Nutritional value and antioxidants in fruiting bodies of (Pleurotus ostreatus) Oyster mushroom

The fresh and dried fruiting bodies of cultivated P. ostreatus
are accomplished by using different chemical analytical methods. The results are showing that the nutritional value is including: energy 236.624 & 56.05 kcal/100g; moisture content 86.33 & 5.155%; also the following constitutes by g/100g DW in fresh and dry samples: dry matters 13.667 & 94.844; total proteins 22.6 & 9.6; amino acids 3.43 & 0.68; total carbohydrates 35.1 & 2.83 and total lipids 0.91 & 0.77. Each of K, Mg, Zn, Na and Cu are determined by mg/100g DW. Antioxidant metabolites are detected and included ascorbic acid 2.395 & 0.6204 g/100g DW in fresh & dry samples, respectively; free phenols are 23.99 & 163.515 and bounded phenols are 2.85 &1.96 µg/100g in fresh & dry samples, respectively.

Comparison between the fresh and dry P. ostreatus samples appeared that the fresh sample has high nutritional value with highest values in all tested parameters. Also the dry samples had the higher contents of four minerals (1696.25 K, 90.25 Mg, 21 Zn, and 4.5 Cu mg/100g DW comparing to the fresh sample (1402.5 K, 74.25 Mg, 18.25 Zn, and Cu 4.0). On the other side, the levels of each of Fe were 179.75 & 78 and Na 417.7 & 204.25 mg/100g DW, respectively).

Since human civilization, fruiting bodies of mushrooms (Agaricus bisporus, Pleurotus spp. and Lentinula edodes) are appreciated for texture and flavour as well as widely accepted as food flavouring material in soups for centuries. Global production of the cultivated mushroom around the world are 6.2 million tonnes with approximate value at least 14 billion $US in 1997, with a more than 12% increase annually from 1997 to 1981. Paul Stamets is a mycologist who used the tree oyster mushroom names Pleurotus ostreatus (Jacq. ex Fr.). Pleurotus ostreatus takes the third mushroom kind in the mushroom production around the world. It also represents 70% from the total global mushrooms production.

Pleurotus ostreatus is very popular wild and cultivated edible mushroom around the world and having a high rank in the market because of low cost, production technology as well as high biological efficiency, nutritional, flavoring and medicinal values. It often has the scent of anise with delicious, texture and high productivity/unit area and has been recognized as an exceptional food source to alleviate malnutrition in developing countries.

It is used as a healthy as a nutritive manufacturing. Pleurotus has a high biological activity, low toxicity and is used in folk classical medicine, flavour of food industry, perfume, cosmetics and pharmaceutical industries, as defoaming
agents and to improve shelf life and safety of minimally processed fruits. The wild P. ostreatus favorite for
cocustomer due to its flavor and texture.

The highest nutritional value of P. ostreatus depend on the presence of high level of protein 25-50%, essential amino acids (arginine, alanine, glutamine, & glutamic acid), carbohydrates 17–47% (no starch, but found the glucans, mannitol, trehalose and it also contains small amounts of arabitol, which may cause gastrointestinal upset for some people [4]), many of vitamins as "thiamine (B1), riboflavin (B2), niacin (B3), folic acid (B9), C, D and K", fibers (7–38%) and ash (8–12%). It has a high contents of minerals such as Ca, P, Fe, K, Mn, Cu, Zn, Mg and Se.

Pleurotus ostreatus has higher content of iron and acts as a very good iron source for treatment the anemia, it is also very poor in lipid content and have high contents of lovastatin as anticholesterol agents and essentials unsaturated fatty acids including oleic, linoleic, α-linolenic and palmitic. On the other side P. ostreatus contains few digestible carbohydrates and very low (calories "each 100 g have 28 k/Cal", 2-5% fats and Na). Pleurotus contains high potassium to sodium ratio, which makes it is an ideal food for patients suffering from hypertension and heart diseases.

Pleurotus ostreatus has high nutritional value which reassigns their medicinal value and riches by numerous bioactive antioxidant metabolites. It was used as a traditional oriental medicine and has beneficial health effects without any negative side-effects. It used as a source of powerful new pharmaceutical products and has many bioactive metabolites, specially it possess antioxidant metabolites which used in prevention of many dangerous disease such as anticancer, immunomodulatory, hepatoprotective, antidiabites, antimicrobial, antiinflammatory, support human health agents, anticholesterol and anti-cardiovascular diseases.

Pleurotus ostreatus is efficient lignin cellulosic degraders and can grow on wide variety of agricultural wastes. It has the ability to produce many enzymes such as amylases, pectinases, xylanases, cellulases, chitinases, proteases, lipases, β-galactosidases, inulinase, phytase, protease and laccase with broad adaptability. It is also used in bioremediation industries. Pleurotus ostreatus is riches in fatty acid including, myristic, stearic, eleostearic, palmitic, olic, margaric, heptadsenoic, arachidic and icosenoic acids. Fatty acids are important sources of fuel for brain cells, heart and skeletal muscle because when metabolized its yield large quantities of ATP.

Pleurotus ostreatus could be very useful for vegetarians and helpful to overcome the deficiency in protein and amino acid. It contains the most essential amino acids.

This investigation has been designed to determine the nutritional value of P. ostreatus including energy, total
proteins, free amino acids, total carbohydrates, total lipids and mineral analysis. Some antioxidant contents especially ascorbic acid and phenolic compounds were also detected. A comparison between the fresh and dried P. ostreatus samples for selecting the highest nutritional value for being consumed as a healthy food and medicinal diet in international medicinal centers for prevention or treatment numerous human diseases which formed from the nutritional deficiency were also aimed.