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7 steps to a sweet tooth: take the following true or false quiz to see how much you know about the velvety concoction called chocolate. Then, read the answers on the following pages to get the story of how chocolate goes from a bitter bean to a sweet Valentine's Day treat.

DID YOU KNOW?

* The melting point of cocoa butler is just below the average human body temperature--37[degrees]C (98.6[degrees]F). That's why chocolate melts when you put it in your mouth.

* The grayish blotches that you sometimes see on chocolate are called blooms. Blooms occur when chocolate is exposed to warm or fluctuating temperatures during storage. This causes cocoa butter to separate from the chocolate. The fatty cocoa trotter migrates to the chocolate's surface and re-crystallizes, forming grayish blotches. The blooms affect the look, but not the taste, of the chocolate.

CRITICAL THINKING:

* What factors make some chocolates tastier than others?

CROSS-CURRICULAR CONNECTIONS:

HEALTH: Study the nutrition facts label of your favorite candy bar. For help on how to interpret the label, visit: www.efsan.fda.gov/~dms/foodlab.html. Then, do research to design a day's menu that will allow you to eat the candy bar and maintain a healthy daily diet at the same time.

RESOURCES

* To learn more about chocolate's history and how it affects the brain, visit: www.bbc.co.uk/science/hottopics/chocolate/

* This Web site is filled with facts about chocolate: www.candyusa.org/Chocolate/

Choco QUIZ

1 Chocolate grows on trees.

(True) (False)

2 If microbes invade the raw ingredients, the chocolate will be spoiled.

(True) (False)

3 Banana leaves are vital to the chocolate-making process.

(True) (False)

4 Much like coffee beans, cacao beans must be roasted to create the perfect piece of chocolate.

(True) (False)

5 A "nib" is the name given to the tiny fragments of chocolate bars that break off during the packaging stage.

(True) (False)

6 People under the age of 21 should not consume chocolate liquor.

(True) (False)

7 Chocolate manufacturers care about whether or not their candy makes a snapping sound when it's broken in half.

(True) (False)

1. True

You won't find chocolate bars hanging from branches, but the cacao (ka-KOW) beans that will become chocolate grow on trees. The beans, which are nestled inside football-shaped pods, grow on cacao trees that thrive in tropical regions. About 40 beans rest in a white pulp inside each cacao pod.

2. False

When cacao pods are fully ripe, farmers cut them from the tree and whack them open. Then, microorganisms such as yeast move in. Ed Seguine, Vice President of Research and Development at Guittard Chocolates, explains: "As long as the beans are in the [unopened] pod, they're sterile. But as soon as it's opened, you get a microbiological attack on the pulp material."

It may sound gross, but this "microbiological zoo," as Seguine calls it, triggers fermentation. In this process, sugars in the beans and pulp are converted to simpler substances--a step that's necessary to create chocolate's rich, tempting flavor.

3. True

Once farmers have whacked open the cacao pods, they scoop out the beans and pulp, and pile them into wooden boxes. Then, they cover the boxes with banana--or closely related plantain--leaves. Beneath this leafy covering, yeasts start working their magic on the bitter beans. First, the yeasts begin producing enzymes (chemicals that break down substances), which convert sugars in the pulp to ethyl alcohol and carbon dioxide. This reaction generates heat. The leaf-covered boxes trap the heat, so the temperature of the beans rises to a sweltering 52[degrees]C (125[degrees]F)--paradise for these heat-loving microorganisms! Other yeasts then convert the ethyl alcohol into acetic acid (vinegar). The heat inside the boxes triggers more enzymes to break down cells inside the beans. Together, these reactions turn the beans brown and create substances that will later give chocolate its mouth-watering flavor.

After approximately one week, farmers remove the fermented beans from the leaf-covered boxes and put them on trays or mats to dry in the sun. Over the next few days, the farmers flip the beans so they'll dry evenly. During this process, the beans lose more than half their weight. That's because most of the beans' water content, along with some of the acetic acid, evaporates. Next, the beans are packed up and shipped off to the chocolate factory.

4. True

Once at the factory, cacao beans get roasted for up to two hours in huge rotating cylinders heated to 121[degrees]C (250[degrees]F). During roasting, more water and acetic acid evaporate, and the substances that were formed during fermentation begin to develop the chocolate-y flavors you know and love.

5. False

After the cacao beans have been roasted at the factory, a machine cracks them open. Then, fans blow away the beans' thin, brittle shells. The part that's left is called the nib.

Approximately half of each nib's content is cocoa butter, a naturally occurring vegetable fat. If you chewed the nib at this stage, you'd miss out on the full chocolate-y flavor. Why? "All of the flavor is still trapped in the cells inside the nib," Seguine says.

6. False

As grinding mills crush the nibs and break apart their cells, the friction, or rubbing force, of the grinding stones generates heat. This heat melts the cocoa butter into chocolate liquor. Contrary to what the name suggests, chocolate liquor is not an alcoholic beverage; it is simply a thick, dark chocolate-y liquid.

What does chocolate liquor taste like? "It has good pucker power," says Melvin Warnecke, a food scientist at Warnecke Technical in Goodlettsville, Tennessee. To sweeten the taste, workers mix in sugar and flavorings. They also add more cocoa butter to give the chocolate a smoother flow. Then, heavy rollers break down the particles of this chocolate-liquor-based mixture until it is silky smooth.

The mixture now heads to the conch (think of a giant crock pot stirred with heavy rollers), where it will spend anywhere from a few hours to a few days at temperatures up to 88[degrees]C (190[degrees]F). This slow cooking removes the remaining acetic acid and perfects the chocolate flavors.

7. True

As liquid chocolate cools and becomes solid, the cocoa butter molecules line up to form crystals. But cocoa-butter molecules form different crystal types at different temperatures. So in the final step of chocolate manufacturing, called tempering, workers warm the chocolate to melt the different crystal types. Then, they slowly cool the liquid to the temperature that will cause the desired crystal type to form--called the beta crystal.

Tempered chocolate is shiny and snaps when broken. That's because it is made of tidy stacks of beta crystals, much like a bunch of chairs that have been stacked up neatly, explains Warnecke. Untempered chocolate, on the other hand, is crumbly and soft to the touch. Why? It contains crystal shapes that don't stack neatly, somewhat like chairs that have been thrown into a heap.

Why do chocolate manufacturers care about a candy's shine and "snap"? It's all part of their quest to transform bitter purple beans into a boxed treat that's fit for your Valentine.
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Title Annotation:PHYSICAL: CHEMISTRY
Author:Adams, Jacqueline
Publication:Science World
Date:Feb 6, 2006
Words:1147
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