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Easy steam pasturization method/s [merged]

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#1 spacecowboy


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Posted 23 January 2006 - 12:02 PM

Was doing some reading, and came across this bulk sterilizing tek used in Thialand:
Mushroom Growers Hand Book 2: Shiitake, pg.113 (PDF pg.4)

#2 blackout



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Posted 23 January 2006 - 12:11 PM

I have always mentioned bulk when people complain about fractional sterilization taking too long. Load up one of these monster barrels with a $5 heating element and fill it to the brim with jars. heat on 3 different days. Imagine what a 50 gallon autoclave costs.

#3 cyberd0c



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Posted 06 July 2006 - 06:43 AM

Here's a step by step of this steam pasteurization tek (modified from the mushroom compost maker found here composter).
material used:
18 gal sterilite tub
28" x 1.5" heat resistant pipe with suitable cap
hot steam humidifier
1500 watt dimmer switch
wiring to connect dimmer switch
three bamboo or metal sticks cut slightly longer than tub width
perforated heavy duty plastic tray (seedling tray)can be replaced by wire mesh
5 or 10 Liter water bottle with fitted nozzle in the cap and 5/16" OD x3/16" ID vinyl tubing
meat or turkey thermometer
4" (or longer) piece of vinyl for drainage pipe

The tub is prepared by drilling a 1.5" hole in the middle of one of the short sides to fit the steam rod. on the opposite side a 1/2" hole is drilled to fit the drainage pipe which is glued flush with the bottom. on the long side 10" from the bottom three 1/4" holes are drilled at equal distances, these will serve to hold the bamboo rods that will support the plastic tray.

The steam rod is prepared by drilling three or more 1/2" holes all on the upper side to allow steam to pass thru.
The lid of the tub is perforated in the center to allow for the thermometer to be inserted.

The steam rod is inserted first,holes facing upward, then capped.
The bamboo rods go next and the tray seated on top.

Then you fillup the tray with whatever wetted substrate you want to pasteurize. (has to be wetted to field capacity). If the holes in the tray are too big you can use a fine wire mesh to hold the finer substrate and prevent it from dropping and clogging the steam pipe.
Fill up the steam generator and coonnect it to the steam rod (I used three layers of tin Alum foil wrapped around the steam outlet to tunnel the steam into the rod.

The tub has to be elevated up to the level of the steam generator (I used the box of the humidifier which was perfect height lying on its side).

Connect to electricity and play with the dimmer to increase or decrese the amount of steam and regulate the temp. keeping it between 140-160 F.

After 4- 6 hours you have a pasteurized bulk substrate ready for use as soon as it cools off.
ps. you need to control the steam leaking from under the lid because it will condensate and wet the whole area aroung the tub (which is OK if done outside, but a hell of a mess if done indoor), silicon seal with vaseline technique is good.don't forget to put a container under the drainage pipe otherwise you will have a bigger mess from water that collects inside the tub.

The water bottle is to keep a steady supply of water to the humidifier but is not necessary if you want to do it manually every couple of hours.It is tricky to be able to deliver water at a rate that will not flood your humidifier and keepup with the water lost thru steam, you have to experiment with the hole at the other end of the vinyl tubing (only a tiny pinhole is needed) and the bottle needs to be elevated above the level of the humidifier and vented to prevent vacuum from collapsing the bottle.

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#4 dillinger



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Posted 04 December 2006 - 11:35 AM

I would like to turn an old deep freezer into a steam pasterizer. The deep freezer is in the mid-20 cubic foot size. What sized steam generator would i need for something that big. I have found some pics in the archieves that use a wallpaper steam for a large cooler box. it would be the same idea, except, larger.

Originally i was going to run a tankless water heater and pump, but that would use way more electricity.

#5 Soliver1



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Posted 04 December 2006 - 04:44 PM

Woof - that's some bulk you're talking there, not sure if you'll find anyone here who knows about / operates at that level, or if they'd fess up if they knew, but what the hell....



#6 TVCasualty


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Posted 04 December 2006 - 10:40 PM

If you're thinking about a tankless water heater, then you probably have the funds to get a steam generator for steam rooms. I installed one last year in a bathroom I was remodeling (the plumber did the hookups, I just mounted it to the wall and did the tile), and the area it was supposed to ensteam was about 140 ft^3.

Here's a smaller model you might could make work:

It's about $600, plus the control ($60). I don't know if it is suitable for your application, but I don't see why not. Steam rooms aren't sealed and insulated like a chest freezer, so I believe you could get the temp. you need with this. There could very well be other, cheaper ones out there. This one was listed at http://www.steamsaun...products_id/135

If you try this and it works please let us know! This is territory for a better-funded experimenter than me...good luck!

And "ensteam" is a word I just made up.

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#7 Hippie3



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Posted 05 December 2006 - 12:36 PM

i suppose you could run a wallpaper steamer thru some duct into the freezer,
set it up on timed intervals to maintain the temp.

#8 dillinger



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Posted 05 December 2006 - 11:44 PM

i suppose you could run a wallpaper steamer thru some duct into the freezer,
set it up on timed intervals to maintain the temp.

several people that have used the wallpaper steamer say you can barely use for applications greater then 100L (large cooler). Maybe they are impatiant, but i hardly doubt that it will work on a full sized deep freezer. Its output is too low.

TVcasualty, thats pretty much what i need for now. I have been looking at several options and the steam is probably the most cost efficient in the long run.

I am working on making a more permanent pasterization, or steam box with hydraulics. for now i am going to just get a steamer and a hepa. It will be a mini PhaseII tunnel ;)

Thanks for the replies

#9 Guest_MycoGod_*

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Posted 06 December 2006 - 12:03 AM

I have three of those wagner/cooler deals and they work great. I think a wagner wallpaper steamer would work fine, they produce very hot steam. I tested one in a sealed cooler without any holes and it got up to 214F in 2 minutes. If one wouldn't do it, I know 2 would!

#10 dillinger



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Posted 06 December 2006 - 12:36 AM

how much straw was in your cooler...because air is easier to heat then solids

#11 Guest_MycoGod_*

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Posted 06 December 2006 - 01:53 AM

Of course, I load each up with approx. 45-50lbs of straw. It reaches internal temp of 170F with holes in the lid in approx. 10 minutes.

#12 dillinger



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Posted 06 December 2006 - 09:54 AM

thats very reasonable...absolutely exceptional actualy.

How big is your container dimesions and/or volume? Is the the wet weight of the straw or the dry weight?

Not sure exactly how much straw i am putting in my thing yet. i thinks its about 8lbs a cubic feet when 75% wet, according to stamets (1 ton = 250 cubic feet) so i would be doing about 200 lbs of straw.

#13 Hippie3



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Posted 06 December 2006 - 10:35 AM

seems to me the larger problem is pressure,
big masses of wet straw are hard to penetrate
you'd want ducting that went thru the straw leaking steam at various points,
kinda like a soaker hose does with water,
to get your steam into the core regions.
hot water could be piped thru too for heating.

#14 Guest_MycoGod_*

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Posted 06 December 2006 - 11:08 AM

See , which is mine. 120 quart liquid capacity on the cooler(s)

#15 TVCasualty


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Posted 06 December 2006 - 11:21 AM

The steamer I posted has a pressure relief valve set at 15 PSI, so although the pressure it produces is small (if the relief valve is set to 15, the operating pressure is probably only a few PSI) it's going to be higher than a wallpaper steamer. This means it would probably work well to push steam through the straw. Also, the steam comes out of a threaded connection, so instead of the standard steam head nozzle you could connect it directly to a pipe that snakes through the cabinet and maybe the straw itself. I don't know how heat resistant PEX tubing is, but a length of flexible PEX w/ holes drilled in it could be strung throughout the straw to disburse the steam evenly (and I'm sure that there is some type of appropriate flexible tubing if PEX won't work).

When I lived in the woods off-grid, I was using an RV water heater (propane) to heat the gravity-fed water system we used for the shower, etc. Anyhow, RV water heaters are designed to work with very low water pressure (and without electricity), so there might be two possible uses for one: 1) using a small pump and the water heater, circulate hot water through a closed-loop to keep the freezer cabinet hot while introducing steam through some other method or 2) pre-wetting the straw and using the closed loop hot water recirculation to heat the straw to pasteurization temperature without added steam. It'd be cheaper than an instant water heater.

You could unhook the heater part after the straw is pasteurized and circulate cold water through the pipe to quick-cool the straw so you can save time, conceivably.

Maybe you could build shelves and put the straw on them in the freezer to be sure there won't be a mass of unpasteurized straw in the middle, plus it would make running the steam/water pipes easier.

Lots of "maybes" and "potentially's" here. Hopefully someone will 'take one for the team' and spend the $$$ to try this out! And then post pictures! I'll keep on speculating for y'all since that's what my current budget allows. Sigh.

#16 wayback



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Posted 06 December 2006 - 06:23 PM

I have a Wanger wall paper steamer that I have successfully used to pasturize 5 gallon buckets of straw. So I don't really see why a larger area wouldn't heat and hold heat if insulated.

A few seasons ago I simply poked a hole in the bottom of the bucket and used a PC plate to place a straw and worm casting material onto, poked in a hole in the pillow case contining the material, and kept the temps betwwen 160-170. It worked great and I got the steamer for free.

Wish ya luck on your endeavor, yet remember to keep an eye on the temps. Because I tell ya what, those steamer can get upwards of 200 degrees if left unattened. They draw a lot of amps and might pose a fire hazard if not watched. Be cool.

#17 Invitro


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Posted 06 December 2006 - 06:32 PM

A drum heater on a 55 gallon drum with
a spigot down low for drianage would
work too. Plus it would cost less than
$200.00usd to setup. You would be
able to load 2 bales of straw then fill
to the top with water and adjust the
drum heater to 170 degrees.


#18 TVCasualty


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Posted 07 December 2006 - 10:05 AM

Those drum heaters look interesting. I think that if someone is going with drums, they should just use a propane burner. That's definitely the cheapest, and when looking at the drum heaters I noticed this performance graph:

That's 6.5 hours to get to 170 degrees with a 3000W heater! (It's not practical to use the smaller heater at all) The immersion style drum heater's performance wasn't much better, plus it draws 4000W and not many residences have electrical circuits that can handle 4KW.

A 5 Gallon bucket is about .65 cubic feet, or 1/30 the size of the old 20 cu.ft. freezer mentioned above, so the Wagner may not be up to the job, especially if the straw is loaded as one big mass.

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#19 Invitro


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Posted 07 December 2006 - 11:17 AM

If you you wrap the drum with a water heater insulating blanket
it will cut the heat up time down drastically. The 240v heater
only draws 5.5 to 6 amps which makes it fairly cheap to run.

#20 troutlips


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Posted 05 February 2007 - 07:25 PM I've been playing with a method for steam pasturizing small bulk substrates with an electric vegetable steamer.
This appliance was gift that has been languishing unused in my basement for some time.
The base of the unit contains an element that quickly heats water for the steam as well as a spring loaded timer.
A tray with a fine mesh screen sits in the base and a one liter sized cassarole type container sits on top of this tray.
Finally there is a clear plastic cover with holes in the top to let the steam escape,that fits snugly on top.
I discarded the cassarole part and inverted the clear cover.Now the steam comes in through those holes.
I lined the clear peice (now a container) with a pillowcase and filled it with my substrate mix (in this case, coir/verm/castings in equal parts).
Next, I cut a hole in the pillowcase to accomodate a candy thermometer that is sunk into the sub mix and seal the top with aluminum foil.
The unit is then plugged in and I wait until the thermometer read 200 degrees F. Then it is unplugged and the timer set to 60 minutes.
Carefully watching the tempurature, I noted that it stayed at 165F or above for more than an hour.
After using this method several times, even adding straw to the mix, little or no contammination has occured.The only time I had any green was after 6 flushes.
I like this method better than the hot water bath that I had been using because no draining is necessary afterwards, just cooling.
The only down side I can see is that due to the size of the container, the amount of sub I can process(at one time) is relatively small.

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