I had a reader ask about food safety recently and the more I thought about it the more I realized it’s not often talked about. Look for an article on nutrition and you’ll find hundreds, look for something on food safety and you’re lucky to get even a few bites. Surprisingly enough, Dietitians are trained in food safety as well. Any career in Food Service, be it management, health inspector, or menu development, requires a decent understanding of food safety. It makes sense then that RDs would have it in their curriculum, as the aforementioned are common jobs held Dietitians.
Now I don’t want to drag you through the entire textbook on food safety but I do want to explain the condensed version. So let’s start with the basics.
The Basics of Food Safety
1. Food safety is about controlling microbial growth, but I’m sure you already knew that. What are microbes? All the nasty little invisible critters like bacteria and fungi. Everything else is secondary to keeping them under control. Keep in mind there’s a huge variety of microbes in the world so it’s easier said than done. Some grow only on specific foods like rice, or in low oxygen environments, or in warm environments. 1,2,4
2. Despite their variety, almost all grow best at a specific temperature range, 40°F to 140°F (4°C to 60°C). This is appropriately known as the ‘Danger Zone‘. The real reason the danger zone is so, well, dangerous isn’t because microbes can only grow in this range, it’s because they grow fastest in this range. In fact some microbes known as extremophiles can grow even in freezing temperatures, so you can’t just rely on it being frozen. 8,16,32
3. The key is that bacterial growth is exponential, if you start with 32 cells, it doubles to 64, which doubles to 128, 256, 512, etc. If it were linear it would go 32,33,34, etc. With this in mind, it’s important to note how often this doubling happens. Many microbes are so sophisticated that whereas a human cell takes roughly 24 hours to divide, many bacteria can do it in only 30 minutes! (source) This means for every 30 minutes your chicken or beef sits in the danger zone you have twice as many bacteria on it. The colder the food is kept, the longer it takes to divide, kind of like a slowing clock.
4. When a food is frozen, most bacteria stop dividing completely. This is good for keeping the food from spoiling, but it doesn’t mean the bacteria are dead. If you’ve ever heard the remark about not refreezing food that has been thawed, this is exactly why. Every time the bacteria come out of their frozen hibernation they start off exactly where they were before. 1024, 2048, 4096. (4 hours to go from 1 cell to 4096, about the time it takes to thaw at room temperature)
5. Cooking food, whether by heat or acidity, is really the process of denaturing (damaging) the structure of the protein. Once the protein is damaged it usually can’t go back to its normal shape. So you might be asking, if we can destroy the protein why does it matter how many bacteria were on the food? Good question, because in many cases proper cooking does make the food safe. The concern is that some types of bacteria are also able to make toxins.
6. Toxins, unlike protein, don’t always denature from heat or acidity. Meaning whatever the bacteria made before you killed them, is still there with your food. Unless you’re a microbiologist, you probably don’t have a way to figure out if the bacteria on your food can or can’t make these toxins, so you have to treat them like they all do.
7. One of the more well known toxins you might recognize as BoTox. or Botulinum Toxin. BoTox is literally the most lethal toxin known to mankind, and loves growing in a dark low oxygen environment, like dented cans. Ever wonder why they say don’t buy dented cans? Yep, this is why. It’s so toxic that it would take only 50 grams (about 3 Tablespoons) to wipe out the entire human population (source). So in our brilliance we learned we can dilute it enough to not kill us and inject it in our faces. Luckily for us, it’s one of the few toxins that can denature with enough heat.
8. Proteins all have different temperatures they denature at. This is why some foods like chicken call for an internal temp of 165°F while a fish can be cooked to 145°F. It’s important to take each food to its proper internal temp, otherwise whatever bacteria might be inside the food is left intact. If you don’t already I strongly recommend grabbing the list below and keeping it on your fridge.
9. If you’re still with me and not furiously applying hand sanitizer here’s the takeaway. Raw food is a ticking clock, you can slow the clock down but you can’t always stop it. Bacteria grows really really fast and you can’t always cook away the bad, be it toxins or spores. Cooking properly does help, but few people cook with the appropriate temperature guidelines and tools. Lastly, the goal isn’t to have perfectly sterile charred food, but to minimize the chance of food poisoning while still enjoying your food.
10. What I recommend is to treat your kitchen like a restaurant. First, get yourself a proper thermometer that can handle meat, soups, etc. I particularly like Thermoworks but if you’re on a budget Thermowand will work too, follow the temp guidelines from above. Get a thermometer in your fridge, a simple one like the Taylor Classic works great with the added benefit that you can lower your energy bill if you find your freezer below 0°F or your fridge below 32°F. Get color coded cutting boards, I like the Neoflam set because I can’t stand flexible cutting boards. The one in red for raw meats, green for raw vegetables, and blue for misc. things like bread and cheese. Pair the right tools with the advice from above and trust me, your family will thank you.
If you liked this post or learned something new be sure to let me know in the comments!
Be Good to Each Other.
– Joshua Iufer, RD
Starving Dietitian 