As a single male who likes to cook and is also quite thrifty I bend the rules on FDA food safety a lot. I have been burned a couple of times, like when I left a tuna sandwich in my lunchbox at room temperature or when the leftover soup reached day 4 and I decided to eat it anyways. The effects of this was an upset stomach and maybe a little vomit. Not a big deal, but definitely not the ideal outcome. I recently read an article at the Curious Cook, Harold McGee’s food blog. Harold McGee is a food and science writer who penned On Food and Cooking: The Science and Lore of the Kitchen, the definitive guide to culinary science.
In his blog post titled, Bending the rules on bacteria (New York Times), Mr. McGee explores why some chefs ignore FDA guidelines (in their home kitchens, not in their restaurants, that would be illegal). He brings into question their validity since these practices seem to be ubiquitous amongst home cooks with no ill effects. Michael Ruhlman, author of Ratio and Elements of Cooking, wrote a blog post in April of 2011, detailing how he makes Chicken Stock. In this process he says sometimes he lets the stock simmer over night, and in a Tweet he leaves the chicken stock out on the stovetop all week. This is handy because you have stock at-the-ready and the long simmer time maximizes flavor and gelatin formation. You also don’t have to worry about freezing and storing and labeling the chicken stock.
The FDA designates the temperature range between 40F-180F (approx. 4C-83C) as the “Danger Zone”, or the temperature range where bacteria will flourish in your food. It is recommended that food not be left in this temperature range for more than 2 hours (1 hours if the ambient temperature is above 90F). In commercial processes, the FDA states that foods in the temperature range of 41F-135F should not be left out more than 4 hours. Mr. Ruhlman busts all these time limits by a healthy amount. Yet, Mr. Ruhlman and his family have not succumb to E. Coli or Botulism. What gives?
What Mr. McGee found was there are reasons that his family hasn’t gotten food poisoning from his chicken stock, but he is also flirting with danger with this process. The key to “safe” use of the chicken stock is boiling the stock prior to serving or including in whatever meal he is using it for. When the stock falls below 135F, bacteria present in the stock or that are introduced by the environments multiply at a ridiculously fast rate, doubling every 90 minutes at room temperature. A boil of 150F for 1 minute will kill almost all active bacteria in the stock. But there is another threat. As the bacteria grow in the stock, some may create toxins (chemicals which can make us sick). The most well-known and one of the most dangerous of these toxins is produced by Clostridium botulinum, which can cause botulism. If you check out that link, you’ll see the symptoms are not just an upset stomach. Luckily the toxin is inactivated by a boil at 185F for greater than 5 minutes.
Mr. McGee admits to allowing his stock to cool overnight at room temperature, to avoid heating the contents of his refrigerator with cold stock. O. Peter Snyder, the food scientist he consulted on this practice said that the overnight cool isn’t that big of a deal, because the extra few hours at room temperature are probably not enough to allow heat resistant spores to germinate.
So what’s the verdict? While it’s tempting to be lazy and allow foods to cool at room temperature overnight, it’s not a safe practice. The FDA guidelines should be followed in this instance. One way to speed up the cooling process so you can get the stock into the refrigerator without heating up everything else is an ice bath in your sink. Get the stock below 40F in the ice bath and then you can transfer to the fridge in the stock pot or in separate containers. Don’t forget to strain it first, this will help with cooling and removes some of the proteins and other gunk which could coagulate and cloud your broth.
A couple other really good food safety tips for the home were suggested by Dr. Snyder:
- Cool foods uncovered. This allows heat to escape and also prevents the accumulation of moisture in the vessel. No one likes soggy leftovers. Once the food is cool you should cover it.
- Don’t cool foods in mass any thicker than 2 inches. Once again this allows food to cool quicker.
- It’s been mentioned previously in this article, but don’t put hot food in the refrigerator. Leave the food to cool on a countertop and move to the fridge when it’s cool to the touch.
Another case where government regulations and chef’s are at odds are minimum safe temperatures. Kenji Lopez-Alt, Author of The Food Lab: Better Home Cooking Through Science, and regular contributor to the food website Serious Eats lays out a solid argument against following the FDA’s minimum safe temperatures for meat religiously. In his own words: “Take a look at the USDA’s basic cooking guidelines and you’ll see they recommend cooking foods to higher temperatures than anyone in their right mind would want to eat them at. In fact he blames chicken’s reputation as a dry meat on the USDA’s recommendation that chicken be cooked to 165F. As a man of science Mr. Lopez-Alt knew it wasn’t just 164F alive bacteria, 165F dead. Things just don’t work like that. So he dug into the regulations and found out that the USDA knew this as well. At 165F you achieve almost instantaneous sterilization in your dry piece of meat. A reduction of 10 degrees only requires the meat to stay at that temperature for 44.2 seconds, and at 150F you’re looking at 2 minutes 42 seconds.
The lowest Kenji recommends is 145F (which also happens to be his favorite temperature to cook chicken to) which requires 8.4 minutes. Kind of a long time. But don’t forget about carryover cooking. The temperature in your chicken will continue to rise once you remove it from the oven. In his experiments he found whole chickens cooked to 150F rose to 153F in the first few minutes out of the oven. After climbing to 153F the temperature stayed above 150F for a good 6 minutes. So you can easily meet the required time to make sure your chickens safe to eat, even at 145F, as long as you let it rest. Now, would I cook my chicken to 145F? I’ll stick with 150-155F personally, while 145F might be shown safe in Lopez-Alt’s experiment, it is kind of pushing it and salmonella does not sound like fun. Not to mention at 145F chicken has a completely different texture, kind of soft and chewy and a little juicier than we’re used to. I’m a big texture guy so 145F just didn’t do it for me.
So there you go, two examples where seasoned chefs have gone against government recommendations on cooking and food handling and lived to tell the story. I am not saying to throw out these regulations, a lot of smart people did a lot of research to form the basis for these regulations. They are there for your safety and if you follow them you’re chance of contracting a foodborne illness are minimal. If you’re serving anyone but a healthy adult, these recommendations should turn into hard fast rules. Young children, elderly, and those whose immune systems are compromised may not tolerate pathogens or toxins like a healthy adults and the consequences can be much more than a tummy ache. Whenever deviating from government guidelines realize you do so at your own risk. However, if you understand the environment you’re working with and proceed in a deliberate scientific manner, it is possible you can bend or even break some of their recommendations.