Sous Vide, botulism?

6,367
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Joined Feb 1, 2007
I'd take those wikipedia numbers with a very large grain of salt. Have no idea where they came from, and they're questionable at best.

For instance, boutulism bacteria cannot be killed at 212F. If that were so, a simple boiling water bath would be all that's necessary to preserve low-acid foods. Botulism bacteria dies at 240F plus. And, while we're at it, you cannot kill spores. They aren't living creatures.

While 185F to denature the toxin certainly will work, it's unnecessary. CDC says 175F. Phil has sources that claim 165. So I'd like to see the wikipedia sources.

The wiki article sure makes it sound like 35% is a low water content. It's not. Typically, when using a dehydrator, you dry foods to a moisture content of about 7%. I seriously doubt that something which is one-third water would have any problem supporting bottulism bacteria.

In short, a typical wikipedia article. Take it for what it's worth.
 
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Joined Feb 1, 2007
I have always thought that high temperature was useless against the toxin.  I can't wait to tell this to someone.

And not particularly high at that, Byrdie. To put it in perspective, water starts to simmer at 180F. Which means you don't have to even simmer the foodstuff to denature the toxin---unless you accept the wikipedia data.
 
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Joined Sep 18, 2008
Well, so much for Wikipedia, let's look to the U.S.F.D.A.: http://www.fda.gov/Food/FoodSafety/...thogensNaturalToxins/BadBugBook/ucm070000.htm
...Foodborne botulism (as distinct from wound botulism and infant botulism) is a severe type of food poisoning caused by the ingestion of foods containing the potent neurotoxin formed during growth of the organism. The toxin is heat labile and can be destroyed if heated at 80°C for 10 minutes or longer..
If my calculations are correct, 80°C = 176°F
 
6,367
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Joined Feb 1, 2007
Close enough to the CDC's 175F, Pete.

Used to be the USDA recommended that if there was any doubt to boil the food for at least ten minutes. While that would certainly destroy the toxin, there would also be serious quality issues with the food. Which is why most home canners, at least, operate on the premise: if in doubt, throw it out.

But if you look at all the available data, the whole botulism thing is blown all out of proportion. For some reason, USDA, FDA, etc. all jumped on it as the bogyman. Yet, the figures don't support that. In fact, no insurance company would even keep actuarial tables on anything with a risk that low.

In terms of prevalence, in fact, salmonella is a much more serious food poisoning issue.
 
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Joined Jul 2, 2011
Hi, I am a newbie in sous vide cooking: have been experimenting a little bit and have one question about the safety and botulism. I have just cooked a lamb shoulder (36 hours at 63C), which worked out really great. After the dinner we have some left over meat and I am now a bit concerned if I can actually refrigerate it safely for a day or two. Am I right assuming that botulism spores will only produce the toxin in anaerobic environment? Which would mean that if not vacuum sealed the left overs should be ok in the fridge? THanks a lot for help in advance
 
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Joined Apr 3, 2010
It should be ok after a quick chill down . Do not reseal or cryovac again, just cover with plastic wrap.
 
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Joined Mar 11, 2012
I just dry-air cooked a 7lb sirloin tip roast in my turkey roaster for 8 hours.  I have a new PID Temp Controller hung in the air inside the roaster.  I did pierce the beef to insert another internal temp probe alarm.  I started the roaster temp at 165F for 25 minutes to help kill any outside bacteria, then dropped the cooking temp to 150F.  It's taken 8 hours to get the internal center to 145F.  I figured that I'd keep it there for about 20 additional minutes.  So was this a safe cooking strategy for this 7lb roast?  I just don't want to get anyone sick.
 
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Would it have have anything to do with once the the item has been sealed in the air tight bag, It deprives bacteria of oxegen that it needs to survive?
 
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Joined Aug 23, 2012
I am trying to cook beef ribs at 56'C for 72 hours. I am about half way through and I am repeatedly experiencing the same problem. Some of the bags are developing pockets of air. I have the impression that air is being generated or outgassed from the meat or, what worries me, something (could it be bacteria?) in with the meat. I have rebagged a couple of pieces, but I can see one of the bags is beginning to fill with gas again. Does anyone know what this is and what I should do?
 

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