Lie — Food must be cooked at a high temperature to kill bacteria

The Story

We've always been told that food, especially meat, must be cooked until it has a high internal temperature in order to kill whatever bacteria are on or in the meat. Eating meat that hasn't been prepared this way can be unhealthy and possibly even fatal.

I recently received a health bulletin from the federal government giving a chart of safe internal cooking temperatures. It says that whole chicken must be cooked to an internal temperature of 180 degrees Fahrenheit.


Can you imagine how tough and dry the white meat must be after being cooked until it is 180 degrees internally?

Sterilization and the 7 log10 pasteurization standard

Sterilized food, which contains absolutely no living bacteria, can be stored in sealed containers at room temperature for long periods of time. This is commonly used for UHT treated milk and individual serving coffee creamers. The food is safe, but unfortunately the ultra-high-temperature changes its taste, generally for the worse.

The alternative, pasteurization, kills most bacteria, but not all. Health professionals recommend that food be cooked enough to kill all but one in every ten million germs in order to consider it safely pasteurized. Such food can then be safely eaten immediately or stored in a refrigerator for several days.

The base-10 log of 10,000,000 is 7 (the number of zeros), hence the name of this standard.

Temperature versus bacterial survival

Doubling about every 20 minutes, most bacteria multiply rapidly at temperatures between 40 and 140 degrees Farenheit.

The birth rate isn't the only thing affected by temperature though. At higher temperatures, bacteria start dying, but not all at once. The higher the temperature, the faster they die. At above about 130 degrees Farenheit, bacteria die faster than they reproduce. So even at relatively low temperatures, the death rate can be higher than the birth rate, and given sufficient time the bacteria will eventually die off.

Consider salmonella in chicken. At 165 degrees, almost all bacteria are killed almost immediately, while at 135 degrees it takes well over an hour for enough to die to achieve the 7 log10 standard. Similarly, 145 degrees takes less than 10 minutes, while 155 degrees less than 1 minute.

Killing bacteria isn't simply a matter of temperature; it requires both temperature and time.

Temperature versus food texture and taste

The taste and texture of meat varies greatly depending upon the duration and temperature that it is cooked at. Some cuts of meat contain a lot of collagen or connective tissue that requires higher cooking temperatures for proper tenderization. But other cuts are already tender, and higher temperatures only make them drier and tougher.

Chicken breast for example has little fat or connective tissue. Cooking it to an internal temperature in the low 140s produces a tender juicy meal. Cooking it to an internal temperature of 180 degrees produces a tough dry stringy disaster.

Similarly some meat can be cooked at a relatively low temperature but require many hours to become tender.

Again, cooking isn't simply a matter of temperature; it requires both temperature and time.

Proper cooking

To properly cook, one first needs to know the correct internal temperature for the type of meat. Then, based on that temperature, one can easily determine the minimum cooking time to achieve pasteurization once that internal temperature has been reached.

As an added benefit, so long as that required internal temperature is not exceeded, the food can be left to cook for extra time without fear of it's actually overcooking. Overcooking is caused by too much heat far more than by too much time.

In the case of chicken breasts, I'd allow at least a half hour for the internal temperature to reach 143 degrees, another half hour to guarantee pasteurization, and then if it happens to cook at that temperature for another half hour or even another hour or two (maybe I got distracted), it's still going to be tender and juicy, not burnt.

This long-time low-temperature cooking can be achieved quite easily using a technique known as sous vide.

After cooking meat, it's a good idea to let the meat sit for a few minutes after cooking to allow the heat to distribute more evenly and for the juices to be reabsorbed as it cools. So even if one is going to cook by other methods, that five minute waiting time before serving will continue to pasteurize the meat. If the meat reaches only 150 rather than 165, letting it sit and keep warm for five minutes will be more than enough time to complete the process.


So why do health and government agencies keep telling us that meat must be cooked at such high temperatures?

The answer is simply that it is very easy for everyone to remember, and that it is fool-proof. If chicken is cooked to 165 degrees (or even worse, 180 as suggested for whole chicken), it's guaranteed that effectively all the salmonella will be killed.

We'll all be safe and healthy while chewing on our rubber chicken.