Nutritional Value of Mushroom

1. NUTRITIONAL VALUE OF MUSHROOMS AND THEIR POST HARVEST PRESERVATION
Mushrooms are rich in protein, carbohydrates and vitamins. These are low in calorific value and
hence are recommended for heart and diabetic patients. They are rich in good quality protein
containing lysine and tryptophan as compared to cereals, pulses, fruits and vegetables on dry
weight basis. In addition to protein they also contain carbohydrates, fiber, minerals, vitamin B
and C which include thiamine, riboflavin, niacin, biotin and pantothenic acid. Folic acid and
vitamin B12 which are normally absent in the vegetable foods are also present in mushrooms.
Besides vitamins they also contain minerals like potassium, sodium and phosphorus in high
quantities. Mushrooms generally do not contain calcium and iron. Mushrooms possess low
calorific value, high protein, high fiber content, high K: Na ratio, low calories and fat (rich in
linoleic acid and devoid of cholesterol) which makes the choice of the dietician to include
mushrooms in diets for those suffering with or prone to obesity, hypertension etc.
Like other vegetables, the mushrooms also contain 90% moisture. The fat content is very low but
rich in lenoleic acid. Cholesterol is absent and in its place ergosterol is present which gets
converted to Vitamin D by the human body.
Most of the compounds found in mushrooms are classified as Host Defensive Potentiators
(HDP). These compounds include polysaccharides, peptides, nucleosides, triterpenoids,
alkaloids, complex structures and other metabolites produced by mushrooms. During vegetative
stage in the mushroom life cycle, digestive enzymes are excreted to digest the food outside the
cells and then absorbed. The nature of substrates used for the cultivation of mushroom has got a
significant role on the productivity of mushrooms. Therefore, utilization of plant or any other
agricultural waste by mushroom industry would also likely solve waste disposal problem and
help in producing the proteinaceous food in the form of mushrooms. In most of the Asian
countries and other parts of the world, mushrooms are being used as a food or as supplement for
human consumption.
Medicinal properties of mushrooms
There are various types of medicinal mushrooms showing different effects of immune system
related disorders. Medicinal mushrooms not only support immune health but also cardiovascular
health in terms of cholesterol lowering and hypertension, diabetes and skin health. By combining

2. a host of medicinal mushroom species, the immune system receives multiple stimuli, which in
turn awakens the body’s natural defenses. In Japan and China people eat mushrooms almost
every day and most types of cancer are uncommon in those countries. A wide range of
Ganoderma mushroom products are also available in the market.
Antiviral and Antibacterial properties of mushroom
Some new antiviral compounds have been isolated from mushrooms and studied for their activity
inhibiting in vitro the Herpes simplex I and II viruses, as well as Varicella zoster virus, influenza
A virus and the respiratory syncytial virus. Antivirals from many mushrooms have been
identified eg. lentinan from Shittake (Lentinula edodes). The predominant mushrooms showing
promise for their antiviral activites are polypores. Most of these antivirals are water soluble and
relatively heat soluble. It is hoped that mushroom would become a new antiviral medicine and
untapped resource in near future.
Processing of mushrooms
Being a highly perishable commodity, processing and preservation of mushroom is of vital
importance. The serious post harvest problems encountered with mushrooms are microbial
spoilage, blackening, gill opening and weight loss. The rate of respiration activity of mushrooms
is higher as compared to other horticultural crops and this result in a shorter post-harvest life.
Freshly harvested highly perishable mushroom needs to be preserved to extend its shelf life for
off season usage. Mushrooms can be processed in novel ways to extend their shelf life, as it can
be dried, pickled and canned. The various processing methods involved in mushroom
preservation are as follows:
Blanching: Mushrooms are highly prone to enzymatic browning due to a combination of auto
enzymatic and microbial action on the tissue. Blanching of mushroom at 800
C for 3 to 5 minutes
is adequate to inactivate the polyphenol oxidase and peroxidase enzyme activities. However,
blanching for prolonged periods cause substantial loss in nutrients and solids as well.
Steeping preservation: The method is simple, economical and mushrooms can be preserved for
short periods by steeping them in concentrated solutions of salts or acids. Steeping preservation
of mushrooms help to extend shelf life as well as retain whiteness. Steeping preservation not

3. only increases the shelf life of mushroom but also keeps the texture and aroma of the mushroom
like the fresh ones. Whenever we want to consume the steep preserved mushroom, it has to be
washed with water and then it can be used for consumption.
Drying: Drying is the process of removal of moisture from the product to such a low level that
the microbial and biochemical activity is checked due to reduced water activity in the product
which makes the products suitable for safe storage and protection against attack by
microorganisms during the storage. This gives the final product with lower moisture content and
longer shelf life. These dry products can be used or consumed after rehydration whenever the
consumer prefers. Dehydrated mushrooms are used as an important ingredient in several food
formulations including instant soups, pasta salads, snack seasonings, casseroles, meat and rice
dishes.
Sun drying: Sun drying is the cheapest and oldest method among the various drying methods.
Even though the quality of the product is affected by environmental factors due to the free
availability of heat source, it is considered to be the low cost method of drying. In this method,
mushrooms are spread over the trays and kept in open place under the sun, when atmospheric
conditions are above 250
C temperature with less than 50% relative humidity and high wind
velocity. Sun dried product should, however, be oven dried at 55-600
C for 4-6 hours to avoid any
spoilage during storage. The dried product can be stored for longer periods and it regains to a
large extent its flavor and texture after rehydration. Mushrooms are generally sun-dried by small
resource poor growers. Oyster mushroom is generally sun dried for further use.
Cabinet air drying: In cabinet air drying, drying is done by using a cabinet drier to reduce the
drying period of conventional drying methods. Cabinet air drier consists of series of trays placed
in the plenum chamber and hot air at constant air flow rate is allowed to pass through this
plenum chambers. However, the conventional oven drying method results in dark brown
coloured product with a tough texture in case of button mushroom; other mushrooms give
reasonably acceptable product. Due to little air movement inside the conventional oven, the
evaporated water condenses on fruit bodies increasing the mucilage and deteriorating the quality.
The large quantity of condensed water may also damage the equipment. Hence, a cabinet dryer
with circulated air supply is better. The drying temperature of 550
C in the plenum chamber has
been found to give the end product with the desired qualities of texture, colour and rehydration.

4. Freeze drying: Removal of water from a substance by sublimation from the frozen state to the
vapour state is known as freeze-drying. In a freeze drying system, dehydration takes place in
three stages; water present in the product is removed by formation of ice crystals; the ice crystals
are then removed from the outer surface of the material by sublimation; after removal of all the
ice, the little quantity of water left is then removed by evaporation in the frezze dryer. In a freeze
drying system, original shape and size can be retained and the shrinkage, which is a problem
with other drying methods, is negligible. Mushrooms are freeze dried at 200
C and the moisture is
removed by sublimation at a very low vaccum for 12-16 hours. The freeze dried mushrooms are
brittle, but have a superior flavor and appearance; the appearance of freeze dried mushrooms is
very similar to fresh mushrooms but as the product is brittle, it is packed in sturdy packings often
cushion-packs under nitrogen. The product can be stored up to 6 months without any change in
its quality and appearance. However, this is costly and energy intensive process.
Canning: Canning is one of the techniques by which the mushrooms can be stored for longer
periods up to a year. The canning process can be divided into various unit operations viz.
cleaning, blanching, filling, sterilization, cooling, labeling and packaging. In order to produce
good quality canned mushrooms, they should be processed as soon as possible. In case where
delay is inevitable, mushrooms should be stored at 4-50
C till processed. The mushrooms with a
stem length of 1 inch are preferred and are canned whole as well as sliced.
Value added products of mushrooms: The value added products of mushrooms are the need of
hour for the mushroom growers, not only to reduce the losses but also to enhance the income by
value addition and boost the consumption of this important horticultural crop. The possible value
added products that can be developed from mushrooms are: Mushroom nuggets, Mushroom
biscuit, Mushroom ketch up, Mushroom soup powder, Mushroom candy, Mushroom murabba,
Mushroom chips, Ready to serve mushroom curry, Mushroom pickle etc.