Koji – Home Brew Sake

Aroma during koji production

Today as I am making a test batch of koji that I am working on as a new offering (Special Ginjo Koji-kin), I am led to thinking about the aroma of the growing koji. What is that smell? Where does it come from? Well it seems that the answer, at least at the level I can discuss here, is not that complicated.

The aroma of a fresh batch of koji is often described as being chestnut like. This aroma was noticeable during my check of the growing koji at 20 hours into the process, not strong but definitely there. As the time goes by the aroma is strengthening. I am not sure if I would equate the smell of koji with chestnuts but I find the smell nice and even comforting. So what is making this aroma?

It seems that the aroma is coming from a combination of phenylacetaldehyde, 1-octen-3-ol and 1-octen-3-one. Production of phenylacetaldehyde seems to stop at around 40 hours into the process while the production of 1-octen-3-ol and 1-octen-3-one continue and can even double their concentration during the final stages of koji production (hours 44-50). However, as 1-octen-3-ol and 1-octen-3-one concentrations overwhelm those of phenylacetaldehyde a more mushroom like aroma becomes noticeable. Individually phenylacetaldehyde and 1-octen-3-one have a rose like and a mushroom like aroma respectively. Continue reading “Aroma during koji production”

Amazake – it ain’t sake

I have meant to post a little something about anazake for some time but I keep putting it off. Now that I have gotten a question about how to make it I can see that it is overdue and I should get my act together. Amazake is a rice and koji mixture that is most thought of as a drink but has other uses as well.

OK, so to make amazake you need koji and rice. You can make koji with the method discussed in the earlier post, “Making Koji for Sake.” In this case you will need to start with koji-kin. If you prefer you can skip making your own and just buy the koji. I have both koji and koji-kin in the store.

Once you have the ingredients, koji and rice, cook 3 cups of rice just as you would to eat the rice. When cooked, thoroughly mix 1 cup koji with the now 3 cups of cooked rice. Leave this in a warm area (75F-85F is good but could be as high as 140F) for between 6 hours and 12 hours. You should stir this every couple of hours; each time tasting it. It should get sweeter and sweeter until it stabilizes. When it stops getting sweeter it is done. At this point it should be quite mush like. Put it in a sauce pan and boil it for 5 minutes but be careful not to scorch it. This denatures the enzymes and stops the transformation. Continue reading “Amazake – it ain’t sake”

Some Koji History

A little history on Koji

Koji has been used in the orient for two to three thousand years. Its use on a substrate of rice, soybean and wheat bran seems to have originated in China. Use of koji migrated to Japan in the Yayoi period around the change in the western calendar from BC to AD. Somewhere in the Heian and Muromachi period between the thirteenth and the fifteenth centuries AD koji became commercially available.

This was, in part, possible because of the use of hardwood leaf ash. These leaves where burned in an environment with limited oxygen to produce an ash/charcoal that was protective for the koji-kin. Koji-ken base packed, layered, in boxes with a layer of koji-ken then ash and repeated. The use of ash in packing to preserve the koji-kin led to the discovery that adding the ash directly to steamed rice produced more consistent koji production. We now know the alkaline environment from the ash prevents other micro-organisms from getting a foothold and that the minerals in the ash help mold growth.

Moyashi or fermentation starter suppliers, two of them, were established in the Muromachi period about 1400AD. The Koji-za did not license more than these two prior to 1700AD. Currently, there seems to be about five such producers.

Koji What?

This article discusses what koji is and what it contributes to sake.

The most mysterious ingredient use to make sake is koji. What is it? Why is it so important? What does it contribute to sake? Well, these are all important questions we will address here. Koji is a general term that is almost always used as a specific term by those talking about sake. In the general case koji is some kind of substrate with some kind of mold growing on it. How’s that for a technical description. Koji used for making sake is, in most cases, yellow koji consisting of Aspergillus Oryzae growing on milled rice.

Yellow koji is also used for making Shochu, a distilled beverage, but has been mostly replaced by other forms of mold and substrate. The two most common molds now used for koji in the production of shochu are Aspergillus Kawachi (white) and Aspergillus Awamori (black). In the general case the substrates also very quite a bit. Substrates of buckwheat, sweet potato, barley and rice are common. Rice is always the substrate used for sake. Continue reading “Koji What?”

SakéOne Brewer’s Tour, last week

I describe a tour the lead brewer at SakeOne gave to a group of brewer from the Oregon brew crew.

This last weekend I joined a group of brewers for a brewer’s tour of the SakéOne Kura. Greg Lorenz, SakéOne’s Sakémaster gave the tour to a group of brewers from the Oregon Brew Crew.

As we gathered in the tasting room, we sampled the current nama on tap, a junmai ginjo genshu namazake; wow, very nice. What a way to start the tour. Once everyone had gathered we topped off our glasses and headed out with Greg in the lead.

Stopping in front of a picture of Mr Murai, Greg explains how Mr Murai was a man ahead of his time and how he thought that it was time to establish a Kura in the US. How he had pushed this idea for some time without success, until one day on a flight when he sat next to Grif Frost.

Continue reading “SakéOne Brewer’s Tour, last week”

Want to brew sake? Where ya’ gonna get your koji?

This article discusses whether to use ready made koji or to make your own koji for Sake Brewing / Sake Making.

What is koji anyway? Well koji is rice with a white mold covering it. The mold is Aspergillus oryzae and it is the key to sake because of the enzymes it creates. These enzymes primarily break down the starches in the rice creating sugars needed for fermentation. So how do we get koji?

Koji is available in most good sized Asian markets. While this is not the best koji for sake, it is serviceable. Then there is sake brewer’s koji. The one I carry is here. You can also make your own. To make your own you need to start with the Aspergillus oryzae spores. Tane-koji (dried koji that was let go to spore) is one source of these spores. Another is koji-kin which is a processed tane-koji to separate out the spores. Technically speaking I believe tane-koji and koji-kin are the same thing but for the products I have seen it seems to separate out as whole rice vs. powder. In any case we can use these spores to inoculate steamed rice to culture up some fresh koji. Continue reading “Want to brew sake? Where ya’ gonna get your koji?”

Basic Brewing Radio goes to Sake One!

A two part video of SakeOne, the kura and sake.

Basic Brewing Radio, on a trip to Portland, stopped by SakeOne and filmed their tour at the local kura (Sake Brewery). The tour is presented in two parts:

Part One, Jenifer introduces us to the sake brewery. She discusses the water, milling the rice and making the koji.

Continue reading “Basic Brewing Radio goes to Sake One!”

Koji Comparison

Compared Cold Mountain, GEM Cultures, Home made and SakeOne koji for sweetness, texture and appearance.

I have been thinking about how different koji compare with each other. The most meaningful way would be to compare sake made from each. However, I can’t do this at this time so I decided to look at the koji itself. The koji I looked at are: Cold Mountain, GEM Cultures, home made koji from GEM Cultures’ Koji-kin and SakeOne koji.

Both the Cold Mountain and GEM Cultures koji are quite dry and hard. When bit they are a little softer than dry rice but not by much. The home made and SakeOne koji are “fresher” and somewhat soft and chewy.

Cold Mountain and GEM Cultures seem less sweet than SakeOne which much less sweet then the home make koji. Given the minimal fuzz covering of the home made koji, I was surprised it was by far the sweetest. This seems to indicate a healthy amount of enzyme despite the lack of fuzz. To check to see how much the dryness is effecting the sweetness, I soaked some koji from each sample.

After soaking for an hour the water for Cold Mountain and GEM Cultures were a little sweet. The water for the home made koji was almost like syrup. However, the water for SakeOne was the least sweet. As for the koji itself, Cold Mountain was now the sweetest. GEM Cultures koji was noticeably sweeter but has a strong brand taste. Neither the SakeOne nor the home made koji seemed sweet any longer.

Four Kojis: Cold Mountain, GEM Cultures, Home Made, SakeOne

Continue reading “Koji Comparison”

Sake basic ingredients

Sake has four basic ingredients: rice, koji, yeast and water. Each play an important part in producing the taste, aroma and appearance. Each are discussed and how they come together to form the sake we love.

Sake is made with four ingredients: rice, koji, yeast and water. All, except the koji, are familiar to most people. Koji is a mold culture grown on rice in the case of Sake. The mold is Aspergillus oryzae. It forms a white fluffy coating over the rice and excretes alpha-amylase which converts the rice starch into sugar. This is the primary function of koji in brewing sake; to provide enough alpha-amylase to convert most of the starch provided by the rice to sugar. Other compounds produced by the koji contribute to the final taste.

Once the koji converts the starches from the rice to sugar, yeast converts the sugars to alcohol. Beyond this major contribution the yeast also produces other compounds that contribute to the final taste and aroma of the sake. These two processes, conversion of starch to sugar and conversion of sugar to alcohol, proceed at the same time which allows the yeast to produce higher levels of alcohol than is the case in beer and wine. This is not to say that beers and wines can not ferment to the high levels that sake does but that special processes, outside the norm are needed to obtain the same high level normally reached with sake. Continue reading “Sake basic ingredients”