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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.
Sucrose is actually two simpler sugars stuck together: fructose and glucose. In recipes, a little bit of acid (for example, some lemon juice or cream of tartar) will cause sucrose to break down into these two components.
If you look closely at dry sugar, you’ll notice it comes in little cubelike shapes. These are sugar crystals, orderly arrangements of sucrose molecules.
Under a microscope, you can see that sugar crystals aren’t cubes, exactly, but oblong and slanted at both ends.
What happens when you heat a sugar solution?
When you add sugar to water, the sugar crystals dissolve and the sugar goes into solution. But you can’t dissolve an infinite amount of sugar into a fixed volume of water. When as much sugar has been dissolved into a solution as possible, the solution is said to be saturated.
The saturation point is different at different temperatures. The higher the temperature, the more sugar that can be held in solution.
Making Candy
When you cook up a batch of candy, you cook sugar, water, and various other ingredients to extremely high temperatures. At these high temperatures, the sugar remains in solution, even though much of the water has boiled away. But when the candy is through cooking and begins to cool, there is more sugar in solution than is normally possible. The solution is said to be supersaturated with sugar.
Supersaturation is an unstable state. The sugar molecules will begin to crystallize back into a solid at the least provocation. Stirring or jostling of any kind can cause the sugar to begin crystallizing.
Why are crystals undesirable in some candy recipes—and how do you stop them from forming?
Interfering agents
The fact that sugar solidifies into crystals is extremely important in candy making. There are basically two categories of candies - crystalline (candies which contain crystals in their finished form, such as fudge and fondant), and noncrystalline, or amorphous (candies which do not contain crystals, such as lollipops, taffy, and caramels). Recipe ingredients and procedures for noncrystalline candies are specifically designed to prevent the formation of sugar crystals, because they give the resulting candy a grainy texture.
One way to prevent the crystallization of sucrose in candy is to make sure that there are other types of sugar—usually, fructose and glucose—to get in the way. Large crystals of sucrose have a harder time forming when molecules of fructose and glucose are around. Crystals form something like Legos locking together, except that instead of Lego pieces, there are molecules. If some of the molecules are a different size and shape, they won’t fit together, and a crystal doesn’t form.
A simple way to get other types of sugar into the mix is to "invert" the sucrose (the basic white sugar you know well) by adding an acid to the recipe. Acids such as lemon juice or cream of tartar cause sucrose to break up (or invert) into its two simpler components, fructose and glucose. Another way is to add a nonsucrose sugar, such as corn syrup, which is mainly glucose. Some lollipop recipes use as much as 50% corn syrup; this is to prevent sugar crystals from ruining the texture.
Fats in candy serve a similar purpose. Fatty ingredients such as butter help interfere with crystallization—again, by getting in the way of the sucrose molecules that are trying to lock together into crystals. Toffee owes its smooth texture and easy breakability to an absence of sugar crystals, thanks to a large amount of butter in the mix.
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Chocolate-Caramel Pecan Clusters
Makes:
18 to 20 large or 30 to 35 small candies
Prep Time:
40 minutes
Cook:
35 minutes
Ingredients:
4-1/2 cups pecan halves (1 pound)
2 cups sugar
2 cups whipping cream
3/4 cup light-colored corn syrup
1/2 cup butter
1/8 teaspoon salt
1 cup semisweet chocolate pieces (6 ounces)
1 cup vanilla baking pieces
1/3 cup semisweet chocolate pieces (2 ounces)
1 teaspoon shortening
1/3 cup vanilla baking pieces
1 teaspoon shortening
Directions:
1. In a shallow baking pan, spread pecan halves in a thin layer. Bake in a 350 degree F oven for 5 to 10 minutes or until pecans are a light golden brown, stirring once or twice. Remove from oven. Set aside. Line baking sheets with parchment paper or greased foil.
2. For caramel mixture, in a 3-quart saucepan, combine sugar, 1-1/2 cups of the whipping cream, the corn syrup, butter, and salt. Cook and stir over medium-high heat to boiling.
3. Keeping mixture boiling, very slowly add remaining 1/2 cup whipping cream. Clip a candy thermometer to side of the pan. Reduce heat to medium-low; mixture should boil at a moderate, steady rate over entire surface.
4. Cook, stirring occasionally, until mixture reaches 244 degree F (firm-ball stage). Keep an eye on the mixture so it doesn't boil over. Remove from heat immediately. Remove candy thermometer. Pour into a 4-cup glass measuring cup.
5. For large candies, mound pecans in 20 groups, 3-1/2 inches apart on the baking sheets. For small candies, arrange 3 or 4 pecan halves 2 inches apart.
6. Quickly pour half of the caramel mixture over pecans. (If caramel is very hot, it will run more. Just push caramel back to pecan mound with a small spatula.) Repeat with remaining caramel mixture. (Caramel will have cooled enough to mound.)
7. In a small saucepan, melt the 1 cup semisweet chocolate pieces over low heat. In another small saucepan, melt the 1 cup vanilla baking pieces over low heat. Spread half of the caramel mounds with semisweet chocolate and the other half with vanilla baking pieces.
8. Using the same small saucepans, melt the 1/3 cup semisweet chocolate pieces and 1 teaspoon shortening in one saucepan and the 1/3 cup vanilla baking pieces and 1 teaspoon shortening in the other. Drizzle semisweet chocolate over vanilla-frosted candies; drizzle the melted vanilla baking pieces over the semisweet chocolate-frosted candies. Drag a toothpick through the drizzle, if you like. Let stand until set. Makes 18 to 20 large or 30 to 35 small candies.
Note: Vanilla baking pieces are the same size and shape as the familiar semisweet chocolate pieces.
Nutrition facts per serving:
calories: 526
total fat: 38g
saturated fat: 14g
cholesterol: 50mg
sodium: 100mg
carbohydrate: 42g
fiber: 4g
protein: 4g
vitamin A: 11%
vitamin C: 1%
calcium: 5%
iron: 4%
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