There's nothing like sneaking to the fridge on midnight the day after Thanksgiving. Standing in the cool air in a pool of artificial light, that familiar incriminating pop as you ease open a tupperware container and pick out a slice of breast meat or a spoonful of stuffing. What is it about leftovers that make them so damn tasty the next day—or even later the same day?
There are a few things going on here, according to Kantha Shelke, a spokesperson for the Institute of of Food Technologists who holds a PhD in food science and cereal chemistry from North Dakota State University.
When we pack away our leftovers and pop them in the fridge, she explained in an e-mail, all the fat from the turkey skin and basting sauce seeps into the now-sliced and stored meat, distributing spices and flavors that might not have penetrated through the thicker cuts of meat during cooking. This makes the leftover turkey much more evenly-flavored than the cooked turkey you enjoyed the night before. This difference gets amplified if you reheat the turkey to melt those solidified fats back into the meat, Shelke said.
The best foods for leftovers are those which contain multiple ingredients and spices, according to Shelke, because the refrigeration and reheating process redistributes these flavours.
"A plain slice of turkey refrigerated and then reheated will likely taste no different from the day it was made," she explained. "But a turkey covered in broth or cooked with herbs and spices will have a distinctly different and more flavorful taste when reheated."
The same thing happens with mashed potatoes or dressing, so long as there are a lot of ingredients and seasonings. Starches like these are generally pretty bland straight out of the fridge (though this has never inhibited me, personally). This is because when you cook potatoes or dressing, the starches soften and the flavorings (milk, butter, salt, garlic, etc) can seep through them. But when they get refrigerated, they "retrograde" and turn back into a more solid form.
"Retrogradation is the process of starch molecules rearranging and realigning into a crystalline structure. As this happens, the surrounding flavor compounds get trapped inside the crystalline structure," Shelke said.
"This is why cold mashed potatoes and cold gravy are not as flavorful as their heated or re-heated counterparts. Reheating melts the crystals and releases the flavor from the crystal cage and the foods taste and smell flavorful."
As for a peak leftover window, Shelke said bigger cuts of meat will improve with flavor in the fridge after about 24 hours. But if you've carved your turkey before storing it, it will start to taste better in as little as 12 hours.
"That accounts for the popularity of midnight snacking associated with Thanksgiving and Christmas meals," she noted.
But I had a lot of more questions about leftovers (for science), so I got Shelke on the phone. Turns out, she had some more tips. Want your turkey leftovers to be extra tender? Skip the fridge and pop them in the freezer instead.
"During the freezing process, the liquid becomes crystals of ice and crystals of ice are very pokey," she said. "They literally poke through the pieces of turkey and break up the fibers. So when you thaw it and reheat it, it makes it more tender. The meat becomes like a croissant. It's got many, many layers."
"People are amazed at how wonderful it tastes," Shelke added. No kidding.
Based on our extensive research, here is…
Motherboard's guide to the perfect leftover turkey sandwich:
- When packing your leftovers, be sure to carve the turkey into slices before storing. Add pan drippings or gravy mixed with water to the container and store in the freezer.
- Make sure your starches (stuffing, potatoes, etc) are well-seasoned, pop them in the fridge.
- After at least 12 hours, reheat the turkey, gravy, potatoes and stuffing.
- Use fresh bread and your favorite sandwich accoutrement. Shenke prefers honey mustard and crisp lettuce. I'm partial to a slice of tomato with ground pepper. Cranberry sauce in a classic choice.
- Layer up this monstrosity. Drizzle the gravy over all of the ingredients.
- Sit in the dark and revel in your perfection.
- Leave room for a slice of leftover pie.