Introduction of Mushrooms

Overview of Mushrooms

Mushrooms are fleshy fruiting bodies of microorganisms called fungi arising from a group of mycelia buried in substratum (basically any organic matter). In general, mushrooms play a significant role in forest ecology, as they help decompose dead plants and animals, including dead trees, branches, leaves, fruits, seeds and animal droppings on the ground. In organic soil, 90% of dead plants’ wood is made up of cellulose and lignin primarily, which could decay very slowly. However, mushrooms are capable of producing some enzymes that could easily decompose these substances more rapidly and create nutrients for other plants and microorganisms, thus completing the natural forest growth cycle.

Unusual & Interesting Facts About Mushrooms

• The mushroom fungi are uniquely different from plants, as plants vary from animals. In fact, fungi and animals are now grouped into the same super-kingdom called Opisthokonta.
• After plants die, their remains are recycled by Fungi transforming it into rich soil. If mushrooms or fungi are not present, the Earth would have been buried several feet deep in debris and life on the planet would have disappeared eventually.
• Some wild mushrooms when boiled were found to be making beautiful colours, and this was once used to colour cloth just by dipping in that resulting broth.
• Many mushrooms grow towards light, following the sun just like plant. Unlike plants, scientists do not know how mushrooms use the sunlight yet.
• The spores of mushrooms are made of chitin, the hardest naturally-made substance on Earth.
• Under the right conditions, some of the mushrooms' spores can lay dormant for decades or even upto a century, and still grow!
• Other than food and medicinal use, some strains of mushrooms were also being used in bioremediation, aiding in the absorption and digestion of dangerous substances like oil, pesticides and industrial waste, in places where they threaten the environment.

The world of fungi holds many secrets yet to be discovered. Perhaps, the present younger generation could help us unveil their mysteries.

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Mushrooms Nutritional Facts

Mushrooms in general have been much sought after for their nutritive and medicinal aspects. They are low in calories, contain no cholesterol and almost no fat, sugar and salt and are a rich source of proteins, vitamins (B1, B2, C, D specifically), minerals (phosphates and potassium) and dietary fibres. Several varieties of mushrooms are found to have significant therapeutic properties. Mushrooms are found to have some bioactive substances called beta-glucans, which are shown to be immuno-modulating. They trigger the body’s immune system to fight infection. Mushrooms are often listed among the foods richest in folic acid which is one of the most successful weapons against anaemia.Mushrooms are low in calories and fat and high in water content, and hence are ideal for healthy diet. To ensure that one get the complete health benefits of mushrooms, they need to keep mushrooms from becoming mouldy or mushy during storage by leaving them unwashed.

Mushroom Nutrition: Mushrooms have a nutritional profile is perfect for today's consumer. One serving (five medium-sized white Mushrooms) has only 20 calories, and is free of fat, cholesterol and sodium.

LifeCycle of Mushrooms

On a microscopic level, these fungi form a mycelium in its growth stage and propagate through saprophytic mode, thereby generating spores in the gills of its fruiting body, which we call mushrooms, for dispersal, thus completing its reproduction cycle. The dispersed spores generate hypae/mycelium in favourable climatic conditions on suitable substrates and the life cycle process continues. As mushrooms lacks chlorophyll, they don’t photosynthesize (process energy from sunlight) like green plants. Most of the mushrooms appearing in the forests are poisonous, if consumed raw, and people often fall sick due to consumption of such mushrooms. Fortunately, many of the edible mushrooms have now been cultivated world over and mushrooms like button, oyster, shiitake, paddy straw are common household names.

Anatomy of a Mushroom!

Cap: the top part of the mushroom that grows upward above the stalk. When fully grown, these mushroom caps will spread out like an umbrella, e.g. the Straw Mushroom, the Button Mushrooms, the Milky Mushrooms, etc. Caps of some mushrooms (like the Oyster Mushroom, Abalone Mushroom) are flatter and may be indented in the middle.

Gills: the underside of the mushroom cap that has thin sheets connecting in a row around the stalk, and extends upward to the tip of the mushroom cap. The gills of some mushrooms are connected tightly to the stalks, some have pores, and others have teeth.

Stalk or Stipe: Stalks of each type of mushroom vary in size and length. Usually, stalks are cylindrical. The bottom part of the stalk is big and gets slimmer as it nears the top. The top part of the stalk joins the cap or gills. The skin outside the stalk of some mushrooms is rough while some are scaled like nets (Reticulum). Inside the stalk some mushrooms are loosely woven with fiber similar to sponges, while others are bound together tightly. This makes the stalk hard, soft or crispy; the texture varying according to the type of mushroom.

Spore: Mushroom spores are called basidiospores, which are produced in the gill area. Mushroom spores are very small and mostly colourless. When these spores gather into clusters, they will display similar colour to that of the gills. Different types of mushrooms have differently shaped spores. If the mushroom cap is put on a piece of paper in a sheltered area, spores will fall on the paper spreading along the gills’ lines.

Ring: Mushroom rings are thin tissues connecting the caps around stalks. When mushroom caps spread out, the tissues fixed between the caps and stalks will break and there will be some tissues left on stalks that will look like thin film wrapping. Types of rings can be used to classify types of mushrooms

Volva: located at the base of the mushroom. Depending on the type of mushroom, the thickness of the volva will vary. The Volva is left over from the wrapping tissues of budding mushrooms. When mushrooms grow, they will push these tissues out and stalks will push the caps upward, leaving the tissues below.

Mycelium: Mycelium is a cluster of fiber woven tightly together. Some mushrooms have tightly gathered mycelium around the base of the stalk. Some mycelium contain rough fibers, while others contain fine ones.

Each type of mushroom may not have all of these components. Most of them have caps and stalks while other components vary depending on the type of mushroom.

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Classification of Mushrooms

Most of the mushrooms belong to the Sub-Division: Basidiomycotina and a few belong to Ascomycotina of Kingdom-Fungi. Worldwide, there are more than 50,000 identified types of mushroom species. Around 20% (i.e. about 10,000) of these are safely edible. Researchers believe that the currently identified mushroom species represent roughly about 25% of all the mushroom species available on earth, indirectly saying that there are still several thousands of undiscovered mushroom species that are yet to be identified for their effects on human health. It is also important to note that there are several wildly available mushrooms that are poisonous and deadly to humans, if consumed. Therefore, in general the mushroom industry has three main segments: Cultivated edible, wild-mushrooms and medicinal mushrooms.

Of the identified mushrooms, information on several edible species had been collected and sorted for culinary purposes throughout the world, these culinary significant mushroom species varies widely between 200 and 3000. Of these, edible mushrooms, approximately 180 species can be cultivated artificially or commercially, and around 70 are accepted as food, out of which the cultivation techniques for about 20 varieties have been perfected on an industrial scale in our country.

However, only about six mushrooms are widely preferred for large-scale cultivation in India.

They are:

• Oyster mushroom - Pleurotus spp.
• Milky mushroom - Calocybe spp.
• Paddy straw mushroom - Volvariella spp.
• Button mushroom - Agaricus spp.
• Shiitake mushroom - Lentinulla spp.
• Jew’s ear mushroom - Auricularia sp.

Mushroom Cultivation

Mushroom cultivation is a biotechnological process wherein the waste plant materials or negative value crop residues can be converted into valuable food. Protein conversion efficiency and productivity of mushrooms per unit land area and time is far superior than plant and animal sources.

Mushroom Distribution

Fresh mushrooms rank among the most perishable food materials known to mankind, with a very short shelf life of only 1–3 days at ambient temperature. This factor considerably limits their distribution and marketing. Deterioration after harvesting, such as colour changes, particularly browning, weight loss, texture changes, or cap opening, is caused by high water content, high respiration rate, and lack of physical protection to avoid water loss (transpiration) and microbial attack.

Various endogenous enzymes participate in biochemical changes after disruption of cellular integrity such as by mechanical damage of tissues. Quick deterioration of mushrooms has been an obstacle for both manufacturers and consumers. Drying, canning, or deepfreezing have been traditionally used for mushroom preservation; however, emerging technologies have been studied. Gamma irradiation has been shown to be a preservation method that saves chemical parameters of various mushroom species to a greater extent than drying or freezing (Fernandes et al., 2012). Nevertheless, the period between research results and industrial application can be rather long.

Mushroom Preparation for Storage

Mushrooms should never be washed before being stored. Leave in the container or paper bag in which they are bought, do not store in plastic bags. Store in the bottom of the refrigerator or in a cool place. Don't let the mushrooms freeze.

Mushrooms should have a fresh, well-shaped appearance, firm texture and be free of spots. Avoid mushrooms that show signs of deterioration, mould, or that appear slimy.When cleaning mushrooms try using a damp paper towel or a soft brush to remove any dirt. You can also rinse them in cool water a little at a time then pat dry with a paper towel. Mushrooms absorb moisture very quickly and too much moisture causes them not to brown well when cooking.

Despite all care, mushrooms will dry out. To revive them immerse the mushrooms in boiling water for up to 1 minute and then pat them dry carefully.

Here are a few general instructions to prepare and store mushrooms:

• Microwaving, Sautéing & Roasting Mushrooms
• Freezing Mushrooms
• Canning Mushrooms
• Pickling Mushrooms
• Dehydrating Mushrooms

Choose your texture: To begin with, the length of time a Mushroom is cooked will dictate its texture. Short cooking yields a more delicately textured Mushroom; longer cooking actually renders them denser and chewier (this is because the longer they cook, the more water they lose).First, clean the mushrooms. It is best to get all of the dirt off with a brush. Go ahead and wash them in water, scrubbing with a vegetable or mushroom brush as necessary. This will make your prep much easier.

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1a) Microwaving Mushrooms: Mushrooms cook extremely well in the microwave. Simply clean and cook as follows: put thickly sliced Mushrooms in a microwaveable bowl; cover and cook on HIGH (100% power) for two to three minutes, stirring once.

1b) Sautéing Mushrooms: For each quarter kilo of Mushrooms, heat one tablespoon butter or oil in a large skillet. Add Mushrooms; cook, stirring occasionally, until golden and the released Mushroom liquid has evaporated, about five minutes. Don't overcrowd skillet, else Mushrooms will steam rather than brown.

1c) Roasting Mushrooms: Put Mushrooms in a shallow baking pan; toss with a little oil and roast in a 450° F oven, stirring occasionally until brown, about 20 minutes. Use about one tablespoon of oil for each eight ounces of Mushrooms.

TIP: If sliced raw Mushrooms are prepared in advance, dip slices in lemon juice to preserve colour.

Preparation: Sort mushrooms based on size and choose those that are free from spots and decay. Wash thoroughly in cold water. Trim off ends of stems. If mushrooms are larger than 1 inch across, slice them, or cut them into quarters. Mushrooms can be steamed or heated in oil in a frying pan. Steamed mushrooms will keep longer than those heated in fat.

To Steam: Mushrooms to be steamed have better colour if given anti-darkening treatment first. To do this, dip for 5 minutes in a solution containing 1 teaspoon lemon juice or 1½ teaspoons citric acid to half-litre of water. Then steam whole mushrooms 5 minutes, buttons or quarters 3½ minutes, and slices 3 minutes. Cool promptly, drain and package, leaving 1/2-inch headspace. Seal and freeze.

To Heat in Fry Pan: Heat small quantities of mushrooms in margarine or butter in an open fry pan until almost done. Cool in the air or set pan in which mushrooms were cooked in cold water. Pack into containers, leaving 1/2-inch headspace. Seal and freeze.

* This document was extracted from "So Easy to Preserve", 4th ed. 1999. Bulletin 989, Cooperative Extension Service, The University of Georgia, Athens. Revised by Elizabeth L. Andress. Ph.D. and Judy A. Harrison, Ph.D., Extension Foods Specialists.

Quantity and Quality: An average of 6kg is needed per canner load of 4 kg. Select only brightly coloured, small to medium-size domestic mushrooms with short stems, tight veils (unopened caps), and no discoloration. Caution: Do not can wild mushrooms

Procedure: Trim stems and discoloured parts. Soak in cold water for 10 minutes to remove dirt. Wash in clean water. Leave small mushrooms whole; cut large ones. Cover with water in a saucepan and boil 5 minutes. Fill jars with hot mushrooms, leaving 1-inch headspace. Add 1/2 teaspoon of salt per half-litre to the jar, if desired. For better colour, add 1/8 teaspoon of ascorbic acid powder, or a 500-milligram tablet of vitamin C. Add fresh hot water, leaving 1-inch headspace.

Adjust lids and process following the recommendations in Table 1 or Table 2 according to the method of canning used.

Table 1. Recommended process time for Mushrooms in a dial-gauge pressure canner.

			Canner Pressure (PSI) at Altitudes of
Style of Pack	Jar Size	Process Time	0 – 2,000 ft	2,001 – 4,000 ft	4,001 – 6,000 ft	6,001 – 8,000 ft
Hot	Half-pints or Pints	45 min	11 lb	12 lb	13 lb	14 lb

Table 2. Recommended process time for Mushrooms in a weighted-gauge pressure canner.

			Canner Pressure (PSI) at Altitudes of
Style of Pack	Jar Size	Process Time	0 – 1,000 ft	Above 1,000 ft
Hot	Half-pints or Pints	45 min	10 lb	15 lb

* This document was extracted from the "Complete Guide to Home Canning," Agriculture Information Bulletin No. 539, USDA. Revised in 1994.

Procedure
Select very fresh unopened mushrooms with caps less than 1-1/4 inch in diameter. Wash. Cut stems, leaving 1/4 inch attached to cap. Add lemon juice and water to cover. Bring to boil. Simmer 5 minutes. Drain mushrooms. Mix olive oil, vinegar, oregano, basil, and salt in a saucepan. Stir in onions and Pepper and heat to boiling. Place 1/4 garlic clove and 2-3 peppercorns in a half-pint jar. Fill jars with mushrooms and hot, well-mixed oil/vinegar solution, leaving 1/2-inch headspace.

Ingredients
3 kg small whole mushrooms
1/2 cup bottled lemon juice
2 cups olive or salad oil
2-1/2 cups white vinegar (5%)
1 tbsp oregano leaves
1 tbsp dried basil leaves
1 tbsp canning or pickling salt
1/2 cup finely chopped onions
1/4 cup diced pepper
2 cloves garlic, cut in quarters
25 black peppercorns
Yield: About 5 kg

Adjust lids and process according to the recommendations in Table 1.

Table 1. Recommended process time for Marinated Whole Mushrooms in a boiling-water canner.

		Time at Altitudes of
Style of Pack	Jar Size	0 – 1,000 ft	1,001 – 3,000 ft	3,001 – 6,000 ft	Above 6,000 ft
Hot	¼ litre	20 min	25 min	30 min	35 min

* This document was extracted from the "Complete Guide to Home Canning," Agriculture Information Bulletin No. 539, USDA. Revised in 1994.

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Clean the mushrooms and slice the mushrooms between 1/4 to 1/2-inch thick.The thicker the slices, the longer they will take to dry. Arrange the cleaned, sliced mushrooms on the dehydrator trays, making sure that none of the pieces touch or overlap.Dry them at 110°F/43°C until the pieces are crispy dry. This will take 4 to 6 hours for 1/4-inch slices, up to 8 hours for thicker slices.

Allow the dried mushrooms to cool completely before transferring them to glass jars. Cover tightly with lids and store away from direct light or heat. To use dehydrated mushrooms, pour boiling water over them in a heat-proof bowl. Let them soak for 20 to 30 minutes. Drain, reserving the richly flavoured soaking liquid for soup stocks and sauces. Use the rehydrated mushrooms.

* This information was provided by the Mushroom Council. For more information about preparation, nutrition, and varieties of mushrooms, please visit mushroomcouncil.org.

* This information provided by About Food. For more information please visit foodpreservation.about.com