Go to the Article: Sous Vide Geekery
One of the most over looked parts about good health and cooking.
Thanks for including this in the class!
Great class as always, thank you!
I have read that Salmonella and E.Coli cannot penetrate muscle fibers and are only present on the surface of meats, like chicken breast for example. So I'm wondering if the entire surface area of a chicken breast is cooked to 165F, what is the risk of food poisoning if the interior is slightly below 165F. I see in some of your videos chicken being cooked to around 140F, if I remember correctly. I'm just a bit paranoid of getting food poisoning.
You guys are awesome!
Hi Evan, great question.
You've no doubt heard that the "interior of intact muscle is essentially sterile." This is a reasonable assumption for people with robust, healthy immune systems: almost all the food-borne pathogens are on poultry and not inside it. From a review article by Petra Luber in the International Journal of Food Microbiology (vol. 134, 2009, pp. 21–28) about Salmonella and Campylobacter species on and in poultry meat:
• Campylobacter was found on the surface of 62.3% of 3,235 samples and on the inside of 10.3% of 613 samples.
• The amount of Campylobacter inside was less than 1 cfu/g, while there was 10^4 to 10^5 cfu on breasts and 10^5 to 10^6 cfu on whole carcass. (Here, cfu stands for colony forming unit and indicates the number of active bacteria.)
• Only one study looked for Salmonella inside poultry and found it in 3.8% of 53 duck breasts.
But since a healthy person requires a dose of 10^5 to 10^7 cfu of most food-borne pathogens to become ill, it's unlikely that a healthy person would get sick from eating undercooked poultry where the surface was heated sufficiently. That's why we stress working clean and killing surface pathogens.
It's the immuno-compromised that need to be careful: they need only 1–10 cfu to become ill, so they'd do best using a time-temperature combination equivalent to the FDA's 2 min / 70 °C for everything (see, for instance, Table 1 that I generated for the NSW Food Authority's sous vide guidelines). Luckily, if you're a bit paranoid, my tables give times-temperature combinations for pasteurizing starting at 131 °F / 55 °C.
Thanks for the reply. Great information!
Colony forming units of bacteria is something I haven't heard of, I just want to make sure I fully understand. So if a healthy person does come into contact with Salmonella or Campylobacter and it is much less than a 10^5 does, like 10^2 or some other lower number, does that mean the pathogen isn't strong enough to harm them?
If someone was to ingest a very small sliver of a raw piece of chicken with a pathogen on it, would they become less sick or as sick as if they ate an entire chicken breast that was covered in the pathogens?
And one last thing, when they say to cook to 165F to get rid of Campylobacter and Salmonella, does the bacteria only die once it hits that target number? Or does it slowly die as the temperature climbs to that number? So maybe by the time it gets to 140F, for example, the cfu is reduced by half or something?
Does the advice of icing sous vide foods (if you're not going to consume immediately, I assume) apply to everything or just certain items- eg. Chicken liver pate or Creme brûlée?
Anything you don't plan to consume immediately should be chilled and refrigerated until needed. This is because cooking sous vide doesn't eliminate spores, only active pathogens; if there are spores, then they can regenerate and become active pathogens again during cooling. By cooling rapidly, you reduce the number of spores than can regenerate during cooling.
