Currently, the food and agricultural sectors are concerned about environmental problems caused by raw material waste, and they are looking for strategies to reduce the growing amount of waste disposal. Now, approaches are being explored that could increment and provide value-added products from agricultural waste to contribute to the circular economy and environmental protection. Edible mushrooms have been globally appreciated for their medicinal properties and nutritional value, but during the mushroom production process nearly one-fifth of the mushroom gets wasted. Therefore, improper disposal of mushrooms and untreated residues can cause fungal disease. The residues of edible mushrooms, being rich in sterols, vitamin D2, amino acids, and polysaccharides, among others, makes it underutilized waste. Most of the published literature has primarily focused on the isolation of bioactive components of these edible mushrooms; however, utilization of waste or edible mushrooms themselves, for the production of value-added products, has remained an overlooked area. Waste of edible mushrooms also represents a disposal problem, but they are a rich source of important compounds, owing to their nutritional and functional properties. Researchers have started exploiting edible mushroom by-products/waste for value-added goods with applications in diverse fields. Bioactive compounds obtained from edible mushrooms are being used in media production and skincare formulations. Furthermore, diverse applications from edible mushrooms are also being explored, including the synthesis of biosorbent, biochar, edible films/coating, probiotics, nanoparticles and cosmetic products.
1. Introduction
Mushrooms have long been stated as a gourmet food, especially for its subtle flavor and taste, and they have been regarded as a culinary wonder by humankind. There are 2000 different mushrooms, out of which 25 are usually consumed as food, and only a few are commercially grown
. Mushrooms are also used as nutraceutical foods for their high functional and nutritional value. Moreover, they have gained considerable attention due to their economic importance as well as organoleptic and medicinal properties
. It is not easy to differentiate between medicinal and edible mushrooms, as few medicinal mushrooms are edible, and many common edible mushrooms have therapeutic potential
. The most widely cultivated mushroom is Agaricus bisporus, followed by Flammulina velutipes, Lentinus edodes and Pleurotus spp. The crude protein content of edible mushrooms is usually high, but it varies greatly and is affected by factors such as species and stage of development of the mushroom
. The free amino acid level of mushrooms is usually low, ranging from 7.14 to 12.3 mg g
−1
in dry edible mushrooms, and contributes to the main flavor properties of mushrooms
. The essential amino acid profiles of mushrooms reveal that the proteins are deficient in sulfur-containing amino acids, including methionine and cysteine. However, these edible mushrooms are comparatively rich in threonine and valine. Several vitamins such as folates, niacin and riboflavin are found in abundance in cultivated mushrooms. Mushrooms have a higher vitamin B2 content compared to most vegetables, making them a good vitamin source
. The bioavailable form of folate in mushrooms is folic acid
. Cultivated mushrooms also comprise vitamin B1 and vitamin C in small quantities and traces of vitamin B12
. Edible mushrooms contain a low amount of total soluble sugars, whereas oligosaccharides are found abundantly
. The carbohydrate content of edible mushrooms ranges from 35 to 70% by dry weight and varies from species to species. The fatty acid level ranges from 2 to 8% in mushrooms. Additionally, polyunsaturated fatty acids account for ≥75% of total fatty acids, in contrast to saturated fatty acids, and palmitic acid is the major saturated fatty acid
.
Many by-products (caps, stipes, spent mushroom substrate) are produced during mushroom production, which cause environmental pollution and increase industry management costs
. Spent mushroom substrate (SMS) encompasses extracellular enzymes, fungal mycelia and other substances
. The circular economy concept of industrial ecology is regarded as the leading principle for developing new products by using waste as a raw material
. From economic and environmental perspectives, the waste produced during mushroom production often leads to massive damage to valuable organic constituents and raises severe management complications. Thus, there is a need to exploit mushroom residues to extract valuable compounds that could be used in different industries, such as food, cosmetics, agricultural and textile industries, as depicted in Figure 1. The current review aims to summarize information related to edible mushrooms and discuss the utilization of edible mushrooms and their residues as a valuable good for future industrial applications.
Utilization of edible mushrooms and their residues in novel industrial products.
2. Edible Mushrooms Fortified in Ready-to-Eat and Ready-to-Cook Foods
As the lifestyle of people is changing dramatically (due to liberalization policies, dual incomes, separate living of couples, innovative kitchen applications, media proliferation, etc.), the demand for convenient and health-promoting food is also increasing. Nowadays, people prefer fast and simple cooking methods instead of spending a long time in the kitchen
. Mushroom powder can be used in the food industry, especially in preparing baked goods (bread, biscuits and cakes) and breakfast cereals. The supplementation of mushroom powder in bakery products substantially increases crude fibers, minerals (calcium, copper, magnesium, manganese, potassium, phosphorus, iron and zinc), proteins and vitamins
. These components impart the abilities to fight tumors, lower blood pressure and blood sugar levels, maintain cholesterol levels and improve the immune system to fight against infection
prepared cookies fortified with Calocybe indica mushroom, and the results depicted a decrease in starch hydrolysis and glycemic index. Wheatshiitake noodles enhanced the nutritional profile and reduced the glycemic index of foods
. The different food products developed by using mushrooms are listed in Table 1.
Mushrooms fortified in ready-to-eat (RTE) and ready-to-cook (RTC) foods.
Edible Mushroom Common Name |
Scientific Name |
Food Product |
Edible Mushrooms Common Name |
Scientific Name | Beneficial Effects |
Reference |
Product Used |
Compounds |
Key Findings |
References |
Lingzhi |
Ganoderma lucidum |
60 °C/72 h |
Maximum biosorption against malachite green (40.65 mg g |
−1 |
), safranine T (33.00 mg g |
−1 |
), and methylene (22.37 mg g | −1 | ) |
[ | 89] |
King trumpet |
Pleurotus eryngii |
60 °C/24 h |
Removed 88.38% of NO3− |
[90] |
RT—room temperature; ND—not defined.
Biochar is a stable, carbon-rich solid prepared by thermochemical decomposition or pyrolysis of organic material at high temperatures in an anaerobic environment
. The highly porous structure permits the extraction of humic and fluvic-like substances from biochar
. Furthermore, its molecular structure demonstrates high microbial and chemical stability
, and physical and chemical properties depend on several factors such as the feedstock form, residence time, pyrolysis and furnace temperature
. A wide range of common raw materials are used as the feedstock, including wood chips, organic wastes, plant residues and poultry manure
. The elemental composition of biochar generally includes carbon, nitrogen, hydrogen and, to a lesser extent, K, Ca, Na and Mg
. Biochar is a polar or non-polar material with a high specific surface area and good affinity towards inorganic ions such as phosphate, nitrate and heavy metal ions
. Different studies have reported on biochar production from a variety of edible mushrooms and their spent substrates (Table 6).
Applications of biochar derived from mushrooms and their residues. . The use of NPs is rising, especially in biomedicine and pharmaceuticals, because of their unique physicochemical properties. In the bottom-up approach, biogenic NPs are synthesized, resulting in atoms/compounds that act as the building blocks and possess the ability to self-assemble to form the final product
. Numerous metal oxide/noble metal NPs have been developed using extracts of edible mushrooms, as listed in Table 7.
Mushroom-derived nanoparticles and their applications.
ND—not defined; CFU—colony-forming unit.
The consumption of high dietary fiber food has gained considerable interest owing to its ability to reduce triglycerides and blood cholesterol via the gut microbiome. A diet rich in fibers acts as a substrate for microbes and aids in their proliferation. Thus, microbial digestion products enter the systemic circulation and help in maintaining energy homeostasis
. Pleurotus spp. (Oyster mushroom) comprises soluble fiber compounds, particularly a small amount of glucans (chitin and galactomannans) and non-starch glucans, favoring the proliferation of lactobacilli
. Edible mushrooms are stated to have carbohydrates, which help them to act as prebiotics
. The supplementation of oyster mushroom and probiotics in poultry feed has been reported to show beneficial, synergetic effects on the immune response, performance and serum lipids in broiler chickens
. The blend of prebiotics and probiotics also is beneficial because of the synergistic effect between them
conducted a study to determine the effects of dietary supplements Pleurotus eryngii (as a prebiotic), Eryngii mushroom and Lactobacillus plantarum (as a probiotic), alone as well as in combination, on the innate immune response, growth and protection against Aeromonas hydrophila. The results showed stimulation in growth, immunity and disease resistance against Pangasius bocourti. Table 3 lists studies of different mushrooms and dietary supplementation with probiotics.
Applications of mushrooms as prebiotics.
RT—room temperature; ND—not defined; DPPH-2,2-diphenyl-1-picrylhydrazyl-hydrate; ABTS-2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid).
Carbon dots (CDs), photoluminescent substances with a size of less than 10 nm, can be synthesized by top-down and bottom-up approaches
. The top-down synthetic route involves a complex and synthetic condition; a broad carbon structure is broken down using electro-oxidation, acid-assisted chemical oxidation, and laser ablation
. However, the bottom-up approach, which relies on plants and their by-products instead of the chemicals, is superior compared to the top-down approach. Proteins, carbohydrates, lipids, lignin and cellulose are all abundant in biological materials. Edible mushrooms are relatively inexpensive and contain various chemical constituents such as carbon, oxygen, phosphorus and nitrogen, often depicted as carboxyl and amine groups. The presence of carbohydrates, amino acids, polysaccharides, citric acid, flavonoids, lipids, vitamins and proteins make them ideal for CDs development
. CDs have also shown effectiveness in biomedical applications and energy storage systems, including water purification, pathogen identification, environmental research and heavy metal and additive detection in food (Table 8).
Mushrooms as a carbon source for preparing carbon dots.
Cosmetics are personal care products that are used to cleanse and beautify the skin
. The demand for cosmetics containing natural ingredients is increasing due to their organic, healthier and environmentally friendly characteristics
. Lentinan, carotenoids, ceramides, schizophyllan and ω-3, ω-6 and ω-9 fatty acids as well as resveratrol obtained from macro fungi, especially mushrooms, are now paving their way into cosmetics
. These are reported to treat beauty issues such as fine lines, wrinkles, uneven tone and texture due to the antioxidant and anti-inflammatory traits. There are few studies where edible mushrooms are used in skincare formulations, as compiled in Table 9.
Mushroom-based skincare formulations.
The high concentrations of extracellular enzymes serve as bio-reducing and stabilizing agents for NP synthesis. NPs made from mushrooms are of better quality than those made from bacteria. Metal NPs synthesized using constituents such as enzymes and metabolites secreted by mushroom cells reduce the toxicity of substances
LDL—low-density lipoproteins; HDL—high density lipoproteins.
Nowadays, mushroom processing is the primary solid-state fermentation process in fermentation industries
. At the commercial level, the processing occurs on a substrate made up of lignocellulose materials (corncobs, sawdust, rye, rice straw and wheat) either alone or in combination with supplements to address nutritional deficiencies
. For instance, approximately 5 kg of SMS is produced, a by-product of mushroom harvest and cultivation, from 1 kg of mushrooms
. The SMS comprises a high amount of residual nutrients, which pollutes the atmosphere if improperly discarded as waste
. Thus, further treatment and utilization of SMS are essential. Different types of edible mushrooms and their SMS have been used to produce low-cost growth media for various horticultural plants and microorganisms (Table 4).
Mushrooms and their residue-based media. . Various studies were done to produce biosorbents from edible mushrooms to remove metal ions and dyes from an aqueous solution, as shown in Table 5.
Mushroom-derived biosorbents and their applications. 3. Edible Mushrooms Based Films/Coatings
Edible films/coatings are thin layers applied on the food surface to extend their shelf-life and preserve their features, functionality and properties at a low cost
. The mechanical strength and barrier properties of these edible films provide sufficient strength to withstand stress while handling. These films have a promising application in the agricultural, food and pharmaceutical industries. Mushrooms and their residues have many applications in food industries, but significantly fewer studies have been conducted in regards to edible film/coatings. Polysaccharides extracted/derived from edible mushrooms are extensively used in functional foods, pharmaceuticals and nutraceuticals
. In this regard, Bilbao-Sainzand his colleagues
obtained chitin from mushrooms and transformed it to chitosan.
Moreover, layer-by-layer (LbL) electrostatic deposition is used to prepare edible coatings applied to fruit bars. The application of edible mushroom coatings/films has increased the antioxidant capacity, ascorbic acid content, fungal growth prevention and firmness during storage. Additionally, Du et al.
developed edible films using Flammulina velutipes polysaccharides, which acted as a barrier to oxygen and water vapor, had the lowest elongation at break values and highest tensile strength for future use in food packaging industries. Table 2 lists some edible films and coatings derived from mushrooms.
Mushrooms and their residue-based edible film/coatings.
Polysaccharide |
High tensile strength, barrier property to water vapor and oxygen |
[ | 46 | ] |
Shiitake, Velvet shank |
Lentinula edodes, Flammulina velutipes |
ND—not defined.
Biosorption is a process in which a sorbate reacts with biomass or biomaterial (biosorbent), causing sorbate ions to acclimatize on the biosorbents surface and, as a result, lowering the concentration of sorbate in the solution
. This mechanism has gained significant attention among researchers because of its ability to immobilize heavy metals, which can contaminate the water as they are discharged untreated from electroplating, mining industries and metal processing industries. Various processes that explain the mechanism of how these biosorbents function in removing pollutants are expressed by the natural biomass complex compendium. Several functional groups (amides, amine, carboxyl, carbonyl, hydroxyl, sulfonate, sulfhydryl, phosphate and phenolic groups) are attached to these biosorbents to sequestrate contaminants