Batch # 40: Back on track

After the last batch which turned out okay, I made a really good batch of natto. Mainly it is due to the new frozen natto pack that I used to ferment this batch. I did note the brand: Shukuba Nattou by Murakami. I bought it a few weeks ago probably because it was on sale.

Batch #40 looked slightly wet but had good sticking power. With shoyu, it formed thick long threads.

The freshly made natto almost had a pleasant apricot smell

One thing I like about making natto in the summer is that the fermentation seems to go smoother. I have come to associate this with temperature. This is especially true when I was making natto with only a yutanpo as the heat source. I have not seen many homemade natto makers mention this, but natto fermentation is truly a metabolic marvel. Each individual natto bacteria is going about its life eating and multiplying. This in itself is an insignificant event that is too small in scale to matter but in large numbers, it takes a whole new dimension.

I mention this in relation to natto making in the summer time because I have noticed that when the ambient temperature is high enough, the natto fermentation can continue with its own generated heat. I did not notice this at the beginning and was baffled why the natto fermentations in the summer seemed to go better than the winter fermemtations when using a yutanpo. After a while, I bought a thermometer to keep track of the fermentation temperature and I discovered something truly amazing. Seven hours into the fermentation to somewhere around the fifteenth hour of fermentation, the natto superorganism consisting of billions of individual natto bacteria metabolize the food in soybeans and generate enough heat to keep it at its ideal growth temperature without requiring an external heat source. This is evident when making large quantities of natto, in my case 400 grams of dry soybeans (~1 lb), when the ambient temperature is somewhere around 23C/75F or higher. The glass baking dish which has insulating qualities in addition to the double cling wrap to cover the top helps to retain the heat.

So in essence, it is possible to make natto if it is possible to maintain an ideal temperature in the first 6 hours of the fermentation using a low tech, cheap method such as warming the oven for a few seconds every hour or by using a yutanpo. Using a small cooler or styrofoam box, which I have not tried, would probably suffice to make good natto if ideal temperatures can be kept for the first 6 hours until the natto kick in to generate its own heat. After the natto slows down, the natto could be kept in the cooler for another few hours to let it ferment with the latent heat.

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.

Discovering Lauras Natto Soybeans (Kotsubu Soybean)

For the majority of my natto making year, I bought the organic soybeans found in the bulk section of Whole Foods. They taste great and are of very good quality. Initially, I made the natto with this and enjoyed it. After a few months my wife pointed out that they were too large and texturally were not ideal. So we settled on making "hikiwari natto" which is the chopped up version. Usually, hikiwari natto is said to be chopped before fermenting it. This was too hard at home so I chopped it right before we ate it.

photo link

The only thought that was nagging me was that they were not the "kotsubu" (small bean) variety. The natto that is store bought is made of this kotsubu variety and it was impossible to find in the US. On one of my deep googling expeditions late at night, I hit upon the gem I was looking for. Finally, I found kotsubu soybeans at Lauras Soybeans!

Homemade Natto Using Packaged Natto -Batch #37

Updated May-2020. Please read again if you came before.

Note: Please use the "Contact Me" or email me directly at nattodad[at]gmail.com if you would like a reply. I will not reply to comments made in the "Comment" section.


Preparation:

Day 0, 9pm

-400gr Kotsubu Laura's Soybean 16-20 hour soak, summer time 25C (77F). 20-24 hour soak, winter time 10C (50F).
Note: I prefer longer soaks over short soaks. So even in the summer, my tendency will be to soak it the night before even if I am steaming the soybeans the next day in the evening.

Day 1, 630pm

-Place beans in strainer and discard hard beans.

-Set up pressure cooker with water and place ramekin/small plate in the pot.

-Once boiling, put soybeans into strainer and place on top of ramekin inside the pressure cooker so the beans are not touching the water.

-Close lid on pressure cooker and build pressure. (My pressure cooker starts to whistle, at 1.5 bars or ~21 psi).

-After it builds pressure, set timer to 40 mins and lower range temp to medium-low. The Taylor thermometer is really handy as a timer and as a thermometer.

-While cooking, set oven temp 104-108F (40-42C) with a heat source (yutanpo, lamps, pre-heat, etc). In my case I use a 150W Ceramic Infrared Heat Emitter (plus a socket power plug) connected to a Digital Controller Thermostat. I now set the temp to 108F (42C).
Note: Due to fire safety reasons, use at your own risk.

Alternatively, you can use a single coil cooking range (like this one) inside on the very bottom set to warm, and plugging it to a Digital Controller Thermostat. 
Note: Due to fire safety reasons, use at your own risk.

-Place a pot or soup plate with water on the bottom wire rack (for humidity) and leave the top wire rack empty to place the baking dish later.

-Sanitize baking dish for 20 mins with 1 TBL of chlorine and fill to the rim with water. Discard and rinse with water.

Note: Natto fans have suggested other sanitation methods such as Heat, Steam, and Sterisan. Please use the method that fits your needs.Using Boiling water over the trays and draining works well.

-Also boil two spoons in a pot for 10 mins. Dump boiling water into the glass baking dish and discard water after 5 mins.  Alternatively, you can leave the two spoons in the baking dish that is sanitizing with chlorine. You will have to rinse with water afterwards so this is less sanitary. 

-When the 40 mins are up, place pressure cooker aside to cool for 20 min.

-After 20 min, open lid and put cooked soybeans into the glass baking dish. The soybeans should have turned from a pale yellow to a light caramel/beige color.

-Put a cube of frozen packaged natto (1/9 th of a package, will work with 1/12th of a package or 6gr ~ 4gr, 5gr avg.) into the hot soybeans and make a little mound of hot soybeans on top to cover the natto with the sterile spoon. Wait a minute or two until frozen natto cube thaws.
Note: I usually keep the packaged natto in the freezer and cut it into 9 frozen cubes per 50gr pack which are kept in a zip lock bag for later batches. So a 3 pack (150gr) of Okame Natto frozen natto will yield 27 batches of natto!

-Mix the melted packaged natto with the sterile spoon and add 2-4 soup spoons (about ~2-4 measuring teaspoons) of the hot water from pressure cooker. Add enough while making sure it does not puddle on the bottom. Mix the soybeans, packaged soybeans and water with the sterile spoon until well incorporated. 

-Tightly wrap the cling wrap and poke holes with a tooth pick all over the surface of the cling wrap. Then, detach from edges and rest cling wrap on top of the soybeans.

Double Cling Wrap Method: One on top of soybeans, second one on the top tight on dish. Creates an air pocked in the middle slowing drying of soybeans. I poked holes on both wraps with a toothpick.

-Cut one more piece of cling wrap and wrap tightly on the baking dish and poke holes. This will form an air pocket that will maintain the moisture on the beans. Cool until it is luke warm and then place on the top rack of the oven.
-I will leave a soup plate or shallow pan with water on the rack below the natto dish to maintain moisture in the oven. Note: Shown in the pic below is a pot, which is too big and not needed.

-Leave the natto to ferment for 16 to 20 hours at 38C-42C (100F-108F)

Day 2, around 3 pm 

-Take out natto from oven and place at room temperature on the countertop. Cool before putting into fridge. You can leave to cool anywhere from 1 to 5 hours, I usually put it in the fridge after dinner or before going to sleep.

-Natto is finished fermenting! There should be a pleasant natto aroma with a slight hint of ammonia, but should not be overpowering. If eaten at this time, it will have a sharp taste. The threads should be thick, sticky and silky when pulled. They can be eaten at this time.

The threads should be thick, but should form really long threads when pulled.

-Refrigerate and let it rest for 3-5 days in which time the natto will become mellower and will deepen in flavor. It will keep in the fridge for up to 2 weeks. If there is still any left, they can be put in the freezer. Time to eat natto!
Note: After two weeks in the fridge, the natto will form animo acids crystals which are texturally a bit sandy akin of the crunchy bits in aged parmesan cheese. If the sandy texture is not desired, natto can be moved to the freezer  after about a week. 

Natto in its full glory

Natto should have silky threads that are thick when initially mixed. When made successfully, the threads will be silky even after adding liquid seasoning such as shoyu and mentsuyu. I also have made so-so natto which is silky, but looses its threads when shoyu is added. A few thoughts on this on a future post.

Note: Please use the "Contact Me" or email me directly at nattodad[at]gmail.com if you want direct replies.

Natto Making Overview

Natto making, no matter what the scale, follows this basic steps:

1) Soaking
2) Cooking
3) Fermentation
4) Maturation
5) Eat

1) Soaking of the soybeans takes anywhere from 20+ hours in the winter to as little as 12 hours in the summer. This relates to the soaking time of the bean hydrates the soybeams. From what I gather germination happens in 3 steps: Step 1) Imbibition of water (aka hydration), Step 2) Saturation of water, enzyme activity, Step 3) Visible growth and axis elongation. I makes sense to me that for natto making you want to stop on step two. Some people have commented that a good indication of when the soybeans are fully hydrated is to look for bubbles on the water surface. The presence of bubble indicates respiration due to enzymatic and metabollic activity signaling a fully awake soybean. At this time, look for soybeans that did not hydrate and discard them.

2) Cooking the soybeans can be done either by boiling the soybeans or steaming them. After my initial failure of boiling the beans, I realized that this is not ideal. Boiling the soybeans takes too long and the flavors leach out into the boiling water. The second method is to steam them in a regular pot. This can be done by putting a steamer in the pot and suspending it above the boiling water. The flavors will not leach out, but this too will take time. You can boil the soybeans in a pressure cooker which is faster, but will leach out the flavor in the boiling water. So the most ideal way to cook them is to steam them with a pressure cooker. This cuts the cooking time down to 40 minutes from 4-6 hours and they will turn out very soft with an almost creamy texture. The pressure cooked soybeans will have a nice light caramel color and will be slightly sweet in taste.

3) Fermentation temperature needs to be controlled so it remains around 38C (100F) to 42C (108F). Popular heat sources include a yutanpo, oven light, and lamps. I have tried to use an area heater used for small pets and also a single-coil range. Moisture also needs to be kept so the soybeans don't dry out during the fermentation. Most suggest to ferment the beans for 18 to 24 hours. I have seen different containers used for this purpose. One can use a styrofoam box or cooler or use the oven as a fermentation box.

For the inoculant, you can use Dry natto spores and store bought natto packs.

4) Maturation can take place at room temperature or in the refrigerator. To achieve the best flavor, it is recommended to leave the natto maturing anywhere from 1-7 days. I have found that maturing them for a day at room temperature and then storing natto in the fridge for another 3-5 days produces the best flavor. After that, I will store natto in small containers and freeze them. They should taste good for a few weeks if it does not get freezer burn or get that funky freezer smell.

5) Eating is the best part! This is when you get to taste the fruit of your labor. I usually pour a combination of shoyu, mentsuyu and and a little bit of sugar and mix it until it is well combined. I have put some olive oil at times because of some trivial health benefit that was mentioned by a doctor on a Japanese show.

The Early Days

I wanted to make natto with what I had at home at first. I used a big pot, soybeans bought at Whole Foods and a ceramic baking dish. I wanted to start with a clean inoculation so instead of using store bought natto as a starter, I ordered Mitoku Natto Spores from Cultures for Health. My heat source for the fermentation was a yutanpo (hot water bottle) with boiling water wrapped in a towel.

I soaked the soybeans overnight and I boiled the soybeans on a weekend, which took foreeeeeever (4-6 hours?). Then I followed the instructions for the natto spores and poured the inoculant on the drained cooked soybeans. I put some tinfoil with poked holes and stuck it in the oven with the yutanpo inside. I replaced the yutanpo water with boiling water before I went to sleep and fermented it overnight.

Next morning I woke up looking forward to what I imagined to be my wonderfully delicious natto waiting to be eaten for breakfast. The truth could not be farther from what I had imagined. The soybeans were well... still soybeans. They looked like slightly drier version of the soybeans I had put the night before with a hint of "what the heck is that smell which I cannot put a finger on???!!". It did not smell rotten, but at the same time it did not smell like natto. Maybe propane gas smell? The natto was not stringy. I proceeded to put it in my mouth with some reluctance. It almost had a crunchy texture and it was flavorless.

With that one bite full of barely edible natto, a got hooked on natto making.

Natto Credit Where It Is Due

At the beginning of this journey I had zero knowledge of how to make natto. So as anybody would do, I googled it. The most prominent and informative sites that I remember now as I am writing this are Natto King, Cultures For Health, Natto made in Germany (japanese), Natto made in Sweden (japanese), Natto by Nipotan (japanese) and many more which I cannot recall at the moment.

So to get this out of the way, I do not claim to have come up with a completely original way to make natto. From all the googling that I have done through the year, many of my views have been shaped by this collective knowledge. So in return, I wanted to give back any insights I have gleaned to the collective knowledge which is the internet. In case I do not quote somebody please inform me and I will do my best to be fair and correct any mistakes.

Oh, and for that matter, this is my first blog EVER so I do not know any blogging manners and/or link manners. I will learn this as I go along.

Criteria for Good Natto

So basically, I wanted to make natto at home that would be as good as the store bought packaged natto. So in order to meet this,

A) It had to have nice long silky threads
B) and have great flavor

At first this goal seemed simple as they were only two criteria to meet. In my mind, this would only take a few failed attempts until I reached natto nirvana. I could not have been more wrong. It was indeed a humbling journey as homemade natto took me into many branching paths with most of them leading to dead ends without any knowledge gained.

Natto Dad's Beginning Journey

Welcome to Natto Dad's blog on how to make natto! I wanted to share my journey of making natto at home. This saga started a little over a year ago and I have been trying out various methods to see what works best. Repeated failures and bad natto have only fueled my interest. I would like to share these stories with you. I currently make natto about once a week for my family. In essence, we are Nattoholics.