1.Oyster Mushroom
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1.1 Introduction:
The Oyster mushroom, or Pleurotus florida Asia , it is now cultivated around the world for food. It is related to the similarly cultivated "king oyster mushroom". Oyster mushrooms can also be used industrially for mycoremediation purposes.
1.2 How this name Oyster came?
Both the Latin and common name refer to the shape of the fruiting body. The Latin pleurotus (sideways) refers to the sideways-growth of the stem with respect to the cap while the Latin ostreatus (and the English common name, oyster) refers to the shape of the cap which resembles the bi-valve of the same name. Many also believe that the name is fitting due to the flavor resemblance to oysters.
In Chinese, they are called píng gū (平菇; literally "flat mushroom").
The oyster is one of the more commonly sought wild mushrooms, though it can also be cultivated on straw and other media. It often has the scent of anise due to the presence of benzaldehyde.
1.3 How This Mushroom Looks Like?
Cap: 5-25 cm broad, fan or oyster-shaped; Natural specimens range from white to gray or tan to dark-brown; margin inrolled when young, smooth and often somewhat lobed or wavy. Flesh white, firm, varies in thickness due to stipe arrangement.
Gills: Gills are white to cream, descend stalk if present. If so, stipe off-center with lateral attachment to wood.
Spores: The spores form a white to lilac-gray print on dark media.
Stipe: Often absent. When present it is short and thick.
Taste: Mild
Odor: Often has a mild scent of anise.
2. Oyster Mushroom Cultivation
2.1 Facilities:
Building
We have said that most ordinary buildings are not suitable for mushrooms.
Oyster mushrooms have some basic requirements for the environment
provided by the growing-buildings:
1.A temperature of 15 to 27°C (59 to 68°F)
2.A humidity of 80 to 95%
3.Good ventilation
4.Light
5.Sanitation
Temperature and humidity should be kept as constant as possible and the
exact needs may depend on the variety. Any rapid changes in temperature
will cause disastrous changes in humidity. At 20°C (68°F) and 90% humidity,
if the temperature drops to 19°C (66°F) the humidity rises to 100%. If the
temperature rises to 21°C (70°F) the humidity drops to 82%. At 15°C (59°F)
the change will be approximately 1% less. That is 99% for 1°C loss and
83% for 1°C increase. The relation between temperature and humidity make
insulation a must. Insulation may be a commercial material, but a thick layer
of soil over a masonry building or straw or even paper between the inner and
outer wall surfaces can be adequate.
At 100% humidity, everything is suddenly wet. Conversely, at 80%
humidity, the mushrooms begin drying. If everything becomes wet, then many
building materials will rot and others will corrode. So growing conditions
limit our choice of building materials. Concrete and plastic are two materials
that will withstand considerable moisture with little damage. Some growers
use wood or metal structures and cover them with plastic. Others just use
wood or metal and accept its very limited life. The biggest problem with
wood and some other porous materials is that they can harbor diseases and
pests.
Light is required for oyster mushrooms and most other tree inhabiting
species. One may read many things about the amount of light, but there have
been very few carefully done experiments. I mentioned that forest light is
blue. I have tried and failed to produce mushrooms with incandescent light.
It is a rather yellow light. Fluorescent lights come in a variety of colors, The
most common are “cool white.” With cool white if there is enough light to
read and they are lit 8 hours each day you will have enough light. Natural
daylight does not work well because the temperature will be affected by the
sun. Algae and other plants are more likely to cause trouble in daylight.
2.2 Production
2.2.1 Variety
<!--[if !supportLists]-->ü<!--[endif]-->APK is a short duration variety released from the TNAU with good cooking quality and consumer acceptability and can be grown in wheat, paddy and sorghum straw. On an average, it takes twelve days from spawning to harvest. Yield potential is 800 g per kg straw. Mushroom comes in pink Color.
<!--[if !supportLists]-->ü<!--[endif]-->Florida
<!--[if !supportLists]-->ü<!--[endif]-->CO-2 is a variety released from the TNAU with good cooking quality and consumer acceptability and can be grown in wheat, paddy and sorghum straw. On an average, it takes twenty five days from spawning to harvest. Yield potential is 800 g per kg straw.Mushroom comes in dull white.
2.2.2. Substrate and raw materials
Pleurotus can be successfully cultivated on a variety of agro-wastes like saw dust, vegetable and paper wastes, oil palm pericarp waste and straw. But the best suitable substrate is found to be paddy straw.Other raw materials required are polythene bags, antiseptic solution, sand and water.
2.2.3.Production house
A thatched shed or room, preferably with optimum relative humidity of 80 - 95 % and room temperature of 24ºC - 28ºC with diffused light and ventilation is required. Lower temperature adversely affects growth and production of oyster mushroom. Normally for small scale growing thatched sheds roofed with coconut leaves will be useful. Approximately two sheds with an area of 30 m2 each are required for growing 20 Kg of oyster mushrooms per day. The room should be kept cool by hanging gunny screens with periodical sprinkling water on the gunnies. Sand must be spread on the floor up to 2-3 cm and be kept moist. The room should be made rodent and insect proof.
2.2.4.Sterilisation/pasteurisation
One kg of well dried, one-year-old paddy straw is cut into small bits of 5-8 cm in length and immersed in water for 18 hours. Then the soaked straw is taken out from water and kept inside the basket for 1-2 hours to drain away excess water. The soaked straw is kept under boiling water (100ºC) for 30-40 minutes for surface sterilization or to achieve pasteurization and then taken out and kept inside the basket to drain excess water and allowed to cool down. The pasteurized straw is ready for filling the bags.
2.2.5.Preparation of bed
Polythene bags or tubes of 30 x 60 cm size with 150-200 gauge are taken for filling the substrate. If the tubes are used, the free-end is tied with a string. Seven to eight holes of 0.5-1.0 cm diameter are made all over the bag for aeration. Now the perforated polythene bag is filled for about 5 cm height with the above processed straw and pressed with hand for making it even. Care should be taken to fill the bags as compactly as possible for the proper growth of mycelium. Instead of straw bits, small round straw bundles of 20 cm diameter are also used for filling the bags. This method is followed to save time and labour.
2.2.6.Spawn requirement and availability
Spawn is the propagating material of mushrooms. It is the productive mycelium of the fungus multiplied in a suitable substrate. One bottle containing 300 gm of spawn is required for two beds of straw. Quality spawn materials are available to the farmers from the Q3 Mushroom Farms – Chennai. Progressive farmers can also make spawns for themselves after proper training.
2.2.7.Production of mushroom spawn
Sorghum or wheat grains are used for spawn preparation. Half cooked grains, are mixed with calcium carbonate @ 20g per kg of grains(dry weight), thoroughly mixed and filled in polypropylene bags ( 15x30 cm size) provided with PVC rings as neck. The bags are tightly plugged with non-absorbent cotton and sterilized at 1.42-kg/cm2 pressure and 126ºC temperature for 1.5-2.0 hours in an autoclave. When the bags are cool, they are aseptically inoculated with fresh cultures of oyster mushroom fungus. The work should be done in a culture room or in a laminar flow chamber. After inoculation the spawn bags are stored in a clean room for 15-20 days before use. These bags with white mycelial growth serve as mother culture. Each mother spawn bag can be used for inoculating 30 bed spawn bags that can be prepared following the above procedure. It is advisable to have a thorough training in the Q3 Mushroom Farm - Chennai, before starting spawn production unit.
2.2.8. Inoculation/ spawning
Spawn is taken out from packets and kept inside a clean container or paper. From this, one tablespoon full of spawn is sprinkled over the filled straw around the peripheral region. A second layer of processed straw is filled and spawned as above. Repeat the process as above until the soaked straw is finished. Every time before spawning, press the straw with hand for making it compact. If bundles are used for filling the bags care should be taken to keep the bundles inside the bag as compact as possible without leaving any space in between the bundle. Finally the bag is closed tightly with a string and the beds are kept for spawn running.
2.2.9. Spawn running
The prepared beds are kept undisturbed for spawn running for about 15-20 days inside the production room. The best temperature and humidity for spawn running ranges from 28-30ºC and 80-85%, respectively. The beds can be arranged over a platform or in shelves. The spawn running can be judged from the whitish growth covering the straw completely. Periodically observe the beds and discard the contaminated ones. After 15 days when the spawn running is complete, remove the polythene bag by cutting it with blade and keep the bed for sporocarp formation. The opened beds are kept in well-ventilated rooms. Relative humidity of the room should be 80-85%. If temperature inside the room rises above 30ºC, the room should be sprinkled with water to lower the temperature. Diffused light is essential for normal fruiting. Pinhead formation starts on 20th day and 2-3 days are required for the maturation of the fruiting body.
2.2.10. Pest
Mushroom fly/ Phorid fly (Megaselia halterata)
The phorids cause damage to mushroom by feeding on mycelium. For controlling phorid flies, fix nylon net of 35 or more mesh size in the mushroom house to prevent the entry of flies. Regularly remove the waste materials. Install sticky trap to attract the phorid flies.
2.2.11. Harvest and yield
Matured and fully opened sporocarps are harvested by placing the thumb and forefinger near the base of the fruiting body and twisted in clockwise direction to get detached from the mycelium. First harvest will be ready on 15 - 21 days. After first harvest spray water for keeping moisture at 60 - 65% in beds. Second harvest may develop after one week. Totally four harvest can be taken from one bed within 35 - 45 days period. An average yield of 500-700 g can be harvested from 1 kg of straw. The spent straw can be used as enriched cattle feed.
2.2.12.Factors responsible for sustainable yield of oyster mushroom
Though the production technology for mushrooms is relative simple, utmost care has to be taken to maintain hygiene in the growing place, since the contamination can ruin mushroom. Care should be taken to use only good quality spawn and paddy straw for mushroom production. Paddy straw should be treated properly before bed preparation. Also, maintain good hygiene in the cropping rooms and bed preparation yard.
3.Mushroom processing
Freshly harvested mushroom is highly perishable as it is susceptible to deterioration by the enzyme and microorganisms.It has been realized that merely producing mushroom is of no use unless these are properly preserved, keeping in view the export objectives. Hence, following proper processing and storage methods is of supreme importance. Two types of preservation techniques are available:
1) Short term preservation
2) Long term preservation
Short-term preservation
Low temperature is effective for short-term preservation. Mushrooms may be packed in wooden cases with three compartments; ice is placed in the central compartment and mushrooms are packed in the two other sections. Mushrooms may also be packed in bamboo baskets and transported by airfreight. An aeration channel is formed at the center of the basket and dry ice, wrapped in paper, is placed above the mushrooms.
Mushrooms stored in a perforated plastic box at 10-15ºC have excellent keeping quality for up to 4 days and the loss of moisture is less than 5 per cent. Straw mushroom can be stored more effectively at button stage than at any other stage. At temperatures below 10ºC, however, the mushrooms liquefy rapidly, irrespective of type of packaging due to chilling injury.
Long-term preservation
Canning, pickling, and drying processes are employed for long-term storage. These processes are not always suitable for all types of mushrooms. The quality of the finished product is rarely comparable with that of fresh mushrooms.
a) Canning
Canning is the most common process for preserving mushrooms. For this, cleaned mushrooms are placed in cans containing 2.5 % sodium chloride and 0.25–0.5 % citric acid. The cans are then sealed and sterilized in autoclave for one hour at 100-120ºC.
b) Drying
Mushrooms can be dried by sun drying and thermal power drying. For general drying, the picked mushrooms are exposed to the sun for about 2-4 days. Dried mushrooms are highly hygroscopic and readily absorb moisture from the air. The dried mushrooms should therefore, be put into polyethylene bags, sealed, and kept in a dry, cool, and dark place. For prolonged storage, dried mushrooms should be packed in cartons or wooden boxes and kept at 2-5ºC in a low temperature store.
c) Use of chemicals
Fresh mushrooms can be preserved for about 10 days at room temperature by steeping in a solution containing 2.5 per cent common salt, 0.2 per cent citric acid, 0.1 per cent ascorbic acid, 0.1 per cent sodium bicarbonate and 0.1 percent potassium metabisulphite. This method of preservation can be used at places where facilities for canning, freezing and dehydration do not exist.
Market potential
Mushrooms are delicacy with definite food value. It has already acquired commercial status almost all over the world. Govt. of India
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