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A growth industry

Zero waste initiative produces gourmet oyster mushrooms.

A Gisborne entrepreneur will soon open the region’s first “zero waste, grow your own mushroom” business that focuses on reusing waste products.

Mariska Van Gaalen is the founder of Mushroom Zero Waste an initiative that reuses plastic containers and waste materials to grow mushrooms in a sustainable way.

She says that for her to start a business meant being responsible for the entire life cycle of the product, and avoiding the production of any additional waste.

Ms Van Gaalen uses plastic containers collected from a restaurant to hold unused wooden shavings, coffee grounds and mycelium — the fungus — to grow native oyster mushrooms.

“Oyster mushrooms are a gourmet mushroom and they are easy to grow

. . . there are a number of people growing them but not (like this) as far as I could see.

“So I thought let’s start that, it could be a cool thing I can learn and contribute and make that available,” she said.

The process to grow the mushrooms involves her preparing the container before it is sold to the customer with an instruction pamphlet on how to finish growing them.

Ms Van Gaalen pasteurises the wood shavings, cleans the containers and then mixes the shavings with the coffee grounds and the grain spawn that have mycelium. The mixture fills the container which is then put aside for incubation — with the ideal temperature being 25 degrees Celsius — during which the fungus colonises (spreads) and then the container is ready to sell.

The balance of the materials and temperature determines the time for them to colonise. For example, more coffee grounds and a colder temperature make the colonisation process longer.

While prepping could take some weeks, she planned to build an “incubation chamber” that should reduce the time and, more importantly, make her production consistent.

“If I prep about 20 containers to sell at the Farmers’ Market, and some are ready after three weeks or some are ready after six weeks, that could be a problem,” she said.

Provided the customer takes care to keep the container exposed to moisture and fresh air, “fruiting” would happen within a week.

“Fruiting is what you call it when they start making mushrooms,” Ms Van Gaalen said.

“They” refers to the mycelium that feeds on the substrate (food) like the pine shavings and coffee grounds to produce the fruit — which are the mushrooms.

“Once they start to grow they also need to have enough oxygen. It is good to keep them close to a window so they can get fresh air to grow properly.

“The oxygen is especially needed to grow their caps — that is the thing we like to eat the most,” she said.

From the start of fruiting to harvest is about five days, with the mushrooms doubling in size every day.

Customers could expect to get about 150 grams of oyster mushrooms in the first flush, and to have a further two flushes from the same container.

They then need to bring back those containers for either re-use or, if damaged, to be recycled — making the business model eco-friendly.

The idea for the initiative came during lockdown last year when she remembered her experience at a restaurant in the Netherlands — where her family lives — and her encounter with its eco-circular economy policy.

“I really loved that . . . I hadn’t known that you could grow mushrooms from coffee grounds and waste products,” she said.

Ms Van Gaalen said that initially she bought a kit from another grower in New Zealand, but the process involved a lot of single-use plastic.

“The kit came with a plastic bag that the sawdust was in and then you had to put that into another plastic bag, and so in the end I thought, this involves a lot of plastic.

“But I was still keen to do it and started to think of a way that isn’t going to create plastic waste, because for me it doesn’t feel right to start a business that by design is going to send X amount of plastic bags per week to the landfill,” Ms Van Gaalen said.

Many people did not know that mushrooms were more like animals than plants, she said.

“People assume that it is a vegetable, right? But mushrooms are not plants. Fungi are not plants. They are just fungi.”

Ms Van Gaalen will be selling her products at the Farmers’ Market from October.

MUSHROOMING: Native oyster mushrooms blooming from a reused plastic container. Picture supplied
SUSTAINANBLE MUSHROOMS: Mariska Van Gaalen says the ideal temperature for growing the mushrooms is 25 degrees. Picture by Avneesh Vincent