Sterilizing casing mix in oven

[Nydex]

So I've been following Gordo's easy pan cyan tek and am at the stage where I have almost fully colonized substrate in a tote, and the tek calls for a thin layer of casing mix made out of 2-2-1 parts of peat moss, vermiculite, and water, with a bit of calcium hydroxide/carbonate for pH purposes. I have the mix, but the issue is I don't have a pressure cooker, and I need to sterilize it in some way.

Now, hear me out: can I just put the mixture in a pan, and shove it in the oven for a set amount of time to heat-sterilize it? If yes, what do you think would be safest in terms of temperature and time? Should I cover the pan with aluminium foil? Should I poke holes in the foil?

I got this far, I would hate to mess it up at the last stage before fruiting lol

Thanks a lot

 

[Sakkadelic]

I imagine heating it in a pan would messup the water content, not sure how much foil would help preventing that. I'd put it in a jar with a hole in the lid filled with polyfill or closed with micropore tape, and then cook it in a closed saucepan similar to how PF cakes are cooked. I am not well experienced with growing mushrooms, only a couple cubensis grows under my belt, but that's what comes to my mind.

 

[Nydex]

I imagine heating it in a pan would messup the water content, not sure how much foil would help preventing that. I'd put it in a jar with a hole in the lid filled with polyfill or closed with micropore tape, and then cook it in a closed saucepan similar to how PF cakes are cooked. I am not well experienced with growing mushrooms, only a couple cubensis grows under my belt, but that's what comes to my mind.

The water content shouldn't be an issue, I think the 1 part water in the recipe is there to properly bind everything, because after the casing is done the tek calls for heavily spraying down the surface with water, so that would take care of the moisture. Once that's done, the tote is to be subject to 3 waterings a day, ensuring the substrate can never dry out.

And I imagine cooking the mix in a saucepan (I image something like a double boiler method?) wouldn't ever reach the high temps required for sterilizing, i.e. 250F/120C?

 

[Sakkadelic]

Yeah that makes sense, for casing the water content isn't critical as it will be sprayed.

Often substrate or casing is not sterilized but pasteurized, it will be exposed to air right away before it gets colonized. But if the tek calls for sterilization maybe it works better that way.

 

[Nydex]

Yeah that makes sense, for casing the water content isn't critical as it will be sprayed.

Often substrate or casing is not sterilized but pasteurized, it will be exposed to air right away before it gets colonized. But if the tek calls for sterilization maybe it works better that way.

That was my thought process as well, but I suppose Gordo calls for sterilizing the casing mix as well just to decrease the contamination chance. Fully eliminating it makes no sense in the context of substrate exposed to air, and sprayed with tap water

I guess I'll try and roast it in the oven at 120C for like 3 hours and hopefully that's enough, unless someone has another suggestion.

I'll definitely get a proper pressure cooker for my future grows.

 

[doubledog]

Ime casing mix works better when pasteurized. I always had contamination issues with sterilized material.

 

[Nydex]

Ime casing mix works better when pasteurized. I always had contamination issues with sterilized material.

To someone inexperienced with growing mushrooms such as myself, that sounds counterintuitive. Could you please explain to me why you think that happens? I'd expect the opposite.

 

[Jamie01]

You end up killing off all the beneficial bacteria? That has been my assumption from what I recall anyway. I do not grow the species you are currently growing though.

 

[Sakkadelic]

To someone inexperienced with growing mushrooms such as myself, that sounds counterintuitive. Could you please explain to me why you think that happens? I'd expect the opposite.

Because on a dead (sterilized) substrate organism that land can easily take hold (if the conditions are appropriate) while on a live (pasteurized) substrate the good organisms can fight and prevent incoming organism taking hold.

 

[doubledog]

I don't really know the reason why it happens. Conventional explanation is that there are some bacterias which keeps pasteurized material not prone to contamination by other unwanted lifeforms, but are not detrimental for mycelium.

 

[Nydex]

Ok, that makes sense, thanks for explaining. So theoretically I should stand a better chance of not contaminating by putting the casing mix in a few jars with polyfill-plugged holes in the lids and cooking them in boiling water for some time instead of roasting it in the oven. Considering the tek says I should try and sprinkle the casing mix over the substrate without touching it with my hands, working with jars instead of a single massive pan would probably make that job much easier.

How long do you think would be optimal to pasteurize for?

 

[doubledog]

I've always pasteurized casing substrate in half filled jars covered with loose screwlids in the oven at 75°C for 45-60 minutes, then left to slowly cool to RT.

Btw. beginner's luck is quite important factor in mushroom growing.

 

[Sakkadelic]

Ok, that makes sense, thanks for explaining. So theoretically I should stand a better chance of not contaminating by putting the casing mix in a few jars with polyfill-plugged holes in the lids and cooking them in boiling water for some time instead of roasting it in the oven. Considering the tek says I should try and sprinkle the casing mix over the substrate without touching it with my hands, working with jars instead of a single massive pan would probably make that job much easier.

How long do you think would be optimal to pasteurize for?

No that would still kill the good bacteria, it should be kept around 70° C. I suggested the jar method as a way of achieving almost sterile (live organisms would die but endospores can survive) material which is good enough for PF tek and I believed would be for the purpose of casing in gordo tek.

There are crude recipes for pasturisation without temp control but probably work best at for specific amounts and type of substrate.

 

[Nydex]

Right, right, I'm a bit tired, sorry. Ok, I'll try the loosely-lidded jar in oven method then. That should work well enough.

 

[bezevo]

you can easly pasturise using turkey roasting bag in oven , put moistend substrait or casing mix in roasting bag cpl smal holes for a vent .
then place the bag in half inch or so water bath, in a desposable foil roasting pan. then set oven for your target temp
..what umm 160f to 180f ,
you can use a cheapo logstem brewing dial thermomator to check adjust internal temp

or some variatons of this ,, just off top head