What is Pasteurization?
To “pasteurize” is to heat food to a temperature for a certain amount of time in order to reduce enough of the pathogens to deem it safe. We often pasteurize in sous vide cooking.
In the fridge, bacterial action and reproduction slow way down; we can keep food in there for days or weeks without worrying about pathogens growing. And at the temperatures reached when we boil or bake food, the bacteria are killed. It’s between those low and high temperatures that bacteria are happiest, so that’s where extra care is called for.
When food sits between 40°F/4°C and 140°F/60°C, it is often said to be in the “danger zone” for bacterial growth. It’s between these temperatures that potentially harmful bacteria can thrive. But what is not often referenced is that danger—and, thus, safety—isn’t just about temperature. It’s also about time. “Most people, when they talk about food safety, they oversimplify,” explains Baldwin.
For example, the FDA recommends cooking chicken breast meat (which is comprised of 5 percent fat) to 165°F/74°C in order to pasteurize it. When the center of the meat reaches that temperature, virtually 100 percent of Salmonella is killed immediately. When brought to 160°F/71°C, it takes 14 seconds to kill the Salmonella. At 155°F/68°C, it takes 50 seconds. At 150°F/65.5°C, our favorite temperature for chicken, it takes 3 minutes. We don’t recommend cooking chicken at 136°F/58°C—it’s a little more like chicken sashimi, really—but you can. It will just take 69 minutes at that temperature to be safe.
With enough time, most food pathogens are killed at 130°F/54.5°C, according to the FDA and Baldwin. For our sous vide recipes, this is our magic number. We cook almost everything either at or above that temperature. (When cooking in a water bath set to 130°F/54.5°C, the food will eventually become that temperature as well.) As an extra precaution, if we plan to cook meat below our magic temperature, the first thing we do is sear it in a hot pan in order to kill off any bacteria on the surface before we circulate (for example, see Butter-Basted Rib-Eye Steak).