SHIITAKE: PROPERTIES, CHARACTERISTICS, HABITAT, REPRODUCTION - NUTRITION - 2024

The shiitake (Lentinula edodes) is a lignolytic Basidiomycota fungus of the order Agaricales that is characterized by a rounded cap, about 12 cm in diameter and brown in color with whitish warts. In addition, it has adnate and whitish lamellae in young organisms, as well as reddish-brown and separate in older organisms.

It is native to East Asia, where it thrives on decaying trunks of trees such as oak, maple, blackberry, among others. Today it has been introduced in many countries for cultivation purposes.

Shiitake mushroom. Taken and edited from: frankenstoen from Portland, Oregon.

Thanks to its organoleptic and medicinal properties, it has been cultivated for more than a thousand years and is currently the third most widely consumed mushroom in the world. Its cultivation was traditionally carried out by inoculating trunks of the shii tree, but nowadays new cultivation technologies have been developed, which include artificial substrates.

According to traditional medicine, the fungus has multiple medicinal properties, among them we can mention that it strengthens the immune system, is antifungal, antibacterial, vermicidal, serves to prevent cavities, protects skin, liver and kidneys, as well as it has also been suggested that it has anticancer properties.

Despite its medicinal properties, the consumption of Lentinula edodes can also have adverse effects, such as shiitake dermatitis, an allergic reaction that appears 24 hours after ingestion and is characterized by erythematous, micropapular and itchy rashes all over the body and lasts between 3 days and 3 weeks.

characteristics

The cap (crown) generally measures between 5 and 12 cm, although it can reach 20 cm in diameter; it has a convex surface that becomes nearly flat over time. The cuticle is light colored towards the edges and dark brown towards the center, initially smooth but later breaking into scales of variable shape and size.

Internally (context) it is compact, fleshy leathery, light or brown in color near the cuticle, firm. Its flavor is sour and has a slight odor.

The blades are white or slightly brown and tend to darken or acquire yellowish spots over time. They are moderately wide, with smooth or irregular edges, without being completely serrated.

The stipe or foot is between 3 and 5 cm long and up to 13 mm wide, it is uniform or slightly wider towards the base. Its consistency is solid and fibrous, and its surface is thin, with an ephemeral ring in the most distal third and formed by the remains of the veil. The coloring is similar to that of the hat.

The spores are white, 5.5 to 6.5 mm long by 3 to 3.5 mm wide, are sub-cylindrical in shape, non-amyloid and smooth, and have a thin wall. The basidia, on the other hand, are tetraporates, the hymenium lacks pleurocystidia.

Health properties

The properties of Shiitake mushrooms are numerous: in addition to stimulating the immune system, it is also a rich source of minerals, vitamins and enzymes, which make it a powerful antimicrobial.

The use of shiitake in traditional Chinese medicine dates back more than 500 years, there are records from the time of the Ming dynasty, where its use is recommended to treat respiratory ailments, liver, circulatory system and even general body weakness.

Lentinan is a beta-glucan synthesized by shiitake, has antitumor properties and is used as a drug in cancer patients. Preliminary studies have shown that this compound reduces the appearance of genital warts, increases the CD4 count in patients with HIV and acts on various types of cancer in combination therapies.

The presence of vitamins and minerals in the mushroom helps activate the immune system and lowers cholesterol, while selenium reduces the risks of heart disease and prostate cancer and increases metabolism.

Boosts the immune system

These mushrooms have the ability to strengthen our immune system. In addition, they fight some diseases by containing vitamins, minerals and enzymes that are beneficial to the body.

Reduces cancer cells in the body

Studies indicate that shiitake fights cancer cells in the body; helps heal chromosome damage caused by chemotherapy or other cancer treatments. Therefore, this fungus would be a potential natural treatment against this disease.

Protects cardiovascular health

Among the compounds in shiitake, sterol stands out, an element that interferes with the production of bad cholesterol in the liver.

This mushroom also contains phytonutrients, which help cells adhere to the walls of blood vessels, maintaining healthy blood pressure and improving circulation.

It is a good antioxidant

Specialists say that antioxidants help the body fight free radicals, which can mutate cells and cause cancer. Well, experts point out that shiitake contains a powerful antioxidant: L-ergothioneine.

Develops B vitamins

This mushroom provides B complex vitamins, which boost our metabolism, helping the body convert food into energy. These vitamins also drive the body to produce red blood cells, which protects against the development of anemia.

Good source of minerals

A 100 gr portion of this mushroom provides one twentieth of the magnesium and potassium the body needs daily, as well as 10% of phosphorus. It should be noted that cooking these mushrooms depletes three-quarters of their phosphorus content and two-thirds of their potassium content, but consuming them dry or raw does not lose these nutrients.

Fight thrombosis

This fungus is also a good treatment to combat thrombosis, a medical condition in which blood clots form, which block the veins, which hinders proper flow. The condition mainly affects the legs and is accompanied by severe pain.

The use of these mushrooms in the form of oil can help alleviate this disease. When used regularly, shiitake might even thwart the onset of thrombosis. The presence of lenthionin in significant amounts in this mushroom helps the body to maintain control over the aggregation of platelets.

Strengthens the digestive system

Since this mushroom has a good amount of dietary fiber (in 100 gr there are 2.5 of fiber, which is equivalent to 10% of the recommended daily value), it is a compound that effectively enhances the digestive system.

On the other hand, the fiber binds with the stool and softens it and thus also contributes to suppressing constipation.

Fight aging

The application of shiitake extract on the skin has the potential to improve and increase its appearance, making it smoother and younger.

As the fungus contains kojic acid, this helps to lighten the skin tone, helps to remove age spots and scars. Consequently, it delays aging, keeping the skin young.

It is a good anti-inflammatory

Shiitake also has the ability to fight inflammations that affect the skin. It could even alleviate various anti-inflammatory conditions, including rosacea, eczema, and acne.

This is due to the presence of vitamin D and selenium, along with antioxidants that protect the skin from damage caused by environmental conditions.

Compensates for lack of iron

Shiitake mushrooms are a good source of iron and minerals.

Pregnant women could eventually use these properly cooked mushrooms to meet their iron needs. However, you should consult a doctor, as you could be allergic or intolerant to these fungi.

Control the weight

This mushroom is low in calories and is a rich source of fiber, therefore it is a suitable food for those who want a low calorie diet and lose weight.

In addition, it gives the possibility of feeling full for a long time and also ward off constipation because it stimulates the metabolism, which helps to eliminate bad cholesterol in the stool.

Nutritional value

Shiitake mushroom harvest (Lentinula edodes). Taken and edited from: Rob Hille.

In addition to its organoleptic properties, shiitake has a high nutritional value, as it contains twice as much protein as vegetables, including some of high biological value due to their content of essential amino acids. It is a source of B-complex vitamins and its fat and carbohydrate content is low.

One hundred grams of shiitake provide only 34 calories and in addition to protein and vitamins, they provide the diet with minerals such as calcium, phosphorus, magnesium, potassium, sodium and even selenium. Additionally it contains lentinan, a compound with anti-cancer and anti-infective properties.

On Dr. Mercola's site, the nutritional value of the mushroom is delivered in 100 grams:

* Daily Values ​​based on a 2,000 calorie diet. The daily values ​​can be higher or lower, depending on the calorie consumption.

Components

Some of the components of this mushroom:

• Hypolipidemic eritadenine.
• C-1-2 (polysaccharide) Immunoactive.
• Immunoactive Lectin.
• Lentinan (polyaccharide) Immunoactive.
• Emitanine (polysaccharide) Immunoactive.
• EP3 (lignin) Antiviral, immunoactive.
• KS-2, KS-2-B Antiviral, immunoactive (peptide) antibacterial.
• Immunoactive poly ribonucleotides.
• Ac2p (polysaccharide) Antiviral.
• FBP (protein) Antiviral.
• Thioproline (TCA) Nitrite scavenger (amino acid).

Adverse effects

Most of the adverse effects of shiitake are due to lentinan. Although very rare, consuming raw to lightly cooked shiitake can trigger an allergic reaction known as shiitake dermatitis, which is characterized by itchy, micropapular, and erythematous rashes.

These effects can last up to three weeks. Proper cooking of the mushroom before ingestion prevents the appearance of this type of allergies. It can also cause hypersensitivity to the sun.

The administration of lentinan as a drug in cancer patients has occasionally shown various adverse effects. Among these are depression, stiffness, fever, abdominal pain, eosinophilia, back pain, dry throat, abdominal obstruction, among others.

Researchers have also reported problems of hypersensitive pneumonitis due to inhalation of spores, and allergic contact dermatitis in personnel who work in the cultivation of the fungus.

Habitat and distribution

Shiitake is a fungus that grows and develops on decaying tree trunks, mainly on trees of the Castanopsis cuspidata species, as well as the Lithocarpus genus, although they can develop on a great variety of other plants such as maple, blackberry, beech, poplar, among others. Its growth occurs in the autumn and spring months.

This mushroom is native to East Asia, where it has been traditionally cultivated in countries such as China, Korea, Japan, Singapore, Thailand, among others. Currently its cultivation has spread worldwide, mainly among the countries of Europe and America.

Taxonomy

Lentinula is a genus of Basidiomycota fungi belonging to the class Agaromycetes, order Agaricales and to the family Omphalotaceae. The genus was erected by the North American mycologist Franklin Sumner Earle in 1909, to contain mainly tropical species and currently consists of eight species.

Shiitake was originally described as Agaricus edodes in 1877 by Miles Joseph Berkeley, an English botanist, father of plant pathology. Later it has been relocated to various genres, including Armillaria, Mastoleucomyces and Cortinellus, or has received other names, with extensive synonymy.

The location of the species in the genus Lentinula was made by the British mycologist David Pegler in 1976.

Reproduction and life cycle

The sexual reproduction of Lentinula edodes is of the tetrapolar heterothalic type. In this type of mating, the sexual compatibility of the hyphae is controlled by two different pairs of chromosomes, instead of a single pair as occurs in bipolar heterothallic crosses.

The crossover between haploid homokaryon hyphae gives rise to a new hypha with two different nuclei (dicariont), only when both homokaryons are hetero-allelic for two incompatibility factors. The new fungus will grow as a dikaryote and the fusion of the nuclei will occur in the basidia for the formation of the basidiospores.

Lifecycle

The shiitake life cycle begins with the germination of the spore, which will develop to produce a uninucleated mycelium. When two compatible varieties cross, they produce a dycariont that will present binucleated cells with staple connections.

The dikaryote will grow in the substrate and after a while the fruiting body will emerge. The fusion of the nuclei of the binucleated cells will occur in the basidia, forming a short-lived zygote that will undergo meiotic division to form the haploid basidiospores.

Once the basidiospores are formed, they will be released from the filaments that attach them to the basidia (sterigmas) to be disseminated by the wind and insects, germinate and start a new cycle.

Nutrition

Lentinula edodes is a saprophytic species, that is, an organism that feeds on non-living organic matter, absorbing soluble organic compounds from it. It feeds by breaking down lignin and other complex carbohydrates from dead tree trunks by secreting enzymes from the distal ends of its hyphae.

The degradation of these complex carbohydrates leads to the release of glucose and other simple sugars that constituted them, which the fungus will later absorb.

Culture

- History

Shiitake cultivation began in China more than a thousand years ago. According to some authors, the first indications of this cultivation can be found in the Longquan County Records book, compiled by He Zhan in 1209. However, other authors maintain that much earlier Wu Sang Kwuang (between 960 and 1127) had documented such activity.

The first book on the cultivation of this mushroom was written in Japan in 1796 by the horticulturist Satō Chūryō. Traditionally the cultivation was only carried out on trunks of the tree known as shii, cutting trunks that already had the fungus or its spores.

Only until 1982 were new methods of cultivation of the fungus developed that opened doors for its commercial cultivation and massification, being today the second most important cultivated fungus after the mushroom (Agaricus bisporus).

Traditional cultivation of shiitake in Pradejón. Taken and edited from: Pradejoniensis.

- Cultivation systems

Cultivation on wood

It is the traditional way of cultivation. In this, pieces of logs of approximately 1 meter long by 10 to 15 cm in diameter are obtained. Originally only the shii tree was used, but currently other species such as oak, beech or eucalyptus are used.

In this trunk, small holes are made in the bark, where the mycelia of the fungus will be placed for its growth.

Culture on synthetic block

This type of cultivation was developed in China in 1986 and is based on the cultivation of the fungus on an artificial substrate, made with plant remains and other materials. The plant materials used to make these blocks may vary depending on their availability and costs.

Among the plant remains used are shavings and sawdust from different trees, such as oak, palo mulato and residues of agricultural crops such as corn, sugar cane, sorghum, oats, among others. Nutritional supplements such as calcium are also added.

Among the most notable advantages of this type of cultivation is its low cost due to the use of waste materials, which allows a faster development of the fungus and reduces the total cultivation time. All these advantages allowed the massification of the cultivation of Lentinula edodes and it is currently carried out in many countries worldwide.

Culture by fermentation in liquid state

A technique that has been explored to obtain greater profitability from the culture is the use of liquid fermentation (FEL). Different studies have been carried out with L. edodes evaluating pH, culture media, carbon sources, temperature, among other variables.

This type of cultivation has been carried out with shiitake for various purposes, such as the production of pellets, exoproteins, bioactive compounds with antioxidant and antifungal properties, among others.

- Importance of the crop

Shiitake is the second mushroom cultivated for food purposes worldwide, only surpassed by the mushroom (Agaricus bisporus). Following the development of the synthetic block culture technique, shiitake production has been steadily growing as cultivation techniques are improved.

The annual growth of the edible mushroom market, in general, has exceeded 4% in recent decades. In Latin America, for example, production went from less than 50 thousand tons in 1995 to more than 65 thousand tons by 2001.

- Main producing and consuming countries

Global shiitake production is largely dominated by East Asian countries, with China, Japan, Taiwan, and Korea contributing more than 98% of the world's total shiitake production. In Latin America, the main producers are Mexico and Chile, followed in third place by Brazil.

In terms of consumers, these four Asian countries, along with Hong Kong, Singapore and Malaysia, are at the top of the list. China is also the country with the highest rate of increase in per capita consumption, doubling consumption in the period between 1990 and 2006.

The mushroom is sold mainly fresh, although a good part of the production is also sold in dehydrated form. The United States is one of the main consumers of shiitake in that last presentation.

References

1. Shiitake. In Wikipedia, Recovered from en.wikipedia.org.
2. Lentinan. In Wikipedia, Recovered from en.wikipedia.org.
3. Lentinula edodes. In Catalog of Fungi and Mushrooms. Fungipedia Mycological Association, Recovered from: fungipedia.org.
4. DS Hibbett, K. Hansen & MJ Donoghue (1998). Phylogeny and biogeography of Lentinula inferred from an expanded rDNA dataset. Micological Research.
5. PG Miles & S.-T. Chang (2004). Mushrooms: Cultivation, Nutritional Value, Medicinal Effect, and Environmental Impact. CRC Press.
6. PS Bisen, RK Baghel, BS Sanodiya, GS Thakur & GB Prasad (2010). Lentinus edodes: a macrofungus with pharmacological activities. Current Medicinal Chemistry.
7. Lentinula edodes. In An eco-sustainable world within i covetous nature. Recovered from: antropocene.it.