As cardboard products accumulate in landfills, a new sustainable alternative is gaining momentum: mushroom materials.
Yes, you read that correctly. In the past decade, scientists and designers have engineered mushroom houses, furniture, and clothing. More recently, companies such as IKEA and Dell began using fungi-based packaging. But what exactly is this mysterious fungus medium, and how can we continue to apply it?
A mushroom is the fruiting body of a fungus. Underground, fungi are composed of mycelium, a white tissue made of continuously branching filaments called hyphae. Flexible and intricate, this root-like network facilitates nutrient absorption and decomposition. For their role connecting trees and plants throughout the forest, mycelial networks have been coined the ‘Underground Internet.’ Fungi-webs extend far beneath our feet, spreading for kilometers. In fact, one of the largest organisms in the world is a fungus.
Mycelium is strong and resilient. It can break through concrete and survive off of minimal resources. When grown on an organic substrate, mycelium forms a strong biocomposite material. Myco-materials are lightweight, with insulation rates comparable to hardwoods. One study found that their compressive strength is “fully competitive” with that of standardized materials such as Styrofoam™, paperboard and cardboard (Girometta et al.). The material can be grown into any form, from bricks to poles. Mycelium materials are so promising that NASA is currently funding a myco-architecture project in Silicon Valley, exploring the use of mycelium buildings for Mars colonization.
A more immediate usage for mycelium is as a sustainable single-use material. Mycelium biocomposites are far more environmental than cardboard and paperboard. The material’s production requires low energy and no high carbon processes, and involves the recycling of agricultural waste products such as plant fibers. Mycelium has an infinite growth capacity, does not depend on deforestation, and is 100% biodegradable (Jones et al.).
With proper sterilization techniques, just about anyone can cultivate mycelium materials. Production and experimentation is inexpensive and innovative.
Given these green incentives, in 2021 Jasmine Li and I conducted a fungi-biocomposite research project to test a new product: mycelium-based cup sleeves. Single-use paperboard cup sleeves are victim to discard culture; in 2018, 99.75% of paper cups world-wide were not
recycled, implying that a large amount of accompanying cup sleeves were not recycled either (Team). Although compostable alternatives such as Starbucks’s EarthSleeves™ exist, all paperboard products rely on deforestation and industrial processes that emit carbon dioxide. A mycelium biocomposite sleeve appears to be an apt eco-solution.
The research process consisted of three phases: modeling, cultivating, and prototype testing. We constructed a reusable cup sleeve model out of cardboard, and used coffee chaff (the flaky husk of coffee beans) as a substrate. While growing mushrooms can be difficult- with variable factors of humidity, darkness, and mold- growing mycelium is far easier. We attained Blue Oyster mushroom grain spawn, sterilized our substrates by bringing them to boiling point, then layered the models as if baking a coffee-fungi cake.
After two weeks, the mycelium threads began to poke through the substrate in wispy white strands. Without any additional water or nutrients, the fibers soon wove into a dense, opaque material. Once removed, the cup sleeves were well-formed, with a smooth surface and snug fit. The mycelium resembled rubber: white and firm with a subtle earthy scent.
In our study, the biocomposite cup sleeves exhibited equal thermal resistance to paperboard cup sleeves. There were, however, several product disadvantages; the mycelium material was rigid, thick, and took 3 weeks to grow. Nonetheless, at a manufacturing plant these challenges could be resolved with advanced cultivation methods and technology. Companies such as Mylo™ Unleathered, for instance, use mycelial cells with extra polymers to achieve a flexible material. Finer substrates and isolated growing chambers can speed up growth.
These home-grown mushroom cup sleeves add to the list of inventive, slightly wacky, yet purposeful fungal designs. As consumer culture begins to prioritize sustainability and companies search for practical cardboard and styrofoam alternatives, mushrooms may emerge MVP. Green biocomposite products are likely key to fighting climate change, deforestation, and waste accumulation globally. After all, as many mycologists and the occasional T-Shirt will tell you, the Future is Fungi.
BIBLIOGRAPHY
Girometta, C., Picco, A. M., Baiguera, R. M., Dondi, D., Babbini, S., Cartabia, M., . . . Savino, E. (2019). Physico-Mechanical and thermodynamic properties Of Mycelium-Based Biocomposites: A review. Sustainability, 11(1), 281. doi:10.3390/su11010281
Jones, M., Mautner, A., Luenco, S., Bismarck, A., & John, S. (2020). Engineered mycelium composite construction materials from fungal biorefineries: A critical review. Materials & Design, 187, 108397. doi:10.1016/j.matdes.2019.108397
Team, R. (2018, April 17). Plastic recycling: Why Are 99.75% of coffee cups not recycled? Retrieved February 25, 2021, from https://www.bbc.com/news/science-environment-43739043
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Photo by Christopher Cassidy on Unsplash; https://unsplash.com/photos/EYlS8SiHcYg
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