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Agro-Waste for Cultivation of Edible Mushrooms in Taiwan
Jin-Torng Peng
TPHealth Co., Ltd.
No. 44, Sec. 2, Yongsing Rd., Dongshan Township
Ilan, Taiwan ROC, 2010-05-04

Abstract

The most extensively used agro-waste for cultivation of edible mushrooms in Taiwan are rice straw, rice bran, wheat bran, cotton waste, chicken manure, and sawdust or wood chip. Rice straw, cotton waste and sawdust derived from different kinds of trees are used as basic raw materials for the cultivation of edible mushrooms. These basic raw materials with or without fertilizers or other nutrient supplements have been converted into more than 20 mushroom species creating a total value of more than US$0.24 billion per year contributing to the prosperity of the rural economy in Taiwan. Cotton waste is used for growing Volvariella volvacea after it has been wetted and pasteurized at 70oC for 12 hr or 60oC for 24 hr in a traditional plastic mushroom house. The optimum bed and air temperature for cropping are 31-35oC and 28-31oC, respectively. About 1,000-1,500 kg of mushrooms are usually produced in each mushroom house with a bed surface of 165 m2. There are three types of combination in the preparation of rice straw compost, spawn running, and cropping in Taiwan: 1) Phase I conducted outdoors, Phase II, Phase III and cropping in a mushroom house with or without environmental control; 2) Phase I carried out outdoor, Phase II and Phase III in tunnel, and cropping in a mushroom house with environmental control; and 3) Phase I, II and III in tunnel and cropping in a climatically controlled mushroom house. The mushroom house for cropping is constructed differently according to the mushroom species to be grown and the capital of mushroom grower. Bag mushroom growers usually buy their bag substrate, which has been inoculated by the professional bag substrate producer because these mushroom growers do not need to invest in buildings, facilities and equipment for production of bag substrate. However, bottle cultivation growers prepare their substrate by themselves and do not sell it to any other mushroom growers because of the difficulties in transportation and in collecting back the bottles with used substrate.

Key words: Key words: Agro-waste, cultivation, edible mushroom, Taiwan

Introduction

Different kinds of agricultural and food wastes have been used or tried for growing various edible mushrooms in the world (Akinyele and Akinyosoye 2005, Peng 1989, Ragunathan et al. 1996, Rajkumar and Dharmara 1999). These wastes are produced in big volumes during production of agricultural products every year causing lots of environmental problems in many countries (Belewu and Banjo 2000, Chang 1999). Only a very small part of these agro-wastes has been properly converted into useful or high-value products. Production of edible or medicinal mushroom is a successful example of agro-waste recycling (Chiu et al. 2000). Nowadays, the most extensively used agro-wastes for production of edible mushrooms are wheat or rice straw, sawdust or wood chip, sugarcane bagasse, cotton waste and cotton seed hull, corn cob, rice or wheat bran, chicken or horse manure. Other green materials, such as cotton stalk and soybean straw (Panjabrao et al. 2007), coffee pulp (Martinez-Carrera 1989) etc. have also been used or tried for growing edible mushrooms in some countries. In Taiwan, the most popular agro-waste for mushroom cultivation are rice straw, cotton waste, sawdust or wood chip, rice or wheat bran, and chicken manure (Peng 1989). These agro-wastes with or without fertilizers or other nutrient supplements have been converted into many edible and medicinal mushrooms creating a total value of more than US$0.24 billion (farm gate price) per year contributing to the prosperous economy of rural areas and the development of the mushroom industry in Taiwan (Ho and Peng 2006).

Production of Edible and Medicinal Mushrooms in Taiwan

Before 1980, production of edible mushrooms, such as Agaricus bisporus, Volvariella volvacea and Auricularia polytricha, was mainly for canning or drying for export, but these are not affordable to consumers and mushroom growers themselves. Mushroom products were regarded as a luxury food at that time. Now, nearly all production of edible mushrooms is for domestic fresh market and a very small proportion is exported to other countries. The market price of mushroom products are now affordable to health- conscious people. As such, the consumption of edible mushrooms is increasing in Taiwan, thereby benefiting our mushroom growers and the mushroom industry.

More than 20 species of edible and medicinal mushrooms have been commercially cultivated in Taiwan ( Table 1(1185)), and the major species are Flammulina velutipes, Lentinula edodes, Auricularia spp., Pleurotus eryngii, Pleurotus sajor-caju, Agaricus bisporus, Volvariella volvacea, Pleurotus cystidiosus, Hypsizigus marmoreus, Agrocybe cylindracea, Pleurotus citrinopileatus, Pleurotus ostreatus, Ganoderma tsugae, Agaricus braziliensis and Agaricus bitorquis (Ho and Peng 2006).

Basic Raw Materials for Growing Mushrooms

The basic raw materials for growing mushrooms in Taiwan are classified into three categories, i.e., cotton waste, rice straw, and sawdust or wood chip. Cotton waste is used for growing Volvariella volvacea, rice straw for A. bisporus, A. bitorquis, A. braziliensis, Lepista nuda and Coprinus comatus etc., while sawdust is for growing F. velutipes, L. edodes, Pleurotus spp, Auricularia spp, Agrocybe cylindracea and H. marmoreus etc.. Some of these mushrooms can be grown with rice straw or sawdust as their basic raw materials, such as C. comatus and A. braziliensis.

Cotton Waste As Basic Material for Growing V. Volvacea

In using cotton waste as basic raw material for growing V. volvacea, the material is not fermented. To reduce production cost, at the end of A. bisporus or A. bitorquis crop, the casing soil on the surface of used mushroom compost is removed and then covered with wetted cotton waste with a thickness of about 5 cm to grow V. volvacea ( Fig. 1(1355)). Cotton waste from spinning mill is wetted and pressed and stacked outdoors about one week to make sure it has been thoroughly wetted before use. After filling and covering the surface of the used compost with the cotton waste, the mushroom house is closed for 2-3 days before pasteurization using ventilator to introduce fresh air and allow air to circulate in the house. The wetted cotton waste and used mushroom compost are then pasteurized at 70oC for 12 hr or 6oC for 24 hr depending on the farmer's preference. After cooling down to 35oC, the surface of cotton waste layer is spawned with rice straw spawn of V. volvacea. The bed temperature is necessary to be kept at 31-35oC and the air temperature at 28-31oC. Proper amount of fresh air and light is given during spawning and cropping in order to secure normal development of the mushroom. First flush to be ready for harvest will be 12-15 days after spawning. About 1,000-1,500 kg of straw mushrooms are usually produced in each mushroom house with a bed surface of 165 m2. Most growers have two to three crops between May and October before the season of growing A. bisporus. The growers do not remove the spent cotton wastes and rice straw compost after each crop; they keep covering the mushroom bed with new wetted cotton waste for the next crop of V. volvacea. This operation can easily keep the mushroom bed at required temperature and save both labor cost in removing the used compost and energy cost for pasteurization and for keeping mushroom bed temperature during cropping. Before starting a new crop of A. bisporus in the same mushroom house, the mushroom growers will remove the used cotton waste and rice straw compost and recycle it for making organic fertilizer to grow other agricultural crops or for the improvement of soil physical structure.

Rice Straw As Basic Material for Growing Mushrooms

There are mainly three types of combination in the preparation of rice straw compost, spawnrunning and cropping in Taiwan: (1) Phase I (stacking and composting) conducted outdoors, Phase II (peak heating), Phase III (spawn running) and cropping done in a mushroom house with or without environmental control; (2) Phase I carried out outdoors, Phase II and Phase III done in a tunnel, and cropping performed in a mushroom house with environmental control; and (3) Phase I, II and III done in a tunnel and cropping in a climatically controlled mushroom house. The raw materials for making rice straw compost are air-dried rice straw (100%), chicken manure (20%), rice bran (4%), soybean meal (1%), ammonium sulfate (2%) or urea, calcium super-phosphate (3%), calcium carbonate (2%) and gypsum (3%). Rice straw is cut into short pieces with a length of 2.5-5 cm. When Phase I is conducted outdoors, wetting of rice straw, addition of above organic and inorganic ingredients as well as stacking and composting are done on a concrete floor. The compost is turned 3 to 4 times with compost turning machine before filling onto mushroom bed or into a tunnel for peak heating, which includes pasteurization and conditioning. The purpose of Phase II is to eradicate or to reduce the mushroom diseases and pests, and to complete composting process. This means that the prepared mushroom compost has selectivity to allow only mushroom mycelium to grow while other weed fungi or insects or mites cannot survive in this substrate. Pasteurization of mushroom compost is done at 58-60oC for 6-8 hr and conditioning of compost is at 52 to 55oC for 2 days, 48-52oC for 4 days, and 45-48oC for 2-3 days before clearance of ammonia in the compost. The thermophilic fungus, Scytalidium thermophilum, plays an important role in the conversion of straw to compost during Phase I and II (Straatsma et al. 1995).

When Phase II is carried out in a mushroom house on bed, the compost temperature must be higher than the air temperature for good air exchange. Proper air circulation is helpful in the uniform distribution of the air and compost temperature in the mushroom house. In a traditional plastic or red mud plastic mushroom house without environmental control, the introduction of fresh air and air circulation in mushroom house is operated through a ventilator and a plastic air duct. For Phase II, supply of live steam is necessary to keep the required temperature of the compost and the air in the mushroom house. When Phase II is conducted in a tunnel, the fresh air and re-circulated air or their mixture can go through the compost almost evenly from the bottom to the top layer of compost resulting in uniform fermentation. Due to the good insulation of the tunnel, the heat given off by microbial activity in compost layer is enough for pasteurization and conditioning of the compost. It is usually not necessary to supply extra live steam into the tunnel. The temperature of compost at different stages of Phase II is controlled by introducing proper proportion of fresh air and re-circulated air.

When Phase I is done in a tunnel, i.e., so-called indoor composting, the rice straw is cut into short pieces with a length of 2.5 to 5 cm and must be thoroughly wetted before mixing it with all the organic and inorganic ingredients in a large mixer. Spawning machine can be used to mix these ingredients. The mixture is then transferred to a tunnel for conducting Phase I. Due to the loose structure of the green compost layer, at the beginning of the Phase I the fan speed must be slowed down to accumulate enough heat given off by microbial activity in the compost. After

12-24 hr, the temperature of the compost may go up to 70oC and even above 75oC. Usually it is not necessary to control the temperature of compost during Phase I of indoor composting, however, it will be better to control the oxygen level not below 10% by intermittently introducing fresh air into the tunnel. Using oxygen detector and controller can do this. It takes 4-5 days to complete Phase I process and the compost must be removed to mix with about 5% of Phase II compost, which contains the thermophilic fungus, S. thermophilum and other beneficial microorganisms because the high temperature has killed them during Phase I in tunnel. After this, the compost is transferred to a tunnel for Phase II and the temperature of the tunnel is kept at 48-52oC for 2-3 days for the multiplication of the beneficial thermophilic microorganisms including S. thermophilum before pasteurization. The following operations are similar to those described above for Phase II in tunnel, of which Phase I is conducted outdoors.

Whether Phase I is done outdoors or indoors, after completion of Phase II, the compost can be filled into a mushroom house with or without environmental control for spawning and spawn running (Phase III) on mushroom bed. Such compost can also be filled into a tunnel for spawn running after spawning outside the tunnel with spawning machine. The Phase II compost can be used for growing A. bisporus, A. braziliensis, A. biotorquis and Coprinus comatus in a traditional plastic mushroom house without an environmental control or for A. bisporus and Lepista nuda in a climatically controlled mushroom house. The optimum temperature for spawn running depends on the mushroom species, for example, 25oC for A. bisporus and 30-32oC for A. bitorquis.

When the compost is filled into a traditional plastic mushroom house, the compost temperature must be regularly checked by regulating the ventilation and opening and closing the doors or windows during spawn running. After the compost has been fully colonized by mushroom mycelium, it is cased with casing material, such as disinfected soil or peat-moss. When the mushroom mycelium goes through the casing layer to the surface, it is time to stimulate the mushroom mycelium to transfer from vegetative stage to reproduction one. In growing mushroom in a traditional mushroom house, a suitable season to grow the mushroom must be selected. For example, to grow A. bisporus from November to March of the next year or to grow A. bitorquis from April to September in Taiwan. the mushroom grower must be able to adjust the operation of the ventilator, fan or the opening and closing of door and window according to the change in natural climate and the development of the mushroom.

When the compost is filled into a tunnel with a cooling system, the compost temperature during spawn running can be easily controlled. After completion of Phase III, the compost has been fully colonized by mushroom mycelium. It can be filled into different containers, such as plastic bags, plastic or iron boxes which are then moved to a mushroom house with environmental control. The Phase III compost can be cased immediately with casing soil after filling. In all the cases of spawn running in tunnel, the mushroom species is exclusively grown in a climatically controlled mushroom house of which carbon dioxide level, temperature, relative humidity and air movement can be properly controlled. The way to grow the individual mushroom species in a mushroom house depends on its climatic requirements.

Sawdust As Basic Material for Growing Mushrooms

Sawdust or wood chips derived from various trees can be used for growing edible or medicinal mushrooms, such as Lentinula edodes, Flammulina velutipes, Pleurotus spp., Auricularia spp., Hypsizigus marmoreus, Ganoderma tsugae, Agaricus braziliensis and Agrocybe spp. etc.. The kind of sawdust most suitable for growing these mushrooms depends on the individual mushroom species. To speed up spawn running and increase the productivity of these mushroom species, the mushroom growers add rice bran, wheat bran, soybean meal or corn flour to sawdust or wood chips and adjust the acidity of the substrate with calcium carbonate or ground power of burned oyster shells. Water content of the substrate is adjusted to 63-67% depending on the size of sawdust or wood chip particles. Sawdust or wood chips must be added with water and stacked for 2-4 months and turned once a month before use to remove some detrimental components. Sawdust or wood chips and other ingredients of substrate are usually mixed mechanically in a mixer equipped with an apparatus to add water to the mixture. Then the substrate is filled into polypropylene bags or bottles by a semi-automatic or fully automatic filling machine ( Fig. 2(1167) and Fig. 3(1188)). The bags or bottles are then moved into an autoclave for low or high temperature sterilization. In low temperature sterilization the air temperature in autoclave reaches 98-100oC in 3 hr and is maintained at this temperature for 4 hr with supply of live steam. The steam supply is then cut off for one hour before pulling out the bags or bottles from the autoclave for cooling. In high temperature sterilization, the substrate temperature reaches 110oC in 1.5 hr, the live steam is then released to cool down the substrate temperature to 100oC. Then the substrate temperature is increased to 122oC in about 1 hr and maintained at this temperature for 1 hr with supply of live steam, steam supply is then cut off for 30 minutes before pulling out the bags or bottles from the autoclave for cooling. The bags or bottles are first cooled with filtered air, then with a mechanical cooling system. When the substrate temperature is cooled down to 25-27oC, the substrate is ready for spawning in an inoculation room which is equipped with an automatic inoculating machine, air-shower, air filter and a mechanical cooling system. The mother spawn for inoculation needs to be checked to see if any contaminants exist in the spawn. Bag substrate is inoculated manually, while bottle substrate is inoculated with an automatic inoculating machine. After inoculation, the bags or bottles are moved to a spawn running room of which temperature can be adjusted according to the different stages of spawn running. The length of spawn running time depends on the mushroom species to be grown. It usually takes one to six months before the bags or bottles can be moved to a mushroom house or to a cropping room for fruiting. The method to induce the initiation of fruit body and the management of mushroom crop varies with mushroom species ( Fig. 4(1244), Fig. 5(1200), and Fig. 6(1193)).

The mushroom house for cropping is constructed differently according to the mushroom species to be grown and the capital of mushroom grower. Some mushroom species, such as

Pleurotus spp., Auricularia spp., and Agaricus spp., can be grown efficiently and less expensively in a mushroom house without any environmental control, however, its stability of production is greatly affected by natural climate. These mushroom species can only be grown in some seasons of the year. The mushroom species grown in a mushroom house with an environmental control can be grown throughout the year, however most mushroom growers cannot afford to invest the construction of the house and its sophisticated equipment Many mushroom growers cannot afford to buy the facilities and equipment for the preparation of substrate either. In the case of bag cultivation several professional producers make bag substrate which has been inoculated with mushroom mycelium. They sell such bags to mushroom growers for cropping in the latter's mushroom house. Such mushroom house can be a traditional one without any environmental control or a modern one with all sophisticated equipment depending on the capital of the grower. Most of our mushroom growers do not prepare bags of substrate for themselves and most of the producers of bag substrate do not grow mushrooms on a large scale either. However, in bottle cultivation, all mushroom growers prepare their substrate by themselves and do not sell it to other mushroom growers because of the difficulty in transportation and in collecting back the bottles with used substrate. These bottles can be used for more than ten years.

References

  • Akinyele, B.J. and F. A. Akinyosoye. 2005. Effect of Volvariella volvacea cultivation on the chemical composition of agro-wastes. African Journal of Biotechnology 4:979-893.
  • Belewu M. A. and N.O. Banjo. 2000. Pre-treatment of sawdust and cotton waste by white rot fungi (Pleurotus sajor-caju). Proceedings of the 26th Annual Conference of NSAP. pp. 159-160.
  • Chang, S.T. 1999. Global impact of edible and medicinal mushrooms on human welfare in the 21st century: Non-green revolution. International Journal of Medicinal Mushrooms. 1:1-7.
  • Chiu, S.W., S.C. Law, M.L. Ching, K.W. Cheung and M.J. Chen. 2000. Themes for mushroom exploitation in the 21st century: Sustainability, waste management, and conservation. Journal of General Applied Microbiology 46:269-282.
  • Ho, M.S. and J.T.Peng. 2006. Edible mushroom production in Taiwan. Mushroom International issue 104.
  • Martinez-Carrera, D. 1989. Simple technology to cultivate Pleurotus on coffee pulp in the tropics. Mushroom Science 12(Part 2):169-178.
  • Pabhabraom, M.V., P.S. Sopanrao, S.A. Ahmed and B.M.M. Vaseem. 2007. Bioconversion of low quality lignocellulosic agricultural waste into edible protein by Pleurotus sajor-caju (Fr.) Singer. Journal of Zhejiang University - Science B 8:745-751.
  • Peng, J. T. 1989. The cultivation of edible mushrooms in Taiwan. Mushroom Science 12(Part I):769-788.
  • Ragunathan, R., R. Gurusamy, M. Palaniswamy and K. Swaminathan. 1996. Cultivation ofPleurotus spp. on various agro-residues. Food Chemistry 55:139-144.
  • Rajkumar, M. and J.K. Dharmara. 1999. Reuse of agro-wastes for culture of oyster mushroom Pleurotus citrinopileatus (Fr.) Singer. Indian Journal of Environmental Health 41:130-134.
  • Straatsma, G, R.A. Samson, T.W. Olijnsma, Jan P.G. Gerrits, Huub J.M. Op den Camp and Leo J.L.D. Van Griensven. 1995. Bioconversion of cereal straw into mushroom compost. Canadian Journal of Botany 73 (Suppl. 1):S1019-S1024.

Index of Images

Figure 1 Volvariella Volvacea Grown on Cotton Waste.

Figure 1 Volvariella Volvacea Grown on Cotton Waste.

Figure 2 Filling Machine for Bag Substrate.

Figure 2 Filling Machine for Bag Substrate.

Figure 3 Automatic Machine for Bottle Substrate.

Figure 3 Automatic Machine for Bottle Substrate.

Figure 4 Pleurotus Eryngii Grown Sawdust Substrate in Bags.

Figure 4 Pleurotus Eryngii Grown Sawdust Substrate in Bags.

Figure 5 Pleurotus Ostreatus Grown on Bag Substrate.

Figure 5 Pleurotus Ostreatus Grown on Bag Substrate.

Figure 6 Flammulina Velutipes Grown on Bottle Substrate.

Figure 6 Flammulina Velutipes Grown on Bottle Substrate.Table 1 Yearly Production of Edible Mushrooms in Taiwan (2005)

Table 1 Yearly Production of Edible Mushrooms in Taiwan (2005)

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