The Food Lab: Better Home Cooking Through Science

by J. Kenji López-Alt

32°F (0°C): The freezing point of water (or the melting point of ice). • 130°F (52°C): Medium-rare steak. Also the temperature at which most bacteria begin to die, though it can take upward of 2 hours to safely sterilize food at this temperature. • 150°F (64°C): Medium-well steak. Egg yolks begin to harden, egg whites are opaque but still jelly-like. Fish proteins will tighten to the point that white albumin will be forced out, giving fish like salmon an unappealing layer of congealed proteins. After about 3 minutes at this temperature, bacteria experience a 7 log reduction—which means that only 1 bacteria will remain for every million that were initially there). • 160° to 180°F (71° to 82°C): Well-done steak. Egg proteins fully coagulate (this is the temperature to which most custard- or egg-based batters are cooked to set them fully). Bacteria experience a 7 log reduction within 1 second. • 212°F (100°C): The boiling point of water (or the condensation point of steam).

300°F (153°C) and above: The temperature at which the Maillard browning reactions—the reactions that produce deep brown, delicious crusts on steaks or loaves of bread—begin to occur at a very rapid pace. The hotter the temperature, the faster these reactions take place. Since these ranges are well above the boiling point of water, the crusts will be crisp and dehydrated.

Radiation is transfer of energy through space via electromagnetic waves. Don’t worry, that’s not as scary as it sounds. It doesn’t require any medium to transfer it. It is the heat you’re feeling when you sit close to a fire or hold your hand above a preheated pan. The sun’s energy travels to the earth through the vacuum of space. Without radiation, our planet (and indeed, the universe) would be in a lot of trouble! An important fact to remember about radiant energy is that it decays (that is, gets weaker) by the inverse square law—the energy that reaches an object from a radiant energy source is proportional to the inverse of the square of its distance. For example, try holding your hand 1 foot away from a fire, then move it 2 feet away. Even though you’ve only doubled the distance, the fire will feel only about one-quarter as hot. Here are some examples of radiant heat transfer: • Roasting a pig on a spit next to hot coals • Toasting garlic bread under the broiler • Getting a tan from the sun • Broiling some marinated salmon

At 180°F: The main protein in the egg white, ovalbumin, will cross-link and solidify, giving you a totally firm but still tender white.

a chicken is actually a remarkably simple beast in culinary terms. Its matter can be divided into roughly four different parts: • Muscle is what we think of as the meat on the chicken. It’s the fleshy stuff that twitches and makes the bird go, and it can be further divided into two categories: slow twitch and fast twitch. • Slow-twitch muscles are meant for sustained movement—i.e., the legs and thighs that keep the chicken standing, walking, and bending down or up. Because slow-twitch muscles are aerobic (they require oxygen to function), they are typically dense with capillaries carrying oxygen-rich red blood cells. That’s why they appear to be darker. • Fast-twitch muscles are used for short bursts of intense energy—they’re the muscles that are found in chicken breasts, used to power the wings when a frightened chicken needs to escape from a dangerous situation. Because their activity is anaerobic (they don’t require oxygen to twitch), they tend to be less dense with capillaries, giving them their characteristic pale color. Incidentally, the same distinction between fast- and slow-twitch muscles occurs in pretty much all animals, even humans. Ever wonder why a tuna is deep red while a cod is pale white? Tunas are made almost entirely of all-powerful slow-twitch muscles, which allow the fish to rapidly torpedo their way through the water for long periods of time. A cod moves only when he’s eating or frightened. • Fat provides insulation and energy storage for chickens...

Depending on the part of the chicken you use, these parts are present in different ratios. To sum up, chicken legs are high in slow-twitch muscle, have plenty of fat, and contain a good amount of connective tissue and bones. Breasts are almost completely fast-twitch muscle. Backs and carcasses have little meat of either kind but plenty of bone, connective tissue, and fat. Wings have the highest concentration of connective tissue of all, with a high proportion of fat and some bone.

umami flavor is triggered by glutamates—essential amino acids found in many protein-rich foods. The key to getting many dishes to taste meatier—turkey burgers, chili, stew, soups, etc.—is to increase their level of glutamates. Now, you can do this with powdered monosodium glutamate—a natural salt extracted from giant sea kelp—but some folks are squeamish about using it

There’s a reason that fish is far more prone to spoilage than the flesh of land animals. Spoilage occurs via two means: the breakdown of cells through the action of enzymes naturally present in meat# and the proliferation of bacteria. Both of these things occur at faster rates as the temperature increases. Now, land-based, warm-blooded animals like cows, chickens, and pigs are used to living in warm environments and they have metabolisms to match. Take their meat and refrigerate it, and enzymatic and bacterial action slows down to a crawl. Fish, on the other hand, are designed to operate in the low temperatures of ocean waters. Some species of Arctic or deepwater fish spend most of their lives in water that is just barely above freezing. Compared to that, the 40°F of an average refrigerator is positively balmy. So fish-related enzymatic action will occur just fine in your fridge or the fish market’s display case.

Anyone who has taken a ServSafe food-handling course has heard of the “danger zone”: the temperature range between 40° and 140°F where bacteria supposedly multiply at accelerated rates. According to ServSafe directives, no food can stay in that zone for longer than 4 hours total.

Below 38°F or so—fridge temperature—the bacteria are lethargic, multiplying very, very slowly. Take the meat all the way down to freezing temperatures, and the water necessary for the basic life functions of a bacterium turn into ice, making it unavailable to them. That’s why frozen meat can last for months, even years, if properly sealed.

Ah, you’re thinking to yourself, so I only need to cook my meat to 131°F for it to be safe. Well, yes and no. Just like cooking, destroying bacteria—the process of pasteurization—takes both temperature and time to accomplish.