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All about “Oyster mushroom”

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Health profile

There are more than thirty varieties of oyster mushrooms. Most of them are edible, and several are grown commercially. The oyster mushroom represents about 25% of the world mushroom production. The oyster mushroom in the shell (or oyster-shaped) is the best known. It is eaten fresh or dried. This mushroom contains significant amounts of vitamins and minerals, especially B complex vitamins and copper.

Active principles and properties

Several prospective and epidemiological studies have shown that a high consumption of fruits and vegetables reduces the risk of cardiovascular disease, certain cancers and other chronic diseases , 2 . Some mechanisms of action have been proposed to explain this protective effect. The presence of antioxidants in fruits and vegetables could play a role.

Antioxidants . Antioxidants are compounds that protect cells in the body from damage caused by free radicals . The latter are believed to be involved in the development of cardiovascular diseases, certain cancers and other diseases linked to aging 3 .

Among the antioxidants found in foods of plant origin are phenolic compounds. They are partly responsible for the coloring of fruits and vegetables 4 . The oyster mushroom contains small amounts 5 .

The antioxidant activity of oyster mushrooms can vary considerably, depending on where it comes from. For example, one study found that the oyster from China contained more phenolic compounds than many other fungi (including shiitake mushroom and common) and it showed superior antioxidant activity 6 . On the other hand, oyster mushrooms from the United States have one of the lowest amounts of phenolic compounds, despite a significant antioxidant activity , 7 .

In addition to phenolic compounds, ergothionein (an amino acid produced by fungi) may contribute to the antioxidant activity of oyster mushroom 5 . In animals, recent studies have shown that oyster mushroom extracts help improve antioxidant levels in various organs, including the liver , 9 . Even if the oyster mushroom is not one of the vegetables richest in antioxidant compounds, its consumption can still help to increase the intake.

Cancer . In vitro studies have shown that oyster mushroom extracts exerted an anti-tumor effect on certain prostate or colon cancer cells 10 , 11 . A few studies in animals have also reported results in the same direction 12 , 13 . It is possible that polysaccharides (such as glucans) or certain proteins present in oyster mushroom have a role to play 10,11 . For example, in an in vitro study, beta-glucan (an indigestible sugar) was shown to inhibit the proliferation of colon cancer cells and stimulate apoptosis 11. The oyster mushroom also contains an interesting amount of beta-glucans, compared to the button mushroom (“white” or “layer” mushroom) 14 . Despite this, for the moment, no link can be established between the consumption of oyster mushrooms and the reduction of cancer in humans.

Cholesterol . Studies have shown that adding dried oyster mushroom to the diet of rats with hypercholesterolemia significantly lowered their blood and liver cholesterol levels after eight weeks 15 , 16 . The oyster mushroom is believed to contain compounds that act at different stages in the regulation of blood cholesterol (from intestinal absorption to the formation of cholesterol in the liver) 15 . For example, glucans and pectin, found in oyster mushroom, are soluble fibers known for their ability to bind bile acids. This action reduces the absorption of cholesterol in the intestines 17 .

In addition, some species of oyster mushrooms produce lovastatin, a compound used as a cholesterol-lowering drug 18 . Finally, chitin, present in the insoluble fraction of mushroom fibers 14 , has been shown to reduce cholesterol in animals 19 . Studies in humans will be necessary to assess whether the usual consumption of oyster mushrooms could have an effect on certain risk factors for cardiovascular disease.

Other properties

Is oyster mushroom an antioxidant? Oyster mushroom is known to contain certain antioxidants, but its TAC index is not available at the moment.
Is oyster mushroom acidifying? Data not available.
Does oyster mushroom have a high glycemic load? Data not available.

Most important nutrients

See the meaning of the nutrient source classification symbols

Nutrient content that stands out
Oyster mushrooms can contain up to five times more protein than most vegetables 20 . However, it should be remembered that vegetables are not an important source of protein. In terms of dietary fiber, oyster mushroom differs from other varieties of mushrooms (white, crimini and portobello) by a content that is two to five times higher 20 .

Vitamin B3 . Oyster mushroom is an excellent source of vitamin B3 for women and a good source for men (men have greater vitamin B3 requirements than women). Also called niacin , vitamin B3 is involved in many metabolic reactions and particularly contributes to the production of energy from the carbohydrates, lipids, proteins and alcohol that we ingest. It also helps in the process of DNA formation , allowing normal growth and development.

 Copper . Oyster mushroom is a good source of copper. As a component of several enzymes , copper is necessary for the formation of hemoglobin and collagen (a protein used for the structure and repair of tissues). Several copper-containing enzymes also help the body’s defense against free radicals .

 Vitamin B2 . The oyster mushroom is a good source of vitamin B2. Vitamin B2 is also known as riboflavin . Like vitamin B1, it plays a role in the energy metabolism of all cells. In addition, it helps in the growth and repair of tissues, the production of hormones and the formation of red blood cells.

 Pantothenic acid (vitamin B5) . The oyster mushroom is a good source of vitamin B5. This vitamin is part of a key coenzyme that allows the body to adequately utilize the energy from the food we eat. It is also involved in several stages of the manufacture of steroid hormones, neurotransmitters and hemoglobin.

 Phosphorus . The oyster mushroom is a source of phosphorus (see our Phosphorus nutrient list ). Phosphorus is the body’s second most abundant mineral after calcium. It plays a vital role in building and maintaining healthy bones and teeth. In addition, it participates among other things in the growth and regeneration of tissues and helps maintain normal blood pH . Finally, phosphorus is one of the constituents of cell membranes.

 Potassium . The oyster mushroom is a source of potassium. In the body, it is used to balance the pH of the blood and to stimulate the production of hydrochloric acid in the stomach, thus aiding digestion. In addition, it facilitates the contraction of muscles, including the heart, and participates in the transmission of nerve impulses.

 Iron . The oyster mushroom is a source of iron. Each body cell contains iron. This mineral is essential for the transport of oxygen and the formation of red blood cells in the blood. It also plays a role in the production of new cells, hormones and neurotransmitters . It should be noted that the iron contained in foods of plant origin (such as oyster mushrooms) is less well absorbed by the body than the iron contained in foods of animal origin. The absorption of iron from plants is however favored when it is consumed with certain nutrients, such as vitamin C.

 Zinc . The oyster mushroom is a source of zinc. Zinc participates in particular in immune reactions, in the production of genetic material, in the perception of taste, in wound healing and in fetal development. It also interacts with sex and thyroid hormones. In the pancreas, it participates in the manufacture, storage and release of insulin.

 Vitamin B1 . The oyster mushroom is a source of vitamin B1. Also called thiamine , vitamin B1 is part of a coenzyme necessary for the production of energy mainly from the carbohydrates that we ingest. It also participates in the transmission of nerve impulses and promotes normal growth.

 Vitamin B6 . The oyster mushroom is a source of vitamin B6. Vitamin B6, also called pyridoxine , is part of coenzymes involved in the metabolism of proteins and fatty acids as well as in the manufacture of neurotransmitters . It also helps in the production of red blood cells and allows them to carry more oxygen. Pyridoxine is also necessary for the transformation of glycogen into glucose and it helps the proper functioning of the immune system. Finally, this vitamin plays a role in the formation of certain components of nerve cells.

 Folate (vitamin B9) . The oyster mushroom is a source of vitamin B9. This vitamin is involved in the manufacture of all cells in the body, including red blood cells. It plays an essential role in the production of genetic material ( DNA , RNA), in the functioning of the nervous system and the immune system, as well as in the healing of wounds and wounds. As it is necessary for the production of new cells, adequate consumption is essential during periods of growth and for the development of the fetus.

What is a “portion” of oyster mushroom worth?
Weight Raw oyster mushroom, ½ large mushroom / 74 g
Calories 26
Protein 2.5 g
Carbohydrates 4.7 g
Lipids 0.3 g
Dietary fiber 1.7 g

Source  : Health Canada. Canadian Nutrient File , 2007 version.

Oyster mushroom over time

“Pleurote” first appeared in the written language in 1874. It comes from the Greek pleuron , which means “side” and ôtos , which means “ear”. This refers to the shape of the mushroom and the fact that its foot is off-center from the hat.

We know about forty species of Pleurotus . Oyster mushrooms are distributed all over the world, in both tropical and temperate regions. They usually grow on trees, alive or dead. Depending on the region, many species serve as hosts: maple, ash, beech, oak, fir, larch, spruce, pine, hemlock, eucalyptus, hibiscus, grapevine. There is even a species that grows almost exclusively on the stumps of the panicaut, a thistle. We have also gathered it on railway sleepers … In short, oyster mushrooms are opportunists who adapt to the most diverse hosts. All they ask is to find their sustenance, that is to say the woody material essential for their growth.

Many species are edible and none are known to be fatal. Historically, oyster mushrooms have enjoyed an excellent reputation as a food and, in some countries, as a medicinal plant. Grown in many places, they are placed at the third rank in the commercial production of edible mushrooms, after the mushrooms (1 ers ) and Shiitake mushrooms. Pleurotus ostreatus , the oyster-shaped oyster mushroom, is the most common species in trade, but more and more others are found, including the yellow oyster, or citrus oyster, and the erect oyster or panicaut oyster. .

Naturally more protein
By adding residues of legumes to the substrate on which the oyster mushrooms are grown, their protein content is increased. The best results have been obtained with a substrate made up of equal parts of cereal grains and legumes.

Commercial oyster mushrooms are generally grown in mushroom beds on a variety of substrates, including cereal grains or crop residues and cotton seed pods. Several other substrates are currently being tested and much remains to be discovered in this regard. For example, in the 1990s, we experimented with a substrate based on sawdust and apple pomace, which made it possible to obtain a higher yield compared to just one of these ingredients.

China is by far the largest producer of oyster mushrooms of all species. Alone, it accounts for almost 90% of world production (1997 data). The rest of Asia, the Americas and Europe also produce it. All over the world, the production of this fungus is growing rapidly. For example, in the United States, it increased on average by 14% per year from 1996 to 2002.

Culinary uses

Choose well

The oyster mushroom should be firm, non-viscous and fleshy. His hat should be light in color and free from red or greenish spots. It should give off a slight odor of anise (oyster-shaped oyster mushroom).

Culinary preparations

It is recommended not to wash the mushrooms with plenty of water. Being porous, they would absorb too much water. Rather, they should be wiped down with a damp cloth or paper towel, then the damaged parts and the earthy base removed.

Its flesh being rather firm, the oyster mushroom requires relatively long cooking. Its foot, even firmer, should be finely chopped and cooked a few minutes before the hat. Sweat the hats and feet over low heat until they release their water. They can then be pan-fried, braised or sautéed in butter or oil, alone or with other species of mushrooms. Add garlic during cooking and sprinkle with fresh parsley.

  • The fry and sprinkle with grated Parmesan cheese before the serve over pasta for example, or as an accompaniment to fish or game meat.
  • When they are almost cooked, add beaten eggs to the pan and cook as an omelet .
  • Simply grill them on the barbecue , brushing them with oil flavored with thyme, rosemary, bay leaf, garlic and lemon. They can also be marinated for a quarter of an hour in a mixture of orange juice (2 tbsp), lemon juice (1 tbsp), red wine vinegar (1 tbsp. ) and olive oil (6 tablespoons) that will have been beaten together. Drain the mushrooms, preserving the liquid. Grill them on the barbecue, turning them several times. Then put them back in the mixture, salt and serve.
  • Poach them delicately in a chicken or vegetable broth and serve as a soup .
  • Pan-fry them and then add them to the rice for the preparation of a risotto .
  • Finely chop them, sauté in olive oil, then mix them with garlic, gray shallot, fresh basil, oregano and a cup of chicken and vegetable broth. Stuff tomatoes, peppers or round courgettes with this preparation and bake for about 20 minutes.
  • In Japan, we prepare an appetizer with small oyster mushrooms that we poach whole, a few minutes in boiling water. They are then simmered for two or three minutes in a mixture of dashi (400 ml), soy sauce (4 tbsp), mirin (4 tbsp) and sugar or honey (1 tbsp. ). Finally, the mushrooms are left to marinate in the preparation for two hours, drain them and mount them on toothpicks or, better yet, pine needles.

Conservation

The oyster mushroom being one of the most perishable mushrooms, it should be consumed as soon as possible. It can be stored for a few days in the refrigerator, in a partially open container or plastic bag, to allow it to breathe.

Organic gardening

There are various sets on the market for growing oyster mushrooms at home. Follow the manufacturer’s instructions, which vary depending on the substrate: test tube, glass jar, Petri dish, sawdust, grains, etc.

Ecology and environment

Critically Endangered
Pleurotus nebrodensis is the only fungus to be included in the “Top 50” endangered plants of Mediterranean islands. This species is only found on the Madonie mountains in northern Sicily. It is sold at a very high price, and its excessive picking, both by amateurs and professionals, is the main cause of the precariousness of its status. It is believed that less than 250 individuals per year reach maturity.

Agro-industrial waste – the production of which is constantly increasing – causes serious environmental problems. The industry is therefore looking for ways to recycle these wastes. In Uruguay, the cultivation of oyster mushroom was successfully tested on the “waste” of rice straw and citrus residues. Each year, this country produces 300,000 and 50,000 tonnes respectively. The primary goal was not the production of oyster mushrooms, but the valorization of the rejects via the mushrooms. In fact, under the action of fungi, woody and cellulosic substances, such as straw or bark, can be transformed enough to be used directly in animal feed. Thanks to mushrooms, they become more digestible and more nutritious, especially richer in protein.

We also managed to grow oyster mushroom on coffee grounds, this time for commercial production. Interestingly, thanks to the richness of this substrate, it is possible to shorten the production cycle of the fungus by several days and correspondingly increase the profitability. Its cultivation has also been tested on cotton and tobacco waste, residual tea leaves, paper and sludge resulting from its manufacture, etc.

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