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January 18, 2023 Ganna Reshetnyak By Ganna Reshetnyak My Articles

Fungi in Sustainable Food Production

Fungi are not just fun to forage and delicious to eat, they can also be useful for food manufacturers looking to make the food system more sustainable. Here’s how fungi are leading the change towards more sustainable agriculture and food production.

Fungi: what are they?

Fungi used to be considered ‘imperfect plants’, however, we now know that they are neither plants nor animals. Instead, fungi exist as an entirely separate kingdom of life. They do not derive energy from photosynthesis, like most plants,  but instead digest organic matter externally, before absorbing it into their mycelium, an underground network of filaments.1 While the words ‘fungi’ and ‘mushrooms’ are often used interchangeably, mushrooms are in fact the overground part of some fungi. Also called the fruiting body, the mushroom is generally developed as a way for the fungi to disseminate spores - as well as being delicious food. They have long been a favoured ingredient amongst various global communities, chefs and food companies for their ability to mirror hearty texture and umami flavour of meat.

Fungi are an extremely diverse group of organisms - both in the number of species and the shapes and sizes they form. While just 120,000 species have been identified and described, there are an estimated 2.2 - 3.8 million species of fungi that range from microscopic yeasts and moulds to the one of the largest organisms on Earth – the honey mushroom, found in Oregon, which stretches for 10 square kilometres or the size of 1,665 football fields.2,4 They can even survive in space despite extreme conditions and are capable of growing on a wide range of surfaces.3 


The Armillaria Ostoyae honey fungus,  growing in the Malheur National Forest of Oregon, USA, is one of the largest and oldest living organism in the world. (DeAgostini/Getty)
 

When did people start eating mushrooms?

Fungi have been consumed all over the world for a millennia. Ancient Romans considered them as “food of the Gods”, Greeks and Vikings used them as a booster before war campaigns, while Indigenous American tribes consumed mushrooms in ceremonial and spiritual rituals.5

Even without the understanding of the biochemical processes, ancient humans leveraged the fungal potential to preserve and transform their food and beverages, such as bread and beer. Recent findings in Israel suggest that the familiar fungi known commonly as yeasts were used in food fermentation as early as 11000 BCE.6 Naturally present in the environment, yeasts feed on sugar in cereals or flour, converting it into alcohol and ​​CO2 - the process helping bread rise and beer carbonate. 

Archeological evidence from Austria suggests that the first blue cheeses were already consumed back in the Iron Age in Europe.7 It’s the mould, Penicillium roqueforti, that degrades fats and proteins in milk, creating the distinct blue veins, flavour and smell we all love… or hate. Today, fungi still play a key role in Meju and Soy Sauce fermentation by breaking down soybean macromolecules into smaller nutrients. For example, in Korean cuisine, traditional Meju is a fermented soybean starting material that is used to make products such as doenjang (soybean paste) and ganjang (soy sauce). It is naturally fermented by bacteria, yeasts, and fungi.29,30 


A sake brew master treats steamed rice with a mold called 'koji' in preparation for brewing sake in Himeji, Japan. (Buddhika Weerasinghe/Getty)
 

How are fungi cultivated?

Large-scale mushroom cultivation started in the 17th century in France with white button mushrooms. It is still the most widely consumed variety in Europe, but shiitake (Lentinuda edodes) is the world's leading cultivated edible mushroom species representing about 1/5 of the world's supply.8 It is especially popular in Japan and China, praised not only for its taste but also for antioxidant and anti-inflammatory properties.9 

Fungi can be cultivated on a wide variety of surfaces that includes wheat, rice or cotton straw, corncobs, sugarcane, bagasse, coffee and tea leaves, banana skins, potato starch, and even sawdust, paper, and cardboard.10 In addition to degrading and upcycling waste and sidestreams, growing mushrooms on them can provide valuable food and feed.11,12 A good example of this is the lavender fields in the Mediterranean region that are used to produce essential oils. Traditionally, leftover straw was considered agricultural waste with little value, often burned. Nevertheless, research has shown that it can be used as a substrate both for white-rot fungi that produce valuable enzymes and for oyster mushrooms that can be harvested commercially.13 Although mushroom growth rates are slower than using barley straw, the mushrooms contain compounds that have antioxidant and pharmaceutical properties.14 Fungi can also be used to turn food waste, such as stale bread and apple pomace, into vegan foods high in protein, linolenic acid, and vitamin D.15,16 

You can even try cultivating oyster mushrooms yourself, without any sophisticated equipment, using just toilet paper.17

Learn more about button mushroom farming from the expert

What are the benefits of fungi in traditional agriculture?

Even though the majority of commercially sold mushrooms are cultivated indoors, they can also be grown in the field. By growing mushrooms outdoors, farmers are able to use space between seasons for main cash crops, which can increase their income. In addition, growing mushrooms can also benefit soil quality by improving nutrient cycling. Furthermore, by decomposing dead organisms and recycling nutrients, such as phosphorus and nitrogen, fungi help new plants grow by providing them with nutrients they need.18

Additionally, some fungi form beneficial interactions with plants by enhancing their photosynthetic capacity and improving their ability to uptake water and nutrients from the soil around them,reducing the need for chemical fertilisers and excessive irrigation.19 Research suggests that mycorrhizal fungi also reduce soil erosion by binding soil particles into solid aggregates and boosting plants' immunity to pathogens.20

Serendipitously, many of the most sought-after mushrooms, such as morels, chanterelles and truffles, are mycorrhizal fungi.

Check out this article to learn more about how truffles are grown

What role do fungi play in food manufacturing?

The production and processing of many modern foods depends on enzymes and acids. As well as adjusting pH and extending shelf life, acids can also be used to enhance flavours and leaven foods. While enzymes degrade complex compounds, they also ensure better texture, taste, and digestibility.21

While these enzymes and acids can be obtained from plants or animals, these methods tend to be unsustainable, costly, and cannot satisfy the growing demand for them. One example is citric acid, the common additive used to preserve many canned and jarred foods. Citric acid creates a hostile environment for bacteria, preventing major food-borne diseases such as botulism.22 As its name suggests, citric acid was first isolated from citrus fruits back in the 18th century. However, today instead of sacrificing entire lemons, cheap side-stream materials such as fruit peels or cotton waste can be fermented by Aspergillus niger, a black mould, to produce it more efficiently.23

Enzymes help break-down complex compounds, such as proteins or fats and accelerate chemical reactions.24 For example, in cheese production, liquid milk is coagulated, creating solid curdles that are then separated, and further processed. This reaction is mediated by an enzyme - chymosin, which used to be extracted from calf stomachs. Nowadays, chymosin is produced either by bacteria or fungi in bioreactors, a method that is significantly less costly and far more energy-efficient, without having to compete for land usage or killing animals. Overall, fungi now account for more than half of the enzymes produced worldwide, contributing to the production of not only cheese but also tea, coffee, fruit juices, bread, and meat products as well as numerous other applications outside the food industry.24,25

Is fungi the new protein alternative?

The bioreactor cultivation of fungi can also be used to produce valuable peptides and proteins both for food and feed. For instance Quorn®, a UK-based company uses Fusarium venenatum, a type of fungus that naturally occurs in the soil to produce mycoprotein.25 In addition to being a good source of protein, mycoprotein also contains many vitamins and minerals (e.g. vitamins B2, B9, phosphorus, magnesium, and zinc) necessary for a healthy diet.26 Several clinical studies have shown that consuming mycoprotein could help reduce cholesterol levels as well as stimulate muscle gain and regulate satiety.27 However, these studies were usually short-term, focused on a relatively small number of participants, and were funded by Marlow Foods Ltd (the owner of Quorn®). 

Additionally, mycoprotein consumption is considered better for the environment due to its efficient nutrient and energy use, as well as low water and land footprint. According to a study that estimated future population, income, and livestock demand, replacing 20% of beef consumption with mycoprotein could reduce deforestation and CO2 emissions by half by 2050.28 

While Quorn® had been commercialising its mycoprotein-based products since 1985, numerous new companies are emerging with the aim to replace both meat and seafood protein with fungal alternatives.

For an in-depth look at how mycoprotein is made, watch this video
 

Next time you are upset by a mouldy piece of fruit, think of all the good the fungi are doing elsewhere. As these are just a few examples of how fungi play a crucial role in current and future sustainable food production. Is there one that surprised you the most?

January 18, 2023 Ganna Reshetnyak By Ganna Reshetnyak My Articles

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References

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