Dear Lydia,
A few thousand years ago, humans discovered that beans inside the bright green pods of cacao trees could be made into a real treat.
In South America, people harvested the beans to make a warm, chocolaty drink. Ever since, we’ve found ways to make all kinds of chocolate from cacao beans.
“Chocolate is both a science and an art,” said my friend Jessica Murray. She’s an expert on chocolate and a graduate student in food science and business at Washington State University.
She explained that cacao beans can be separated into a couple different parts. We can extract the fat, or cocoa butter, from the beans. The rest of the bean can be ground up into solids. When we mix these two parts back together, we can make dark, white, or milk chocolate.
In Murray’s kitchen here at the university, she takes 10-pound bricks of chocolate and melts them to 115 degrees Fahrenheit. It turns into a nice, chocolaty liquid.
“Making chocolate is a lot like the experiment where you grow sugar crystals in a jar,” she said.
If you’ve ever tried this experiment, you know that sugar crystals grow on a string inside a jar full of sugar water. In a couple weeks, as the crystals multiply, a giant crystal is left in the jar.
Cocoa butter actually contains crystals, too. It has thirteen different kinds.
“You can’t see the crystals unless you look under a microscope, but that’s what makes the chocolate set correctly and all shiny,” Murray said.
If you’ve ever let a chocolate bar melt on a hot summer day, then later noticed it had a bunch of white spots, you’ve seen some of these crystals in action.
As a chocolatier and a scientist, Murray is after one particular crystal to make the chocolate look and taste the best: the beta crystal.
“But crystals have to have something to grow off of. They don’t just miraculously happen, they have to form,” she said.
When making chocolate, Murray will add more solid chocolate to the liquid chocolate, to help the beta crystals form. The solid chocolate is added into the batch when the temperature of the melted chocolate reaches precisely 105 degrees.
Once the conditions are right, a beta crystal will form. Then, the chocolate is ready to be poured into molds.
“You fill the mold, let it cool, then tip (the mold) upside down, you kind of spin it around and it flings chocolate everywhere and makes a giant mess. But it’s really fun,” she said.
Once the chocolate cools and becomes a solid again, she can add fillings or creams. This year she’s starting her own line of chocolate. She’s calling it WSU Crimson Confections.
As much as I’d like to try Murray’s new chocolates, we cats can’t taste sweets. I’ll have to leave the taste-testing experiments up to those of you with a sweet tooth.
Sincerely,
Dr. Universe
Got a science question? E-mail Dr. Wendy Sue Universe at Dr.Universe@wsu.edu. Ask Dr. Universe is a science-education project from Washington State University.