Oyster Mushroom Information
(Pleurotus species)
Cultivation
Oyster Mushrooms are by far the easiest and least expensive to grow. For small cultivators with limited budgets, Oyster mushrooms are the clear choice for gaining entry into the gourmet mushroom industry. Few other mushrooms demonstrate such adaptability, aggressiveness, and productivity as the species Pleurotus. The Pleurotus species, being a pre-eminent wood decomposer, grows on a wider array of forest and agricultural wastes than any other mushroom group. They thrive on most hardwoods, on wood by-products (sawdust, paper, pulp sludge), all the cereal straws, corn and corncobs, sugarcane baggasse, coffee residues (coffee grounds, hulls, stalks and leaves), banana fronds, cottonseed hulls, agave waste, soy pulp, and numerous other materials containing lignin and cellulose. More than any other group of mushrooms, Pleurotus species can best serve to reduce hunger in developing countries, and to revitalize rural economies. To this end, worldwide Oyster mushroom production has surged in recent years, from 169 000 tons in 1987 to 909 000 in 1990.
On a dry weight basis, Oyster mushrooms have substantial protein, ranging from 15-35% and contain significant quantities of free amino acids. They are replete with assorted vitamins such as vitamin C (30-144mg per 100 grams), vitamin B, and niacin (109 mg per 100 grams). The variation in the reported nutritional analysis of Oyster mushrooms is due to several factors. Not only does the type of substrate affect the protein content, but also by the spawning medium and rate. Finally strains of Pleurotus vary in their nutritional composition and yield performances.
What is most extraordinary about growing Oyster mushrooms is their conversion of substrate mass into mushrooms. Biological efficiencies often exceed 100%, some of the greatest, if not the greatest, in the world of cultivated mushrooms. In the course of decomposing dry straw, nearly 50% of the mass is liberated as gaseous carbon dioxide, 20% remains as “spent” compost, and 10% is converted into dry mushrooms. This yield can be also expressed as a 25% conversion of the wet mass of the substrate into fresh mushrooms. This formula is greatly affected by the stage at which the mushrooms are harvested.
A notable disadvantage in the cultivation of Oyster mushrooms is that the mushrooms are quick to spoil, presentable to the market for only a few days. This can also be a good argument that local producers supply local markets.
The Oyster mushroom species is very colourful: varieties are found in white, blue, grey, brown, gold and pink! In growing Oyster mushrooms several valuable by-products are generated. After the crop cycle is complete, the remaining myceliated substrate mass is an excellent ingredient for building composts and new soils.
Oyster mushroom cultivation worldwide
Internationally, oyster mushrooms are cultivated on a variety of agricultural wastes (more than 200) from artichokes to water hyacinth. The methods chosen vary according to the available materials, financial limitations and individual growers expertise.
Cultivation Methods of Oyster Mushroom:
Log or Stump Cultivation
Bag Cultivation
Shelf Cultivation
Bottle Cultivation
Log or stump cultivation was until recently the most widely used method of cultivating oyster mushrooms and involves the least financial outlay. Comprehensive understanding of natural mushroom cultivation methods such as log and stump cultivation can be gained by attending the Golden Oak Mushrooms Level 1 - Introduction to Mushroom Cultivation.
Today, bag cultivation is the most widely utilized method worldwide. This method involves a greater financial outlay for equipment as well as the need for climate controlled growing rooms. This cultivation method will be dealt with in more detail in the Golden Oak Mushrooms Level 2 Introduction to Commercial Gourmet and Medicinal Cultivation Course, which covers the principals of several mushroom species.
Shelf cultivation is used extensively in Europe. This method of cultivation is much like the bed culture used by button mushroom growers, but requires an extremely high degree of sterility, which on a large scale is very costly to achieve. Not recommended for inexperienced cultivators.
Bottle cultivation is the most widely used method of commercial growers in China, Japan and Korea. This method is by far the most expensive to set up, but has the advantage of being almost completely mechanized. Equipment used was adapted from the canning and packaging industry. The greatest advantage of this method is the high degree of sterility attainable through the absence of human workers, which represent the greatest challenge to a sterile environment.
Harvesting mushrooms
Mushrooms vary in the ideal stage for harvest, but the majority are tastier when younger. The ideal stage for harvest is before the curled edges of the mushroom cap starts to flatten out. However in nature, by this stage the mushrooms have released many thousands of spores and in so doing have attracted many insects who love to lay eggs in the caps and stems. Before preparing these mature mushrooms for consumption you should split the stem down the middle and inspect for small holes or the presence of insects. These mushrooms are suitable for using to inoculate more garden beds, but are not fit for consumption. Very young mushrooms however should not be picked until the cap has opened and the gills exposed lest they should be confused with a poisonous variety.
Oyster mushrooms have traditionally been cultivated in China and Japan. Since the late 1940’s however Europe and America have become increasingly aware of the diversity of edible mushroom species, which often have far superior tastes to the button mushroom as well as having numerous health giving properties; such as anti-cancer sacharides. Consumers are becoming more conscious of the quality of foods they eat and are beginning to seek out healthier and more natural foods, hence the success of the Woolworths organic food range.
In South Africa, the Button Mushroom (Agaricus sp.) cultivated by Denny, has always dominated the minds of consumers and supermarket shelves, leaving the market for ‘new’ varieties wide open. The Gourmet restaurant market, which relies heavily on foreign tourists, represents a huge and untapped market that is already accustomed to the exotic fungi.
With most mushroom species being up to 90% water, a substantial reduction in quantity can be expected when cooking. However the flavour left behind after the moisture has evaporated more than makes up for this. Mushrooms are best used as a seasoning added to other recipes such as casseroles, stir fries, soups and indeed most meals would benefit from the addition of some variety of fungus.
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