Edible Mushrooms: Its Cultivation and Benefits

Humans have long considered mushrooms as a culinary marvel and a gourmet delicacy, especially for their distinctive flavour. More over 2,000 mushroom species exist in nature, but only around 25 are commonly acknowledged as food and just a few are economically produced. Mushroom cultivation is a technology of growing mushrooms using plant, animal and industrial waste. In short, it is wealth out of waste technology. This technology has gained importance worldwide because of its dietary fibers and protein value.

Mushroom is a fungus belonging to basidiomycetes. Mushrooms are regarded as a delicacy with high nutritional and functional value, and they are also recognized as nutraceutical foods; they are of great interest due to their organoleptic quality, therapeutic characteristics, and nutritional worth as well as economic relevance. The most often cultivated fungus is Agaricus bisporus, followed by Lentinus edodes, Pleurotus species, and Flammulina velutipes. China is now the world's largest producer of mushrooms, with output rising steadily. But wild mushrooms are becoming increasingly significant because of their dietary, sensory, and particularly medicinal properties. In addition to some primary metabolites like oxalic acid, peptides, and proteins, mushrooms might potentially be a source of novel antimicrobial chemicals, mostly secondary metabolites including terpenes, steroids, anthraquinones, benzoic acid derivatives, and quinolones. The most researched species, Lentinus edodes, appears to exhibit antibacterial effects on both gram-positive and gram-negative bacteria.

They offer good nutritional value since they are relatively high in protein, contain considerable amounts of fibre and necessary amino acids, and are low in fat but high in vital fatty acids. A nutritionally substantial amount of vitamins (B1, B2, B12, C, D, and E) are also present in edible mushrooms.

Cultivation Procedure in general has four main steps:

• Compost preparation

• Spawning.

• Cropping and harvest administration.

The basic requirements for mushroom cultivation are manure/compost, spawns, right temperature and humidity. Favourable growing conditions involve 80%-90% of relative humidity, ample ventilation, a temperature range of 20-28⁰ C during spawn run and12-18⁰ C for reproductive growth. Initially for a week temperature must be maintained at 23 ± 2⁰ C and then it can be reduced to 16 ± 2⁰ C for subsequent weeks. The CO₂ concentration should be 0.08-0.15 %. The above stated conditions are maintained appropriately the pin heads start to appear within few days and progressively mature into button stage. Apart from these insecticides, nutritional supplements like nitrogen, vermiculite, water are also required for a healthy harvest. The following steps are to be followed for mushroom cultivation:

Compost Preparation:

Compost (either synthetic or natural) used for mushroom development is often composed of wheat straws, horse manure, chicken manure, rice bran, gypsum, and other materials. The raw compost is protected from rain and other external moisture, which might introduce harmful bacteria. To allow fermentation, chopped wheat straws or rice bran are combined with horse manure, sprayed with water, and stacked in a mound. The fermentation process, together with heat development, degrades chemical molecules into tiny components. Frequent turnings and watering are performed at regular intervals to prevent compost from drying out. Gypsum is occasionally added to compost to lessen greasiness and allow for better aeration. Within 15 to 20 days, the compost is ready to use.

Spawning

Spawns are mycelium that has been carefully propagated on agars or grains. The process of seeding or mixing spawns in compost is known as spawning. Although mushrooms release spores that function as seeds for subsequent multiplication, they are rarely widely employed due to poor germination and development. The spawns are well mixed with the compost, covered with newspaper, and appropriately watered to retain moisture. To reduce moisture loss, humidity is kept high during the cultivation period. They gradually transform into white cottony mycelium growth.

Casing is a type of sterilised soil or dressing that contains cow dung that is applied to the spawn mixed compost. When mycelium growth begins on the compost surface, it is applied. After 15 to 20 days of treatment, mushroom heads or pins begin to appear on the surface. They are allowed to mature for a set amount of time before being harvested before the cap is opened. Mushrooms with an open cap (which resembles an umbrella after being opened) are unpleasant and of low grade.

Harvesting

Harvesting is done by plucking them from soil using hands or the heads are chopped off using knife. The harvested mushrooms are then subjected to primary processing.

Yield

10-14 kg fresh mushrooms per 100 kg. fresh compost can be obtained in two months crop. Short method used for preparation of compost under natural conditions gives more yields (15-20 kg. per 100 kg. compost).

Main edible mushrooms worldwide are as follows:

Agaricus

The most cltivated fungus in the world is Agaricus bisporus, which belongs to the Agaricus genus (Figure 1). This edible mushroom group is currently widely utilised and researched for its medicinal and therapeutic potential.

A lectin from A. bisporus and a protein from A. polytricha have been shown to be effective immune stimulants; consequently, these macromolecules may be evaluated for medicinal use, and this fungus may be designated as healthy food. The extract of A. bisporus has been demonstrated to inhibit cell growth in breast cancer.

blazei is an edible fungus native to Brazil that has been grown extensively, particularly in Japan. It is a famous basidiomycete known as "sun mushroom," and due to its therapeutic benefits, it is currently consumed internationally as food or in tea. Its fruit bodies are antimutagenic, anticarcinogenic, and immunostimulatory and its extracts are immunomodulatory, anticarcinogenic, and antimutagenic. Furthermore, it has been observed that this mushroom inhibits liver lipid peroxidation.

Lentinus

Because of its beneficial benefits on human health, L. edodes, sometimes known as the "shiitake mushroom," has been utilised for many years to research functional qualities and isolate chemicals for medicinal application (Figure 2). It has been used for hundreds of years to treat the common cold, and some scientific data supports this idea.

Experimental data on L. edodes aqueous extracts as possible sources of antioxidant and anticancer chemicals. These extracts also greatly reduced tumour cell growth. L. edodes has a high concentration of 𝛽-glucans in the soluble component of dietary fibre. Shiitake mushrooms generate lentinan and 𝛽-glucan, which inhibit leukaemia cell growth and have anticancer and hypocholesterolemic properties.

Pleurotus

This genus, usually known as oyster mushrooms, contains about 40 species (all of which are edible and widely available) (Figure 3). These species have long been utilised as medical mushrooms due to the presence of numerous substances with essential pharmacological/nutritional characteristics.

These chemicals include lectins, which have immunomodulatory, antiproliferative, and antitumor properties; phenolic compounds, which have antioxidant properties; and polysaccharides (polysaccharide peptides and polysaccharide proteins), which have immunoenhancing and anticancer properties. 𝛽-glucans isolated from Pleurotus pulmonarius decreased leukocyte migration to acetic acid-injured tissues in rats with colitis, whereas P. ostreatus prevented leukocyte migration to acetic acid-injured tissues. Inflammation was reduced by a P. florida extract. Pleurotus has also been linked to haematological, antiviral, anti-tumor, antibacterial, hypocholesterolic, immunomodulatory, and antioxidant activity.

Ganoderma

For thousands of years, traditional Chinese medicine has employed the "mushroom of immortality," also known as Lingzhi or Reishi, to promote health and longevity as well as to cure conditions including neurasthenia, hypertension, hepatopathy, and cancer (Figure 4).

In China, Japan, and Korea, it is one of the most widely used medicinal mushrooms. Over the past few decades, it has been the subject of cutting-edge biochemical and pharmaceutical study. Some significant traits of this fungus, including immunomodulating, antiallergic, antiradiation, anticancer, anti-inflammatory, antiparasitic, and antioxidant capabilities, have also been proven by contemporary pharmacological testing.

Ganoderma has been used as a cancer treatment in Asia for centuries; it has an anticancer impact both on its own and when combined with chemotherapy and radiation. Ganoderma lowers the motility of invasive breast and prostate cancer cells, reduces the survivability of human cancer cells, triggers cell apoptosis, inhibits cell proliferation, and delays the beginning of many cancers.

Nutritional Composition of some edible mushrooms:

Table.1. Proximal composition of some edible mushrooms (dry basis).

Species	Protein %	Fat %	Ash %	Carbohydrates %	Energy kcal/kg
Agaricus bisporus	14.1	2.2	9.7	74.1	325
Lentinus edodes	4.5	1.73	6.7	87.0	772
Pleurotus ostreatus	7.0	1.4	5.7	85.2	416
Ganoderma	5.2	2.0	6.1	82.6	425

(Source: Velverade et al. 2014)

Fatty acids content of some edible mushrooms:

Table.2. Fatty acids content of some edible mushrooms

Species	Palmitic	Stearic	Oleic	Linoleic	Linolenic
	(g/ 100 g of fresh weight)
Agaricus bisporus	11.9	3.1	1.2	77.1	0.1
Lentinus edodes	11.3	1.6	1.4	81.3	0.1
Pleurotus ostreatus	11.2	1.5	12.0	68.9	0.1
Ganoderma	10	1.3	1.6	65.4	0.1

(Source: Patel and Goyal 2012)

Reference:

Khan, M.A., Tania, M., Liu, R.. and Rahman, M. M., 2013. Hericium erinaceus: an edible mushroom with medicinal values. Journal of Complementary and Integrative Medicine 10: 253–258.

Patel, S. and Goyal, A., 2012. Recent developments in mushrooms as anticancer therapeutics: a review. Biotech 2: 1–15

Valverde, M.E., Perez, T.H. and Lopez, O.P., 2014. Edible Mushrooms: improving human health and promoting quality life. International Journal of Microbiology 15: 1-14

Authors

1. Aniruddha Govind Deshmukh

Ph.D. Research scholar, Dept. of Plant Pathology, Dr. P.D.K.V., Akola

Contact no. 8975959333

2. Gajanan K. Giri

Professor (CAS), Dept. of Plant Pathology, Dr. P.D.K.V., Akola

3. Aniket Ambadasrao Patil

Ph.D. Research scholar, Dept. of Agronomy, Dr. P.D.K.V., Akola