METHOD OF GROWING EDIBLE MUSHROOMS

Abstract: A method of producing wood-rottening edible mushrooms on a bed prepared from a carbonhydrate, lignin and protein containing compound material, said bed comprising mainly a cellulose containing material, minor amounts of proteinaceous and farinaceous substance as well as water, the bed is packed and pasteurized, a mushroom mycelium is transferred onto bed by injecting, the mycelium is grown in bed by varying the amount of temperature and light, the bed is removed from package for the production of edible mushrooms. According to the invention the bed material is mixed with minor amounts of peat during the preparation of the material, the total amount of starch and protein is restricted to less than 10% and the pH value of bed is adjusted to less than 5.

Description: METHOD OF GROWING EDIBLE MUSHROOMS The present invention relates to the pro¬ duction of edible mushrooms in commercial or house¬ hold scale by making use of solid nutrition beds that are made of low-priced cellulose and lignin contain- ing materials. A particular object of the invention is the production of wood-rotting edible mushrooms, such as Lentinus edodes species. Growing of wood-rotten mushrooms has tradit¬ ionally been effected in blocks chopped off the trunks of oak or oak-related or other hardwood species. Growing is usually done outdoors and for climatic reasons the production of e.g. Lentinus edodes has only been possible in such subtropical countries where the relative humidity of air is sufficiently high for growing. This mode of growing is also quite labor intensive. In order to compensate for growing in blocks of wood, efforts have been made also toward developing compound nutrition beds and growing technique applic- able to the use thereof. One such method has been described in'US Patent No. 4 127 965. In this method, the raw material comprises substantially sawdust ob¬ tained from hardwood species, the share of hardwood being necessarily at least 60 %, and farinaceous and proteinaceous waste materials, the amount of starch having been 5-15 % and the amount of protein 1-15 % of the entire nutrition bed. As for its reaction, the growth bed is neutral or slightly acidic (pH 4,5-7) and, thus, the competitivity of mycolium and the pre- vention of contaminations require sterilization of the nutrition bed followed by aseptic treatment there¬ of. The most serious drawbacks of prior art methods are manual processes and high contamination percentage resulting therefrom. The performance of various steps of growing is quite labor intensive, requiring e.g. designing of nutrition beds in the growing step of mycolium and/or the use of special moulds, which further add to the growing costs. The present invention strives to eliminate drawbacks of the prior art methods by developing the growing technique of wood-rottening mushrooms, such as Lentinus edodes, Kuehneromyces mutabilis, Pholiota spp. and Pleurotus spp. in solid compound materials, while also striving to decrease raw material costs and to simplify the process as well as to clear up possibilities of mechanizing it, the objective being however to maintain the sensory properties of mush¬ rooms and satisfactory level of crop. When looking for economically available raw materials it was found out that the mycolium of Lentinus edodes grows well also in northern Europe on beds con¬ taining the sawdust of general hardwood species, such as alder, (Alnus incana, A. glutinosa) , birch, (Betula pubescens, B. pendula) and aspen, (Populus tremula) , the sawdust of alder and birch being clearly superior to that of aspen.In order to increase the nutritive content of a- nutrition bed use is made of a material containing some farinaceous and proteinaceous substance, preferably e.g. threshing and assorting wastes of grain. By limiting the amount of readily hydrolyzable poly- saccharides, such as starch, and mono- as well as oligosaccharides and added proteins used for the growth bed to less than 10 % of the nutrition bed material as well as by extending the growing time of mycolium it has been possible .to.increase the ability of mycolium to exploit the polysaccharides and lignin of wood and at the same time to substantially increase productivity of the culture as compared to the prior art methods. In the method of the invention, minor amounts of peat are mixed with the bed material during pre¬ paration. The peat balances water content of the bed and solidifies the bed, thus eliminating the necess¬ ity of using moulds in this method. In addition, the peat decreases pH value of the bed. The amount of peat preferably exceeds 4 %. In order to simplify the prevention of contaminations and to decrease the investment and operating costs of the equipment needed therefor, it proved preferable to adjust the pH value of a bed to less than 5, whereby a sufficient effect will be achieved by means of a pasteurization treatment effected to the internal temperature of not more than 100 C. In a preferred application, the pH value is adjusted to less than pH 4,5, whereby it may be possible to further lower the temperature of said pasteurization treatment. This also cuts down the heat resistance requirements to set for a compound bed packaging material and it is possible to use as a package an oxygen permeable sufficiently thin * plastic film and it shall not be necessary to employ special air intake ports for ensuring oxygen inlet and, thus, protection of such ports against bacterial and mildew contamination is eliminated. Packing in such a package is also readily mechanizable likewise heating to temperatures close to 100 C can be readily made continuous e.g. by means of an extruder, and such heating can also be combined with packing step. Following the pasteurization, the method of the invention comprises growing of mycolium pre¬ ferably at the temperature of circa 20-30°C in the dark for several weeks, preferably for circa 10-14 weeks, during which time the packages are opened and the beds kept at the temperature of circa 10-15 C in the light for several days, preferably for circa 10-18 days time. Thereafter, the beds are removed out of the packages and kept at the temperature of 15-20 C, with relative humidity 85-95 %, for several weeks, pre¬ ferably for 10-20 weeks. During this storage period, the beds are submerged several times in water for 5 several hours for inducing the formation of spore cases. The growth of mycolium, inducement of the formation of spore cases and the production of spore cases take place in the conditions according to the 10 temperature and moisture requirements of each mush- oom species and strain. The durations of various growing steps are mainly determined according to a mushroom species and strain, temperatures, a nutrit¬ ion bed composition and oxygen supply. 15 The following examples illustrate growing according to the invention: Example 1 Growth bed: birch sawdust, air-dry 75 % 20 wheat threshing and drying waste, with grains appr. 20 % 20 peat 5 Water content of bed is adjusted to 60-70 % 25 and it is packed mechanically or manually in a poly- ethene sleeve of HD (high density) quality, whose thickness is 0,02-0,04 mm and diameter 6-15 cm, into 20-40 cm long pieces. The sleeve ends are sealed by means of a wire clamp and growth bed are pasteurized 30 by heating so as to increase the internal temperature of bed to at least 80, preferably to 100°C. After pasteurization, the pH value of bed is 4-5 depending on the composition of waste, the total nitrogen content of bed is 1,1-1,3 % and ammonium nitrogen 35 content 0,2-0,3 % on the basis of dry weight. /A * WIP After cooling, said growth beds are faulted by injecting therein through packaging film a homogen¬ ized mycolium ofLentinus edodes mushroom, either in its growing bed or suspended in water or an aqueous solution. The amount of faulting is appr. 0,5 % of the bed weight. The injection holes are sealed with adhesive tape or other suitable means. The mycolium is grown at the temperature of 25°C in the dark for about 3 months time. During this period, the sleeve ends are opened and beds are kept in a light room at 10-15°C temperature for 2 weeks time. The packaging sleeves are removed from growth beds. At this time, the beds have reached a proper shape and sufficient firmness without shaping or mould treatment. The production of spore cases takes place at 18°C temperature and at appr. 90 % relative humid¬ ity and takes 3-4 months, during this period the beds are submerged about 5 times for 24 hours in cold (appr. 10°C) water for inducing the formation of spore cases. The growing room is illuminated with regular fluorescent tubes for 8 hours a day during the pro¬ duction stage of mushrooms. Mushroom yield is about 1 kg of fresh mushroom per 1 kg of nutrition bed dry matter. Example 2 Growing of Lentinus edodes mushroom as set out in example 1 by combining mixing, heating and packing of a nutrit¬ ion bed into a single operation by using an extruder and a packaging device connected thereto. Example 3 Growing of Kuehneromyces mutabi is and Pholiota spp. mushrooms OMPI Growth bed: birch sawdust (air-dry) 60 % wheat threshing waste ( " ) 30 % peat ( " ) 10 % Growing as set out in example 1. The above specification of the invention and the attached work examples, only describe some of the applications of the invention. The method of the invention can vary in a plurality of ways within the scope of the annexed claims.

Claims: CLAIMS 1. A method of producing wood-rottening edible mushrooms on a bed prepared from a carbon- hydrate, lignin and protein containing compound material, said bed comprising mainly a cellulose containing material, minor amounts of proteinaceous and farinaceous substance as well as water, the bed is packed and pasteurized, a mushroom mycolium is transferred onto bed by injecting, the mycolium is grown in bed by varying the amount of temperature and light, the bed is removed from package for the production of edible mushrooms, c h a r a c t e r ¬ i z e in that, during its preparation, the bed material is mixed with minor amounts of peat, the total amount of starch and protein is restricted to less than 10 % and the pH value of bed is adjusted to less than 5. 2. A method as set forth in claim 1, c h a r a c t e r i z e d in that peat is mixed with bed in a manner that the amount of peat exceeds 4 %. 3. A method as set forth in claim 1 or 2, c h a r a c t e r i z e d in that the pH value of bed is adjusted to less than 4,5. 4. A method as set forth in any of the claims 1-3, c h a r a c t e r i z e d in that the bed is pasteurized at the temperature of less than 110°C. 5. A method as set forth in any of the claims 1-4, c h a r a c t e r i z e d in that mycolium is grown in bed by keeping at appr. 20-30 C temperat¬ ure in the dark for several weeks, preferably for 10-14 weeks, during which time the package is opened and bed kept at appr. 10-15°C temperature in a light room for several days, preferably for appr. 10-18 days. 6. A method as set forth in any of the claims 1-5, c h a r a c t e r i z e d in that a bed OMPI removed from package for the production of the spore cases of edible mushrooms is stored at the temperature of 15-20°C, with relative humidity 85-95 %, for several weeks, preferably 10-20 weeks, and that said bed is submerged several times in water for several hours for inducing the formation of spore cases. 7. A method as set forth in any of the claims 1-6, c h a r a c t e r i z e d in that the bed material is packed in thin, air-permeable plastics in a manner to make the bed into pieces, whose diameter is 6-15 cm and length 20-40 cm.

Inventors: MAELKKI YRJOE, NISKANEN AIMO, PELLINEN MARKKU, MAELKKI, YRJOE, NISKANEN, AIMO, PELLINEN, MARKKU
Applicants: VALTION TEKNILLINEN, VALTION TEKNILLINEN TUTKIMUSKESKUS
Application year: 1984
Main classification: A01G1
IPC codes: A01G1