# Sous Vide, botulism?



## mustaroad (May 15, 2010)

So its anarobic, but how can the food locked up in a little pouch being cooked at 140'f for 3 days stay in the 'danger zone' for so long without the bacteria thriving?


----------



## eastshores (Oct 23, 2008)

I recently asked about sous vide and doneness.. moderator Greg replied with this link, a goldmine:

http://amath.colorado.edu/~baldwind/sous-vide.html

The key part for your question being:

Moreover, while keeping the food sealed in plastic pouches prevents recontamination after cooking, spores of Clostridium botulinum, C. perfringens and B. cereus can all survive the mild heat treatment of pasteurization. Therefore, after rapid chilling, the food must either be frozen or held at

below 36.5°F (2.5°C) for up to 90 days,
below 38°F (3.3°C) for less than 31 days,
below 41°F (5°C) for less than 10 days, or
below 44.5°F (7°C) for less than 5 days
to prevent spores of non-proteolytic C. botulinum from outgrowing and producing deadly neurotoxin (Gould, 1999; Peck, 1997).

By the way, I don't think this is an issue regarding the cooking, rather if you freeze them this way. The article goes on to talk more about it though.


----------



## mustaroad (May 15, 2010)

I will look into these things you've posted. BTW does this imply that sous vide is generally a process used for processed foods and not generally for restaurant items? -based on the fact that you immediately freeze the sealed foods instead of holding toem for service.


----------



## petemccracken (Sep 18, 2008)

Mustaroad said:


> I will look into these things you've posted. BTW does this imply that sous vide is generally a process used for processed foods and not generally for restaurant items? -based on the fact that you immediately freeze the sealed foods instead of holding toem for service.


No, that is just another use of Sous Vide. As a first step, you might want to read the reference cited: http://amath.colorado.edu/~baldwind/sous-vide.html and it will answer a majority of your questions.

Sous Vide requires a degree of understanding as it is NOT a simple "do this" process but a much more complex process with many alternative solutions that lead to the same result, safe, tasty, food.


----------



## mustaroad (May 15, 2010)

ok, I will do that. Thanks fo the info chefs.


----------



## the-boy-nurse (Aug 9, 2010)

We're talking about spores, and toxins. Most bacteria is easy enough to kill with heat, the problem w /  C. botulinum, C. perfringens and B. cereus is that they are spore forming. Spores are very resistant to harsh environmental conditions, including high/low PH, Hypertonic solution, high and low temperatures. They are relatively harmless however, in spore form- as they are inactive. The problem occurs when the spores are given a window of opportunity to become active bacteria, and reproduce. In the absence of oxygen, anaerobic metabolism is required and in the case of Clostridium botulinum, a rather potent neurotoxin is the byproduct of anaerobic metabolism. The toxins are not bacteria but rather the result of bacterial metabolism or in some cases bacterial death. These toxins often survive the cooking process and are capable of causing illness despite being heated or re-heated.

Just for clarification most food probably has trace amounts of all kinds of bacteria in it (especially raw foods). But as long as the amounts are small and they are not particularly virulent strains of bacteria, the hydrochloric acid in you're stomach, the competition w/ normal flora of the gut and a healthy immune system takes care of those contaminants.  If any of those are compromised however one is at greater risk for infection. Contrary to what the manufacturers of Nexium would have you believe, a healthy concentration of stomach acid is a good thing.


----------



## kyheirloomer (Feb 1, 2007)

Just as an example of TBN's point, raw honey is loaded with boutulism bacteria. Yet most of us enjoy eating it with no ill effects.

According to CDC, boutulism toxin is destroyed at sustained temperatures of 175 F. I've never been able to find a definition of "sustained." But based on other food-safety procedures, I would guess a minimum of ten minutes.


----------



## mustaroad (May 15, 2010)

ok, my concern comes from stories like the holiday classic; Grandma cooks a stuffed bird in the oven at 170 degrees for 20 hours, whole family gets botulism and falls down like birds. How does Sous Vide avoid the exponential multiplication of such pathogens while taking it's sweet time getting up to temperature? (still working on Baldwins Sous Vide page, thick stuff )


----------



## petemccracken (Sep 18, 2008)

Mustaroad said:


> ok, my concern comes from stories like the holiday classic; Grandma cooks a stuffed bird in the oven at 170 degrees for 20 hours, whole family gets botulism and falls down like birds. How does Sous Vide avoid the exponential multiplication of such pathogens while taking it's sweet time getting up to temperature? (still working on Baldwins Sous Vide page, thick stuff )


As pretty well explained in Baldwin's Sous Vide, the "key" is the difference in thermal conductivity of air and water AND that pasteurization is a time-temperature function, not just temperature.

Sous vide is generally portioned, or at least portion-sized, vacuum sealed, fairly thin, and in close contact with the water. As Figure A-2 of Baldwin's Sous Vide guide shows, the internal temperature reached nearly the water bath temperature within, oh, 20-30 minutes.

Conversely, "Grandma's turkey" is a large mass (lots of thermal inertia) being heated by hot air so a majority of the turkey probably doesn't get out of the "danger zone" for several hours.

We all "know" that turkey has to be heated to, what, 185°F to be "safe", right? "Safe" being equivalent to pasteurized, right? Well, look at the government pasteurization table C:11 and you will see that zero seconds at 165°F is sufficient for pasteurization. In fact, 150°F for five minutes works as well as does 136°F for 64 minutes


----------



## redzuk (Dec 7, 2010)

Mustaroad said:


> ok, my concern comes from stories like the holiday classic; Grandma cooks a stuffed bird in the oven at 170 degrees for 20 hours, whole family gets botulism and falls down like birds. How does Sous Vide avoid the exponential multiplication of such pathogens while taking it's sweet time getting up to temperature? (still working on Baldwins Sous Vide page, thick stuff )


Never heard of botulism in the stuffing. Usually canning something, infused oil. On the net I found a case of baked potato's as the cause, wrapped in foil, baked the day before and left at room temp until serving the next night. Isnt sous vide process usually just an hour or so? Even so I would cool it in an ice bath to get temp below 40' as quick as possible.


----------



## mustaroad (May 15, 2010)

Pete McCracken: Ah, I assumed that since items are cooked at lower-than-poaching temperatures (assumption) wouldn't act so fast. I guess I was thrown off by the remarks of overnight sous vide cooking (which doenst follow the time-temp. safety guidelines unless it is cooked within 4 hours and continues to cook to achieve a fiberless protein).


----------



## petemccracken (Sep 18, 2008)

Mustaroad said:


> Pete McCracken: Ah, I assumed that since items are cooked at lower-than-poaching temperatures (assumption) wouldn't act so fast. I guess I was thrown off by the remarks of overnight sous vide cooking (which doenst follow the time-temp. safety guidelines unless it is cooked within 4 hours and continues to cook to achieve a fiberless protein).


Hmm, I think you may be misinterpreting the Food Code requirements, the "four hour" rule, does NOT say it must be cooked within four hours, only that it must be above 135°F (140°F in some jurisdictions) within four hours and it cannot be removed from the heat until pasteurized, which involves the "doneness" temperatures that everyone has on their mind, i.e. 155°F for ground beef, 165° for poultry, etc. FWIW, those are the zero time pasteurization temperatures.

Here in California, we are permitted to hold food indefinitely at 135°F or greater. IMLE, most sous vide cooking is done above 135°F and the food, in pouches, reaches that temperature relatively quickly, say within, oh, not more than 10-15 minutes.

The Food Code temperatures specified as minimum cooked to temperatures are for 15 seconds or less. For sous vide, most health inspectors require a HACCP plan to be in place which probably uses the time-temperature pasteurization tables approved by the FDA, USDA, and other federal agencies.

Sous vide is a complex process that involves numerous factors, procedures, and practices to produce safe, edible products. IMHO, unless you understand it thoroughly, DO NOT ATTEMPT IT! It is NOT for the inexperienced or the uninformed.

Besides, why do you think the NYC health department has such a problem with Sous Vide???


----------



## mustaroad (May 15, 2010)

I don't know mutch about NY except that crackheads will try to sell you their rags and prostitutes in mini skirts are more common than bus stops. Thanks for the leads and warnings. Ill sure to fully figure out the Sous Vide method before I attempt it.


----------



## chrislehrer (Oct 9, 2008)

The "grandma's turkey" problem and the potential of botulin toxicity in sous vide are completely different things. The turkey isn't anaerobic: the problem is that if you don't cook it hot enough, long enough, you've got a great breeding space for salmonella. Also a nasty thing to get, but not botulism. Botulism is anaerobic, which is why it's a danger in improperly canned foods and things like that. As a previous poster noted, the problem with botulism isn't the bacteria but the toxins they produce; the problem with salmonella is the bacteria, so if you kill it, it's dead, end of story.


----------



## mustaroad (May 15, 2010)

That makes sense because bacteria cannot multiply in anaerobic conditions. The botulism probably feeds off something in the food -- would it be because the food wasn't properly packaged or sterilized?. Salmonilla multiplies to dangerous amounts if it's in suitable conditions for a long enough window of time (temperature, moisture, protien, oxygen, acid...).


----------



## the-boy-nurse (Aug 9, 2010)

Mustaroad said:


> That makes sense because bacteria cannot multiply in anaerobic conditions. The botulism probably feeds off something in the food -- would it be because the food wasn't properly packaged or sterilized?. Salmonilla multiplies to dangerous amounts if it's in suitable conditions for a long enough window of time (temperature, moisture, protein, oxygen, acid...).


Many bacteria are quite prolific in anaerobic conditions. C. botulinum is one of them. The difference is byproduct of metabolism. For example Human muscle cells work most efficiently aerobically, and the byproduct is carbon dioxide. However when oxygen demand exceeds supply muscle metabolize anaerobically and the byproduct is lactic acid. When C. botulinum engages in anaerobic metabolism (like in a bag or can free of O2) then the byproduct is botulism toxin. These toxins can be destroyed but it requires extreme temperature. toxins are not alive, bacteria are. You don't kill a toxin you denature it. You can kill C. botulinum with pasteurization temperatures, but not its spores, or it's toxin.


----------



## phatch (Mar 29, 2002)

The toxin can be denatured. Temps above 160 will do that. And no, I'm not confusing it with salmonella temps. The temp KYH quoted is higher than that but we must be using different source material.


----------



## the-boy-nurse (Aug 9, 2010)

Upon further review- Phatch you are quite correct I was confusing _B. cerus_ toxin w/ botulism toxin. B. cereus toxin "survives" at higher temperatures. However so do _C. botulinum_ spores.

See you're witnesses, I can admit when I'm wrong- someone tell my wife.


----------



## petemccracken (Sep 18, 2008)

Not sure of the accuracy but :http://wiki.answers.com/Q/How_do_you_denature_botulism_toxin states


> Despite the bacterium's fearsome reputation, _C. botulinum_ is still a microbe, and can be killed using a little basic microbiology. Preserving recipes utilize at least one of these 5 microbiological facts, good recipes often use several.
> 
> 1. _C. botulinum_ bacterium dies at 212 F/ 100 C.
> 2. _C. botulinum_ spores die at 240 F/ 116 C.
> ...


----------



## byrdie (Nov 24, 2010)

phatch said:


> The toxin can be denatured. Temps above 160 will do that. And no, I'm not confusing it with salmonella temps. The temp KYH quoted is higher than that but we must be using different source material.


That is enlightening. I have always thought that high temperature was useless against the toxin. I can't wait to tell this to someone.


----------



## kyheirloomer (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.


----------



## kyheirloomer (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.


----------



## petemccracken (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


----------



## kyheirloomer (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.


----------



## noosch (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


----------



## chefedb (Apr 3, 2010)

It should be ok after a quick chill down . Do not reseal or cryovac again, just cover with plastic wrap.


----------



## noosch (Jul 2, 2011)

Thanks a lot for your answer.


----------



## chase212327 (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.


----------



## chef cozza (Mar 22, 2012)

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?


----------



## alexmay (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?


----------

