Mushrooms, coffee and sustainability

Mushrooms, coffee and sustainability… How are these three things related you might ask? Read on and you’ll find out.

Last Friday I went to a really interesting workshop on how to grow mushrooms on coffee grounds, organized by Green Keys Leiden and the Leiden University Green Office as part of the Sustainability Week 2019 program.

The workshop was given by Jeroen Schrama, a local sustainability expert, who explained to us how the edible oyster mushrooms can grow on many different types of organic waste, among them coffee grounds. This makes them really easy to cultivate and presents a lot of opportunities to produce sustainable vegetarian food using waste.

Oyster mushrooms (Pleurotus ostreatus) are tasty, healthy and can easily grow on discarded coffee grounds (pngtree).

Most of us drink and enjoy coffee on a regular basis, but it turns out that brewing it is not very sustainable, as less than 1% of the coffee biomass actually ends up in each cup. This means that a whole lot of waste is being created by the used coffee grounds.

To put this in perspective, in the Netherlands around 90 thousand tonnes of coffee were consumed in 2015. This means that more than 89 million kilos of waste were generated from that consumption.

So this is where the mushrooms come in as a sustainable solution, as all that discarded biomass can be used to grow tasty and healthy oyster mushrooms on it. As Jeroen put it, this is a really good field of opportunity, not only to lead a more sustainable lifestyle by growing your own mushrooms with your household’s coffee waste, but also even in setting up a mushroom farm business or as a way to help solve world hunger.

After this explanation on the link between mushrooms and sustainability, the workshop proceeded with the actual preparation of our own grow-your-own-mushrooms kits.

The workshop taking place (Green Keys Leiden/LUGO).

We first prepared the containers, cutting small holes into buckets with lids, from where the mushrooms will eventually grow out of. Then we broke apart the mycelium, the vegetative part of a fungus, and mixed it with the coffee grounds, forming a layer at the bottom the containers.

And that was it. Now for the following weeks we have to wait for the mycelium to grow and keep adding coffee grounds until the buckets are full, at which point the fungi will start fruiting – this is, producing the actual mushrooms that we can eat.

Oyster mushroom mycelium growing on coffee grounds (Wikimedia Commons).

And the beauty of this is that, once you harvest and enjoy your oyster mushrooms, you can start all over again, reusing the still alive mycelium by dividing it (so that you can even give some of it to your friends) adding more coffee grounds and repeating the process.

I hope learning about the possibility of growing edible mushrooms on coffee waste made you appreciate fungi more (I certainly did!) and maybe now you are considering to give it a go and grow your own mushrooms on coffee grounds, in which case you are lucky as there is an organization in Rotterdam, Rotterzwam, which specializes in this and from which you can easily get pre-made kits and mycelium.

Good luck and enjoy the experience!

About Daniel Salinas

¡Hola! My name is Daniel and I’m a second year RMA student at the Faculty of Archaeology specializing in heritage. Besides my academic interests, which include history, tourism and museums, I enjoy photography, spending time in nature and drawing. Since arriving to Leiden back in the summer of 2017 I have been drawn by the history and heritage of this lovely university city. In this space I will be writing posts mainly about those topics, sharing interesting spots, art, museums, cultural events and little known stories of Leiden so you all can get to know the city a little better!

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