by Jeff Potter
Proteins in meat can be divided into three general categories: myofibrillar proteins (found in muscle tissue, these enable muscles to contract), stromal proteins (connective tissue, including tendons, that provide structure), and sarcoplasmic proteins (e.g., blood). We’ll talk about myofibrillar proteins here and save the stromal proteins for the section on collagen later in the chapter. (We’re going to ignore sarcoplasmic proteins altogether, because understanding them doesn’t help in cooking many dishes, blood-thickened soups aside.)
Muscle tissue is primarily composed of only a few types of proteins, with myosin and actin being the two most important types in cooking. About two-thirds of the proteins in mammals are myofibrillar proteins. The amount of actin and myosin differs by animal type and region. Fish, for example, are made up of roughly twice as much of these proteins as mammals.
Lean meat is mostly water (65–80%), protein (16–22%), and fat (1.5–13%), with sugars such as glycogen (0.5–1.3%) and minerals (1%) contributing only a minor amount of the mass. When it comes to cooking a piece of fish or meat, the key to success is to understand how to manipulate the proteins and fats. Although fats can be a significant portion of the mass, they are relatively easy to manage, because they don’t provide toughness. This leaves proteins as the key variable in cooking meats.
Of the proteins present in meat, myosin and actin are the most important from a culinary texture perspective. If you take only one thing away from this section, let it be this: denatured myosin = yummy; denatured actin = yucky. Dry, overcooked meats aren’t tough because of lack of water inside the meat; they’re tough because on a microscopic level, the actin proteins have denatured and squeezed out liquid in the muscle fibers. Myosin in fish begins to noticeably denature at temperatures as low as 104°F / 40°C; actin denatures at around 140°F / 60°C. In land animals, which have to survive warmer environments and heat waves, myosin denatures in the range of 122–140°F / 50–60°C (depending on exposure time, pH, etc.) while actin denatures at around 150–163°F / 66–73°C.
Food scientists have determined through empirical research ("total chewing work" and "total texture preference" being my favorite terms) that the optimal texture of cooked meats occurs when they are cooked to 140–153°F / 60–67°C, the range in which myosin and collagen will have denatured but actin will remain in its native form. In this temperature range, red meat has a pinkish color and the juices run dark red.
The texture of some cuts of meat can be improved by tenderizing. Marinades and brines chemically tenderize the flesh, either enzymatically (examples include bromelain, an enzyme found in pineapple, and zingibain, found in fresh ginger) or as a solvent (some proteins are soluble in salt solutions). Dry aging steaks works by giving enzymes naturally present in the meat time to break down the structure of collagen and muscle fibers. Dry aging will affect texture for at least the first seven days. Dry aging also changes the flavor of the meat: less aged beef tastes more metallic, more aged tastes gamier. Which is "better" is a matter of personal taste preference. (Perhaps some of us are physiologically more sensitive to metallic tastes.) Retail cuts are typically 5 to 7 days old, but some restaurants use meat aged 14 to 21 days.
Soy Ginger Marinade
The salt in the soy sauce and zingibain in the ginger give this marinade both chemical and enzymatic tenderizers. Mix this up, transfer it to a resealable bag, and toss in some meat, such as flank steaks. Allow to marinate for an hour or two in the fridge, and then pan sear the meat.
1 cup (290g) soy sauce
2 tablespoons (15g) grated fresh ginger or ginger paste
1 teaspoon (2g) ground black pepper
Then there are the mechanical methods for "tenderizing," which aren’t actually so much tenderizing as they are masking toughness: for example, slicing muscle fibers against the grain thinly, as is done with beef carpaccio and London broil, or literally grinding the meat, as is done for hamburger meat. (Some industrial meat processors "tenderize" meat by microscopically slicing it using very thin needles, a method called jacquarding.) Applying heat to meats "tenderizes" them by physically altering the proteins on the microscopic scale: as the proteins denature, they loosen up and uncurl. In addition to denaturing, upon uncurling, newly exposed regions of one protein can come into contact with regions of another protein and form a bond, allowing them to link to each other. This process is called coagulation, and while it typically occurs in cooking that involves protein denaturation, it is a separate phenomenon.
Temperatures required for various levels of doneness. Note that seafood cooked very rare or medium rare and chicken cooked medium must be held for a sufficiently long period of time at the stated temperature in order to be properly pasteurized. See the section on sous vide cooking in Chapter 7 for time and temperature charts.
Salmon Poached in Olive Oil
Fish, such as salmon and Atlantic char, becomes dry and loses its delicate flavor when cooked too hot. The trick with poaching fish is to not overcook it. Poaching fish is an easy way to control the rate of heat being applied, and it is amazingly easy and tasty.
Place a fillet of fish, skin side down, in an oven-safe bowl just large enough for the fish to fit. Sprinkle a small amount of salt on top of fish. Cover with olive oil until the fillet is submerged. Using a bowl that "just fits" the fish will cut down on the amount of olive oil needed.
Place into a preheated oven, set to medium heat (325–375°F / 160–190°C).
Use a probe thermometer set to beep at 115°F / 46°C and remove the fish when the thermometer goes off, letting carryover bring the temperature up a few more degrees.
Note
Consider this fish as raw/undercooked. See Chapter 7’s section on sous vide cooking for a discussion on pasteurization and time-at-temperature rules.
Notes
Try serving on top of a portion of brown or wild rice and spooning sautéed leeks, onions, and mushrooms on top. (A squirt of orange juice in the leeks is really good.) Or serve with string beans sautéed with red pepper flakes and white rice, with a splash of soy sauce drizzled on top.
Salmon contains a protein, albumin, that generates a white congealed mess on the outside of the flesh, as shown on the bottom piece in the following photo. This is the same protein that leeches out of hamburgers and other meats, typically forming slightly gray "blobs" on the surface. You can avoid this by brining the fish in a 5–10% salt solution (by weight) for 20 minutes, which will set the proteins. The top piece in the first photo below was brined; you can see the difference.
Salmon contains a protein, albumin, that is expressed out of the flesh and leads to an un-sightly, curd-like layer forming on the surface of the fish when poached, as shown in the bottom piece in this photo.
If your fish doesn’t fit in your pan, you can fold the tail bit over in a pinch, or cut it and poach it face down. This won’t win you any Foodie Points, but as long as you don’t take a photo and publish it in a book, who’s going to know?
Seared Tuna with Cumin and Salt
Pan searing is one of those truly simple cooking methods that produces a fantastic flavor and also happens to take care of bacterial surface contamination in the process. The key to getting a rich brown crust is to use a cast iron pan, which has a higher thermal mass than almost any other kind of pan (see the Metals, Pans, and Hot Spots sidebar in Chapter 2). When you drop the tuna onto the pan, the outside will sear and cook quickly while leaving as much of the center as possible in its raw state.
You’ll need 3–4 oz (75–100 grams) of raw tuna per person. Slice the tuna into roughly equal-sized portions, since you’ll be cooking them one or two at a time.
On a flat plate, measure out 1 tablespoon cumin seed and ½ teaspoon (2g) salt (preferably a flaky salt such as Malden sea salt) per piece of tuna. On a second plate, pour a few tablespoons of a high-heat-stable oil, such as refined canola, sunflower, or safflower oil.
Place a cast iron pan on a burner set as hot as possible. Wait for the pan to heat up thoroughly,
until it just begins to smoke.
For each serving of tuna, dredge all sides in the cumin/salt mix, and then briefly dip all sides in the oil to give the fish a thin coating.
Sear all sides of the fish. Flip to a new side once the current facedown side’s cumin seeds begin to brown and toast, about 30 to 45 seconds per side.
Slice into ⅓″ (1 cm) slices and serve as part of a salad (place fish on top of mixed greens) or main dish (try serving with rice, risotto, or Japanese udon noodles).
Notes
Keep in mind that the temperature of the pan will fall once you drop the tuna in it, so don’t use a piece of fish too large for your pan. If you’re unsure, cook the fish in batches.
Use coarse sea salt, not rock (kosher) salt or the table salt you’d find in a salt shaker. The coarse sea salt has a large, flaky grain that prevents all of the salt from touching the flesh and dissolving.
Coat all sides of the tuna in cumin seeds and salt by pressing the tuna down onto a plate that has the spice mixture evenly spread out on it.
Make sure the pan is really hot. Some smoke coming off the fish as it sears is okay!
Pan-seared tuna will be well-done on the outside and have a very large "bull’s eye" where the center is entirely raw.
144°F / 62°C: Eggs Begin to Set
The lore of eggs is perhaps greater than that of any other food item, and more than one chef has gone on record judging others based on their ability—or inability—to cook an egg. Eggs are the wonder food of the kitchen—they have a light part, a dark part, and bind the culinary world together. Used in both savory and sweet foods, they act as binders holding together meatloaf and stuffing; as rising agents in soufflés, certain cakes, and cookies like meringues; and as emulsifiers in sauces like mayonnaise and hollandaise. Eggs provide structure to custards and body to ice creams. And all of this so far doesn’t even touch on their flavor or the simple joys of a perfectly cooked farm egg. Simply put, I cannot think of another ingredient whose absence would bring my cooking to a halt faster than the simple egg.
Egg whites are composed of dozens of different types of proteins, and each type of protein begins to denature at a different temperature. In their natural "native" state, you can think of the proteins as curled-up little balls. They take this shape because portions of the molecular structure are hydrophobic—the molecular arrangement of the atoms making up the protein is such that regions of the protein are electromagnetically repulsed by the polar charge of water.
Important temperatures in eggs.
Because of this aversion to water, the protein structure folds up on itself. As kinetic energy is added to the system—in the form of heat or mechanical energy (e.g., whipping egg whites)—the structure starts to unfold as kinetic energy overtakes potential energy. The unfolded proteins then get tangled together, "snagging" around other denatured proteins and coagulating to form a linked structure. This is why a raw egg white is liquid, but once cooked becomes solid. (Well, technically, raw egg white is a gel that coagulates into a solidlike substance when heated. We’ll get to gels in Chapter 6.)
Hydrophobic proteins in their native state (left) remain curled up to avoid interacting with the surrounding liquid. Under heat, they denature (center) and uncurl as the kinetic energy exceeds the weaker level of energy generated by water molecules and regions of the proteins that repel each other. Once denatured and opened up, the hydrophobic parts of the protein that were previously unexposed can interact and bond with other proteins.
The most heat-sensitive protein is ovotransferrin, which begins to denature at around 144°F / 62°C. Another protein, ovalbumin, denatures at around 176°F / 80°C. These two proteins also are the most common in egg whites: ovotransferrin accounts for 12% of the proteins in an egg white and ovalbumin 54%. This explains the difference between soft-boiled and hard-boiled ("hard-cooked") eggs. Get that egg up to about 176°F / 80°C for sufficient time, and voilà, the white is hard cooked; below that temperature, however, the ovalbumin proteins remain curled up, leaving the majority of the egg white in its "liquid" state.
Note
Most of the proteins in egg yolks set at between 149°F / 65°C and 158°F / 70°C, although some set at lower temperatures.
Proteins in foods such as eggs don’t denature instantaneously once they reach denaturation temperature. This is an important point. Some cooking newbies have the mental model that cooking an egg or a piece of meat is something like melting an ice cube: all ice below a certain temperature, ice and water at the freezing/melting point, and all water above that temperature. From a practical perspective in the kitchen, it’s not an entirely incorrect picture, because heat pours into the foods so quickly that the subtle differences between a few degrees aren’t obvious. But as heat is transferred into the food more slowly, the subtleties of these chemical reactions become more noticeable. And unlike melting an ice cube, where increasing the heat transfer by a factor of two causes the ice to melt in half the time, cooking foods do not respond to additional energy in a linear fashion.
You might find it easiest to think of the different proteins in foods as having particular temperatures at which they denature, and try to shoot for a target temperature just above that of the proteins you do want denatured. Just remember: there’s more to a piece of meat or egg than one type of protein or connective tissue, and the different proteins have different temperature points at which they’re likely to denature.
Here are some examples of cooking eggs that show how to take advantage of the thermal properties of different portions of the egg.
Hard-Cooked Eggs, Shock and Awe Method
There’s a silent war of PC-versus-Mac proportions going on over the ideal way to make hard-cooked eggs. Should you start in cold water and bring the water up to a boil with the eggs in them, or should you drop the eggs into already boiling water? The cold-start approach yields eggs that taste better, while the boiling-water approach yields eggs that are easier to peel. But can you have both?
Thinking about the thermal gradient from shell to center of egg, it would make sense that cooking an egg starting in cold water would result in a more uniform doneness. The delta between the center and outer temperatures will be smaller, meaning that the outer portion won’t be as overcooked once the center is set compared to the boiling-water method.
The conjecture for ease of peeling in the boiling water approach is that the hot water "shocks" the outer portion of the egg. Into industrial-grade cooking? Steam ’em at 7.5 PSI over atmospheric pressure and quick-release the pressure at the end of cooking to crack the shell. (Hmm, I wonder if one could do this in a pressure cooker...) But what about the rest of us? What if we shock the outside, and then cook in cold water?
Try it. Place your eggs into rapidly boiling water. After 30 seconds, transfer the eggs to a second pot containing cold tap water, bring to a boil, and then simmer. The second-stage cooking time will take about two minutes less than the normal cold-start approach. Cook for 8 to 12 minutes, depending upon how well cooked you like your eggs.
The 30-Minute Scrambled Egg
This method involves ultra-low heat, continuous stirring, and a vigilant eye. I wouldn’t suggest this as an everyday recipe, because it takes a while to make, but after however many years of eating eggs, it’s nice to have them cooked a new way. Cooking the eggs over very low heat while continuously stirring breaks up the curds and allows for cooking the eggs to a point where they’re just cooked, giving them a flavor that can be described as cheese or cream-like. It’s really amazing, and while the thought of "cheese or cream-like" eggs might not have you racing off to the kitchen, it’s really worth a try!
In a bowl, crack two or three eggs and whisk thoroughly to combine the whites and yolks. Don’t add any salt or other seasonings; do this with just eggs. Transfer to a nonstick pan on a burner set to heat as low as possible.
Stir continuously with a silicone spatula, doing a "random walk" so that your spatula hits all parts of the pan. And low he
at means really low heat: there’s no need for the pan to exceed 160°F / 71°C, because enough of the proteins in both the yolks and whites denature below that temperature and the proteins will weep some of their water as they get hotter. If your heat source is too hot, pull the pan off the stovetop for a minute to keep it from overheating. If you see any curds (lumps of scrambled eggs) forming, your pan is getting too hot.
Stir continuously to avoid hot spots so that the eggs are kept at a uniform temperature. If you have an IR thermometer, make sure your pan doesn’t exceed 160°F / 71°C.
Continue stirring until the eggs have set to a custard-like consistency. When I timed myself, this took about 20 minutes, but you might reach this point in as few as 15 minutes or upward of half an hour.
Oven-Poached Eggs
Here’s a simple way to cook eggs for a brunch or appetizer. In an individually sized oven-safe bowl (ideally, one that you can serve in), add:
Breakfast version
Dinner version
1 cup (30g) fresh chopped spinach
½ cup (100g) crushed tomatoes
3 tablespoons (20g) grated mozzarella cheese
¼ cup (50g) black beans (canned are easiest)
