Tuesday, January 29, 2008

More humidification ideas

I just received an email from another reader, Drew N., about another method for maintaining humidity in the curing chamber.

It would seem that a 50/50 mix of propylene glycol and distilled water will maintain somewhere around 70% RH. I'm told this would be considerably cheaper than using the beads or sheets I mentioned yesterday, since PG is about $8/pint. I'm not sure where you can buy it, but I can't imagine it being that difficult to source. Again, I have no idea how fast or slow this method changes the RH, but it might be worth a try.
PS: It does seem to be FDA approves, and food safe based on the Wikipedia entry.


gan911 said...

PG is used by cigar enthusiasts as well to control humidity...as far as getting it...i think its available from drugstores (CVS, walgreens, etc.)

Jasonmolinari said...

Thanks gan911, i forgot to mention in the post, the idea came from cigar humidors.

ken peters said...

Just started reading your blog. What a great resource.

You should be able to order Propylene Glycol from any of the large chem-lab distributors. Both VWR Scientific and Sigma Aldrich carry it.


Anonymous said...

Propylene Glycol is used as a food additive and in human medicine. Please do NOT confuse it with Ethylene Glycol, howere, the common atifreeze for automobiles. Ethylene Glycol is very toxic.

EagleCycle said...

Yes, one of the best blogs about sausage. congratuldations !

I am new and living in China where having totally different knowledge set than western cuisine, I am very keen on learning western cooking,bakery and butchery. I am learning making sausage recently, and spent a quite of time to understand fermentation, curing, bacteria, discease ....... I brawsed your equipment list too. one of my question is how you measure water activity? I looked into Chinese manufacture of instrument measuring aw, it seems one of the most costly instrument I can say, not sure how much might cost in US?

I also searched a lot sources in China regarding thermo hygrometer. some producer told me that their instrument can be integrated with room air conditioner and altrasonic humidifier to automatically control the temperature and RH level. I am amature in this area, not sure if this is true or not that simply binding three equipment can make a automation of thermo-hygro controlling? if this is realisable, I think it won't be too expensive to convert a small room into a curing chamber, and one can do many type of sausages

Jasonmolinari said...

Thanks, i'm glad you enjoy the blog.

I do not measure water activity directly. I measure weight of the sausages as they cure, and using that information and how they feel, i know when they are ready. Generally, when the sausage has lost about 30-45% of it's weight, it's ready to be eaten.

What you've found about the thermohygrometer is correct. It can be found in a single instrument that is used for room air conditioners, but normally these have to be wired into a circuit with relays of some sort. The ones for home air conditioners do not have a high voltage output

The ones i've been using you can plug other stuff right into them, so that the humidifier or the fridge is switched directly. If you can get some help from someone on wiring and combining the thermometer and hygrometer, there should be no problem using it..it should work. But it might be more complicated and require some additional circuits to work.

Maybe try explaining to your supplier what you're trying to do, and see if he can help you. Maybe bring him pictures of the hygrometers and thermostats i have posted on here so you can show him that they run the fridge and the humidifier directly. Maybe he can help.

Good luck!

Daniel said...

Hey Jason I was checking out your blog about a month ago. But I couldn't remember where I got the PG I use in my humidor. I seem to remember you need to get a food grade quality PG.I don't know if this place carries a Propylene Glycol USP/EP (PG USP/EP)quality you should call them to confirm. But anyway this place sells a gallon for about Twenty dollars it's even cheaper if you buy a drum Seventeen dollars per. :-D
Great blog I hope to start curing meats some day just not ready to commit just yet. keep it up.

Daniel said...

OOPS, forgot to paste the link.

Jasonmolinari said...

Thanks for the info on the PG Daniel. I'll keep it in mind if i ever need a drum of it :)

Jimmy said...


I have been experimenting with the propylene glycol for the past few days, and am ready to throw in the towel. The setup:

I have converted my stand-up freezer into the proto-curing chamber. The thermostat works just fine, and I also purchased two thermo-hygrostats -- two because the first one measured the humidity of the "inside" unit (the one that goes on the door) and I obviously am interested in the humidity of the "outside" unit (the one that goes in the chamber).

In the bottom of the (former) freezer I have a large aluminum tray with 50 / 50 propylene glycol and water.

Using the second remote theromo-hygrostat, I was never able to get the RH in the fridge above 60%. It would mostly hover around 57%.

We disabled the timer for the auto-defrost feature on the fridge, thinking that it might be robbing the propylene glycol / water from its utmost abilities to humidify. But that didn't work.

Next, I tried adding sponges to the tray, thinking that the increased surface area provided by the sponges would allow for greater diffusion of water into the air. That didn't work, either.

Finally, I wondered if the thermo-hygrostat might be miscalibrated. So I put the first thermo-hygrostat into the chamber and let it sit there overnight. At this point, Unit 2 (on the door) reads 57% RH and Unit 1 (inside the chamber) reads 53% RH.

I believe I am going to have to go the more expensive route of a hygrometer + humidifier. I thought I would post my experiences here in case there might be someone who has had success trying this route. Even if 57% is "good enough" for some applications, I want to have greater control over RH anyway.

One question (and forgive me if I've asked you before): does the ultrasonic humidifer serve as a canine torture device? I have three dogs who will share the room part-time with the curing chamber.

Jasonmolinari said...

Jimmy, not having dog, i don't know how they are affected by the ultrasonic humidifiers.
I'm sorry to hear the propylene glycol + water ddn't work. Have you tried putting a small computer fan near the tray to speed evaporation?
If your freezer is frost free and actually running, chances are the water mixture just can't keep up with the drying of the refrigeration cycle. Even with the auto defrost removed, the water is still being pulled out of the air and condensed somewhere.