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
[1]. 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
[2,3][2][3]. 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
[4]. 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
[5]. 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
[6]. 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
[7]. The bioavailable form of folate in mushrooms is folic acid
[8]. Cultivated mushrooms also comprise vitamin B1 and vitamin C in small quantities and traces of vitamin B12
[7]. Edible mushrooms contain a low amount of total soluble sugars, whereas oligosaccharides are found abundantly
[9]. 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
[10].
Many by-products (caps, stipes, spent mushroom substrate) are produced during mushroom production, which cause environmental pollution and increase industry management costs
[11]. Spent mushroom substrate (SMS) encompasses extracellular enzymes, fungal mycelia and other substances
[12]. The circular economy concept of industrial ecology is regarded as the leading principle for developing new products by using waste as a raw material
[13]. 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 . 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.
Figure 1. 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
[14]. 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
[15]. 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
[16]. Rathore et al.
[17] 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
[18]. 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 |
Beneficial Effects |
Reference |
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.
[46] 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. lists some edible films and coatings derived from mushrooms.
Table 2. Mushrooms and their residue-based edible film/coatings.
| Edible Mushrooms Common Name |
Scientific Name |
Product Used |
Compounds |
Key Findings |
References |
| Milky white |
Calocybe indica |
Cookies |
Increase in protein, fiber, minerals and β-glucan, phenolic, flavonoids and antioxidants; decrease in starch, reduction in glycemic index |
[17] |
| White button |
Agaricus bisporus |
Fruit bars |
Chitosan |
Increased antioxidant capacity, ascorbic acid content, fungal growth prevention and firmness |
[45] |
| ] |
| Shiitake, Velvet shank |
Lentinula edodes, Flammulina velutipes |
ND |
Insoluble dietary fibers |
Highest tensile strength and an effective barrier to water vapor |
[48] |
| Indian oyster |
Pleurotus pulmonarius |
ND |
Flour |
Significant barrier properties and mechanical strength |
[49] |