Just for Fun /Try Exploratorium online! What is sugar? The white stuff we know as sugar is sucrose, a molecule composed of 12 atoms of carbon, 22 atoms of hydrogen, and 11 atoms of oxygen (C12H22O11). Like all compounds made from these three elements, sugar is a carbohydrate. It’s found naturally in most plants, but especially in sugarcane and sugar beets—hence their names. Emulsion at work Sometimes eggs function as mediators. Try mixing oil and water, and you'll get, well, oil and water. But with the addition of an egg yolk, oil and water—or fat and water—can blend together into a smooth mix. In hollandaise sauce, melted butter and water form a creamy mixture. Tiny droplets of the butter are dispersed in the water, creating a delicious combination. A chemist would call this an emulsion. A substance that helps two liquids remain in this state is called an emulsifier. Egg yolks contain a number of emulsifiers. There are many different recipes for hollandaise—every chef seems to have a variation of his or her own. Recipe Conversions Makes 1 to 1 1/2 cups     You'll Need... • 3 egg yolks • 1 tablespoon lemon juice • 1 tablespoon water • 1/4 teaspoon salt • a pinch of white pepper • 1 1/2 to 2 sticks (6–8 ounces) melted butter   Tip If you use a double boiler over hot (but not quite boiling) water, you'll get a more even heat and reduce the possibility of the eggs' coagulating. But this precaution comes with a price—you'll have to whisk the mixture for a longer time. • a wire whisk • a medium-weight stainless steel, enameled, or glass saucepan, or a double boiler Did You Know? Without the egg’s ability to join fat-based and water-based liquids, we wouldn't have cake or mayonnaise or Caesar salad dressing! What Do I Do?  1. Put the egg yolks in the pan and beat them with a wire whisk for a minute or two until they are slightly thickened.  2. Beat in the lemon juice, water, salt, and pepper until they are well combined.  3. Place the pan over low heat and stir the mixture with the wire whisk until it becomes smooth, creamy, and thicker. You’ve now created the initial emulsion. Tip Remove the pan from the heat occasionally to keep the mixture from cooking too quickly.     4. Remove the pan from the heat. Begin adding the melted butter by no more than a quarter teaspoon at a time, quickly beating in each addition before you add the next. Make sure you scrape the mixture from the sides and bottom of the pan. When the sauce is as thick as heavy cream, you may beat in the butter by half tablespoons. It takes about 5 minutes to create the final emulsion. Did You Know? This rich sauce is perhaps best known as a companion to the poached egg in the classic Eggs Benedict. It is often poured over asparagus and other green vegetables as well.     5. Serve at once—or keep the sauce warm by setting it over a pan of lukewarm water. Hollandaise is served warm, not hot. Flan, also known as crème caramel, is a popular dessert in many parts of the world, including Europe, the Caribbean, the Americas, and the Philippines. A baked custard, its essential ingredients are eggs, milk, and sugar. As a custard bakes, the egg proteins form a network that traps liquid, creating a gel. Recipes for this smooth, creamy treat abound, and for good reason: It’s happy to accommodate substitutions, changes in proportions, and the addition of flavorings, offering many opportunities for experimenting.    What’s a gel? Recipe Conversions What Do I Need? For the caramel syrup • 3/4 cup sugar • 2 to 3 tablespoons water   For the custard • 2 cups whole milk • 1 cup half-and-half • 2 vanilla beans • 1 teaspoon vanilla extract   • 5 large eggs   • 1/3 cup sugar     • 1-quart saucepan   • a soufflé dish with 3-inch sides or 6 small ramekins   • 2-quart saucepan with cover   • a wire whisk   • a sieve   • 2 mixing bowls   • a paring knife   • a baking pan with 2-inch sides (for water bath)   • a large serving plate or 6 small serving plates  Did You Know? The origins of flan can be traced to early Roman times. The invention of baked custard—containing eggs, milk, and honey—is attributed to Marcus Apicius, a cookbook writer from about the first century. (Translations of his work are still available today.)   What Do I Do? For the caramel syrup   1. Put the sugar in the 1-quart saucepan and stir in enough water to moisten all the sugar. Heat gently until the sugar is dissolved. Then bring to a rapid boil and cook for several minutes until caramel-colored. Do not stir. (Large, thick bubbles let you know that caramelization is about to take place—have your soufflé dish or ramekins ready.) • The temperature needs to be well above 300° F, so the sugar crystals will melt. 2. Pour the caramel syrup into your soufflé dish or ramekins, making sure that the bottom is evenly covered. For the custard   1. Preheat the oven to 325° F.      2. Put the milk and half-and-half into the 2-quart saucepan, add the vanilla beans, and heat to a boil. Cover and remove from heat; leave for 5 minutes.     3. Put the eggs in a mixing bowl and gradually blend in the sugar, stirring with the whisk until the sugar dissolves. Don’t incorporate air into the mixture.     4. Remove the vanilla beans from the milk/cream mixture, and slowly pour the milk into the eggs while stirring gently with the whisk. Tip Vanilla beans can be reused, although, without the seeds, the flavor will be less intense. Just wash and dry them, then store them in a glass jar.   5. Put the sieve over the second mixing bowl and strain the milk/egg mixture through it. 6. Wipe any milk off the vanilla beans and slit them lengthwise. Use the tip of the knife to scrape out the black seeds from the beans. Add the seeds to the custard mixture along with the vanilla extract.     7. Pour the custard into the soufflé dish or ramekins.       8. Place your dish or dishes in the baking pan and put the pan in the oven. Add hot water (not boiling; just hot tap water) until it reaches about halfway up the sides of your dish or dishes. Bake for about 35 minutes if you’re using ramekins; about 50 minutes if you’re using a soufflé dish. Check the water bath from time to time to make sure it isn’t boiling; add ice cubes if necessary. 9. Your flan should be done when it’s lightly colored and firm to the touch but not solid. To double check, stick the blade of your knife in the center of the flan and halfway down; the blade should come out clean. Carefully remove the baking pan from the oven, then remove the flan from the water bath. Let the flan cool to room temperature, then chill, covered, in the refrigerator for at least 4 hours.     10. To remove your flan, run your knife between the side of the custard and its container. Put a serving plate on top of the dish and quickly invert the two. Then lift the dish straight up.     What Else Can I Try? * Is whole milk plus half-and-half too rich for you? Not what you happen to have in your fridge? You can experiment with any milk products. Some recipes, for instance, call for condensed milk, including the sweetened or flavored varieties. * The seeds from vanilla beans provide a visual addition to your flan, as well as adding flavor. But vanilla beans are expensive! You might want to use them only for very special events, increasing the amount of vanilla extract for more ordinary occasions. You might experiment with other favorite flavors, too, such as coconut and lime. You can also flavor the caramel syrup with a tablespoon or so of cognac or various liquors. * The yolks of the eggs contribute to both the smoothness and the stability of a flan, and many recipes call for the addition of extra yolks. If you’re not afraid of the extra fat and cholesterol, and if you happen to have egg yolks left over from, say, making Pavlova, you might want to experiment with adding extra yolks to your flan. *A beaten egg white can foam to eight times its original volume. Soufflés, angel food cakes, and meringue all make use of the exceptional foaming powers of egg whites. Pavlova is a lovely, light dessert made in a meringue shell. This dessert uses only the whites of eggs. Consider making this dish for desert when your meal includes hollandaise sauce, which uses only egg yolks! What Do I Need? . • 4 egg whites at room temperature    Why does the temperature matter? • 2/3 cup finely granulated white sugar • 4 teaspoons cornstarch • 1/2 teaspoon white vinegar   • 1 teaspoon vanilla extract   • 1 cup heavy whipping cream   • approximately 1 cup fresh fruit (kiwis and strawberries are traditional)     • a pastry bag and star tips (a pastry bag is not essential, it just makes your meringue shell prettier)   • baking parchment paper   • a baking sheet   • a bowl (glass, stainless steel, or copper is best)    Why can’t I use a plastic bowl?   • a mixer, an egg beater, or a wire whisk    Is there any advantage to using a whisk?       What Do I Do?   1. Set your oven to 250º F.  2. Put the egg whites in the bowl. Add the vinegar. Beat the egg whites until fluffy.  3. Once the egg whites are fluffy, slowly add sugar.   4. When the egg whites are very stiff, add the cornstarch and the vanilla, whisking a few more turns. Do not overwhisk here!   5. Wet the baking parchment paper, crinkle it up, line the baking sheet with it. Draw a circle on the parchment paper as a guide for the meringue, then turn it over. Add a tip to your pastry bag. (Star tips, open or closed, work well). Fill your pastry bag about half full with the egg foam and twist it closed. Squeeze the pastry bag and make a meringue circle about 10 inches in diameter on the wax paper. If you don’t have a pastry bag, use a spoon to mound the meringue on the wax paper and make a well in the middle, creating a bowl-shaped shell.     6. When your circle is done, pipe a bunch of stars along the edge. Keep piping higher and higher until you have a nice deep bowl.     7. Put the meringue in the oven. After 45 minutes, turn the heat off. Leave the meringue in for another hour, or until it is completely cool. You can even leave it overnight.     8. While the meringue is in the oven, cut up your fruit.     9. Remove the meringue bowl from the oven. Make sure it’s nice and cool—if it’s still warm, wait and try again in a little while.     10. Whisk the cream until until it’s stiff.       11. Fill the meringue bowl with whipped cream and put the fruit on top for a delicate, airy treat.     12. Serve promptly, so the meringue doesn’t get soggy from the cream.  Wood flavors meat?    Visit a Lollipop Factory   Did you know? In the 1920s, the retail price of chicken topped $10 per pound in 1994 dollars, and cookbooks advised homemakers on how to substitute veal for chicken. Chicken was a seasonal meat, produced from eggs laid in the spring. This is the origin of the term spring chicken. Did you know? Rodents' noses are much more sensitive than ours. If we could smell a rose from a mouse's point of view, its scent might be completely unfamiliar. Humans can detect smells at very low concentrations. Vanillin, for example, can be sensed at .0000000002 milligrams per liter of air. There is a strong link between smell and memory. You might add to a dinner guest's enjoyment by making a food with a smell you know they'll associate with a pleasant experience. Did you know? Salt can hide bitter flavors. Prove it to yourself with our quinine cover-up activity. The heat of chili peppers is actually not a flavor, but a response of pain receptors on the tongue. Learn more about chili in our dinner fix-its quiz. As we age, we lose taste buds, and our sensitivity to food decreases. Food tastes blander to older people, so spice it up for them! Did you know? Stem cells are unspecialized cells that serve as the source, or "stem," for specialized cells like heart, brain, or blood cells. Found in days-old embryos and a few adult organs, stem cells have two unique properties: they can change into other types of cells, and theoretically, they can divide without limit.