Saturday, February 23, 2008

sous-vide, and safe food handling

First things first. I've gathered this information by researching the web. I'm not an expert on this subject by any means and I suspect I'm not entirely correct on some of these points, but here is the information that I've gathered.
E. coli or salmonella needs to exist first for you to get e. coli or salmonella poisoning. It doesn't spontaneously generate. Just because you eat chicken that did not reach 165 degrees is not going to give you salmonella. If there is e. coli or salmonella contaimnation, it would make it on the news, and then the meat would be recalled.

I understand that people usually do cook chicken to 165 degrees, but not beef. Hasn't it occured to you that the restaurant needed to cook beef to at least 145 to kill e. coli, yet you ordered your steak medim rare, and you know medium rare means it hasn't come above 125.

So what is really happening here is, the restaurant is taking a calculated risk that, if e. coli outbreak were to be discovered, they would be informed before it is served to their customers. Whenever you order an egg sunny-side up, you are taking a calculated risk. And people who bbq and cook anything at home below medium well are also taking calculated risks.

First lets talk about conventional cooking, not sous-vide cooking. Conventional cooking relies on a specific temperature, where if the core/center of the meat reaches a certain temp, the e. coli and salmonella is killed because it only needs to stay at that temp for a second or two.

e. coli is killed at 145 degrees F (65 celsius)
salmonella is killed at 165 degrees (73-74 celsius)

e. coli can cause serious and life threatening complications.
salmonella is usually not life threatening and most people recover from it without treatment after 4-7 days.

General cooking guide (conventional cooking), center/thickest part of the meat needs to reach
meat: 145 (10 degrees higher for ground meats)
seafood: 145
poultry: 165-175

With sous-vide, you can rely on lower temperatures provided they hold that temperature for a longer time.

You can effectively kill e. coli at a lower temperature than 145 degrees if you hold that temp for a longer period of time. The draw back is that its an exponential curve. So techinically, the sous-vide method has the potential to provide safer food that is cooked at lower temperatures. For example if you cook poultry at 165, and you hold it for 2 seconds kills the same amount of bacteria that you would kill at 145 degrees by holding that temp for 3 minutes, and you would do the same if you cooked at 130 degrees for 1.5 hours. I think at 125 we're talking 6-8 hours, and 120 is like 3 days. For more information, you can check out

There is one catch with sous-vide. On top of the risk of salmonella and e. coli, there is an added risk of botulism. The technique of killing botulism in vacuumed environments is not as crafted and researched like e. coli and salmonella. But to prevent it, you can follow these steps.

  • Don't prepare the food, and freeze it for more than 30 days.

  • Safely handle your food during preparation.

  • Don't let the meat sit in the non frozen section for more than 2 days before preparation.

  • Never let parishable ingredients or any meat sit out during prepartion.

  • Avoid cross contamination.

  • Freeze immediately after preparation.

  • Pasteurize ingredients whenever possible.

  • Store your food below 1 degree Celsius (and don't let it come above 1 C unless you are going to prepare it.)

At the moment, I'm more interested in preparing good food with the sous-vide method, not preparing packaged food days or weeks ahead.Which means I'll be preparing fresh ingredients, vacuum sealing it, and putting it in a water bath right away. So there is no concern there. I'm planning on cooking my chicken to 165 no problem. As for e. coli, steak is never good cooked more than medium rare so I'm going to take a calculated risk by buying from a good source, and relying on myself to not buy or cook funny looking meat.

No comments:

Post a Comment