Temperature ManagementThere's a saying in foodservice: "Keep cold foods cold, and keep hot foods hot."
Keeping Cold Foods ColdKeeping cold foods cold means storing them at temperatures between 40°F, which is where normal refrigeration kicks in, down to about 0°F, which is where you'd want your freezer to be. Bacteria still multiply at cold temperatures, they just do it a lot more slowly.
At freezing temperatures, bacterial growth slows to nearly nil. Freezing doesn't kill them, though — all it does is make them cold. Once you thaw that food, watch out! Any bacteria that were there before freezing will just warm up and start multiplying again — with a vengeance.
Food Temperature Danger ZoneYou see, bacteria thrive between 41°F and 140°F, a range of temperatures that's known as the Temperature Danger Zone. Perhaps not surprisingly, it's the same temperature range that humans thrive in.
Not only that, but our bodies' natural temperature of 98.6°F is so right smack in the middle of that Danger Zone, it's not even funny. Bacteria can't wait to get inside of us. Once they make it to our intestines, it's like a bacteria Mardi Gras.
To minimize this danger, perishable food shouldn't be allowed to spend more than an hour in the Food Temperature Danger Zone — cumulatively. Any longer than that and it should either be cooked or thrown away.
Here's a table showing the key temperatures of the Temperature Danger Zone.
Keeping Hot Foods HotKeeping hot foods hot presents other challenges. Bacterial growth slows down once again at temperatures hotter than 140°F, so hot foods that are being served on a buffet, for example, must be kept hotter than that at all times.
Keep in mind that 140°F doesn't kill bacteria — it only stops them from multiplying. If you actually want to kill bacteria, you've got to heat them up to at least 165°F. The same rule applies to cooked food that should happen to drop below 140°F — you get an hour, total. After that, you either need to heat it up to 165°F again or throw it away. And by the way, you can only reheat it once. If it drops below 140°F a second time, you need to toss it.
Time: It Waits for No One!Time works hand in hand with temperature in encouraging the growth of bacteria. Let's say you buy a package of uncooked chicken breasts. Maybe it's in your shopping cart for 15 minutes while you shop, then it's in your car for another 15 minutes while you drive home. So before you even get that chicken home, bacteria have had a full 30 minutes to run rampant.
Then later they might spend another 15 minutes on your counter while you prep them, bringing the cumulative total to 45 minutes already. As you can see, you really don't have much wiggle room.
MoistureLike all living organisms, bacteria need water to survive. Foods high in moisture like meats, poultry, seafoods and dairy products, as well as fruits and vegetables, are prime breeding ground for harmful bacteria. Low-moisture foods, including dried grains and legumes such as rice or beans, will typically keep for a very long time without spoiling or harboring bacteria.
Another aspect of the moisture factor is that through a process called osmosis, sugar and salt actually suck the moisture out of bacteria, effectively killing them by dehydration. As a result, a high salt and/or sugar content will tend to preserve foods — which is why salt and sugar are used in brining and curing of meats.
Read Part 3 of the article >>