Takahashi's Pure Culture Method 

"Takahashi Pure Active Natto Seed" [strong-string natto bacteria] for Home Use. 


Traditionally natto was produced by packing steam-boiled soybeans wrapped in rice 
straw, and then incubated.  This method uses natto bacteria naturally present to 
rice straw, but this natural bacteria may not have the desired property to form
natto, and bacteria populations tend to be insufficient.  So unless you have
highly optimal conditions for growth and fermentation, other bacteria of rice straw 
interferes with the process and may not produce a high quality natto product.  
Therefore, it is almost impossible to make natto with the traditional method at 
home, if suitable equipment is not available. Also, natto prepared by this method 
has foreign bacteria to a certain extent which continue spoiling the product.  
So the fine natto strings are not strong, flavor/taste is not as good, and it is 
difficult to avoid sanitary problems. 

"Takashi natto seed" is developed as follows. Firstly, numerous natto bacteria 
species are separating from the environment. Then selecting strains which produce 
strong strings with a beautiful white colour, or strains that are active in a wide 
temperature range. And finally fixed in a special media for several generations, 
cultured and then dried. This allows you to prepare natto with favorable characteristics 
of each species of bacteria, without the need for special equipment or technique. 

1. Hand-pick soybean

    * Where possible, choose domestic soybeans [Japanese]. Choose high 
      quality small soybeans. 
    * Remove foreign materials, insect-bitten beans, and beans that are too young, including 
      rotten or discoloured beans.
       
2. Wash soybeans 

    * Remove sand, stones or dust from soybeans. 
    * Do not damage soybean in the process. Wash well followed by rinsing.
   
3. Soaking soybeans 

    * Depending on the type of soybean, soaked soybeans double in volume. Use about 2.5 to 
      3 times volume of water compared to soybeans, and soak overnight [approx. 12 hr].  
      If it's summer and temperature and humidity are high, soak for about 8 to 9 hours.
          
4. Cooking soybeans [steam/boil]

    * Drain soy beans. 
    * If using a cooking pot, cover beans with fresh water and cook for 9 hours. Check to make 
      sure the beans are covered with water every few hours and also check for tenderness. 
      The beans should crush easily between the fingers. If cooking with pressure cooker pot, 
      refer to manufacturer's manual for cooking details.
       
5. Seeding the spores [Inoculation]

    [Following instructions assume that the cooked drained beans weigh 1kg] 
    * Use attached spoon to measure the spores. 
      Dissolve one scoop [about 0.1gm] in 10ml of pasteurized water [once-boiled, 
      cooled down water].  You may directly sprinkle the powder onto the cooled beans, but  
      the spores mix more evenly if dissolved in water. 
    * If this is the first time you make natto, try a little more seed, to ensure a good natto. 
    * Transfer the cooked beans into a sanitized bowl, cool to 45°C and then add the 
      spores before the beans cool down too much. Mix well with sanitized spoon.
      
6. Packaging

    * Use a plastic lunch box. 
    * Pack the box with as much as three layers of beans in depth. If you stack more than three 
      layers, beans nearer to the surface will ferment but the beans in the middle will fail to ferment.    
    * If any beans are dropped on the table or on the floor, discard them! Don't put them into your 
      box. This is to avoid contamination. 
    * After packing the box, cover the box with preboiled and then cooled cotton cloth, then place 
      a lid on the box, to cover the cloth. This prevents the beans from drying in the following step.
        
7. Heated storage [Incubation]

    * Use kotatsu, or electric anka, or an incubator for heated storage [incubation for fermentation]. 
    * Preheat the storage or incubator to 38°C. 
    * Aim for 40°C during fermentation, and incubate for 22 to 24 hours. Excessive temperature 
      will cause "heat-burn" and the natto will fail to culture. 
       
8. Additional time to improve flavour

    * To halt fermentation, remove the lid, but keep the cloth covering the beans, and refrigerate overnight. 
    * The natto is now ready eat. 
     
** Try to follow all the steps under good sanitary conditions. Avoid at all cost, failure due to foreign bacteria! 

                      Dried powder for home use, sufficient for 30kg soybeans 

Manufactured by Tahashi Yuzo Laboratory 
P.O. Box 34, Chuo Yubinkyoku, Yamagata, 990-8691, Japan 
2-chome 1-ban 17-go, Yokacho, Yamagata-City, Yamagata, 
Japan
   
tel 81-23-622-4001 
fax 81-23-622-4002
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English translation of the origianl Japanese instructions were kindly provided by slug... thanx slug!
With addendum by Dominic N. Anfiteatro 
Email: dna@chariot.net.au

This document resides on the Internet here:
http://users.chariot.net.au/~dna/nattomoto/natto.txt