Sous Vide, botulism?

Discussion in 'Food & Cooking' started by mustaroad, Dec 12, 2010.

  1. mustaroad

    mustaroad

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    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?
     
  2. eastshores

    eastshores

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    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
    1. below 36.5°F (2.5°C) for up to 90 days,
    2. below 38°F (3.3°C) for less than 31 days,
    3. below 41°F (5°C) for less than 10 days, or
    4. 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.
     
    Last edited: Dec 12, 2010
  3. mustaroad

    mustaroad

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    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.
     
  4. petemccracken

    petemccracken

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    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.
     
     
  5. mustaroad

    mustaroad

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    ok, I will do that. Thanks fo the info chefs.
     
  6. the-boy-nurse

    the-boy-nurse

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    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.
     
  7. kyheirloomer

    kyheirloomer

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    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.
     
  8. mustaroad

    mustaroad

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    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 )
     
  9. petemccracken

    petemccracken

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    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
     
     
  10. redzuk

    redzuk

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    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.  
     
  11. mustaroad

    mustaroad

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    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).
     
    Last edited: Dec 15, 2010
  12. petemccracken

    petemccracken

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    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???
     
     
  13. mustaroad

    mustaroad

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    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.
     
  14. chrislehrer

    chrislehrer

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    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.
     
  15. mustaroad

    mustaroad

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    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...).
     
  16. the-boy-nurse

    the-boy-nurse

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    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.
     
  17. phatch

    phatch Moderator Staff Member

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    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.
     
  18. the-boy-nurse

    the-boy-nurse

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    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.
     
  19. petemccracken

    petemccracken

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

    byrdie

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