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Foam during first couple days of moto?

So I have to be honest, I did make a mistake here… I accidentally added 2.5 cups of steamed rice to start the moto instead of 1.5. I compensated by adding more koji and more water to maintain the proper ratio.
… but now, day 3 when I open the bucket to add the yeast, it’s bubbled up about two inches (from what I can tell by the residual on the inside of the bucket), and it smells much different than my first batch… very strong smell, almost like vinegar. Most of the rice has already liquified also. My first batch, at this point, still appeared like an oatmeal consistency. Has something gone wrong? Should I toss the batch and start over?

Remember this is only my second batch, so I am still very new to this process.


The extra rice, koji, and water is not a problem. Just adjust/decrease your san dan shikomi additions to end up with 2 gal water, 10 lbs rice and 2.5lbs koji by the end.

Since you haven’t added yeast yet, the moto shouldn’t really be bubbling up. Most likely what you are seeing are the remnants of the rise and fall of the rice due to water absorption and then the subsequent decrease in volume due to liquefaction.

Vinegar is not a good smell in sake. Perhaps you could be mistaking lactic acid/koji aroma with acetic acid?

I think you should keep going with the ferment and taste along the way. Hopefully it will turn out great and not have any vinegar smell/taste by nakazoe and tomezoe.



Thanks M. It was a very strong smell, so it may have just been the intensity that made me think of vinegar. In about an hour the 12 hour wait for the yeast will be over, and i can stir it up… mybe it will have calmed down then.

Appreciate the help man!

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