Monday, January 28, 2008

Food Safety

Our second class at FCI, which was almost a week ago now, consisted mainly of a lecture and some short videos about food safety. I became interested in exploring the details of food safety issues almost immediately after I began thinking about cooking more seriously years ago. Knowing the hazards, their sources, and exactly what it takes to eliminate them goes hand in hand with being able to cook things so that they are safe but still have nice texture, tenderness, and moisture. I've long maintained, for example, that when properly cooked, the breast meat of a chicken or turkey has a softer texture and retains more moisture than the thigh meat. Most people do not believe this, mainly because nearly all of the chicken we consume has been overcooked, due to practices handed down across generations and various authorities that prescribe cooking it to somewhere between 165F and 180F. Once we know some of the details about the dangers we're trying to eliminate when we cook chicken, we can cook the white meat to a very nice, moist, soft texture.

There were a number of interesting tidbits in our lecture on food safety. For me, one of them was just how little bleach it takes to sanitize things. We had been told on the first day to put about a capful of bleach into roughly a half gallon of water. The guest chef who talked about food safety brought along some test strips that measured chlorine concentration. The FDA prescribes specific concentrations, temperatures, and contact times to ensure sanitization and to ensure that no significant amount of bleach remains on surfaces (like cutting boards) that will contact food. It turns out that our capful of bleach per half gallon is way off the high end of the scale; the right amount was about a quarter teaspoon. The contact time required to sanitize a surface if the solution is about room temperature is about 7-10 seconds, so as long as you get your towel wet enough that the surface doesn't completely dry in under 10 seconds, you'll successfully eliminate bacteria with that surprisingly low concentration of bleach.

Another thing that surprised me was the idea that, even when stored properly and cooked to a high temperature, some foods develop chemicals that can trigger allergies. The example here is eggs, which many young children are allergic to. As you store eggs, they slowly develop higher levels of a protein that can trigger a permanent allergy to eggs if it is eaten enough by children. This is true even if the eggs have been handled properly, are well within their expiration date, and have been cooked to temperature.

The dangers of fish I hadn't really understood before this lecture. I think I've heard bits of this information, but I'd never put it together enough to get to this salient fact: the safety of many fish depends entirely upon the waters in which it was caught. This is not due to pollution, but rather to the types of algae growing in the waters of different parts of the world. Many algae produce substances toxic to humans, which are eaten by small fish, which are in turn eaten by the snapper and grouper that we eat. These toxins are not mitigated by cooking (which is why sushi, properly handled, is about as safe as cooked fish). I've always known that the black market for fish is enormous, and now I know why that is so dangerous not only to the environment and the fisheries, but also to us. These toxins are not detectable by any superficial means: they have no odor and do not change the appearance of the fish in any way. For many fish, the only way to know that they are safe to eat is to trust the source from which you bought your fish to be conscientious about considering health and safety more than profit and convenience when acquiring seafood.

Many midwesterners still have an instinctive fear of raw fish, and will say something like, "I don't know how anyone eats raw fish -- wouldn't that make you sick?" My question back to them is, "Why would you eat cooked fish?" The point is that most people have no reason to think that cooked fish is any more or less safe than raw fish: it is something they have simply made up. You are better off to base your fear on knowledge than you are to limit yourself to your own immediate experience. We eat unsafe food all the time (my favorite example being stuffed poultry), but our statistical experience of it is that we typically do not suffer for it. I will eat a stuffed turkey, because I know that statistically I'm not likely to be made sick by it; but I would prefer not to eat it, because I know that statistically I have a better chance of spending a very bad twenty-four hours as a consquence of a stuffed turkey than I do if I eat raw salmon every day. In fact, when I feel a bit queasy and have an upset stomach but find myself hungry, I often go eat a big meal of simple sushi, because I find the proteins that have not been cooked in any fat are easy to digest, and the accompanying rice and soy sauce give me a lot of flavor without weighing me down.

It wasn't part of our lecture, but another tidbit I overheard recently is that in the coming year it will become illegal to use non-stick pans in restaurants in New York (it was unclear to me whether this meant the city or the state). Non-stick pans give off some toxic gases when heated close to 500F, and they give off several carcinogenic chemicals if heated to about 700F. Those temperatures are easily attained on a commercial stovetop if the cook is not attentive; at home there is a bit less danger.

Circling back to my favorite food safety issue, the danger we want to eliminate by cooking chicken is salmonella bacteria. Salmonella is killed if it is heated to 140F for 5 minutes, or 160F for 1 minute. (And this is why stuffing poultry doesn't work: the bacteria migrate from the surface of the cavity into the stuffing, and you need to get the stuffing heated all the way through if you want to know that it is safe, by which time the white meat of the bird is inedible.) One of the points made repeatedly by the French chef giving our lecture was that "the rules" are written so that if most of them are followed, the food produced by cooks who know nothing about the dangers but simply follow the guidelines will be completely safe, even under less than ideal conditions, but that when we prepare food for fine dining we can use our more precise knowledge of the dangers to avoid unnecessarily overcooking things. He said, "For me, a turkey should be cooked to 141 in the breast; anything more, then you cut it thin, hide it under a heavy sauce, and you can serve it in a hospital."

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