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mycoryfic
Stranger
Registered: 08/13/13
Posts: 56
Last seen: 9 years, 2 months
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Pasteurization Problem
#18745439 - 08/23/13 02:25 AM (10 years, 5 months ago) |
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Hi, im having problems with pasteurizing my straw.
I did it as usual, cut it in 1 inch pieces boil a large pot of water and wait till it goes down to 170 farenheit and add the straw and cover.
I come 30 minutes later to check the temperatures like i always do and the temperature of the water where all the straw is compressed is 152 farenheit and the water on top was like 140 farenheit ,so i started heating up the water and only the water with the straw heats up quickly while the water on top is at a 20 farenheit difference,
does anyone have problems like this and what should i do so i got the same temperature always ?
I think i know now why i failed most of my straw projects.
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forrest



Registered: 11/16/12
Posts: 1,011
Loc: The Netherlands
Last seen: 4 years, 6 months
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Re: Pasteurization Problem [Re: mycoryfic]
#18745641 - 08/23/13 04:38 AM (10 years, 5 months ago) |
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when you add the water to the straw, the straw and container are gonna ''absorb'' a part of the heat, so you better add the water at 180 or higher. i had trouble with heat pasteurisation, but since i started adding hydrated lime to it, it worked well every time.
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forrest



Registered: 11/16/12
Posts: 1,011
Loc: The Netherlands
Last seen: 4 years, 6 months
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Re: Pasteurization Problem [Re: forrest]
#18745647 - 08/23/13 04:41 AM (10 years, 5 months ago) |
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also, in what kind of container you you let it sit? if you use a well insulated box like freezer, you shouldn't have to add heat anymore during the pasteurisation. just figure out what temp you need the water to be when you add it to the straw, so that in the first few minutes the water will drop to about 170 f.
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eddieblake
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Registered: 10/12/09
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Re: Pasteurization Problem [Re: forrest]
#18745711 - 08/23/13 05:27 AM (10 years, 5 months ago) |
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I use two rubbermade tubs, one inside the other. i get the water to almost 200 before adding straw. close the lid and cover with a fleece blanket. the temp drops to about 160 to 170, and will stay at 160 for hours.
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ebruckner
Stranger


Registered: 11/29/12
Posts: 25
Loc: Northeast Ohio
Last seen: 8 years, 8 months
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Re: Pasteurization Problem [Re: mycoryfic] 1
#18745951 - 08/23/13 07:39 AM (10 years, 5 months ago) |
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I think it is detrimental to use water that is much higher than 150, as it kills beneficial bacteria such as lactobacilli that help inhibit pathogens before the oyster mycelium takes hold. Also, it is a waste of time and energy to boil the water first. I use 55 gallon drums, and heat the water to 150 degrees. I turn the heat off and then add a basket of tightly-packed, chopped straw with weights on the top to keep it submersed. Yes, the straw does absorb some heat, but it has a VERY low heat capacity and I haven't seen the core temperature drop below 145, which is perfectly adequate for pasteurization if you allow it to soak for 1 hour. Any longer than that is also detrimental to the beneficial bacteria.
Heating the water after adding the straw does absolutely NOTHING to affect the temperature of the bulk of the straw. In order for that to happen, you have to have CONVECTION through the interior of the straw, which simply does not occur due to the density of the tightly-packed straw. Furthermore, the lack of convection also keeps the inside of the bulk of the straw from losing much heat. The only way for heat to get into or out of the core is through conduction, which is extremely slow. Note that after draining, if left in the barrel, my straw's core temperature is still 90-100 degrees after 18 hours.
I have done about 40 or so barrels of straw this way, with only one batch that had any signs of contamination, and that was caused by slowly growing, nearly dead spawn that had been damaged by heat in shipping during a hot week. Even then, it took almost 2 weeks to see any signs of the green mold that eventually ruined the logs.
The bottom line is that I think your contamination problems are caused by over-pasteurization, with too high of a temperature. Try heating to 150 degrees and soaking for 1 hour. Since you are using a much smaller vessel, you should wrap your pot in blankets during the soak to prevent the outside of the vessel from cooling excessively, which may allow the outer inch or so of straw from pasteurizing effectively.
I hope this helps.
-------------------- "Unthinking respect for authority is the greatest enemy of truth." -Albert Einstein Polecat Pines Mushroom Farm
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Forrester
aspiring sociopath


Registered: 02/05/13
Posts: 9,351
Loc: Northeast USA
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Re: Pasteurization Problem [Re: ebruckner]
#18745962 - 08/23/13 07:43 AM (10 years, 5 months ago) |
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^^ Good information. I remember someone saying pasteurizing on the lower end improved yields as well. Don't remember who or where though...
-------------------- Repugnant is a creature who would squander the ability to lift an eye to heaven, conscious of his fleeting time here. ------------------- Have some medicinal mushrooms and want to get the most out of them? Try this double extraction method.
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mycoryfic
Stranger
Registered: 08/13/13
Posts: 56
Last seen: 9 years, 2 months
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Re: Pasteurization Problem [Re: ebruckner]
#18750037 - 08/24/13 02:40 AM (10 years, 5 months ago) |
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Quote:
forrest said: also, in what kind of container you you let it sit? if you use a well insulated box like freezer, you shouldn't have to add heat anymore during the pasteurisation. just figure out what temp you need the water to be when you add it to the straw, so that in the first few minutes the water will drop to about 170 f.
I usually do it in a rubbermaid tub on the ground in my basement but i always forgot to put something under since the cement is cold.
But yesterday i was using my PC since there was alot of straw but not enough to do a big rubbermaid tub like mine.
Quote:
forrest said: also, in what kind of container you you let it sit? if you use a well insulated box like freezer, you shouldn't have to add heat anymore during the pasteurisation. just figure out what temp you need the water to be when you add it to the straw, so that in the first few minutes the water will drop to about 170 f.
Quote:
ebruckner said: I think it is detrimental to use water that is much higher than 150, as it kills beneficial bacteria such as lactobacilli that help inhibit pathogens before the oyster mycelium takes hold. Also, it is a waste of time and energy to boil the water first. I use 55 gallon drums, and heat the water to 150 degrees. I turn the heat off and then add a basket of tightly-packed, chopped straw with weights on the top to keep it submersed. Yes, the straw does absorb some heat, but it has a VERY low heat capacity and I haven't seen the core temperature drop below 145, which is perfectly adequate for pasteurization if you allow it to soak for 1 hour. Any longer than that is also detrimental to the beneficial bacteria.
Heating the water after adding the straw does absolutely NOTHING to affect the temperature of the bulk of the straw. In order for that to happen, you have to have CONVECTION through the interior of the straw, which simply does not occur due to the density of the tightly-packed straw. Furthermore, the lack of convection also keeps the inside of the bulk of the straw from losing much heat. The only way for heat to get into or out of the core is through conduction, which is extremely slow. Note that after draining, if left in the barrel, my straw's core temperature is still 90-100 degrees after 18 hours.
I have done about 40 or so barrels of straw this way, with only one batch that had any signs of contamination, and that was caused by slowly growing, nearly dead spawn that had been damaged by heat in shipping during a hot week. Even then, it took almost 2 weeks to see any signs of the green mold that eventually ruined the logs.
The bottom line is that I think your contamination problems are caused by over-pasteurization, with too high of a temperature. Try heating to 150 degrees and soaking for 1 hour. Since you are using a much smaller vessel, you should wrap your pot in blankets during the soak to prevent the outside of the vessel from cooling excessively, which may allow the outer inch or so of straw from pasteurizing effectively.
I hope this helps.
Thanks that helps alot, im gonna start doing it at 150 farenheit then.
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ebruckner
Stranger


Registered: 11/29/12
Posts: 25
Loc: Northeast Ohio
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Re: Pasteurization Problem [Re: mycoryfic]
#18754352 - 08/25/13 07:57 AM (10 years, 5 months ago) |
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Great! Let us know how it works out for you.
-------------------- "Unthinking respect for authority is the greatest enemy of truth." -Albert Einstein Polecat Pines Mushroom Farm
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