Flavor Adjustments from Koji

[todd35]

Have begun my second batch of Genshu sake and am following the same methods used previously this past spring. This summer I successfully made a batch of koji derived from growing and collecting spores from a container of Cold Mt Koji. I plan on using the Cold Mt rice and my own batch of koji in the brewing this time. There is a noticeable difference in taste and smell between the store-bought koji and what I grew and made using it. Cold Mt has a more neutral aroma, leaning towards vanilla, while what I made has a strong uniform nutty aroma and a tangy taste/flavor while Cold Mt is not very aromatic and only slightly sweet.

My question about mixing koji…is using my own going to create a totally different product, or does all the rice dissolve equally and temperature the only major taste/aroma factor?

[dray]

Hello,

Assuming the spores you were able to make are the right kind (reads like they are from the description of aroma and look) you product will be similar to something made from vision or gem or AK. Its fresh, so you get to see what its like when new, vs something sitting in the cooler for a few months/years.

As for flavor contribution? Absolutely most definitely koji will effect your sake’s flavor. How you grow your koji, under what moisture/oxygen/temp conditions all determine not only flavor but enzymatic activity - which also controls flavor.

Your koji being tangy might be due to some lactobacillus or other organisms in with your koji. Is your koji white/offwhite?

If its green, do not use it.

Do you have enough for 2 batches of sake? Make one with yours the other with cold mountain and compare. Sounds like your koji is good to go?

[todd35]

Thanks Dray, it seems to be going well and ready for Nakazoe this weekend. The rather strong nut flavor seems to be dissipating nicely and will use more of the frozen koji, which is an off-white yellowish color. I was concerned because the smell was rather potent and not as yummy as when I finished making it. When frozen, it dehydrated to look very similar to the CMK but less fuzzy.

Doing a full 6 gallon batch, so I’m gonna use up most of the batches this round and just see how it turns out. One thing I made a mistake in doing for the koji-kin production was not airing out the mason jar to total dryness and I think I lost my supply of CMK-grown spores…it seems to be turning to a dark dirt and even smells a little like vinegar…No way to salvage any of that stuff is there?

[todd35]

BTW, I made the koji at 96 degrees…supposedly for the upper-limit of enzyme production. Observations so far is that the rice in the Moromi stage turned to mush much faster than last spring with Cold Mt Koji. Time will tell.

[dray]

You can actually go up to 110 or so, but 104F is a good zone for more sugar enzymes, 96F is good. 75-88F is for more protein enzymes.

Koji is chestnutty in of itself, with some earthy sometimes fruity contributions. At least, that’s what I’ve seen so far.

[todd35]

My batch of sake is a total success. Using the Taylor Method, I gave the batch a few extra days and that made the biggest difference between a sweeter taste and the full dry effect, probably 19 percent strength or so.

It has a more mild flavor than my previous batch when I used WYeast’s Pasteur Champagne. (I used Red Star Pasteur and a Montrachet packet to pick up the extra few gallon slack) Generally, I saved a lot of money by using the 99 cent yeasts and growing half of my koji from leftover Cold Mt Koji supplies.

Now, the question arises whether I needed the extra week of fermentation for the finished strength because of the weaker yellow koji I made, or my yeast mixing experiment. I’ll definitely try the higher temperature next time for growing the koji.