Introduction
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 to 140°F (0 to 60ºC) “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 (74ºC).
Yet sous vide-style precision cooking often takes place well below the 140°F (60ºC) mark, in excess of four hours, and our own recommendations for cooking chicken fall in the 145 to 150°F (63 to 66°C) range, well below the 165°F (74ºC) target we’ve all learned. What gives? Is it 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 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 in chicken is a 7.0 log10 relative reduction in salmonella bacteria. 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. At 165°F (74ºC), you achieve pasteurization nearly instantly. It’s the bacterial equivalent of shoving a stick of dynamite into an anthill. At 136°F (58ºC), 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 meats as low as just above 130°F (54ºC), but we don’t recommend that for poultry. Chicken cooked to 130°F (54ºC) has a very soft, almost raw texture that is simply not appealing.
In a standard oven, it’s difficult to safely cook meat to anything below around 150ºF (66ºC) to 145ºF (63ºC) — you just can’t hold its temperature in that range for a long enough period of time. With a Precision Cooker, we can cook as low as we’d like. So long as bacteria are actively being destroyed, it’s just a matter of timing.
Pasteurization Charts
It’s important to note that the times below represent the minimum safe cooking time for meat after it has reached those temperatures internally, which can take up to 45 minutes or so. To be safe, we recommend tacking on an extra hour to the time recommended in the government charts when starting with food from the fridge, or two hours when starting with frozen meat.
| Temperature | Time |
|---|---|
| 136ºF (58ºC) | 68.4 minutes |
| 140ºF (60ºC) | 27.5 minutes |
| 145ºF (63ºC) | 9.2 minutes |
| 150ºF (66ºC) | 2.8 minutes |
| 155ºF (68ºC) | 47.7 seconds |
| 160ºF (71ºC) | 14.8 seconds |
| 165ºF (74ºC) | Instant |
Note that these times are specifically for salmonella. Because it’s hardier than many common bacteria, pasteurizing with respect to salmonella will render your meat relatively safe. If you are particularly nervous about food-borne illness, you might consider pasteurizing with respect to an even hardier bacterium, like listeria. Simply extend holding times threefold.
| Temperature | Time |
|---|---|
| 136ºF / 58ºC | 64 minutes |
| 140ºF / 60ºC | 28.1 minutes |
| 145ºF / 63ºC | 10.5 minutes |
| 150ºF / 66ºC | 3.8 minutes |
| 155ºF / 68ºC | 1.2 minutes |
| 160ºF / 71ºC | 25.6 seconds |
| 165ºF / 74ºC | Under 10 seconds |