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Kokeilun oppi

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Experiment created 15.01.2019
Chris Holtslag
Chris Holtslag

Eliminating single use plastics in mushroom cultivation

Miksi tämä kokeilu on tarpeellinen?

Cultivating oyster mushrooms indoors requires the substrate to be put in special plastic bags with breathing filters which contain the growing medium. These bags are used only for one growing cycle and then discarded, creating large amounts of plastic waste. Helsieni Oy wants to develop a reusable container that has a similar performance to the plastic bag. We want to find out if this process does not take more time or cost more than the use of bags, making the solution viable. The goal of the experiment is to develop a process that takes the equivalent amount of time, produces a similar amount of mushrooms while using a reusable container as a substrate holder. This would completely eliminate the need for single use plastic bags in the cultivation of oyster mushrooms. After enough data has been collected we can make a good estimation of the total costs (labor + money) of this new process and decide if it we want to implement it at the complete farm scale.

Miten kokeilu toteutetaan?

The containers we want to test are made of a high quality reusable plastic and can withstand temperatures of pasteurization. We need to develop a proper filling and emptying system and test the time it takes to operate. We will also test if there is any difference in performance concerning contamination risk and mushroom yields. If the time, contamination and emptying process are comparable to the bag system we will switch our production to this new system, preventing the need for buying new plastic and disposing of it. The amount of plastic waste produced would be significantly reduced since the plastic might only be disposed after several tens of cycles. We will test the idea at Helsieni Oy’s facility in Vantaa. We will collect the buckets from restaurants that would otherwise throw these food grade plastic buckets away. When we reuse containers, we need to build a filling mechanism and design an emptying and cleaning process. The buckets will be used in our current pasteurization step and cultivation facilities and the performance will be time tracked. We will start the experiment in February 2019 and hope to get all the results by the end of April 2019.

Kuka tai ketkä kokeilun toteuttavat?

Helsieni Oy will perform the experiment. If the results are successful, results will be shared with the Mushroom Learning Network, a network of european growers that share experiences on growing mushrooms on urban waste streams like coffee waste.

Mikä on kokeilun budjetti?

The budget of the experiment is 5000 euros, which allows us to finance the necessary equipment, raw materials and process testing. In addition, Helsieni Oy will fund the experiment itself with labor and the necessary space within our facility for 2000 euros.

Millaista osaamista ja rahoitusta kokeilulla on käytettävissään?

Helsieni Oy has 2 years of experience in growing oyster mushrooms and has the necessary skills needed to perform the experiment. Our facility is built for cultivating mushrooms and is available.

Learned from the experiment

Saavuttiko kokeilu tavoitteensa?

Yes. We managed to find suitable containers that have the desired properties, and tested them on an experimental scale. In order to reuse these boxes we needed to add a new pasteurization process to our production process. Since it is a new process it still takes more time to perform than the first process we had, making it slightly more costly in terms of labour costs. However due to decreased spawn costs and avoided contamination, the net result is still positive with the main goal achieved of complete elimination of single use plastic bags.

Mitä uutta tietoa kokeilulla saatiin?

We learned that the containers we tested for this project are suitable for mushroom cultivation, are compatible with a heat pasteurization process, and can be reused multiple times. We learned that the pasteurization process is not always easy to control and needs to be further fine-tuned. We also discovered that we can significantly reduce our spawn rate when using this system, and so save money on raw material input costs. We also learned that even with these new processes contamination is not completely eliminated, so we have to deal with other parts of the production process to improve this system.

Miten aiot viedä kokeilua tai sen tuloksia eteenpäin?

At the end of the experiment we will try to continue developing this process, and we would like to use it for all the mushrooms we produce. The current test is made with 25% of our substrate. We still use plastic bags for the remaining production. We are documenting the solution we came up with and sharing it with the other members of the Mushroom Learning Network, small urban mushroom farmers in Europe. We can scale up the experiment by investing in a batch of new substrate containers and using them for 100% of the substrate that we produce. At the same time we would like to increase our overall mushroom production, because there is demand from our customers for more but also other types of mushrooms. We cannot currently meet this demand due to a limitation of conditioned mushroom fruiting space. We would need to build a second fruiting space to be able to increase our total mushroom production. This would require an investment of around €20 000.

What has happened during the experiment?

23.05.2019

Our current method of growing mushrooms. Transparent PE bags are great, but they can only used once, as you need to cut them in order to let out the mushrooms. They are also not very cheap, besides producing large quantities of hard to recycle plastic waste, usually sent to the incinerator.

Filling smaller rigid PP (which does not melt at 100C) containers needed some less time consuming way, this simple solution works great.

Substrate boxes are filled neatly, without mess.

The grey tank on the left is used for pasteurization, where steam heats the plastic containers and the substrate for 15-25 hours. After cooling period the containers can be inoculated (picture right)

Healthy colonization of the substrate by the mushroom mycelium. Transparent boxes make this monitoring easy.

A healthy flush of oyster mushrooms emerging from the holes we made in the lid.

After harvesting 2-3 flushes from a box the substrate can be sold to gardeners as a mushroom bed or composted.

Empty containers on piles ready for another round of filling and pasteurizing.

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