as useful recipes. This book is absolutely must have for any koji lovers.

Koji spores
20g of quality koji starters to make 15 kg of koji from Hishiroku, Kyoto. The company has nearly 400 years of experience dealing with koji spore, established even before Leeuwenhoek, Dutch scientist, discovered the existence of microbe in 1674.

Miso Video
Two-parts series of miso making video accompanied by salt calculation Excel sheet. These comprehensive video covers not only the details of miso making and practical tips, but also many not so well known facts even among modern Japanese.

Koji packs
250g pack of organic koji grown on assorted substrates. These koji are carefully made in small batch with traditional Japanese koji-buta technique to fully ensure the balanced production of enzymes.

Miso kits
These are four types of traditional Japanese miso making kits which make 500-900g of organic miso (standard rice miso, Saikyo-sweet rice miso, sweet barley miso and very regional umami-rich red miso)
Instruction included.
The Koji Fermenteria's Koji Diary
- other japanese ferments
- soy sauce
- koji making
- how to use koji
- doburoku
- miso