DEAR DR. BLONZ: On a TV show, I watched a hospital nutritionist cook a chicken breast by putting it in a resealable plastic bag, submerging it in a pan of water, bringing the water to a boil, turning off the heat and letting the pot rest for two hours. I am skeptical of this method, because it doesn’t seem that the meat stays hot enough for long enough to be safe. In fact, it sounds like a recipe for promoting bacterial growth, not to mention the dubious wisdom of boiling a plastic bag. What do you think of this cooking method? — A.M., Castro Valley, California
DEAR A.M.: First, it should be noted that, while it may sound similar, the method you describe is different from “sous vide” — an established cooking method gaining popularity in recent years. (More on sous vide below.)
The main concern with any poultry, no matter how it’s cooked, is salmonella bacteria. In the process you describe, a chicken breast is put in a plastic bag, which is then put into a pan of water that’s brought to a boil (212 degrees F). That’s well over the temperature needed to kill those bugs. However, meats are only as safe as the least-cooked portion, and chicken breasts come in a range of sizes and thicknesses.
Our question, then, becomes: Once the heat is turned off, is the thermal mass of the pan and the boiled water sufficient to raise the internal temperature throughout the entire piece of chicken to a level sufficient to zap the bacteria?
According to the FDA, the safe minimum temperature for poultry is 165 degrees F (see b.link/food51). But it should be understood that time is a factor, as well as temperature. For example: Most recommendations say to cook poultry until a thermometer reaches at least 165 degrees F in the thickest part of the meat. It will then be safe to eat. But if the poultry is cooked to 145 degrees F and kept at that temperature for at least nine minutes, you could accomplish the same elimination of bacteria. That, however, requires closer attention to the cooking process, not a one-time temperature read. (Check out the interesting discussion of time and temperature poultry cooking at b.link/chicken97.)
So, how can we be assured that the technique you saw will produce chicken that is safe to eat? That TV technique presents risk variables, with no real way of assuring the safety of the results. The bag must be a material suitable for boiling, and since air is not a great conductor of heat, there must be a step to draw all air out of the bag, such as with a vacuum-sealing device. Handling must eliminate risks of cross-contamination from surfaces that touched the uncooked poultry. Another variable is how rapidly the water temperature drops after boiling. It will cool at one speed if using a metal pan in a cool room, and another if resting post-boil on a conductive surface that drains the heat.
These factors — the bag material, the presence or absence of air, the chance of cross-contamination, and the water-cooling speed — are all potential risks. So without testing, this is not a method I could recommend.
You might instead consider the sous vide method. Here, the food is put into a bag, the air is removed, and the bag gets submerged in water that is then heated to around 145 degrees F and kept there for one to four hours. The advantage here is that the sous vide device heats the water to a specific temperature, then circulates and maintains it for a set period. (For more on sous vide, see b.link/vide10.)