Don’t eat food. It’s all contaminated.
I know, that seems kind of harsh. But seriously, you have no idea how easily you could get sick from food that isn’t handled properly. I have a good idea now that I’m taking this food safety class. Some of it doesn’t seem relevant to pastry—sushi and cheeseburgers aren’t normally produced in the pastry kitchen—but eggs and dairy can be plenty dangerous.
Most people have had food poisoning: What is commonly referred to as “stomach flu” is almost always food poisoning. The five most common causes of food poisoning are food from unsafe sources (e.g., shrimp from a guy selling it from the back of his van), food that isn’t cooked adequately, food that’s kept at an unsafe temperature (leaving cooked rice sitting at room temperature is asking for trouble), food prepared using contaminated equipment (e.g., cutting raw chicken and then cutting tomatoes for salad on the same cutting board), and poor personal hygiene (e.g., not washing your hands).
Every professional kitchen is required to have on staff (not necessarily working on every shift) someone who has passed this certification exam as well as someone on every shift who knows all the rules, even without the certification. I would be able to get a job without the certification, but the certification will make me more employable. The Commonwealth of Massachusetts is also starting a certification program for allergens, so I’ll probably get that too.
In general, pathogens grow most efficiently in protein (milk, eggs, meat, fish), in a neutral to slightly acidic environment (pH 4.6-7.5), at room temperature (but the unsafe range is 41℉-135℉), and in the presence of oxygen and moisture. Under optimal conditions, it only takes 4 hours to grow enough bacteria to make someone sick. Cooking or refrigerating to a safe temperature goes a long way toward preventing food-borne illness. In some cases, cooking or refrigerating are impractical, but you can inhibit the growth of pathogens another way. At the sushi bar, for example, they have that tub of rice sitting at room temperature, and rice is always contaminated with Bacillus cereus (rice grows that way). Rice wine vinegar lowers the pH to below the dangerous range, and now you know why that’s a standard ingredient in sushi.
Bacteria can be killed, but many bacteria protect themselves with spores, and spores are heat resistant, so cooking doesn’t help. Many bacteria produce toxins as they die, and you can’t kill the toxins, either. One common source of food poisoning is from bacteria that grow on food that’s left sitting out; as the bacteria run out of food and die, they produce toxins. Someone eats the infected food and gets sick first from the toxins and then from the live bacteria. Some toxin-mediated infections can reappear after an interval of several weeks. This is why health department inspectors are obsessed with making sure food is kept refrigerated.
Viruses are a problem because they can survive practically anywhere. They don’t grow on (or in) food, but they can survive in food until you consume it, at which point they grow in you. If the person scooping your ice cream has hepatitis and isn’t wearing gloves, the virus can be transferred to your ice cream and then to you.
Parasites, like viruses, don’t grow in food, they grow in us. Sushi made with raw fish is a good source of parasites. Tuna and farm-raised salmon usually don’t contain parasites; wild salmon does, though, as do cod and herring. Freezing fish to -4℉ and storing it at that temperature for 7 days kills parasites, and that’s how you get “sushi-grade” raw fish. Otherwise, it’s best to cook fish to an internal temperature higher than 135℉.
All that seems pretty obvious, but there are some surprising risks in your kitchen. Sprouts and seeds for sprouts (e.g., alfalfa seeds and alfalfa sprouts) can become contaminated in the field and during storage, and because they’re not cooked, they should never be served to persons with less-than-optimal immune systems (children, elderly persons, pregnant women, and persons with immune-compromising diseases). Potatoes baked in aluminum foil and then stored at room temperature have been associated with botulism (but not potatoes baked naked). Tomatoes and peppers can be contaminated with bacteria at the flowering stage; then as the fruit forms, the bacteria are enclosed in the fruit, and the only thing to do is cook the fruit.