Here's another one from the same site on chicken breast:
How to Cook Sous Vide Chicken Breast | The Food Lab
I think the section on food safety is especially interesting:
Sous Vide Chicken and Food Safety
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There is a misconception about what constitutes a safe cooking temperature for meat. If you've ever taken a
ServSafe class, you've probably heard of the 40–140°F (4–60°C) "danger zone," the temperature range in which bacteria supposedly thrive. You've been given urgent warnings to avoid serving any food that has remained within this range for a total time of four hours. You've probably also heard that in order for chicken to be safe, it ought to be cooked all the way to 165°F.
Yet sous vide–style precision cooking often takes place well below the 140°F mark, in excess of four hours, and my own recommendation for cooking chicken falls in the 145–150°F (63–66°C) range, well below the 165°F target we've all learned. What gives? Is my sous vide chicken still safe to eat?
Here's the thing: Industry standards for food safety are primarily designed to be simple to understand, usually at the expense of accuracy. The rules are set up such that anybody, from the turn-and-burner at Applebee's to the fry-dunker at McDonald's, can grasp them, ensuring safety across the board. But for single-celled organisms, bacteria are surprisingly complex, and despite what any ServSafe chart might have you believe, they refuse to be categorized into a step function.
The upshot is: Food safety is a function of both temperature
and time.
What the USDA is looking for is a 7.0 log10 relative reduction in salmonella bacteria in chicken. That is, a reduction that ensures that out of every 10,000,000 bacteria living on that piece of chicken to start, only one will survive.
Take a look at this simplified chart I drew using data from the
USDA's guide.
Pasteurization Time for Chicken With 5% Fat Content (7-log10 lethality)
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Temperature Time
136°F (58°C) 68.4 minutes
140°F (60°C) 27.5 minutes
145°F (63°C) 9.2 minutes
150°F (66°C) 2.8 minutes
155°F (68°C) 47.7 seconds
160°F (71°C) 14.8 seconds
165°F (74°C) Instant
Or, if you prefer it in graph form, here you go. Regardless, this follows a pretty straightforward logarithmic decay curve: The hotter you get, the faster bacteria die, and the faster the rate of bacteria dying increases.
As you can see, at 165°F, you achieve pasteurization nearly instantly. It's the bacterial equivalent of shoving a stick of dynamite into an anthill.
At 136°F (58°C), on the other hand, it takes a little over an hour for the bacteria to slowly wither to death in the heat. In fact, you can even pasteurize chicken as low as just above 130°F (54°C), but I don't recommend it. Partly because there's a risk that your sous vide device is mis-calibrated by a degree or two, but, more importantly, because chicken cooked to 130°F has a very soft, almost raw texture that is simply not appealing.
It's important to note that these times represent the minimum safe cooking time for chicken
after it has reached those temperatures internally, which can take up to 45 minutes or so. To be safe, I recommend tacking on an extra hour to the time recommended in the government charts when starting with chicken from the fridge, or two hours when starting with frozen chicken.
