Turkey Day Chemistry in the Kitchen

The Secret Science of Sweet-Potato Pie

The sweetest sweet potatoes:
Ever tasted an uncooked sweet potato expecting it to be crisp and sugary like a fresh-pulled carrot? Surprise! Sweet potatoes are made of starch as well as a heat-activated enzyme that turns the starch to maltose, which means their sweetness doesn't develop until they're cooked. The enzyme revs up at close to 135 and is deactivated at about 170. So the longer the sweet potato remains at a temp in the 135-to-170 range, as in a long slow roast, the sweeter it will be.

To roast the potatoes, prick them with a fork and bake them at no more than 400 (remember, the oven must be this hot to make the internal temperature of the potatoes reach the desired 135â€170) until they are soft. Then use them in your favorite pumpkin-pie recipe. You can probably even use a bit less sugar.

The flakiest crust:
The flakes in crust are formed from the layering of strong dough particles (made of wheat-flour gluten and water) with fat. So when your recipe says to break the fat-butter, shortening, lard or a combination-into pea-size chunks, make sure to do so. When the dough is rolled out after resting, those little lumps of fat will separate the starchy dough layers, and these, when baked, will become flakes. Shortening and lard melt at a higher temperature than butter, so their flakes remain more pronounced. Butter has great flavor, though, so a combination makes a nice balance.

Dessert's just the beginning! Pick up more high-tech tips for a fantastic feast:

• Brush up on "The Science of Yummy," then learn how to chop an onion without crying, sear a steak to perfection and more with "Kitchen Science 101."
• Whether pro chef or home chef, our guide to the "Kitchen-Counter Lab" will keep you properly equipped.
• Whip up Doctor Delicious's mojito-strawberry salsa using some food-technology magic you can try at home.
• And for more-advanced kitchen chemistry, check out the recipes in "Molecular Gastronomy for the Masses."

Happy cooking!