Abstract:
Disclosed are novel culture media for the artificial or industrial cultivation of  Sparassis crispa  ( Sparassis crispa  Wulf.:Fr), comprising larch-tree sawdust and/or chips extracted with heated water or vapor, and methods for producing the same.

Description:
TECHNICAL FIELD OF INVENTION 
     The present invention relates to novel culture media for the artificial/industrial cultivation of  Sparassis crispa  ( Sparassis crispa  Wulf:Fr) and methods for producing the same. 
     BACKGROUND OF INVENTION 
       Sparassis crispa  have been conveniently used in French cuisine because of their excellent texture, their brilliant white color and in particular their unique form resembling  Brassica oleracea. Sparassis crispa  is generally referred to in Japanese as “Hanabiratake” and is also occasionally called “Hanabira-maitake” because it grows well on the larch tree. 
     Very little natural  Sparassis crispa  is harvested and the growth rate thereof is terribly slow. It has therefore been understood in the art that the artificial/industrial cultivation of  Sparassis crispa  is not easy. The present inventor had repeatedly tried to cultivate  Sparassis crispa  by inoculating their strain (seed strain) into a culture medium consisting of larch-tree sawdust as the main ingredient along with the various nutrition, but four (4) months were usually necessary to grow the mature  Sparassis crispa  having the ideal form like  Brassica oleracea . Using known culture media, the present inventor could not realize artificial/industrial cultivation of  Sparassis crispa.    
     On the other hand, with respect to the larch tree, there is a huge amount of useless chips produced by thinning young larch trees. Forests of larch trees are widely distributed in many mountainous regions in Japan, and large amounts of larch-tree chips are usually produced through thinning of the larch tree forest to maintain the proper growth thereof. There is currently no use for such chips other than as a pine stake. 
     Unfortunately, the disadvantages realized in the conventional cultivation of  Sparassis crispa  have not been solved yet, and therefore there exists a need in the art for method(s) and means for shortening the cultivation period of  Sparassis crispa.    
     SUMMARY OF INVENTION 
     The present invention is directed to solving such disadvantages. The invention is directed to the pretreatment of larch-tree sawdust or chips, to be employed in the present culture medium, comprising a step of heating them in the presence of water and removing therefrom hot-water-soluble components. 
     The present inventor realized through his research on  Sparassis crispa  that any growth thereof was not observed in broad-leafed trees while such growth was observed in conifer trees, generally in relatively rotten larch trees. This indicates that some component(s) of the coniferous trees may be essential for growth and germination of  Sparassis crispa  mycelium, but some components of fresh conifers may act to inhibit the growth and germination of  Sparassis crispa  mycelium. In nature, such components act as inhibitors that might be eluted slowly through exposure of larch trees to wind and/or rain or through decay thereof in the soil. Thus, such components act as inhibitors that have to be removed to realize an artificial/industrial cultivation of  Sparassis crispa.    
     Generally, the solubility of liquid or solid components in water is increased at a higher temperature. Accordingly, the natural condition of rotting larch trees is simulated in the industrial cultivation to effect the elution of the inhibitor by water. That is to say, culture medium was prepared by treating larch-tree sawdust or chips with hot water, removing therefrom hot-water-soluble components, and adding nutrition thereto. According to the present culture medium, mature  Sparassis crispa  can be grown within about 2.5 months cultivation. 
     The present invention provides a novel culture medium for artificial/industrial cultivation of  Sparassis crispa  produced by heating a mixture comprising larch-tree sawdust or chips as the main ingredient in the presence of water, removing therefrom hot-water-soluble components, and adding nutrition thereto. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The detailed description of the present invention is set forth as follows. 
     The present culture medium comprises larch-tree sawdust or chips as a main ingredient. As an extender, besides sawdust or chips of the other types of trees, any organic or inorganic material may also be used optionally. The amount of such extender to be added to the medium is not limited as long as growth-inhibitors and/or toxic/dangerous components are not eluted into the medium. 
     According to the preferred method of making the present culture medium, first, the raw medium comprising as a main ingredient larch-tree sawdust and/or chips, or a mixture of the raw medium and the extender is prepared. Such raw medium or the mixture is then heated in the presence of water. This step is performed preferably with water at about 100° C. or vapor at about 130° C. under a pressure of about atmospheric pressure or above, for example, up to about five atmospheres. Treatment (heating) time can be shortened by increasing the water temperature and/or the pressure. 
     Then, nutrition and, if necessary, pH adjustor, is/are supplemented into the culture medium so produced. The nutrition may include any of those containing nitrogen, proteins, carbohydrates, minerals or the like, or a combination thereof For industrial cultivation of  Sparassis crispa , industrial waste can also be utilized preferably. The industrial waste may include preferably, for example, brewer&#39;s grain. 
     The culture medium containing the nutrition is sterilized by heating it and is then cooled. A strain of  Sparassis crispa  is inoculated into the medium so prepared. The culture medium thus inoculated is left at a temperature of about 25° C. for about 1.5 months. Upon forming a  Sparassis crispa  fruit-body primordium, the culture medium is transferred into a culture chamber. Mature  Sparassis crispa  are then be harvested by keeping the medium in the chamber for about one month under a relative humidity of about 90% to about 95%. 
       Sparassis crispa  is very popular due to its brilliant white color, its unique form resembling  Brassica oleracea , its excellent texture without any unacceptable taste, and in particular its long shelf-life. According to the present invention, the artificial/industrial cultivation of such  Sparassis crispa  can be realized and provided. 
     It has been quite difficult to cultivate  Sparassis crispa  in the summer because of the relatively high required temperature of from about 20 to about 28° C. for forming its fruit-body primordium. However, according to the present invention, it is possible to cultivate  Sparassis crispa  in the summer by, for example, applying mist thereto and reducing the temperature by the heat of vaporization (about 6 to about 7° C. reduction). Thereby,  Sparassis crispa  can be provided throughout the year without idling cultivation facilities. 
     Further, according to the other preferred embodiment of the present invention, utilization of chips produced by thinning larch trees can now be offered. 
    
    
     EXAMPLES 
     The present invention is further detailed in the following illustrative examples, which are not intended to restrict the invention. 
     Example 1 
     1 kg of larch-tree sawdust was boiled in 5 L of hot water at 98° C. for 180 minutes. Then, to prepare a raw culture medium, it was cooled, dehydrated and was further dried. 
     The following solid components as well as the liquid components respectively are added to the raw culture medium to prepare the present culture medium. 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Solid Components 
                   
                   
               
               
                   
                 Wheat Flour 
                 336 
                 g 
               
               
                   
                 Banana 
                 30 
                 g 
               
               
                   
                 EBIOS (brewer&#39;s grain: 
                 23 
                 g 
               
               
                   
                 Asahi Brewery Co. Ltd.) 
               
               
                   
                 Peptone 
                 0.75 
                 g 
               
               
                   
                 Calcium Chloride 
                 0.3 
                 g 
               
               
                   
                 Liquid Components 
               
               
                   
                 Water 
                 1470 
                 mL 
               
               
                   
                 Honey 
                 23 
                 g 
               
               
                   
                 HYPONEX (liquid fertilizer: 
                 0.3 
                 mL 
               
               
                   
                 Hyponex Japan Co. Ltd.) 
               
               
                   
                   
               
             
          
         
       
     
     The culture medium including the above-listed components was then sterilized by heating it at 115° C. under 1.8 atmospheres for 70 minutes and then cooling it. A strain of  Sparassis crispa  (seed strain) was then inoculated into the sterilized culture medium. 
     By keeping the inoculated culture medium at a temperature of about 25° C. at 70% relative humidity for 1.5 months and growing for another one month, mature  Sparassis crispa  were obtained. 
     Example 2 
     The present culture medium was prepared in the same manner as Example 1 except for performing, prior to washing with water, exposure of the larch-tree sawdust to vapor at 121° C. and 2 atmospheres pressure for 60 minutes, instead of boiling the larch-tree sawdust in hot water. In this example, mature  Sparassis crispa  were also obtained within a shorter cultivation period. 
     Numerous modifications and alternative embodiments/examples of the invention will be apparent to those skilled in the art in view of the foregoing description. This description is to be constructed as illustrative only, and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the culture medium and the methods for making the same may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which come within the scope of the appended claims is reserved.