The Koji Chronicles

What is Umami?

There is a food stuff that has been the epitome of umami for 2500 years. That food stuff is called koji and if you enjoy some Chinese, Korean or Japanese cuisine you will be familiar with its allure by just a mention. Before embarking on this leg of the koji journey, I'll first explain what umami is.

Umami is the name of what is now recognized as the fifth taste after sweet, sour, salty, and bitter. Umami is described as savoury or meaty and causes salivation and is thought to be caused by glutamate (or glutamic acid). Glutamate is found in many foods, including vegetables such as ripe tomatoes and mushrooms, but also in meats. Although fresh/raw foods do contain glutamate, the intensity of umami is more pronounced if two or more rich sources of umami foods are combined together or if the foods are processed/cooked. Boiling, roasting, steaming, salting, smoking,  dehydrating, and aging will bring out the umami flavours in food - think sundried tomatoes, chicken broth, or smoked oysters. Fermenting or culturing is another method of emphasizing or drawing out the taste of umami - think Parmesan cheese, Balsamic vinegar, or Proscuitto. A few other notable fermented foods containing high amounts of glutamate  are soy sauce, tamari, sake, amazake, and miso. What makes these traditional Asian foodstuffs so spectacular is that they all share a common foodstuff - they are all fermented with the culture of koji.

What is Koji?

Koji is grains or legumes which have been cultured with a microorganism, specifically the Aspergillus oryzae mould. The cooked grain (typically rice, soy beans, or barley) are innoculated with the mould spores and the mixture is incubated for about 48 hours while the mould coats and penetrates the grain in a white bloom that has an incredibly sweet floral and mushroom-like aroma. The cultured grain is then added to other cooked grains (or legumes or vegetables) along with salt and water. The mixture is placed into crocks and left to ferment anywhere from one week to several years depending on what outcome is desired.
Koji is the distinct culture that provides the enzymes that break down nutrients like sugars and proteins into their singular components. Desired bacteria and yeasts then feed on those components (aka. fermentation). Unique flavours, aromas, nutrients, and textures are transformed and created during the fermentation phase making these foods umami bombs and incredibly nutritious.

The Basics of Culturing Koji

The process for making tamari or miso requires cultured rice, soy beans or barley to be added to cooked grains with the addition of salt and water. If you can't find cultured rice, the only other option is to make it yourself.
With sourced spores, rice is rinsed until all of the starch is removed then soaked overnight in water. The drained rice is then steamed until it is tender which can take several hours. A pressure cooker quickens this process. The cooked rice is cooled before the spores are added and the mixture is stirred. To encourage the spores to bloom, the rice needs to be kept in a warm and humid environment for 48 hours. During the first phase (0-24 hours) added heat is necessary to keep the desired temperatures high enough. For the second phase, hours 24-48, the heat generated from the culturing grains is more than sufficient. In fact, at this point the grains will have to be constantly monitored every couple of hours to ensure overheating doesn't take place. Too hot and the mould will be killed.
Once the grains are completely cultured, the koji is then ready to use or be preserved for future use.

With a bit more flexibility in my schedule over the past few weeks I have finally been able to set aside blocks of time to prepare several types of koji. A previous attempt at koji making resulted in a successful culture and a cabbage condiment. A beet miso-type condiment, however, was a failure after the water bags used to weigh the ferment leaked. This time around I wanted to prepare larger quantities and different varieties. If I'm having to stick to the kitchen for 60 hours I might as well be as efficient as possible and do as much as I can.

Using white polished rice seems to be the recommended medium to use but in any literature I could find on preparing koji it isn't specified if sushi grade or long grain is best. I chose long grain and had great results. Organic brown rice, pearled barley, and organic soy beans were also all successful.

With the koji complete, I could now begin experiments using the koji as a culture or flavouring.

Hatcho tamari and miso are two traditional Japanese varieties of ferments. Both use only soy beans in their preparation which is of higher quality but also comes with a higher price compared to rice. Both preparations also use the very same ingredients (koji soy beans, cooked soybeans, sea salt, water). Miso is a thick paste (sometimes chunky, sometimes smooth) so doesn't require as much water. With tamari, the liquid after fermentation is the desired product so more water is added. Salt content of either one varies on how much koji is added and the desired aging. More koji requires less salt as there is less chance of unwanted bacteria to take hold. Quick aging requires less salt as well. The higher salt content of longer aged ferments usually mellows over time.

Using the same method as for traditional miso, I also prepared four vegetable-based miso-type pastes: honeynut butternut squash, roasted beet, yellow carrot, and black bean. All were prepared using white koji rice. My initial thoughts were the misos would only ferment for 3-4 weeks but my salt content may have been higher than optimal so I expect they won't be ready until at least 6-8 weeks. The batches of hatcho miso and tamari will be aged at least a year.

Koji isn't just used for miso or tamari. It can also be used as an ingredient in ready-to-cook foods like porridge, vinaigrettes, marinades, as a pickling medium, or as a flavour enrichment to sourdough bread. I'll continue to post my culinary experiments as they happen.