Nutritional and post-harvest quality preservation of mushrooms: A review

Abstract

The purpose of this review is to provide information on the nutritional value of mushrooms and how to preserve that quality after harvest. Mushrooms contain a variety of vitamins and minerals, including B, C, and D, and are low in calories and high in fiber (iron, phosphorus, copper, potassium and selenium). Consuming mushrooms may help prevent or treat serious health conditions like cancer, diabetes, and cardiac diseases. Mushrooms are high in protein and low in cholesterol. After being harvested, mushrooms' quality continues to deteriorate, showing signs of discoloration, moisture loss, texture changes, an increase in the number of microorganisms, and nutrient and flavor loss. Maintaining postharvest quality and extending the shelf life of mushrooms requires postharvest preservation techniques, such as physical, chemical, and thermal processes. To preserve its quality during post-harvest, there are a number of steps that must be taken, including precooling and refrigeration, washing with hydrogen peroxide, citric acid, sodium erythorbate, and calcium chloride, edible coating with Aloe vera, apple peel powder, carboxymethyl cellulose, lecithin, and tartaric acid, modified atmosphere packages, and use of high-quality packaging materials like polypropylene. Mushrooms can be kept fresher for longer by steeping and canning. Researchers, farmers, and academics interested in mushroom cultivation and its product diversification could benefit from this review.

Mushrooms; Post-harvest loss; Preservation; Quality degradation; Shelf life.

1. Introduction

Mushrooms are high-quality food products that can assist underprivileged populations in developing countries in overcoming food and nutritional issues. This paper discusses mushroom quality, postharvest preservation, commercial growing opportunities, and ways to overcome limitations and future prospects for smallholder farming groups. Mushrooms are achlorophyllous, macroscopic basidiomycetous, or ascomycetous fungus species with spores embedded in fleshy fruiting bodies that are valued as food in the marketplace. Mushrooms can be both edible and poisonous, with the latter being known as "toad stool" (Beach and Strom, 1989). Mushrooms belong to the fungi kingdom and are saprophytic organisms that feed on dead organic waste. Agaricus bisporus, followed by Lentinus edodes, Pleurotus species, and Flammulina velutipes (Valverde et al., 2015). Due to their delicious flavor, enticing aroma, and nutritious value (high in protein, fiber, vitamins, and minerals, low/no in calories and cholesterol), edible mushrooms are a favorite food in many nations (Thatoi and Singdevsachan, 2014). According to Magar et al. (2021), the most commonly cultivated mushrooms in Nepal are Oyster mushrooms (Pleurotus sajor-caju, P. florida, P. ostreatus, P. eryngii), paddy straw mushrooms (Volvariella esculanta, V. diplasia, V. volvacea), milky mushrooms (Calocybe indica), white button mushrooms (Agaricus bisporus), shiitake mushrooms (Lentinula edodes), and red mushrooms (Ganoderma lucidum) whereas Yarsagumba (Cordyceps sinesis), Guchhi chyau (Morchella esculenta), and Nagrum (Grifolia frondosa) are some of the wild edible mushrooms found in Nepal. After eating wild mushrooms that contain toxins, one develops mushroom toxicity, or mushroom poisoning. Numerous accidents have been reported in Europe, North America, and Asia (Chen et al., 2014). About 1291 different species of mushrooms have been identified thus far, of which 159 are edible, 100 are allegedly poisonous, and 74 are said to have medicinal benefits (Khatiwada et al., 2020/21). There are currently more than 1000 different types of mushrooms known to exist in Nepal, 15% of which are edible, 7% of which have medicinal uses, 10% of which are poisonous, and the remainder are still being researched (Magar et al., 2021). In Nepal, there are options for growing mushrooms during the summer and winter. As an illustrative example, farmers typically grow oyster, white button, and shiitake mushrooms in the winter while milky mushrooms and paddy straw mushrooms are more common in the summer (Magar et al., 2021). The most common varieties of mushrooms available in Nepalese markets are white button and oyster mushrooms because they are able to flourish in a variety of climatic conditions (Parajuli, 2014; Yang et al., 2013). Since they contain soluble protein and fiber, both of which are essential for human health, mushrooms offer therapeutic and pharmacological benefits in addition to satisfying human food needs (Munshi et al., 2010). White button mushrooms may be harvested at any time of the year, but 20–28 °C is advised for vegetative growth and 12–18 °C for reproductive development. They should also be harvested when the caps are 2.5–4 cm in diameter, which is known as the button stage (Soni, 2021).

All horticulture goods, including fruits, vegetables, and mushrooms, continue to breathe, lose water, and soften their cells during the post-harvest period (Imahori, 2014). After harvest, this has a big effect on the quality of the product. However, color is the most crucial factor because it is the first thing people notice, and discoloration lessens its appeal to consumers. Other important criteria include texture, cleanliness, maturity, and flush number (Weijn et al., 2011). Environmental control units produce mushrooms throughout the year, but during the winter, seasonal farmers come on the scene, and the excess supply at the local market lowers profit because of price drops, spoiling due to the excess supply, and quality degradation (Wakchaure, 2011). Mushrooms typically have a very short shelf life due to their rapid respiratory rate, high water content, and lack of cuticular structure (Reyes et al., 2021). It takes 1–3 days at room temperature and 8–10 days when refrigerated, which restricts its ability to be shipped and sold (Qin et al., 2015). You can alter its nutritional value, disease susceptibility, flavor, and appearance by preserving it for a long time (Zhang et al., 2018). After being harvested, mushrooms will wilt and lose weight until they are unfit for consumption if they lose more than 5%–10% of their fresh weight (Singh et al., 2010). For instance, significant post-harvest measures are required for blackening, browning, veil-opening, weight loss, and microbiological deterioration (Rai and Arumuganathan, 2008). As a result, there are serious problems with product palatability, long-distance shipping, and marketing expansion.

The purpose of this review is to provide details on the nutritional value of mushrooms and how to preserve that quality after harvest.

2. Nutritional quality of mushrooms

The nutrients found in edible mushrooms include sugars (sucrose, xylose, rhamnose, mannose, and fructose), amino acids (glutamic, aspartic, glutamate, methionine, and cysteine), proteins, fatty acids (linoleic, stearic, palmitic, adrenic, and nervonic acid), vitamins (folate, riboflavin, ascorbic acid niacin, thiamine, ergocalciferol, and cyanocobalamin) mineral contents (Ca, Mg, K, P, Na, Fe, Cu, Zn, Cd, and Mo) and phenolic compounds (gallic acid, caffeic acid, protocatechuic acid, p-coumaric acid, p-hydroxybenzoic acid and pyrogallol) (Das and Prakash, 2022).

Because they are low in calories and fat and high in dietary fiber, mushrooms are regarded as healthy foods. They also contain significant amounts of vitamins (B1, B2, B12, C, D, and E) and trace minerals like zinc and selenium, which are important for good nutrition. Their high protein content (20–30% dry matter) includes the majority of the essential amino acids. Additionally, mushrooms are a good source of biologically active substances like beta-glucans, which may have therapeutic value. People of all ages worldwide consume mushrooms, which are becoming more and more common. Because of their high nutritional value, particularly in terms of protein, dietary fiber, vitamins, and minerals, mushrooms are regarded as a superfood. In addition, bioactive substances like ergosterol, -glucans, lentinan, and peroxidase are known to be present in mushrooms and have health advantages. According to Passari and Sánchez (2020), mushrooms have antiviral, anticancer, anti-cancer, and antihypertensive properties.

Increasing crop yield and quality by nutritionally enhancing mushroom farming is a cost-effective agronomic strategy; however, its global adoption is constrained by practical or financial issues.

2.1. Carbohydrates

Mushrooms have been used clinically as antioxidants, immunomodulators, and antitumor agents because they contain polysaccharides with significant biological activities (Kaur, 2020). According to Samsudin and Abdullah (2019), mushrooms contain both digestible and non-digestible carbohydrates, including mannans, chitin, and beta-glucan. Examples of these include trehalose, mannitol, glycogen, and glucose. Pleurotus mushroom, an oyster mushroom, is unquestionably a good source of carbs and dietary fiber. The most prevalent polysaccharides in mushrooms are chitin and glucans, and other hemicelluloses (such as mannans, xylans, and galactans) (Alam et al., 2008). The content of polysaccharides and dietary fiber varies from species to species and ranges from 36 to 60 g/100 g dry fruit bodies and 10–31 g/100 g dry weight, respectively (Khan et al., 2008).

Coprinus atramentarius contains 24% carbohydrate by dry weight, according to Florezak et al. (2004). The most prevalent free sugar is mannitol, also known as mushroom sugar, which makes up nearly 80% of all sugars (Tseng and Mau, 1999). According to Mc-Connell and (1947), a fresh mushroom has 0.91% hemicellose, 0.9% mannitol, 0.28% reducing sugar, and 0.59% glycogen. The most prevalent sugars in Agaricus bisporus, according to Crisan and Sands (1978), are raffinose, sucrose, glucose, fructose, and xylose (Litchfield, 1964).

2.2. Proteins

A superior source of protein is provided by mushrooms. It contains 20–35% more protein than fruits and vegetables on a dry weight basis, and the protein are of higher quality. Lysine and tryptophan, two essential amino acids that are deficient in cereals, are abundant in this food (Table 1). It is also referred to as "white veggies" or "boneless vegetarian meat." The majority of the dry matter in mushrooms is protein. The amount of protein in mushrooms varies depending on the substrate, pileus size, time of year, and type of mushroom (Chang and Buswell, 1996; Aletor, 1995). Haddad and Hayes (1979) found that the protein concentrations in A. bisporus mycelium ranged from 32 to 42% dry weight. Samajipati (1978) found 30.16, 28.16, 34.7, and 29.16% protein, respectively, in dried mycelium of A. campestris, A. arvensis, M. esculenta, and M. deliciosa. When it comes to crude protein content, mushrooms are only second to animal products, but they are still far superior to most other foods, such as milk (Chang, 1980). Because they contain crucial amino acids found in animal proteins, mushrooms are advantageous to vegetarians, according to Verma et al. (1987). According to Rai and Saxena (1989), after being stored, mushrooms lost some of their protein content. In general, mushrooms contain more protein than the majority of other vegetables (Källman, 1991).

Table 1.

Essential amino acid in 100 g dry mushrooms.

Essential Amino Acid	Agaricus bisporus	Agaricus edodes	Pleurotusflorida	Pleurotusostreatus	Pleurotussajorcaju	Volvereillavolvacea
Leucine	7.5	7.9	7.5	6.8	7	4.5
Isoleucine	4.5	4.9	5.2	4.2	4.4	3.4
Valine	2.5	3.7	6.9	5.1	5.3	5.4
Tryptophan	2	-	1.1	1.3	1.2	1.5
Lysine	9.1	3.9	9.9	4.5	5.7	7.1
Threonine	5.5	5.9	6.1	4.6	5	3.5
Phenylalanine	4.2	5.9	3.5	3.7	5	2.6
Methionine	0.9	1.9	3	1.5	1.8	1.1
Histidine	2.7	1.9	2.8	1.7	2.2	3.8
Total essential	38.9	36	46	33.4	37.6	32.9

(Naeem et al., 2020)

2.3. Fats

A good source of essential fatty acids is mushrooms. Mushrooms are a low-calorie food that has no cholesterol and a low fat content (4–6%). Hughes (1962) found that mushrooms contain significant amounts of the crucial fatty acid linolenic acid. The total fat content of A. bisporus was calculated to be 1.66 to 2.2/100 g on a dry weight basis (Maggioni et al., 1968). According to Yilmaz et al. (2006) and Pedneault et al. (2006), unsaturated fatty acids make up the majority of the fat fraction in mushrooms. The primary source of lipids is mushrooms, and the essential fatty acids linoleic, oleic, and linolenic are frequently found in their lipid profiles. Mushrooms contain more polyunsaturated fatty acids per serving than other plant- and animal-based foods (PUFA). In 100 g of total fatty acids, mushrooms contain varying amounts of these fatty acids, with linoleic acid ranging from 0.0 to 81.1%, oleic acid from 1.0 to 60.3%, and linolenic acid from 0.0 to 28.8% (Sande et al., 2019).

2.4. Vitamins

The vitamin B found in mushrooms is a particularly good source of vitamins (Chang and Buswell, 1996; Mattila et al., 2000). On the vitamin content of mushrooms and vegetables, detailed information was provided by Esselen and Fellers (1946) and Litchfield (1964). In addition to being low in vitamins A, D, and E, mushrooms also only have trace amounts of vitamin C (Mattila et al., 2001; Sapers et al., 1999; Anderson and Fellers, 1942). In addition to promoting healthy skin, vitamin B also helps to ward off heart disease. Red blood cell maintenance and healthy nerve function are two other benefits of vitamins B2 and B3. The immune system is bolstered and cell division is essential for vitamin D, which is associated with healthy teeth and bones. The only non-animal source of this vitamin is mushrooms, which is extremely uncommon and, of course, advantageous to vegetarians. Mushrooms naturally contain vitamin D, but sunlight exposure increases its levels (Table 2).

Table 2.

Major vitamins and minerals (on dry basis).

Major vitamin and minerals	Daily requirement (mg)	Mushrooms content (mg)
Thiamine (B- 1)	1.4	4.8–8.9
Riboflavin (B-2)	1.5	3.7–4.7
Niacin	18.2	42–108
Phosphorus	450	708–1348
Iron	9	15–17
Calcium	450	33–199
Copper	2	12–22

Source: Crisan and Sands (1978).

2.5. Minerals

Easily assimilated mineral elements are highly concentrated in mushroom fruiting bodies (Table 2). Major mineral components of mushrooms include K, P, Na, Ca, Mg, and trace elements like Cu, Zn, Fe, Mo, and Cd (Bano, 1981). According to Mattila et al. (2000), potassium alone accounts for 45% of the ash in mushrooms, while K, P, Na, and Mg account for 56–70% of the total ash. Mushrooms have been found to contain heavy metals like cadmium, lead, arsenic, copper, nickel, silver, chromium, and mercury (Kalač and Svoboda, 2000; Svoboda et al., 2000; Vetter, 2004). According to the species, age, and fruiting body diameter, different mineral proportions exist. It also depends on the kind of substrate (Demirbaş, 2001). It has been found that wild edible mushrooms contain more minerals than cultivated ones (Mattila et al., 2001; Aletor, 1995; Rudawska and Leski, 2005). Selenium is abundant in some types of edible mushrooms. Selenium has been shown to reduce the risk of developing prostate cancer, suggesting that it may have anti-cancer properties. Mushrooms are rich in potassium, a crucial mineral that regulates blood pressure and keeps cells healthy.

2.6. Fiber

In terms of high-quality fiber, mushrooms excel. It assists in lowering cholesterol. Aletor (1995), Sanme et al. (2003), and Manzi et al. (2004) conducted studies on the fiber content of various mushrooms. Fresh mushrooms contain soluble as well as insoluble fiber. Most soluble fiber is composed of beta-glucans and chitosans, which are elements of cell walls. Cardiovascular disease can be prevented and managed with the help of soluble fiber, which has been shown to lower total and LDL cholesterol levels. Additionally, it helps keep blood sugar levels under control.

3. Functional mushrooms

In addition to their nutritional value, functional mushrooms have health benefits. Depending on the type of mushroom used, different benefits apply. However, the two most popular varieties of functional mushrooms are adaptogenic and medicinal.

Molecules in medicinal mushrooms have unique health benefits. According to Durgo et al. (2013), many of these mushrooms have cytotoxic and antioxidative properties, which may allow them to both slow the harmful process of oxidation and eliminate harmful cells. While some types of mushrooms may have therapeutic benefits, it's important to remember that they are dietary supplements. In other words, they are regulated as food rather than drugs.

Medicinal mushrooms have been found to have a wide range of pharmacological effects, including anti-inflammatory, immunomodulatory, antimicrobial, antidiabetic, antioxidant, hepatoprotective, cytotoxic, anticancer, antioxidant, antiallergic, antihyperlipidemic, and prebiotic properties (Elkhateeb, 2020; Guggenheim et al., 2014; Spelman et al., 2017; Jeitler et al., 2020).

Adaptogens, which are substances that help the body adapt to and fight off chemical, biological, and physical stress, are substances that are present in adaptogenic mushrooms. Rather than reducing the inflammation causing a headache or relieving a cough, adaptogens help our bodies' stress response mechanisms to work properly. We should consult a doctor before adding any kind of functional mushroom to our diet because improper use could have unfavorable side effects like nausea and sleepiness.

Health advantages of adaptogenic mushrooms include improved immune function, increased energy, and hormone balancing.

3.1. Types of functional mushrooms

3.1.1. Reishi (Ganoderma lucidum)

The reishi mushroom, also referred to as the "mushroom of immortality," is well known for its capacity to strengthen the body's defenses and increase stamina while having anticancer properties (Yuen and Gohel, 2005). Since they grow in trees, local foragers can find these mushrooms there or by hiking into the forest. The two main chemical components of G. lucidum that are pharmacologically active are terpenoids and polysaccharides. Triterpenoids have also been shown to have anti-tumor and anti-engiogenic activity, platelet aggregation inhibition, complement inhibition, hepatoprotective, anti-hypertensive, hypocholesterolemic, and anti-histaminic properties. It has been demonstrated that polysaccharides, particularly beta-d-glucans, have anti-tumor properties through immunomodulation and anti-angiogenesis (Boh et al., 2007).

3.1.2. Chaga (Inonotus obliquus)

They are a fungus that are high in antioxidants and go well with coffee or tea. The taste of chaga mushrooms is bitter and earthy, reminiscent of the birch trees on which they are found. They could lower cholesterol and blood sugar levels (Cui et al., 2005). One of the main bioactive ingredients in Inonotus obliquus is thought to be Inonotus obliquus polysaccharide (IOPS), which has antitumor, antioxidant, antiviral, hypoglycemic, and hypolipidemic properties (Lu et al., 2021). The chemical components of Inonotus obliquus, which include polysaccharides, triterpenoids, polyphenols, and melanin, have long-term clinical and animal experiments demonstrated that they have anticancer, anti-inflammatory, antiviral, antioxidant, hypoglycemic, and hypolipidemic activity without obvious side effects (Yiyong, 2010; Chen et al., 2010, 2015).

3.1.3. Cordyceps (Cordyceps sinensis)

These mushrooms, which grow on caterpillars that resemble insects and are found in high mountain areas, may help improve physical fitness and reduce physical fatigue. They might raise immunity by energizing immune system cells and particular chemicals. In particular with lung or skin cancers, it may also aid in the fight against cancer cells and reduce tumor size (Tsuk et al., 2018). Nucleoside, polysaccharide, sterol, protein, amino acid, and polypeptide are just a few of the Cordyceps sinensis' numerous bioactive ingredients. Additionally, these constituents were found to have anti-inflammatory, antioxidant, antitumor, anti-apoptosis, and immunomodulatory properties (Liu et al., 2015).

3.1.4. Lion's mane (Hericium erinaceus)

These mushrooms, which have a flavor and aroma similar to seafood, might also enhance cognitive function. The lion's mane mushroom may support healthy nerve development and function, as well as shield them from harm and maintain the stomach lining (Kim et al., 2013). The main chemical constituents of Lion's Mane are hericenones and erinacines. Nerve growth factor (NGF) is produced more actively in the brain when erinacines are present. Erinacines effortlessly cross the blood-brain barrier to boost the generation of new neurons (Tomen, 2022). NGF is a neurotrophin that promotes neuron survival and proliferation and is crucial for protecting, regenerating, and repairing damaged neurons (Kawagishi, 2018).

3.1.5. Shiitake (Lentinula edodes)

East Asian shiitake mushrooms are prized for their meaty, umami flavor. In addition to being delicious, shiitake mushrooms may also help boost immunity and treat stomach cancer (Miles and Chang, 2004). Consumable shiitake mushrooms contain the polysaccharide lentinan. A polysaccharide called lentinan is derived from the plant Lentinula edodes. Glucan is the primary bioactive element of lentinan with immunostimulatory properties (Zhang, 2019).

3.1.6. Turkey tail (Coriolus versicolor)

These mushrooms contain a lot of antioxidants and may help immune cells become active (Benson et al., 2019). It contains two substances that are used in medicine, polysaccharide peptide (PSP) and polysaccharide krestin (PSK). The turkey tail mushroom contains PSP and PSK, which may aid in preventing cancer and boosting the immune system. The turkey tail mushroom is used to boost the effectiveness of radiation and cancer treatments. Additionally, it is used to treat fatigue and weak muscles (WebMD, 2022).

4. Storage life of mushrooms

Most often, fresh mushrooms are sold. Within 2–3 days of harvest, senescence, water loss, microbial attack, and browning reduce its commercial value (Nerya et al., 2006). Due to their thin and porous epidermal structure, mushrooms have a significantly higher respiration rate (200–500 mg/kg h at 20 °C) than other vegetables and fruits (Kim et al., 2006). They must therefore be sold fresh and cannot be kept at room temperature for more than 24 h. Quality control must be conducted during the post-harvest period to maintain the acceptability of fresh mushrooms under various post-harvest procedures.

Due to their delicate epidermal structure and high rate of respiration, mushrooms naturally deteriorate within a day of being harvested. Therefore, at room temperature, the shelf-life of freshly harvested mushrooms is only one to three days (Singh et al., 2016). The components that make the mushrooms high-quality are maintained by temperature and storage time (Azevedo et al., 2017; Gholami et al., 2017; Joshi et al., 2018; Singh et al., 2018). The quality of mushrooms is significantly impacted by the storage temperatures. Azevedo et al. (2017) claim that the lower temperature prevented weight loss during the storage period. It was discovered that temperature had a strong correlation with the bacterial activity and metabolism of mushrooms (Dhalsamant et al., 2015). Low RH encourages water loss from the mushrooms to the environment, which has an impact on their quality, especially their firmness when stored (Mahajan et al., 2008; Rux et al., 2015; and Azevedo et al., 2017). Indirectly, a higher storage temperature raises the relative humidity in the air, which causes more produce to lose water. Alikhani-Koupaei et al. (2014) claim that the gradient of water vapour pressure, which is closely related to vapour-phase diffusion in various environments, has an impact on the percentage of weight loss. Table 3 lists the shelf life and recommended storage temperature for various Nepalese-cultivated mushrooms. The effect of storage temperature in shelf-life of mushrooms is given in Table 4.

Table 3.

Shelf-life of various cultivated mushrooms of Nepal.

Mushrooms	Storage T (°C)	Storage Humidity (%)	Storage life (days)	Reference
Oyster mushrooms	0–5	95%	7–14	NHB, 2019
Straw mushrooms	15	95%	6	Sakinah et al. (2020)
White button mushrooms	4	95%	22	Gholami et al. (2017)
Black forest mushrooms (English) Shiitake mushrooms (Japanese) Shieing- gu (Chinese)	16	>90%	18 14	Takahisa et al. (1980)
Milky mushrooms	It has a very good shelf-life of 3–4 days at room temperature and humidity. Post harvest storage requirements are similar to that of white button mushrooms (Singh et al., 2001)
Supernatural mushrooms/Red mushrooms (English) Reishi/Manentake (Japanese)	Can be stored for several months once it is dried because of its woody nature (IIHR, 2022)

Table 4.

Effect of storage temperature in shelf life of mushrooms.

Storage temperature (°C)	Storage life (days)
0	21
2	8–11
5	4–6
10	2–3
20	1–2

(Harun, 2017).

5. Post harvest problems of mushrooms

Among the many potential causes for the loss of mushrooms, microbial contamination is one of the major issues that cause an economic setback (Biswas, 2014). The quality of the product and the health of those who consume it are both impacted by microbial contamination. Compost and casing are the two substrates most commonly used for commercial mushroom cultivation. The finished product will be of lower quality because the compost contains microbes that can remain on mushrooms after they have been harvested, including bacteria, fungus, and molds (Siyoum et al., 2016). Mushrooms have a high moisture content, which encourages microbe growth, development, and amplification.

After harvest, browning of mushrooms reduces their market value by oxidizing phenol with enzymes or without enzymes (such as tyrosine, laccases, and peroxidases) (Nerya et al., 2006). Phenol oxidase activity increased when white button mushrooms were kept at 0–15 °C, and then decreased at 25 °C (Rajarathnam et al., 2003). The level of mushroom browning could also be predicted because phenol oxidase activity increased as fresh mushroom water content decreased (Rajarathnam et al., 2003).

Due to rising labor costs and a lack of supply, mechanically harvesting mushrooms has caused bruising on their surface, which has led to discoloration, a shorter shelf life, and a lower quality (Gao et al., 2011). Enzymes convert the phenols from mechanically damaged mushrooms to quinones, which then go through additional processes to produce dark melanin (Gao et al., 2015). According to research, damaging mushrooms for 10 s causes the same degree of distortion as storing them for 7 days at 5 °C or 2 days at 18 °C (Burton and Noble, 1993).

Long-term storage of mushrooms causes them to age or undergo senescence, which affects consumer preference because people prefer to purchase fresh, high-quality goods over those of lower quality. In white button mushrooms, the speed at which the veil opens reveal their age (Kale et al., 2021). Along with the growth of gills and spores, veil opening is a normal stage of white button mushroom maturation, but there are some undesirable quality factors at play (Braaksma et al., 2001). In addition to affecting a cell wall's ability to be sealed with lignin, lignification has an impact on the flavor, nutritional value, and quality of mushrooms that are harvested after being harvested (Jiang, 2013).

6. Latest technology for preservation of mushrooms

used for mushrooms: thermal (drying, cooling, and freezing), chemical (edible coatings, washing solutions, ozone, and electrolyzed water), and physical (packing, irradiation, pulsed electric field, and ultrasound) processes (Marçal et al., 2021).

6.1. Thermal process

6.1.1. Drying of mushrooms

A long-term storage technique that preserves the quality of the mushrooms while also enhancing their flavor is drying them. Mushrooms can be quickly dried using heat or air. Drying the button mushrooms is challenging. Mushrooms can also be dried in cabinet dryers at a temperature of 55–60 °C, which produces a dehydrated end product with lower moisture content, a longer shelf life, and superior quality. When drying meaty mushrooms with a lot of moisture, low heat is very advantageous. The dried mushrooms must be stored in a warm, ventilated area. When harvested, mushrooms have 90% moisture, but once the moisture is reduced to 10%–12%, they can be kept for longer periods of time (Rai and Arumuganathan, 2008). The drying process also eliminates diseases and insects. The drying temperature, surrounding humidity, and the initial moisture content of the mushrooms all affect the dried mushroom's color (Yapar et al., 1990).

6.1.2. Cooling of mushrooms

Pre-cooling is done to remove field heat. The mushrooms can be cooled to 2–4 °C using evaporative cooling, hydro-cooling, forced-chill air, ice banks, and vacuum cooling systems (Wakchaure, 2011). Vacuum cooling was the most effective pre-cooling technique, followed by forced air cooling and room cooling, with no deterioration occurring until the sixth day of storage, out of a variety of cooling methods including hydro cooling, room cooling, forced air cooling, and vacuum cooling (Mittal et al., 2014). Pre-cooling to 2 °C before cold storage had a positive impact on the storage quality, including delaying the permeabilization of the cell membrane and the decay of hardness, whiteness, and pH values, but pre-cooling at 6 °C and 10 °C can be detrimental and lead to a loss of commercial value (Xiangyou et al., 2014).

6.1.3. Freezing of mushrooms

One of the best ways to increase the shelf life of mushrooms is to freeze them, but this reduces their vitamin content. One of the best ways to increase the shelf life of mushrooms and maintain their nutritional value while in storage is to freeze them. Furthermore, freezing permits better preservation of the color, aroma, texture, and flavor of the mushrooms when compared to drying (Berna's and Jaworska, 2016; Fernandes et al., 2013).

According to Fernandes et al. (2013), frozen Macrolepiota procera is abundant in the ash and protein contents, but had a lower amount of carbohydrates, fat, total sugars, tocopherols, and phenolic compounds than fresh ones. This is in relation to the effect of the freezing process on the nutritional composition of mushrooms. The decrease in saturated and monounsaturated fatty acids was the cause of the reduction in fat content (Fernandes et al., 2013). According to Berna's and Jaworska (2016), freezing significantly reduced the amount of vitamin A, ascorbic acid, tocopherol, carotene, & lycopene and the pre-treatment used (such as blanching), method of freezing, frozen storage conditions, such as temperature & relative humidity, and length of storage all have an impact on the nutritional quality and bioactivity of frozen mushrooms.

6.2. Chemical process

6.2.1. Edible coatings of mushrooms

The preservation of total sugar, ascorbic acid, and bioactive compounds during storage is improved by edible coatings and films. White button mushrooms can be prevented from browning too quickly and from degrading by using an edible coating. The edibles coating completely covers the outside of the mushrooms, stopping gas exchange and moisture loss while also preserving their quality. It has been discovered that coating clean mushrooms with Aloe vera that has been enhanced with basil oil at a concentration of 500 mL per liter not only reduces respiration rate but also maintains firmness by inhibiting relative electrolyte leakage and malondialdehyde accumulation (Mohammadi et al., 2021). White button mushrooms are given an apple peel powder and carboxymethyl cellulose coating to preserve their quality and lengthen their shelf life after harvest (Thakur et al., 2021).

6.2.2. Washing of mushrooms with antimicrobial agents

Washing solutions lower the amino acid content. Gamma and electron beam radiation reduces the amount of unsaturated fatty acids, whereas UV-B radiation significantly increases the amount of vitamin D. Typically, decomposing compost is used to grow mushrooms. After harvest, some dirt and soil particles still cling to the surface of the mushrooms; these should be removed to prevent microbial contamination, bruising, and hyphae damage. Therefore, washing the mushrooms is typically done to get rid of any adhered debris. Enhancing the post-harvest life of mushrooms requires cleaning them first before packing (Maini et al., 1983, 1987). Fresh mushrooms were washed in sodium sulfite water to reduce the amount of bacteria present, but subsequent storage led to browning and faster bacterial growth than with unwashed mushrooms (Guthrie and Bellman, 1989). Additionally, browning and microbial infection can be avoided by washing the mushrooms with a reducing and antimicrobial substance. The amount of Pseudomonas bacteria that causes bacterial blotch was reduced when mushrooms were washed with 1% citric acid, but the color of the mushrooms degraded. As a result, washing it with 1% citric acid and then applying 1.5% sodium L-ascorbate to prevent browning was found to be effective in preserving the mushrooms' color and minimizing bacterial blotch (Simón and González-Fandos, 2009). Hydrogen peroxide (H₂O₂) is thought to be effective for retaining the color change in mushrooms because it controls bacterial activity and prevents browning (Guan et al., 2013). By reducing lesion growth and extending the storage life of button mushrooms without compromising nutritional value, H₂O₂ + UV decreased microbial loads. In order to maintain postharvest quality while reducing E. coli O157:H7 populations and background microflora, H₂O₂ + UV could be used (Sharaf-Eldin and Geösel, 2016). Additionally, it has been found that combining ultraviolet light and hydrogen peroxide lowers the microbial population, particularly E. coli O157:H7, and lengthens the storage life of mushrooms by reducing lesion development while maintaining the nutritional value of the mushrooms (Guan et al., 2013). When mushrooms were washed in oxine (50 ppm), sodium erythorbate (0.1%), and calcium chloride (0.5%), the amount of bacteria in the mushrooms was drastically reduced, and the color deterioration process was postponed (Wakchaure, 2011).

6.2.3. Ozone and electrolyzed water

Triatomic oxygen, also referred to as ozone, is a potent antimicrobial that can be used to prolong the shelf life of food. Ozone reacts with intracellular enzymes and cell components to quickly inactivate microorganisms due to its high oxidation capacity (Prabha et al., 2015). Comparatively to aqueous solutions, ozone is less likely to alter the chemical makeup of food matrices. Ozone quickly breaks down into oxygen after decontamination, leaving no unwanted byproducts behind. Gaseous ozone is a safe sanitizing agent that can come into direct contact with food, according to the USFDA.

Another promising disinfectant made by electrolyzing a salt solution is electrolyzed water (EW). The amount of free chlorine that is available to form hypochlorous acid (HClO) and the oxidation-reduction potential (ORP) of EW, as well as the sum of these two factors, determine EW's antimicrobial activity (Lee et al., 2014). The USFDA has approved the use of EW on fresh food products with a free available chlorine limit of 200 ppm. EW treatment has less aggressive corrosion on food quality than other disinfectants.

6.3. Physical process

6.3.1. Packing of mushrooms

To protect harvested mushrooms from transportation shock, use a sturdy packing material. The quality of the mushroom is preserved and bruising and microbial contaminations are reduced with proper packaging. The mushrooms were cleaned and washed before being packed in polypropylene. After three days in both ambient and refrigeration conditions, the mushrooms maintained an acceptable color and texture after being washed with 0.5% CaCl₂ + 5% KMS +0.5% NaCl (Singh et al., 2016). When mushrooms are kept after harvest at 4 °C for 28 days in active packaging enhanced with acai extract and zeolite, their quality (physical and chemical) may be harmed. Mushrooms that were kept in active packaging, especially those that contained zeolite, had higher levels of vitamin C and had more antioxidant power (Hanula et al., 2021). According to Mahajan et al. (2008), the ideal humidity for packaging mushrooms is 96%, and the ideal humidity range for the best color is 87–90% (Wakchaure, 2011).

Because it prevents browning and slows down some biochemical processes, the modified atmospheric package has been widely used for mushroom packing. When designing a particular atmosphere package, various aspects such as permeability, package material, thickness, and product weight should be taken into consideration (Palacios et al., 2011). Utilizing high oxygen levels and micro-perforated films, color and volatile components were preserved, maintaining the color and consumer acceptance. Additionally, it stops water condensation and the creation of unwelcome volatile chemicals inside mushroom packaging, but it has been found to lower pH levels (Pogorzelska-Nowicka et al., 2020). A recommended environment for storing mushrooms is 2.5–5% CO₂ and 5–10% O₂, in addition to polythene bags of thickness 100 gauges with a 0.5 percent venting area for packing mushrooms in refrigeration situations (Wakchaure, 2011).

6.3.2. Irradiation

Irradiation is a non-thermal physical procedure used to rid food products of pests, microorganisms, and toxins (Fernandes et al., 2012). It is regarded as a secure, green, and resource-conserving technique for preserving mushrooms (Fernandes et al., 2014). Furthermore, irradiation leaves no toxic residues while maintaining the flavor, color, nutrients, and taste of mushrooms on a global scale. However, depending on the type of mushroom, the complementary preservation techniques used, the radiation dose, and the source type of radiation, irradiation may have varying effects on the nutrients of mushrooms (Mami et al., 2014). Gamma, electron beam, and UV radiation are some of the irradiation sources. Any food product that has been exposed to radiation doses up to 10 kGy is considered safe by the World Health Organization (WHO) (Mami et al., 2014). However, consumers are still resistant to eating irradiated foods.

6.3.3. Pulsed electric field and ultrasound

The non-thermal method of pulsed electric field (PEF) for food quality preservation. PEF treatment results in temporary or long-lasting pores in the membranes of microorganisms, which leads to irreversible cell disruption and aids in the inactivation of microorganisms (Zhang et al., 2018). This process, known as electroporation, kills cells while allowing charges to move electrophoretically between cellular compartments (Dellarosa et al., 2017; Parniakov et al., 2016). In mushroomstalk tissue, intercellular water can be redistributed to extracellular spaces by combining PEF with low and high temperatures, as was discovered by Dellarosa et al. (2017). The use of PEF as a postharvest preservation technique for mushrooms and its impact on nutritional composition have received relatively little research. Dellarosa et al. (2017) found that polysaccharides, particularly those found in the mushroom cell wall, underwent morphological and molecular weight changes during the PEF process.

Ultrasound is a promising processing, preservation, and extraction method in the field of food technology. It raises food quality, lessens physical and chemical deterioration, and maintains the qualities of freshly produced goods (color, consistency, flavor, and nutrients) (Jiang et al., 2020; Lagnika et al., 2014). The theory behind the application of ultrasound in the preservation process is that as an ultrasonic wave travels through materials, it alternately compresses and rarefies them rapidly in a series. This results in the cavitation effect and the formation of numerous microscopic channels (Zhao et al., 2018).

7. Post-harvest quality of mushrooms

During the postharvest stage, mushrooms experience a number of quality degradations, including moisture loss, discoloration, texture changes, off flavor, and nutrition loss (Ding et al., 2016). During the postharvest period, the moisture content of mushrooms gradually drops, causing continuous weight loss. Due to water loss and enzyme activity, postharvest mushrooms turn brown, which affects consumer purchasing decisions. The quality of mushrooms is affected by a number of factors after harvest. These variables are divided into two categories: internal variables pertaining to the mushrooms themselves (such as water activity, respiration rate, and microbial activity), and external variables pertaining to storage circumstances (storage temperature, relative humidity). Phenolperoxidase (PPO), rather than hydrogen peroxide, is thought to be the main cause of Agaricus bisporus postharvest browning because hydrogen peroxide naturally occurs in mushrooms in small amounts (Lei et al., 2018). Mushrooms' postharvest stage rapid loss of firmness as they get older contributes to their short shelf life and susceptibility to microbial contamination (Gao et al., 2014).

8. Preservation of mushrooms

The mushrooms can be stored for a brief period of time by steeping them in a salt or acid solution. The steeping method is simple and inexpensive. An aqueous solution containing 2% sodium chloride, 2% citric acid, 2% sodium bicarbonate, and 0.15% KMS is used to steep preserve blanched mushrooms for 8–10 days at 21–28 °C. Mushroom steeping is a quick and inexpensive alternative to canning and freeze-drying mushrooms (Bano and Singh, 1972; Adsule et al., 1981; Pruthi et al., 1984; Sethi et al., 1989, 1991; Sandhu and Aggarwal, 2001). The exhausted steeping preservation enhances the whiteness of button mushrooms even more (Rai and Arumuganathan, 2008).

Due to advantages like ease of use, quick preparation, and resistance to food spoilage, canned mushrooms have become more and more popular. Processing the food and sealing it in an airtight container are the steps in the process of canning mushrooms (jars like Mason jars, and steel and tin cans). While it can sometimes last much longer, canning typically has a shelf life of one to five years. Typically, canned button mushrooms are used. Mushrooms that have been preserved in a can or jar are known as canned mushrooms. You can keep mushrooms in cans for up to a year (Rai and Arumuganathan, 2008). Whole or sliced mushrooms with a stem length of 1 cm are canned (Beelman and Edwards, 1989). Mushrooms in cans have the same nutritional value as fresh mushrooms. Cans of mushrooms make a good "meat substitute" due to their high protein content and meaty texture. Cans of mushrooms are a great source of riboflavin, niacin, potassium, phosphorus, copper, pantothenic acid, and selenium. Depending on the demand, mushrooms can be canned whole, chopped, or in stems and bits. The canning process involves several steps, including cleaning, blanching (5–6 min at 95–100 °C), filling cans with brine solution (2% salt with 0.1% citric acid or 100 ppm ascorbic acid), sterilization by heat (118 °C), cooling, labeling, and packaging.

9. Limitations and future prospects in the aspect of nutritional values of mushrooms

Mushrooms are low in sodium and carbohydrates and have very few calories. Chitin, an indigestible carbohydrate found in mushrooms, gives our diet "bulk" (Emberger, 2022). Eating too many mushrooms can have negative effects on some people's bodies and minds. Psychedelic mushroom overdoses can result in anxiety and panic attacks (Kharbanda, 2022). Shiitake mushrooms are one of the most widely consumed varieties of mushrooms and are rich in nutrients that have a number of health benefits. However, consuming these mushrooms has a number of negative side effects. For those who are allergic to them, shiitake mushrooms are also challenging to digest. Some consumers experience allergic reactions, skin rashes, and food poisoning while consuming (Thompson, 2022). One of the plants that produces the most protein per unit of time and space is the mushroom. As a result, they have the potential to guarantee both nutritional security and a sustainable economy. By preserving food production and security, mushrooms help to meet the demands of food scarcity. They are a good source of nutrients like protein, fiber, vitamins, and minerals as well as amino acids. Future solutions to problems with food and nutritional security at the local, national, and international levels will depend on accurate identification of edible mushroom species as well as increased cultivation and production.

10. Conclusion

Mushrooms are a popular vegetarian protein source because they contain a variety of bioactive chemicals with a range of health benefits, such as cholesterol-lowering and cancer-fighting abilities. The commercial cultivation of edible wild mushrooms like Morchella esculenta, Cordyceps sinensis, and Grifolia frondosa ought to be expanded. Mushrooms have a very high rate of deterioration because of their rapid rate of respiration and lack of a barrier to stop them from losing water, like a cuticle. Mushrooms with more water are more prone to microbial contamination. Consequently, a number of post-harvest quality preservation strategies have been implemented. The best post-harvest preservation technique involves long-term storage assisted by steeping preservation. The use of a variety of preservation methods combined with low-investment requirements or expedited processing times should be promoted in order to enhance the quality of mushrooms after harvest.

Declarations

Author contribution statement

All authors listed have significantly contributed to the development and the writing of this article.

Funding statement

This study was not supported by any public funds.

Data availability statement

Data will be made available on request.

Declaration of interests statement

The authors declare no conflict of interest.

Additional information

No additional information is available for this paper.