Saturday, May 25, 2013

Fail: Homemade Natto Using Packaged Natto -Batch #39

A timely failure to keep me humble. After a few successful runs which can be seen on Batch #37, Batch #39 fails on me. I guess I am a little bit harsh on myself because it was not a complete fail. I had mentioned previously that one important criteria for good natto was its silky long strings. I love to make a batch that has strong threads that hold the beans within the string even when lifted.

On Batch #39, the fermentation looked fine and I was looking forward to eating natto. One quick test is to take out a small portion of the freshly fermented natto and do the wet seasoning test. You can use shoyu or mentsuyu. 

On a successful batch, the freshly made natto looks almost gummy and will stick to each other. When mentsuyu is added, it will still be gummy and sticky.

On the other hand, unsuccessful batches will almost have flaky natto growth with thin strings. When this is mixed with mentsuyu, the strings will have a wet look and will not have sticking power. You can see how the natto has not clumped together in the bowl after mixing.

I always thought this was due to a problem with the fermentation, but on this batch I used the same method as the successful batch #37. The only thing that I did different this time was to use a different starter. I had ran out of the old frozen natto so I used a new package. Unfortunately, I did not keep the outer label so I have no idea what the brand was. So assuming that I used a different brand of frozen natto starter, the outcome of the fermentation could be strongly linked to the strain of natto used for the fermentation. I am sure different brands use different strains of natto to establish their style. 

I will start noting what brands I use as the starter to see if there are strains that are more stringy than others. I have heard that in Japan, there is a trend towards less stinky natto. There could be a correlation to natto that turns out less stringy when this less stinky natto is used. 

This is a good remainder to me not to be discouraged by a bad batch. It is very possible that your natto did not turn stringy because of the starter used. If possible, try to use a different brand to see how the natto turns out.


  1. Hi, sorry for digging this up.
    I am relatively new to homemade natto and have tried to make it at home several times.
    The first two batches were very good : stringy, no ammonia smell/taste, natto taste, all good.
    Since then, every single one of them is a failure. I just don't know what is wrong. I used the same exact brand of natto every time. I changed the fermentation process since the first failed batch.
    The first two ones were at a lower temperature (in the corner of my kitchen, about 20-23° depending on the time of the day). But I read this is too cold (and it could explain why my natto was ok but not too stringy).
    Now it's like this second picture in your article. Very weak strings, strong strong ammonia taste/smell. I have to toss it away every time :(

    I can't find answers anywhere. No FB group, and no solution has worked yet. Do you happen to have any idea what could go wrong, natto-sensei? :)

    1. Hi Egga,
      Hope this message gets to you. Being a Blogger novice, I do not know if blogger sends a reply notification. Anyways, to answer your question, I would say temp is the culprit. Natto is different from other fermentations because it likes high temps around 34-42C, average 38C. If the failures correspond with winter ferms, then it is definitely a temp issue. If you have not done so already, please read the "Homemade Natto" and "Troubleshooting" links/tabs at the top of the page.
      Thank you for visiting the blog and update me on how it goes!