Our current process for Kiez Pilz involves pasteurizing bulk-substrate with the following process:
- pickup coffee grounds from a local coffee shop, produced day of
- large sacks of sawdust from a local woodshop that have been sitting in the basement for months
- mix 10% coffee, and 80% sawdust together into 28L coolers that look like this
[image of blue cooler]
- pour boiling water into the cooler, nix it all up quickly with a spoon, and then let it sit over night. We pour water at a volume of 40% of the total substrate volume, which we found leaves the substrate close to field capacity
- then inside of a (somewhat goofy) giant still air box, we mix spawn into the cooled substrate, frequently spraying the air and our hands with 70% alcohol
[image of giant still aribox, made of a rectangular wood frame and plastic sheeting with arm holes]
Using this process, with some small variations, we’ve had 3 successful bulk innoculations, and 2 bulk innoculations where everything was contaminated with green mold.
I’m sure there is some small tweaking we could still experiment with,
… how much coffee, how frequently we spray alcohol, how well sealed is the still air box, do we let the substrate sit in the cooler over night or just for a couple hours etc…
but I’m wondering for any advice on our process, and how to make it more reliable and reduce contamination.
I particularly wonder about the pasteurization.
- is it important that all the substrate is wet and hot? or just that there is steam and its hot in there?
- should we be looking into some way to submerge the substrate completely in boiling water and then strain it afterwards? (I’m not sure how we would do this easily in our space)
- are there other pasteurization techniques that could be practical in the city?
If we only have 3/5 success that is not a great rate. Maybe we just need a little fine-tuning, but posting this here with the hope to sanity check our approach.
We may also get access to a large clean bench soon (which a lab is getting rid of for free) which would give us a nice chance to test if we have better results doing the innoculation with the clean bench.