I eat natto most mornings and I know what it is supposed to smell like. Opened a pack from the back of the fridge today and it was a sharp chemical ammonia smell, the sort you get off a cleaning product, rather than the usual funk.
Best before was about a week ago. The beans look right, the threads are there, no colour on them. Is ammonia a spoilage signal or just an old pack?
If it is only mildly ammoniac, there are three things that help and they are what most people do without thinking about it. Open the pack and leave it for a few minutes, because ammonia is volatile and some of it simply airs off. Then stir it properly, fifty strokes or more, which builds the threads and changes both aroma and texture.
Then the standard seasonings: the sachet, soy, karashi, spring onion, over hot rice. The warmth and the rice mellow it considerably.
@stir_fifty_times · in 1m · 2 replies
Age rather than spoilage, and there is a mechanism behind it. Natto is fermented with Bacillus subtilis, which breaks down the protein in the soybeans, and part of that breakdown releases ammonia. A little is normal and it accumulates the longer fermentation runs.
The part people do not realise is that it carries on slowly fermenting in the fridge. So a pack a week past its date has had extra time to build it up, and if it was ever somewhere warm on the way home that accelerates it.
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@opened_the_pack · in 2m
So is a sharp ammonia pack still edible, or just unpleasant?
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