Scientists have been searching for ethical, high-quality alternatives to animal leather, which notoriously comes with environmental costs and ethical compromises. While synthetic alternatives solve the ethical dilemma, many of them are plastic-based and very difficult to recycle. Now, researchers are trying to find an option that checks all the boxes, and the best material for it seems to be … mushrooms.

The idea of making leather-like material from fungi isn’t new. At first, the main question was whether fungi could be a good alternative to leather at all. Scientists grew mycelium in trays and let the fibers form a solid sheet – think of a leather-like film. The concept was proved possible, but this approach was hard to scale up.

A few years ago, a group of researchers from VTT Technical Research Centre of Finland came up with a new idea. They developed a process for producing continuous sheets of mycelium leather at a pretty good rate of 1 meter (3.3 ft) per minute. This method could potentially be adapted for industrial manufacturing, but there were still limitations to overcome, with the biggest one being the quality of the material. Could it be durable enough for practical, mass-market goods?

This is what the new research from VTT is about.

This time, the scientists took a different approach to the material formula itself. Instead of turning the fungal biomass straight into a leather-like sheet, they first processed it into a thick, wet, pulpy mass and grew it in a nutrient-rich liquid. Then the pulp was harvested, washed, and mixed with sorbitol and cellulose. Sorbitol makes it softer and less brittle, while the cellulose strengthens it, giving the material the right balance of flexibility and durability. The mixture was then spread into a thin layer and dried.

As the approach changed, the same challenge appeared again: how to scale the production up beyond small laboratory samples? The researchers used a roller system similar to the one used in paper manufacturing, and were able to produce mycelium sheets about 20 cm (8 in) wide and 8 meters (26 ft) long. A huge advantage of this technology is that it uses equipment already common in the biotechnology and printing industries, which could reduce some of the financial barriers to scaling it up.

This method didn’t just produce a more durable leather-like material, but also gave the researchers more control over the final result. They could add color to the pulp and adjust the texture of the material.

In laboratory testing, the material showed durability and strength comparable to traditional leather, and was used to create a prototype handbag. It was also very easy to recycle: when submerged in water, it broke down after 28 days and then completely disintegrated under industrial composting conditions in just six weeks.

There are some issues remaining, though. The material still needs to be more tear-resistant before it can move toward mass production, but overall, mushrooms might be getting pretty close to entering the fashion industry.

A paper on the research was recently published in the journal ACS Applied Bio Materials.

Source: American Chemical Society