Before diving into the kitchen this Thanksgiving, it’s helpful to have some basic chemistry knowledge up your sleeve. Ever wondered what the fastest way to defrost a turkey is? Or how to make the perfect, lump-free gravy every time? Yesterday, the American Chemical Society's Sally Mitchell—an award-winning high school chemistry teacher and Albert Einstein fellow at the Department of Energy’s Office of Science in Washington D.C.—hosted a Reddit AMA to share some kitchen chemistry tips ahead of Thanksgiving. Outside of her own classroom, Mitchell teaches other chemistry teachers how to incorporate food chemistry into their lessons. Here are her 10 best chemistry-smart cooking hacks to help you concoct a fantastic feast this holiday.
1. THE SECRET TO PERFECT STUFFING IS STALE BREAD.
When is comes to stuffing, texture is key. According to Mitchell the secret to stuffing that’s neither overly dry or overly soggy is to make sure you’re starting out with stale bread: “The secret to a good stuffing is to make sure the bread is dried before adding the butter and water. If you used a cubed baguette, you need to dry out the bread over night by leaving it out exposed to the air or dry it slowly by placing the cubes in a warm oven until they are dried out before mixing in the other ingredients.”
2. AVOID OVER-SALTING BY PAYING ATTENTION TO FOOD TEMPERATURE.
All it takes is one dash of salt too many to push a dish into inedible territory. When seasoning your dishes this Thanksgiving, Mitchell says to be mindful of the temperatures of the food you’re preparing: “If you were to take a food that is hot such as soup and salt it to taste and then cool it down, it would taste too salty. So cold enhances salty and hot reduces the sensation of saltiness. Keep that in mind when you salt food for others.”
For home cooks who have already salted their food past the point of no return, Mitchell says there’s not much that can be done. This is especially true when it comes to baked goods, but she still attempts to find the silver lining in your over-salted cookie dough: "Too much salt in your cookies is hard to overcome, taste-wise—you should try to shape them into objects with cookie cutters and use them for your decorations since the additional salt will help deter bacterial growth."
3. THE FASTEST WAY TO DEFROST A TURKEY IS TO GIVE IT A COLD BATH.
It’s best to plan ahead as far as possible when it comes to Thanksgiving dinner. But if you find yourself on Wednesday night with a fully-frozen turkey on your hands, Mitchell has some advice on how to get it thawing as quickly as possible: “Give it a bath. I would read the label on the wrapping and follow it. If you need to speed this up, a cold-water bath with running water in it defrosts the fastest. Moving water will defrost faster than standing water."
And if you still haven’t gotten around to picking up your turkey for Thanksgiving, Mitchell’s primary piece of advice is to buy it fresh and avoid the defrosting process all together.
4. WANT THIN COOKIES? CHOOSE BUTTER. WANT AIRY ONES? GO FOR SHORTENING.
When experimenting with cookie recipes, Mitchell says that there is a noticeable difference in cookies that use shortening versus cookies that use butter as their source of fat: “You can make them thin and crisp, soft and puffy, or somewhere in between … Butter will tend to make cookies spread out and shortening makes them puff more.”
5. THE RIGHT AMOUNT OF BUTTERFAT IS THE KEY TO WHIPPING CREAM.
Not all creams are created equal. It may be tempting to substitute heavy cream with light cream and half-and-half when that’s all you have on hand, but there are chemical differences in these ingredients that can have an impact on your final product. According to Mitchell, “The difference between all the different types of creams is the percentage of butterfat. Half and half contains 10 to 18 percent butterfat, light coffee cream contains 18 to 30 percent butterfat, light whipping cream contains 30 to 36 percent butterfat, and heavy cream contains at least 36 percent butterfat. To whip cream, it must contain at least 30 percent butterfat. The more the butterfat, the faster the cream will whip and the firmer it will be. (If you over whip your cream, it turns into butter and butter milk).” But if you’re just looking for a cream to use in your green bean casserole this year, Mitchell says whatever you have in your fridge will do.
6. PUT FLOUR IN COLD WATER FOR LUMP-FREE GRAVY.
Nothing ruins a plate of food faster than drowning it in unsavory, lumpy gravy. After years of putting up with awful gravy from her mother, Mitchell was inspired to teach herself how to make it the right way: “My inspiration to becoming a good cook was my mother, because she made the ‘worst’ gravy each year. I learned how to work with flour and thickening agents because of her gravy mistakes, and now I make perfect gravy every time. I recommend the roux…but you can always use the correct flour (gravy flour, you can buy this at the grocery store under several brand names) and always shake the flour in COLD water before adding to the hot drippings.”
7. KNOWING THE CHEMISTRY OF CARAMELIZATION = DELICIOUS DESSERTS.
Different recipes call for different baking temperatures. For those of you who've ever wondered how the level of heat in your oven impacts the final taste of your dish, Mitchell breaks down the delicious chemistry: “Let me focus on caramelization of sucrose (common table sugar). At 170 degrees Celsius (340 degrees Fahrenheit) the sucrose molecule will start to break apart. As the process proceeds, hundreds of new and different compounds form giving sour and bitter flavors, and browning occurs. The sweetness goes down while the darker and more bitter the food gets. This is why sometimes I bake my cookies at a lower temperature to prevent caramelization and sometimes I bake them at a higher temperature. It depends on the final flavor I am trying to create.”
8. REHEAT LEFTOVER TURKEY RIGHT TO KILL BACTERIA.
Deciding when to toss out your Thanksgiving leftovers can quickly become a game of chance. Just because your turkey has been cooked all the way through doesn’t mean it can’t still harbor harmful bacteria after sitting in your fridge for too long. "Remember to always heat up food to at least 55 to 60 degrees Celsius (140 degrees Fahrenheit) to make sure bacteria that can cause foodborne illness is eliminated,” says Mitchell. “They (food safety.gov) recommend eating leftovers within 4 days if stored properly.”
9. BAKING SODA PAIRS WITH ACIDIC INGREDIENTS, WHILE BAKING POWDER BOOSTS LIFT.
Anyone who’s tried substituting baking powder for baking soda in a recipe knows there is indeed a difference between the two. Mitchell explains the chemical significance of both components in your baked goods: “Baking soda is used when ingredients are acidic. When a carbonate (baking soda is sodium hydrogen carbonate) mixes with an acid (vinegar, lemon juice, chocolate, brown sugar are just some examples of acidic foods) a chemical reaction takes place and carbon dioxide is released. This along with steam generated in the baking process will help leaven your brownies. But for an added lift, baking powder is also added. Baking powder usually contains an acid salt that neutralizes the baking soda found in the baking powder mixture and more carbon dioxide bubbles are released.”
10. YOU CAN PASTEURIZE AN EGG IN ITS SHELL WITHOUT ACTUALLY COOKING IT.
The egg is a magical ingredient. They lend themselves to many different applications and cooking methods, and as Mitchell explains, “raw” eggs can even be made safe to eat through a nifty chemistry trick: “When you cook an egg, at specific temperatures for a specific amount of time, wonderful things can happen. Eggs can be pasteurized in their shells without really cooking them. Now you can have raw eggs, safe to use in recipes for mayo or Caesar salad dressing, without the worry of foodborne illness.” She also illustrates how slow-cooking an egg sous vide–style can result in the perfect boiled egg: “Eggs contain different kinds of proteins and each has its own setting point temperature. By controlling the temperature, you can set the proteins gently and cook them all the way through without the harsh temperatures you cannot control from directly cooking on the stove top.”