DIY Curing Chamber Build - Any Suggestions/Critiques on this Build?

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geostriata

Meat Mopper
Original poster
May 18, 2021
260
165
California
Hi folks,

I laid out the parts for a simple curing chamber with temperature and humidity control. I started with a giant box fan in the chamber, but then read about case hardening, etc... So I figured I should post my current design and see if anyone has thoughts or critiques.

Right now, it's simply:
* Inkbird Temperature control for the freezer (same approach I use for my beer fermentation)
* Inkbird Humidity control, hooked up to an ultrasonic humidifier and a dehumidifier (I had to buy another one, since the stupid touch switch turns off after power loss. So I switched to one with a physical switch).
* Hanging racks (that I cut from the racks that came with the freezer
* Two axial fans for air movement (but not as much movement as the box fan, lol) and equalizing temps/humidity.

Here's how it looks:
1711398717954.png


I have it set to 70% RH and 52F, and it reliably holds both.

My main question is if there's anything folks think I missed or need to do before I start setting this up more permanently. Main concern is airflow or fan placement, but I'm also not sure how important that is beyond simple movement like the above.

Thanks!
 
X2....get rid of the fans. The cooling of the freezer along the walls will generate plenty enough air movement...and also when the humidifier and dehumidifier kick on....

If you think you HAVE to have a fan....run it through the cooling controller to kick on when the freezer is on. Only use the smallest fan and put it on the absolute lowest setting it has...and blowing in a corner, not onto the meat.....
 
X2....get rid of the fans. The cooling of the freezer along the walls will generate plenty enough air movement...and also when the humidifier and dehumidifier kick on....

If you think you HAVE to have a fan....run it through the cooling controller to kick on when the freezer is on. Only use the smallest fan and put it on the absolute lowest setting it has...and blowing in a corner, not onto the meat.....
Hmm, I worry about heat stratification (for the same reason I add a fan to my smoker). When brewing beer in these freezers, the temp and the bottom is cooler than the temp at the top by a few degrees. Probably won't matter in the long run for meat, but I'm just trying to do it right.

One possibility is to orienting the fans vertically... but I'll take your advice for now and nix them. Thanks!
 
, the temp and the bottom is cooler than the temp at the top by a few degrees. Probably won't matter in the long run for meat, but I'm just trying to do it right.
Won't matter. Precise temp. is not necessary, the range is what is important...below 60*F and above about 45*F. Trust me- case hardening is a much bigger concern for the home producer....
 
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Won't matter. Precise temp. is not necessary, the range is what is important...below 60*F and above about 45*F. Trust me- case hardening is a much bigger concern for the home producer....
Sounds good! I'm especially worried about case hardening, given how much I need to dry my non-fermented 6.0pH snack sticks.
 
I need to dry my non-fermented 6.0pH snack sticks.
It is NOT safe to dry non-fermented snack sticks at drying chamber temps.!!!! You need the pH to drop BELOW 5.3 for a safety hurdle. For sticks with a pH of 6, dry them at refrigerator temps.

What percentage of salt did you use? if it is less than 2.5% you are rolling the dice and taking a very dangerous gamble with your life!
 
It is NOT safe to dry non-fermented snack sticks at drying chamber temps.!!!! You need the pH to drop BELOW 5.3 for a safety hurdle. For sticks with a pH of 6, dry them at refrigerator temps.

What percentage of salt did you use? if it is less than 2.5% you are rolling the dice and taking a very dangerous gamble with your life!

It's above 2.5 percent. I added extra salt, per your recommendation in another thread.

In any case, thanks for the warning. There was a suggestion that was made to hang at room temp for 4-5 days, which didn't pan out, even for the fermented variety. This is why my compromise was to try for a few days at 55F instead.

In any case, my basis for justifying this approach was in the USDA guidelines for non-acidified dried sausages (https://www.fsis.usda.gov/sites/default/files/media_file/2021-02/33_IM_RTE_SS_Process.pdf)

In that article, the mention that for non-acidified dried sausages, the requirements were: "the products are cooked to 146F (63.3C) and then dried to a water activity of ≤0.85. Due to the higher pH, these products must be dried to a lower water > activity (less moisture) than fermented products to achieve shelf-stability. The higher pH makes the product more difficult to dry and tight control of temperature, humidity and airflow is critical."

There was no mention of a requirement of ph at 5.3 in the guidelines (maybe your 5.3 target is necessary for folks that cook under the recommended IT of 146F?).
 
Ah, found the 5.3ph reference in other USDA guidlines. However, the guidelines are oriented to folks who aren't cooking to an IT of 146, and are instead relying on "degree-hours" at lower temps combined with a 5.3ph (primarily to combat S. aureus) . Here's the link, page 50: https://www.fsis.usda.gov/sites/default/files/media_file/documents/FSIS-GD-2023-0002.pdf

In short, it seems like it's as I suspected:
1. You can hit an IT of 146, and
2. Suitable salt/cure your sausage, and as a result,
3. You can dry above fridge temps until AW < 0.85.

If you don't hit an IT of 146, then that leads to the PH requirements *and* more nuanced low-temp cooking requirements, it seems.

That's my read, but I'm absolutely not challenging your advice. I'm just trying to understand, learn, and back it up with USDA guidelines.

In appendix 7, they talk about "Fermentation Deviations," where they discuss ph values of 5.6 to 6.0.

A couple highlights:
* "If product takes less time to dry, then the drying process will not be as effective as was shown in the support as the longer drying time can increase stress on the bacteria (Gunvig et al.,2017; Mutz et al., 2019)."
* "After dry-curing and equalization, products are typically dried above refrigeration temperatures so that additional water (moisture) is removed from the product. Saltcured products are dried to meet a water activity level sufficient to achieve shelf-stability by preventing the growth of microorganisms (e.g., water activity ≤ 0.85), especially toxigenic microorganisms such as S. aureus" (however, they note that S. aureus is killed with high-temp cooks).
 
Ah, yes... heat treatment. That was not mentioned in your post. Heat treatment for acidified sausages is lower, 130*F, for pasteurization (fairly certain the time is minimum of 30 minutes for LOG5). This is due to the much stronger safety hurdles of high salt and low pH.

As long as the sausages have lost 20-25% weight during the cooking/heat treat cycle, then you can dry in a chamber @55*F. If that condition is not met, I'm not certain of the safety in the practice-especially with a pH of 6. I recommend talking to someone experienced with HACCP plans for further guidance to ensure safety.

The thing about fermentation using a starter culture are the many benefits. Acidification, Competitive exclusion, Faster drying, and Bio-protective chemicals released into the sausage that act as antibiotics that keep some of the more resilient bad bacteria at bay. I can not think of any good reason NOT to do it.
 
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Ah, yes... heat treatment. That was not mentioned in your post. Heat treatment for acidified sausages is lower, 130*F, for pasteurization (fairly certain the time is minimum of 30 minutes for LOG5). This is due to the much stronger safety hurdles of high salt and low pH.

As long as the sausages have lost 20-25% weight during the cooking/heat treat cycle, then you can dry in a chamber @55*F. If that condition is not met, I'm not certain of the safety in the practice-especially with a pH of 6. I recommend talking to someone experienced with HACCP plans for further guidance to ensure safety.

The thing about fermentation using a starter culture are the many benefits. Acidification, Competitive exclusion, Faster drying, and Bio-protective chemicals released into the sausage that act as antibiotics that keep some of the more resilient bad bacteria at bay. I can not think of any good reason NOT to do it.
Yeah, I was gung-ho about fermentation initially. Was excited about the extra drying, extra protection, and if only the taste wasn't awful then I'd still be doing it. I tried limiting the amount of dextrose to a scant 1.5g/lb, but even then it was no good.

Definitely agree that if I get is tasting OK, fermentation is an added plus for the extra safety.

I suppose I could look to a milder culture. However, I do know that my target stick doesn't use fermentation. I've already fermented 4 batches, and I somewhat tire of wasting the meat...

However, because of this discussion, I took another look at the cultures out there and just discovered Bactoferm T-SPX! It doesn't lower the ph as much (so flavor should hardly be impacted, but it does assist in drying! I'll look into that! I could also try F-LC at 77F, but I think I'll try the drying chamber, T-SPC, and F-LC as a last resort...

In any case, I'm glad you're not as concerned given I get to an IT of 146. My heart certainly jumped when I read your post!
 
If you have not ordered the book:

View attachment 692669
buy it today. Very good resource...
Bought it yesterday :)

Oh, forgot to mention, I ran the Staphtox model as recommended in the USDA docs. I don't know the initial value of S. aureus, so I just ran the model at the highest allowed value. Also gave it the highest possible water value (75%). Report came back saying "No risk" fwiw.

Useful tool. Here's a link: https://apps.teknologisk.dk/dmri-predict/#!/models

You've got to convert your mug/g for your Nitrate value, but I did the math and if you're using 1.1g/lb of cure #1, the value is 150.
 
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Yeah, I was gung-ho about fermentation initially. Was excited about the extra drying, extra protection, and if only the taste wasn't awful then I'd still be doing it. I tried limiting the amount of dextrose to a scant 1.5g/lb, but even then it was no good.

Definitely agree that if I get is tasting OK, fermentation is an added plus for the extra safety.

I suppose I could look to a milder culture. However, I do know that my target stick doesn't use fermentation. I've already fermented 4 batches, and I somewhat tire of wasting the meat...

However, because of this discussion, I took another look at the cultures out there and just discovered Bactoferm T-SPX! It doesn't lower the ph as much (so flavor should hardly be impacted, but it does assist in drying! I'll look into that! I could also try F-LC at 77F, but I think I'll try the drying chamber, T-SPC, and F-LC as a last resort...

In any case, I'm glad you're not as concerned given I get to an IT of 146. My heart certainly jumped when I read your post!
To dial in the pH drop effectively, you really need a pH meter. You can buy an Apera knock off for less than $50 bucks.
Take the starting pH after you have added any wine to the meat as it will drop the pH slightly. Note the pH. I like to use 5.25 as a target pH. Subtract the two to figure the pH drop you need from fermentation. Now.....write this down....0.25g of sugars per kilogram of meat will drop the pH by 0.1 points.

Only other tip is don't use any culture that has pediococcus acidilactici bacteria as it fermented EXTREMELY fast and is efficient at converting sugars to lactic acid.

*see pages 46-47 in that yellow book....

I recommend T-SPX...
 
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point of note- you have to account for ALL sugars you introduce into the meat paste for fermentation. That includes sugars contained in your spices (red pepper powders like cayenne, paprika, calabrian) have a significant amount of sugars and must be accounted for if you want to stop the pH drop above 5.0....otherwise those sugars will be fermented and you will overshoot your target pH by a lot....
 
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BTW, if you are in the United States, you can call the FDA and speak to someone and they can line you out as far as the requirements. It's a free service....well, you pay for it through taxes......but this is what they do.
 
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To dial in the pH drop effectively, you really need a pH meter. You can buy an Apera knock off for less than $50 bucks.
Take the starting pH after you have added any wine to the meat as it will drop the pH slightly. Note the pH. I like to use 5.25 as a target pH. Subtract the two to figure the pH drop you need from fermentation. Now.....write this down....0.25g of sugars per kilogram of meat will drop the pH by 0.1 points.

Only other tip is don't use any culture that has pediococcus acidilactici bacteria as it fermented EXTREMELY fast and is efficient at converting sugars to lactic acid.

*see pages 46-47 in that yellow book....

I recommend T-SPX...
Yep, I've got a probe based ph meter that I've been using. I tried to use my Apera with a ratio of distilled water and meat slurry -- it felt not very precise and I didn't trust it.

One batch with 3g dextrose / lb and it got to 4ph, and my next batch at 1.5g dextrose got it to 4.5ph. So possibly more sugar in the mix than I realized. Didn't realize Cayenne and Paprika had sugar! TIL... But yeah, your formula sounds like a good starting point.

And lol, just to cover my bases, I ordered F-LC as well. Pediococcus Acidilactici in that one, haha. Bactoferm did say reduced temp results in mild acidification... So that might be one way to try that, but definitely T-SPX first...
 
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If you have not ordered the book:

buy it today. Very good resource...

It's really a great book, and I learned a lot, but wow, these Mariansky guys really are bacteriophiles. Makes me think he'd go to a steak house, order the ribeye extra rare, and toss it in his home-brought vat of lactobacillus before eating. Not all meat requires fermentation to be good. I'll still be cooking my ribeyes med. rare, thank you.

Take a look at pg 82-83, where he talks about heat killing bacteria and bacteria being necessary for good meat flavor. Possibly out of frustration at the idea of cooking, or to make a point, he says:
"If cooking is required it makes sense to fully cook meat to FDA recommended 160F (72C) internal meat temperature. This way you'll kill all bacteria and you won't have to worry about Salmonella, E.coli and others."

There's no way he actually believes that! (he contradicts that many times in the book).

In any case, I got a few sentences towards my non-fermented category at the end of the book on page 142. Just a few sentences.

"Generally, after stuffing these sausages are partially cooked to 146F (63C), and then dried to a water activity of < 0.86 (Aw growth limit for Staph. aureus). Due to the higher pH, these products must be dried to a lower water activity than fermented products to achieve shelf stability."

Of course, I had been delaying ordering it because it's exactly what I expected (Fermentation is in the title, after all). Still, glad I got it though.
 
I'm eventually wanting to set up a drying chamber. From what I understand people avoid chest freezers, right? Are they workable because I have a chest freezer I'm not using, but I'm waiting to pick up a fridge of some sort.
 
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