Safe and Clean
I’m taking my food protection exam on Tuesday, so I’m writing my newsletter this week about food safety to help myself study. If bacterial growth and grease disposal sound interesting to you, read on, but if it sounds incredibly boring, skip this one and come back next week to hear how my first week of laminating dough has gone.
Food safety is like defensive driving. Usually things go right: workers aren’t sick and food arrives fresh and unspoiled and sinks don’t get backed up and there aren’t cockroaches or mice hanging around. But because the repercussions of getting guests sick are fairly egregious, a lot of practices have been codified over time to minimize that possibility. There's a system called the Hazard Analysis and Critical Control Point (HACCP) that is basically a way of mapping out your food preparation procedure to identify the steps most likely to introduce risks. I'm studying all this for my NYC Food Protection certificate, which the city requires someone to have at every commercial food establishment.
A lot of food safety rules are concerned with preventing the growth of harmful microorganisms. Most of these microorganisms are bacteria, like salmonella and E. coli, but there are also some viruses out there like Hepatitis A and norovirus as well as parasites that can live in food. While viruses can’t reproduce in food, bacteria can and do. A number of factors affect their growth, including acidity, temperature, time, and moisture. In a warm moist place they can double every 20 to 30 minutes, but even at the lower end of their acceptable temperature range (41°F - 140°F) they can still keep growing given enough time. Refrigerating or even freezing food doesn’t kill bacteria, but just stops it from reproducing.
It’s the cook’s job to keep food out of that temperature range as much as possible. For example, you might try to rapidly cool a hot soup by dividing it up into smaller containers or putting it into an ice-water bath, but you wouldn’t want to put the whole hot dish into the refrigerator if that raised the fridge temperature over 41°F. At the other end of the spectrum, you can warm frozen food by running it under cold running water or even microwaving it, but you’re not supposed to let it thaw by leaving it out at room temperature. When you’re cooking, especially meat, it’s important to get the food to particular internal temperatures.
These rules don’t apply equally to all foods. I work in a bakery after all, where our proofers keep croissants at 86°F for several hours precisely because that’s where the yeast will reproduce fastest (yeast are actually fungi not bacteria, but they like the same temperature range). I’m actually not sure how dough fits into the food safety categories. “Potentially Hazardous Foods” include meat, dairy products, fish and shellfish, tofu, cooked rice, pasta, beans, potatoes and garlic in oil. Generally food that’s high in starch or protein and is moist is what to watch out for.
For home cooks, a few other common practices could be useful in your kitchen. FIFO, which stands for “first-in, first-out,” refers to the process of dating your leftovers or other opened containers and using up the most recent ones first. In refrigerators, raw foods are not supposed to be stored above cooked foods, because the raw food could drip down and contaminate something below it. Grease should never be poured down the sink — at the bakery we have a foul-smelling oil drum full of old cooking grease in the trash room, where we empty the oil from the fryer every night. At home, you could use any container you were planning to throw away or recycle, as long as you can close it. There's a bit more to the test, mostly about plumbing and sanitization and pest control. Most of the practices around preventing vermin from getting into food hopefully aren’t applicable at home; storing food 6 inches above the floor wouldn’t stop our cat getting into it anyway.
Anyway, wish me luck on Tuesday!