Leftovers Survival Guide - Modernist Cuisine

Leftovers Survival Guide

MCNovember 25, 2014

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.

SV5_Frozen Turkey Thawing_MG_9930

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.

MCAH_SV_Slow Cooker Sous Vide Cutaway

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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