November 2014 - Modernist Cuisine

Let’s cut to the chase: we look forward to Thanksgiving leftovers almost as much as the formal dinner itself. One of the most emblematic leftover preparations is undoubtedly the post-Thanksgiving turkey sandwich. A delicious amalgamation of last night’s meal, this sandwich is the essence of Thanksgiving between two slices of structurally sound bread. When it comes to handling leftovers, however, things can get a bit funky. Here’s what you need to know.

Danger, Danger

At the end of dinner, there’s a mad rush to clean the kitchen and pack leftovers so that loafing can begin. It’s usually an afterthought, but proper packaging is a crucial step for ensuring your leftovers survive.

Cooked food should be chilled quickly to inhibit bacterial growth. The “danger zone” range is 4–60°C / 40–140°F, encompassing temperatures between refrigeration and cooking temperature. This zone is notorious because it provides favorable conditions for bacteria to rapidly multiply. The longer food spends cooling in this zone, the more likely it is that your leftovers will harbor unwanted microbes. As a general guideline, food should not sit in the danger zone for more than four hours. The guideline also comes into play for thawing food. A whole turkey and similarly large foods thaw slowly and unevenly, so they should not be left to thaw at room temperature. As the bird slowly thaws, bacteria will develop on the outer tissue layers even though the inside remains frozen.

It’s important to note that these guidelines, developed by the FDA, are an oversimplification of how bacteria behave. Multiplication rates vary according to many factors, such as temperature, moisture, and pathogen type. More conservative recommendations from other organizations, such as the USDA, suggest that two hours is a more suitable estimate, while others expand the window to six.

As you get ready to pack leftovers, do the math and toss anything that could have exceeded this threshold. If it’s particularly warm in your kitchen, dispose of leftovers well before the four-hour mark. Food should be disposed of after an hour if it held in a 32 °C / 90 °F environment.

Rapid cooling has another big benefit: it maintains juiciness and fresh-cooked flavors better than slow cooling can. Juices gel and thicken before they escape, and flavorful aromatics stay locked in your foods.

The obvious remedy to cooling hot food appears to be simply placing it in the refrigerator straight away. But this strategy happens to be the worst way to cool and store leftovers. Warm packages stay warm, well after an hour, and actually raise the temperature of surrounding foods, increasing the risk of spoilage as illustrated in the infrared images below. It’s an interesting problem: food should be chilled rapidly, but cooling via the refrigerator or freezer is problematic.

SV5_Fridge w hot food thermal — Top: Hot food immediately placed in a refrigerator. Bottom: One hour later, leftovers are still hot and neighboring food is now warmer.

The Art of Cooling and Reheating Leftovers

Putting warm leftovers away probably seemed like a mundane task a few paragraphs ago. Now it might feel more like a dilemma, but you have several options.

If you’re cooling lots of sauce, like warm gravy or stock, pour it into a shallow container to increase the surface area. The shallower the container, the faster your liquids will cool. You can also divide the sauce or stock among several smaller containers.

The best way to quickly cool food to refrigeration temperatures is to dunk your sealed foods in ice water, which can be as simple as a sink or bowl of cold water with lots of ice cubes. Once the food is chilled, it can then be stored, still sealed, in a freezer or in the enclosed drawers at the bottom of the fridge, which maintain the most stable temperatures. Avoid the shelves in the door, which are the warmest part of a refrigerator.

When you’re ready for reheating, simply put your bags of leftovers in a heated water bath, and let them warm gradually. Most foods should be reheated to 60 °C / 140 °F, though red meat should be reheated to its original cooking temperature. Avoid reheating any food to temperatures above 65 °C / 149 °F, and take care not to overcook food. Finally, allow reheated food to rest. The rationale is similar to why we let meat rest— resting allows the exterior to cool slightly while juices thicken. This final step will preserve the flavor and moistness of the food.

If dunking your foods in ice water isn’t an option, let them cool on your counter (if time allows), or, if the weather is cold, place covered leftovers outdoors until they’ve cooled enough for safe storage.

Warmed-over Flavors

Turkey and ham come with an additional challenge: the slightly stale, somewhat-rancid aroma that develops after being reheated. It’s an aroma that can put a considerable damper on daydreams of savoring a delicious turkey sandwich.

The underlying cause of rancidity is the oxidation of unsaturated fats found in muscle-cell membranes. When first cooked, these unsaturated fats remain reasonably stable. Once the meat cools, however, the cell membranes readily break down, exposing fat molecules to oxidation. The greater quantity of unsaturated fats, the more likely warmed-over flavors will arise after reheating cooked meat, which is why such aromas are commonly found in seafood, poultry, and pork.

Iron, abundant in meat and myoglobin filaments in muscle, catalyzes these oxidation reactions after food has been heated, cooled, and then reheated. Brines with curing salts can be used as preventative measures against the reaction, but salt alone can do more harm than good. The best way to buy more time for your leftover turkey is to keep it tightly packaged in a sous vide bag after cooking. The air-free environment therein will help slow the process of oxidation.

Now back to that sandwich. There’s a lot to be said for one perfect bite of thanksgiving—getting all of those flavors in a single bite. When it comes to sandwiches, be strategic. First, if you don’t use a water bath to warm your turkey, try reheating it in extra gravy to restore flavors and lost moisture. As you begin construction, use cranberry sauce as a spread, and then add your gravy-soaked turkey. Next comes a rather difficult decision: whether to finish your sandwich with stuffing or potatoes, but not both. Too many carbohydrates will upset the delicate ratio of proteins and condiments.

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When it comes to turkey, there are many different theories about the best way to prepare a bird. The topic can get downright philosophical with every side presenting evidence on behalf of a particular technique, leaving you to exit the fray with over a dozen methods, each one somehow better than the last. While some methods yield far better results than others, the only true loser is your dried-out bird. Here’s our guide, backed by science, for making a truly succulent turkey.

The Mechanics of Dark and White Meat

Structural differences between white and dark meat make succulence a particularly challenging goal. Meat gets its color from an oxygen-carrying protein called myoglobin, which naturally binds and shuttles oxygen throughout an organism’s body. Dark meat is comprised of slow-twitch muscles that are built for endurance and found primarily in the legs and thighs. These aerobic muscles require large quantities of oxygen-friendly myoglobin to help sustain prolonged use—such as long-distance running—hence their dark coloring. They also burn fat for fuel, so the meat ends up richer in flavor.

In contrast, if you were to look at a turkey breast under a microscope, you would see many light-colored, fast-twitch muscle fibers, geared for intense bursts of activity such as fluttering or scrambling across a road. These fibers work anaerobically and don’t burn fat, so few myoglobin proteins are present, resulting in a white, lean meat.

With different compositions and purposes, muscles cook at different temperatures—dark meat, for instance, requires higher cooking temperatures than white meat. That’s why preparing a turkey can get tricky. A Modernist approach is to cook each separately. For Thanksgiving, we like to create a confit of dark meat, brine the breast meat, and cook both sous vide at their respective times and temperatures. Cooking sous vide provides a precision-based strategy for maximizing juiciness, and it has an additional bonus: it frees up precious oven space for other dishes on your menu.

The Whole Turkey

It can be hard to imagine a Thanksgiving meal without an iconic, whole-roasted turkey. Maybe it’s a deep‑seeded, primal instinct based on millennia of roasting meats over a fire. Or perhaps it’s the nostalgia from that special moment when everyone in the kitchen holds their breath in unison to take in the aroma, the color of the skin, and the site of the steaming turkey as it emerges from the oven.

Whatever the reason, there are two issues that make roasting a whole turkey tricky. First, white and dark meat have to be baked together. Second, a crisp, golden skin requires temperatures that will leave the meat underneath undesirably dry. Suddenly, roasting a turkey becomes a juggling act between crispy skin and succulent meat, a task akin to an algebraic formula: if a turkey leaves the station in St. Louis at 15 mph, how long will it take to arrive in Denver with crispy skin and tender meat? Is there a definitive solution for roasting a whole turkey? Likely not. But we’d like to think that injection brining comes pretty close.

How Brines Work

On a fundamental level, brines modify meat proteins. When dissolved, salt dissociates into positively charged sodium ions and negatively charged chloride ions, which are the atoms that actually diffuse throughout your foods. Salinity is a measure of the concentration of these two ions, which equates to a specific ratio of salt to water. Ions flow from areas of high concentration to areas of low concentration, but, due to a shallow gradient in muscle tissues, the diffusion of dissolved salt tends to be quite slow, which is why it can take months to properly cure a ham.

Brining technically does not work via osmosis, as popular opinion suggests. If osmosis alone were at play, water would be drawn out of the meat, but brining works by pulling water into muscles. Chloride ions from dissolved salt diffuse into muscle fibers and accumulate along the surfaces of protein filaments. As these ions increase in number, they generate a negative charge that loosens and pushes neighboring filaments apart. This newly created channel provides enough space for water to enter the muscle, causing it to swell from the influx of ambient water. Ions further modify muscle proteins by causing them to bind tightly to water and resist shrinking as the meat cooks. Muscle will continue to swell until the salinity reaches 6%—after that, it shrinks and begins to lose water.

Brining is a slow process; salt diffuses through muscle roughly 100 to 1,000 times slower than heat conduction. As such, traditional brining can take days—the thicker the cut of meat, the longer it will take to brine. Protein is also found in skin, thus water molecules are bound and trapped there as well. As a result, the skin of brined meat can easily get soggy because of the time it takes for the brining process to work. Excess water can, then, lead to soggy skin and a rubbery texture. Enter injection brining.

Injection Brining

Injection brining speeds up the process, turning a multiday event into an overnight task. This technique will give you more control over where your brine diffuses, allowing you to expose only the bird’s muscles to the brining solution.

The day before Thanksgiving, create a brine of 6% salt by turkey weight—a reasonable rule of thumb is to use at least as much water by weight as you have meat. Pull back the skin so that you only pierce the meat. Then, using a brining syringe, slowly inject the legs, breasts, and thighs. Inject the muscles evenly over the surface, leaving about an inch between injection sites. Turkeys can be large, so this may require dozens of injections. After your turkey is brimming with brine, let it rest overnight in your refrigerator. When you’re ready to roast the turkey, put it on a roasting rack over a drip pan. The rack allows air to circulate around the turkey, which helps amplify flavors and promote even browning of the skin.

Crispy Skin

Skin has an incredibly high moisture content—it’s about 70–80% water by weight. The science behind golden skin is simple: dry it out by removing moisture. For particularly thick skin, however, we like to add an extra step before cooking—don’t cover your brined turkey when you refrigerate it overnight. Instead, leave it uncovered until it’s time to put it in the oven. By doing so, you’re allowing the turkey’s skin to dry out so that it crisps better in the oven.

Crispy skin is also dependent on knowing the internal temperature of your turkey, so we like to combine the drying step with another equally simple step: tracking the oven’s temperature. Cover your turkey with aluminum foil, which will help prevent the skin from getting too dark, and then place it in the oven. Depending on your oven, bake the covered turkey between 191-204 °C / 375-400 °F. Once the turkey reaches an internal temperature of 68 °C / 155 °F, take the foil off, and crank your oven up to 232 °C / 450 °F in order to brown the skin. When the internal temperature reaches 71–72 °C / 160–162 °F, take the bird out of the oven. The turkey will continue to cook from residual heat to an internal, safe temperature of 73 °C / 163 °F. Note that for the most accurate temperature readings, you should insert your digital probe into the thickest parts of the bird, such as the turkey’s breast.

Patience is a Virtue

Once your turkey is out of the oven, it may be hard to avoid a display of turkey worship, but try to resist the urge to immediately carve your bird. Letting the meat rest can be one of the most difficult steps of the entire process, but it makes a considerable difference in flavor and texture. Ripe with brine, your finished turkey will be juicy. If you carve into it too soon, all of those glorious juices will end up on the cutting board instead of in the meat.

Why do we need to let it rest? Some popular theories suggest that the delay allows moisture, forced toward the meat’s interior during cooking, to travel back to the surface. But the slow diffusion rate of water actually prevents moisture from migrating during cooking and resting. In truth, degraded and dissolved proteins slightly thicken the natural juices as the turkey cools. The thickened liquid then escapes slower when the meat is sliced.

We recommend letting your turkey rest for 20 minutes. Use that time wisely by reheating vegetables made earlier in the day. Five minutes before service, gently warm your turkey in the oven.

One Final Debate: Stuffing

The subject of stuffing also happens to be fodder for debate. In one corner, there are devotees of cooking stuffing inside the turkey. In the other corner are those who insist that stuffing must be prepared separately.

If you want Thanksgiving to be memorable for all of the right reasons, make your stuffing in separate cookware, like a cast-iron skillet. Cooking stuffing inside of your turkey introduces food-safety issues—because turkeys are so thick, your stuffing will never reach a safe internal temperature, meaning you must contend with contamination issues from uncooked turkey drippings. Plus, you’ll miss out on the best part of stuffing: the crispy bits on the surface.

Ready for pie and leftovers? We have a recipe and more tips coming your way.

Leftovers Survival Guide