Wednesday, December 13, 2006

Food Safety: what's definitely not safe

Yesterday, I looked at foods that are definitely safe to eat. Today, I'll look at foods that are definitely not safe, and what you can do about it.

The key transmission route for food-borne illness like salmonella and the dangerous strain of E. coli is fecal-oral transmission. In other words, foods that may have come into contact with poop. In a nutshell, any animal product that hasn't gone through a sanitizing step should be considered dangerous. As we discussed yesterday, heat, acids, salt, and fermentation all have the potential to kill the germs on food. Raw animal products--meat, milk, and eggs--are all potentially dangerous; cooked animal products are safe. Let's take a closer look at some animal products.

The food that is most likely to be contaminated is raw poultry. According to the New York Times last week, 83% of raw chickens they tested carried some pathogenic bacteria. You should treat any raw poultry as if it were contaminated, and anything it touches as contaminated. That means that if you handle raw chicken, you must wash your hands before handling other food. If you chop it up, you must wash (with hot, soapy water) the knife, cutting board, and counter. Never, ever handle raw chicken, then immediately touch your hands, cooking utensils, or countertop to something you are going to eat raw. That's the surest way to make yourself sick. The good news is that the bacteria on chicken are strictly external. The inside of any muscle tissue is sanitary, unless the animal was sick. Once you have started to cook the outside of the chicken, it becomes safe. There is actually no danger from eating rare chicken, if you get the outside good and hot. It may be gross, but it's safe.

Red meat also has a high probability of being contaminated, but lower than that of poultry. That's because so much poultry either has the skin on, or is just one cut removed from the skin (meaning the knife pulls through the skin into the muscle, contaminating the meat). Red meat is skinned and cut up much smaller (proportionally), so the bacteria get spread quite a bit thinner. Additionally, the processing of poultry tends to spread the bacteria load much more uniformly over all the animals than large-animal processing does. The same rules for handling poultry still apply, though--clean anything that comes into contact with meat before it touches anything else. Rare meat, like rare poultry, is also safe if you sear the outside.

There is however, one exception to this rule: ground meat. This comes into play much more with beef and pork than with chicken or turkey, because we make sausage out of hogs, and hamburgers out of cattle. With ground meat, the inside of the meat and the outside of the meat get all jumbled up, and so do the accompanying bacteria. Ground meat must always be cooked to an internal temperature of at least 140, or medium. If there's any pink left in a burger or sausage patty, it poses a risk.

Dairy products are generally safer that meats. Most milk is sold pasteurized, so it's safe. Raw milk carries some risk, and its sale is strictly regulated (or sometimes prohibited). Hard cheeses are low-water, fairly salty, and fairly acidic. That renders them pretty safe. By law, soft cheeses must be made from pasteurized milk in the U.S. This interferes with some traditional cheesemaking techniques, but it does produce safe cheese.

Eggs are a slightly different case. The outside of eggs is cleaned and sanitized in the packaging process, so they are safe. However, there is a percentage of hens that carry salmonella in their ovaries, and deposit the bugs into the shell with the yolk. This is much more common with caged hens than free-ranging birds, but all raw eggs should be viewed with skepticism. If you really must have raw eggs (blech), find a pasteurized product like egg beaters, and be safe.

That's a pretty good summary of what's clearly dangerous, but conspicuously absent are green onions and spinach--the culprits behind the two recent scares.

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