Nutritional advantages of J. Future Foods Edible fungi and the development status of industrialization of protein meat analogues

Introduction

Edible fungi are a class of large fungi that can be eaten by people, and their forms are diverse and have high edible and medicinal value
.
Since the 90s of the 20th century, China's edible fungus industry has begun to develop rapidly, and the proportion of edible fungus production in the world has increased year by year, and now it has become the world's largest producer and exporter of edible fungi
.

In order to increase the added production value of edible fungus products and produce higher economic benefits, in addition to the most common edible functions, edible fungi also have considerable processing and development value
in other aspects.
For example, many edible fungi have excellent lignocellulose degradation and heavy metal enrichment capabilities, and can also be used to make mycelium of mycelium composites with good mechanical and adhesion properties, which can be used to replace certain plastic packaging and building materials
.
It can be seen that edible fungi can play an important role
in agricultural and industrial waste treatment and resource utilization, as well as energy conservation and environmental protection.
Nowadays, edible fungi are increasingly used as an alternative source of animal protein, and with the development of food 3D printing technology, it may be possible to make edible fungus protein meat analogues perfectly mimic the taste and flavor of animal meat, which is expected to further improve the nutritional quality
of edible fungus foods.
In addition, people's income and consumption levels continue to increase, and the diet structure is becoming more and more diversified, it is foreseeable that edible fungi in meat replacement foods, as well as the future food industry will have good development prospects
.
What's more, compared to animal husbandry and other cultivations, mushrooms are grown on a substrate based on agricultural and forestry by-products such as straw, wheat straw, wood chips and livestock manure, which reduces raw material costs and turns low-value by-products into treasure
.
At the same time, edible fungus cultivation does not occupy a lot of land, produces less agricultural waste, and does not produce waste gas and wastewater, which can reduce the pressure on the
environment and resources.
Therefore, the future development of edible fungus industry has broad
prospects.

Edible fungi are rich in nutrients

The protein content of edible fungi is very high, containing an average of 19% ~ 35% of the protein with dry mass, which is much higher than ordinary vegetables, comparable to or even higher than pork, beef and other livestock products, and close to the protein content
of soybeans 。 In addition, edible fungi have a full range of amino acids, including 8 essential amino acids required by humans and histidine required by infants, and the amino acid pattern of edible fungi (that is, the content and composition ratio of essential amino acids) is mostly close to the ideal mode, and some species are ideal, such as bisporus mushrooms, enoki mushrooms, matsutake mushrooms, etc.
; In addition, the digestibility range of edible fungus protein is usually 72%~83% (soybean 74%, rice 82%, meat 92%~94%, egg 98%, dairy 97%~98%), making edible fungi a better source
of protein food.
The protein content of 8 common edible fungi is shown in Table 1, and the amino acid content of 8 common edible fungi is shown
in Table 2.

Edible fungi are low in fat, cholesterol-free, rich in unsaturated fatty acids, mainly in the form of linoleic acid, and are a healthy source of
essential fatty acids.
Carbohydrates are the richest components of edible fungi, usually accounting for about 60% of dry mass, and the nutritional sugar content is about 2%~10%.

Edible fungi are a good source of minerals, mainly containing macronutrients needed by the body, such as potassium, phosphorus, sodium, calcium and magnesium, as well as essential trace elements such as copper, zinc, iron, molybdenum and selenium
.
Among them, the potassium content is very high
.
Edible mushrooms are also a good source of vitamins, especially B vitamins
.
Mushrooms are rich in thiamine (B1), riboflavin (B2), niacin (B3), and pantothenic acid (B5)
of B vitamins.
UV exposure from sunlight can boost vitamin D production
in mushrooms.
Edible fungi also contain carotenoids (vitamin A source substances) and small amounts of vitamin C, but are deficient in vitamins A and E
.
Edible fungi are also rich in dietary fiber
.
Among common mushrooms, enoki mushrooms had the highest dietary fiber content, at 137.
2 g/kg
.

Table 1 Protein content of 8 common edible fungi

Table 2 Amino acid content of 8 common edible fungi

A large number of active ingredients in edible fungi that are beneficial to health

In addition to the above common nutrients, there are many health-beneficial active ingredients in edible fungi that are worth noting, such as functional polysaccharides (different from nutritional polysaccharides such as starch and glycogen), terpenes, phenolic compounds, adenosine, etc
.

Functional polysaccharides in edible fungi have a variety of health benefits, such as antitumor, immunomodulatory and anti-inflammatory activities, anti-diabetic, and improved functional constipation
.
At present, many edible fungus polysaccharides have been researched and developed, such as immunoactive lentinan, hairy fungus polysaccharide, schizophyllum polysaccharide and Ganoderma lucidum polysaccharide
.
Among them, the most common simple sugars in edible fungi are glucose, galactose, fructose, xylose, mannose, fucosse, rhamnose, arabinose, alginate and mannitol
.
In addition, the prebiotics in edible fungi promote the peristalsis of the human intestine without digestion
.
At the same time, some polysaccharides in the prebiotics of edible fungi can be degraded by the intestinal flora and absorbed as an energy source for certain specific flora, which has a stimulating effect
on their reproduction and the production of beneficial compounds.
Therefore, edible fungus prebiotics can promote health
by regulating the gut microbiota as well as gastrointestinal function.

Mushroom edible fungi contain a variety of secondary metabolites, such as terpenoids and phenolic compounds, which have various effects
such as antitumor, antibacterial, anti-inflammatory and immunomodulatory.
In functional foods and cosmetics, they have proven to be excellent antioxidants
.
In addition, studies have shown the potential use
of edible fungus terpenoids in liver-protective drugs.

Adenosine is an active substance
with nucleosides and purines as its basic structure.
For example, reishi contains a variety of adenosine derivatives, all of which have strong pharmacological activity and have many benefits
especially for the cardiovascular system.
Another example is adenosine in shiitake mushrooms, which has the effect of regulating metabolism, its properties of inhibiting cell growth and promoting cell differentiation can be used in antitumor, treatment of psoriasis, as well as coronary heart disease and angina
.

Consumption of fewer allergens in mushrooms and their removal strategies

Compared to common allergenic foods such as soy, wheat, and milk, allergies to edible fungi, especially those that ingest mushrooms, are still relatively rare
.
In general, edible fungus allergies can be divided into two categories: "inhalation spore allergy" and "mushroom allergy ingestion"
.

Since food allergens are mainly proteins and can be affected by physical, chemical, and biological factors, the allergenicity
of proteins can be reduced or removed by certain processing means.
Desensitization methods commonly used in the food industry include heat treatment, acid-base treatment, ultra-high pressure treatment, radiation, ultrasound, high-voltage pulsed electric field and biological enzymatic digestion
.
Traditional physical or chemical desensitization methods have different degrees of limitations, therefore, in recent years, the use of biological enzyme technology to remove food antigens has received great attention, mainly based on the following principles: by using the corresponding protease hydrolysis of allergen molecules to reduce their molecular weight and make their structure simple, masking or eliminating antigen determinants, thereby reducing or eliminating their immunogenicity
.

Biological enzyme methods have also been applied to desensitization
of edible fungi.
Edible fungi contain polyphenol oxidase (PPO), formed by a 67 kDa tautomer that can be broken down into two forms by trypsin, 58 kDa and 43 kDa, so its immune properties are completely destroyed
.
Bacillus subtilis protease can destroy the structure of the determining group, making it unsensitized without changing the functional properties of
the enzyme.

Bioenzymatic digestion is an effective way
to remove food allergens.
The mild reaction conditions of enzymatic digestion and the fact that it does not consume as much energy as traditional desensitization methods, as well as the high efficiency and controllability of enzymatic digestion, make it possible
for bioenzymatic digestion to be used in the industrial production of hypoallergenic foods.
Of course, the enzymatic effects of biological enzymatic digestion are influenced by many factors, such as the type of enzyme, the condition of the enzyme, and the degree of
enzymatic digestion.
In the enzymatic process, there are no clear conclusions
about the enzyme type, enzymatic mode, choice of enzymatic degree, and the mechanism of sensitization and flavor of each product.

Edible mushrooms with rich flavor substances

The taste of edible fungi is related
to the free amino acids they contain.
The different taste presentation characteristics of amino acids themselves can present different tastes, such as fresh, sweet and bitter
.
Edible fungi have a high content of glutamic acid and aspartic acid, and in the presence of sodium salt, the presence of glutamic acid and aspartic acid produces the umami characteristic of mushrooms; Serine and alanine are the main components of the sweet taste of edible fungi; The bitter components of edible fungi are mainly histidine, isoleucine, leucine and phenylalanine; Some amino acids have both bitter and sweet tastes, such as arginine and proline; Cysteine, on the other hand, has a slight sulfur taste
.
In addition, the unique umami taste of edible mushrooms is also related to
nucleotides.

The sensory components that form the smell of edible mushrooms may vary from species to species, for example, some different species of mushrooms have their representative and distinctive odor volatiles
.
However, it is generally believed that a series of alcohols and carbonyl compounds rich in eight carbons are the main volatiles that form the odor of edible fungi, mainly including 1-octen-3-ol, 3-octanol, 2-octen-1-ol, 1-octanol, t-2-octenal, 1-octen-3-one, 2,4-octadienal, 3-octanone and 2-ethyl-1-hexanol
.
And 1-octen-3-ol is one of
the more representative sources of mushroom odor in most fresh mushrooms.

Nutritional advantages of edible fungus protein meat analogues are similar to animal and plant protein meat

Edible fungi have unique nutritional qualities (see Table 3 for phytonutrient data on mushrooms, meat, and commonly used plant components used to make meat analogues).

The advantages of using edible fungi as "plant-based meat analogues" over conventional meat and legumes and wheat used to make plant-based protein meat analogues are as follows
.

The protein content of edible fungi is higher than that of wheat, comparable or even higher than that of livestock and poultry products such as pork and beef, and close to the protein content
of soybeans and peas.
Edible mushrooms contain a complete range of amino acids, each of which is composed in an ideal
proportion.
Cereals are lower in lysine compared to animal proteins, and legumes lack sulfur-containing amino acids such as methionine and cysteine
.
Edible fungi are low in fat, cholesterol-free, and contain a high percentage of unsaturated fatty acids
that the body needs.
In contrast, animal fats contain a certain amount of unsaturated fatty acids, but the content of saturated fatty acids is higher, which can lead to hyperlipidemia, coronary heart disease, and atherosclerosis
if consumed in excess.
Therefore, using edible fungi as "meat" can meet the body's demand for unsaturated fatty acids and avoid the harm
caused by excessive intake of saturated fatty acids.
Animal meat products, eggs, and milk are great sources of B vitamins, and edible fungi are also rich in B vitamins, especially niacin (VB3), which is usually higher than legumes and animal meat
.
Allergies to edible fungi are relatively rare
compared to soybeans.
Edible mushrooms are rich in dietary fiber, and their fiber structure also makes the taste closer to real meat
.

It is worth mentioning that modern biomedical studies have shown that if the amount of essential amino acids is missing from the amino acid part obtained by the human body, then the overall utilization of
protein will be greatly reduced.
The protein content and amino acid composition of different types of mushrooms in China are different, and the amino acid composition ratio of a single type generally cannot meet the amino acid ratio
required by the human body.
If the difference in the essential amino acid mass fraction and amino acid ratio coefficient of each mushroom or other variety of foods is rationally used in the diet, the protein will be more effectively bioavailable in the body, and the utilization rate of mushroom protein will be greatly improved, thereby greatly improving the quality and nutritional value
of mushroom protein.
Protein quality and spectral proximity of the WHO/FAO reference model have been found to be greatly improved
by mixing equal amounts of matsutake and shiitake mushrooms, delicious porcini and enoki mushrooms, white mushrooms and bisporus mushrooms, respectively.

Table 3 Nutritional data on mushrooms, meat and common plant components used to make meat analogues

Conclusion

The nutritional characteristics of edible fungi were analyzed from the four perspectives of nutrients, active ingredients, allergens and flavor substances, and compared with animal meat and plant meat analogues, their unique nutritional advantages were summarized, and finally the industrialization and development of edible fungus protein meat analogues at home and abroad were analyzed
.
The authors conclude that edible mushrooms are well suited for meat analogues and are expected to become another major ingredient
after legumes, grains, and other plant-based meat ingredients.
In the future, it is believed that more and more brands and enterprises will see the advantages of edible fungus protein meat analogues, and increase the research and development and promotion of edible fungus protein meat analogues, and edible fungi are expected to become another main raw material in addition to beans and other plant-based meat analogue raw
materials.