Rank aftertaste

[SakeAmateur]

Hi. My first batch of doburoku saké was a delicious success, but my second, which is at day seven of fermentation has a decidedly rank aftertaste that I can only compare to corked wine. I am using a different (lager) yeast this time, and froze/thawed my koji as opposed to fresh the first time. The brew had been precisely temperature controlled at 14° C. I suspect a mould, because the aftertaste lingers like corked wine.

Is it doomed, and should I turf it, or see out the fermentation?

[KramerOG]

I would not build up the sake anymore, but would allow the sake fermentation to go to completion before making a decision to toss the batch. Share it with people who make alcohol at home to see if they recognize the problem.

[SakeAmateur]

Thanks Kramer. I let it run a couple of degrees warmer overnight to try and increase the fermentation activity. The off flavour is far less pronounce this morning, so I am now beginning to suspect that the culprit is yeast. I used 3 grams more years than the recipe called for (23gms instead of 20), and assumed that this would not make much difference, but perhaps it has.

Anyway, I can deal with yeast, it is preferred to mould. I did everything right with this batch so I was surprised to think that I had a mould infection. I'll run it warm for a day or two longer and see what happens.