Auricularia (boltworm, in Asia it is called Yung ngo, Kikurage, Mokurage, in English wood ear mushroom) belongs to the genus Auricularia, which has 10-15 species that have been recognized worldwide. Auricularia is thus a cosmopolitan mushroom. This genus is made up of saprophytic fungi, i.e. they grow on trees, which they use as a source of nutrients but at the same time do not kill. Most often it is found on deciduous trees on which it grows in clusters (elderberry, ash, maple, oak). All species have a typical gelatinous consistency and shape similar to the human ear. This is also the origin of the Czech name boltcovitka. The colour ranges from orange-brown to various shades of brown, some species may be black.

The best known Auricularia are undoubtedly Auricularia-auricula-judae (Judas ear) and Auricularia polytricha (hairy boltcovitka). The fungi are very similar in appearance and composition. Auricularia auricula-judae gets its nickname from the fact that it is most commonly found on the elder tree on which, according to historical records, the biblical Judas committed suicide.

Auricularia is a very common ingredient in Asian dishes. While it does not have the typical mushroom aroma or taste, its unique consistency adds another dimension to the dish. In addition to its use in gastronomy, Auricularia is an integral part of Asian traditional medicine, including Chinese medicine. Indeed, Auricularia has a long history of use and targeted cultivation, as it has been in great demand. There are surviving documents from 600 AD that describe the cultivation of Auricularia. During the Ming Dynasty (1368-1644), Li Shih Chen, who authored Pen Tsao Kang Mu (Classical Chinese Materia Medica), wrote similarly about Auricularia.

However,Auricularia also has a history in Europe, where it has also been used in the context of "herbalism" since about the 18th century. According to the Doctrine of Signatures, plants that have a similar shape to a part of the human body are also suitable for healing it (Böhme, 1651).

Auricularia was scientifically described and classified in 1789 by Jean Baptiste Francois Pierre Bulliard (1742-1793), naming it Tremella auricula-judae. This name, and the classification as a jellyfish, was not changed until 1897 by the Austrian botanist Wettstein. He reclassified Auricularia as Auriculariaceae.

Composition of Auricularia

Auricularia is mostly composed of water, like other fungi. In 100 grams of the natural mushroom there are 239 calories, 9.4 grams of dry matter, 8.1 grams of protein, 1.5 grams of fat and the remaining amount is made up of polysaccharides, i.e. about 80 grams, of which about 7 grams is coarse non-absorbable fibre.

Carbohydrate components of Auricularia

It is clear from the composition that polysaccharides are the most important component of the mushroom. The cell wall of fungi is mainly made up of polysaccharides, which serve as structural components. These include chitin, cellulose, but also polysaccharides such as beta glucans. Beta glucans are branched polysaccharides with many biological effects that depend on their composition. They can form complexes together with proteins and peptides. Auricularia contains mainly 1→3 beta-D glucans in main chains with 1→6 branching. These have the greatest biological potential. It is the 3D structure of β-(1→3)-glucan that makes it capable of interacting with the immune system and giving it signals that increase the activity of immune cells. Glucans are not the only polysaccharides in Auricularia, it also contains other polysaccharides, such as acidic heteropolysaccharides, i.e. composed of various monosaccharides, xylose, mannose, glucose and glucuronic acid. Monosaccharides are also present in smaller amounts, mainly glucose, rhamnose, mannose, arabinose and galactose.

Amino acids and enzymes

Amino acids, which are the building blocks of proteins, can be found in Auricularia. It contains both non-essential and essential amino acids, which are the ones that the body cannot make itself and depends on food for their supply. The highest concentration is glutamic acid, which is more than 5 g per 100 g, then arginine, aspartamic acid, serine, leucine..., cysteine is only 0.3 g per 100 g.

Since Auricularia is a fungus that gets its nutrients from the tree it grows on, it must have an enzymatic apparatus to be able to break down the wood cells. It therefore has enzymes that can break down cellulose, lignin, but also simple carbohydrates, i.e. Auricularia also has enzymes that have a fibrinolytic effect, i.e. they break down blood clots, thrombi. In addition, enzymes that act as powerful antioxidants, reducing oxidative stress. These include, for example, superoxide dismutase and glutathione peroxidase.

Auricularia also contains proteins that are capable of boosting immune system activity similar to polysaccharides.

Fatty acids

Surprisingly enough, mushrooms also contain fats, fatty acids. They have a very suitable composition. In fact, most of them are unsaturated fatty acids, which are very beneficial for our bodies. They are also omega 3 and 6 fatty acids, essential fatty acids that the body cannot make. Oleic and linoleic acid, along with saturated palmitic acid, have the highest concentration in Auricularia. The total amount of fat in Auricularia is 0.13 %.

Ceramides and cerebrosides, which are compounds of fats with sugars, have also been isolated from Auricularia.

Vitamins and minerals

Auricularia is also a source of vitamins and minerals. It contains mainly B vitamins and the important sterol ergosterol, i.e. vitamin D. The mineral and trace elements are represented by the following: calcium, sodium, potassium, magnesium, iron, cobalt, selenium, zinc, copper, etc. (Concentrations of Са> К > Nа > Мg> Fe> Zn >Co/Ni/Cu/Mn.)

Other constituents of Auricularia

The list of ingredients of Auricularia is much more extensive. Important components are polyphenols (e.g. gallic and vanillic acid), triterpenes and flavonoids, all of which are antioxidant and have many other effects.

The sterols (ergosterol) already mentioned include cerevisterol and hydroxycerevisterol.

Like Enoki and other mushrooms, Auricularia has its own "toxin". This is auritoxin, which belongs to the group of heteromannoglucans. However, the dose that could endanger humans is extremely high. In mice, it is necessary to administer a dose of 454 mg/kg of its weight by mouth to cause poisoning and death. This means that an adult 70 kg human would have to eat more than 31 kg of mushrooms in one sitting. Auritoxin inhibits blood clotting, thus causing bleeding, as well as drowsiness, drowsiness, tremors and tearing.