About lizanichini

Hi, My name is Elizabeth Anichini and I am a Senior Biochemistry Major at DePauw University. As a science research fellow I have worked on two biology projects at DePauw; first with swallowtail butterflies and later with regeneration in salamander tails. This past summer I strayed from science a bit and did a research project with the Spanish department in Cuetzalan, Mexico. In the future I hope to combine my Biochemistry major, Latin American and Caribbean Studies minor, and Spanish language skills to serve the healthcare needs of the growing Latin American population in the United States. While I do not plan on jumping straight into graduate school, in the next few years I plan to enroll in some variation of a MS/MPH (MS in Nursing, Advanced Community Health/Master of Public Health joint degree).

A Tricky Treat

Seen in its natural form, many may swear they’ve never tried the fruit pictured below. However the foreign looking pods are actually the fruit of the Theobroma cacao, the tree that grows the main ingredient in chocolate, cacao. Below you’ll find a quick Q and A to test your knowledge of the science behind chocolate.

Figure 1. Inside view of the cacao pod. A white pulp surrounds the cacao beans—the main ingredient in chocolate. The pulp can be used to make a juice in some areas, while the seeds contain a large quantity of fat (cacao butter) that allows them to be ground into a fine paste and refined into the treat we know as chocolate!

Who were the first chocolatiers?

The first historical evidence of chocolate reaches as far back as 650BC in the Mayan culture. Archaeologists recently used a combination of high performance liquid chromatography and atmospheric pressure chemical-ionization mass spectroscopy to prove that residue of cacao existed in 14 jars found in Mayan burial sites. The found evidence of cacao in the form of theobromine, a molecule found only in cacao and a few other plants [3].

Figure 2. A vase tested in a recent study for theobromine, an component of cacao plants. The vase is from previously civilizations living in what is now northern Belize

What makes chocolate smell so good?

Chocolate has 600+ compounds volatile compounds that contribute to its smell. Volatile compounds transform into gasses at room temperature and react with odorant receptors in the upper half of the nostril [1]. Recent research shows that some of the individual aromas found in chocolate are human sweat, raw beef fat, and cooked cabbage. So how does chocolate maintain its sweet aroma despite these foul smelling components? According to Gary Reineccius at the University of Minnesota, when more than four scents are simultaneously present, the brain ceases to be able to differentiate individual smells, giving us a pleasant chocolate scent rather than cabbage and human sweat[1].

Is Chocolate really dangerous for my dog?

Yes! One of the main compounds in chocolate is theobromine, a relative of caffeine. Dog and cats metabolize theobromine much slower than humans do, and small doses can lead to poisoning. Dogs have similar tastes for sweets like humans do, so they are more susceptible to consuming a lethal dose of chocolate than cats, who can not taste sweets [6].

Why did the Hershey’s that melted in my pocket turn white once it hardened?

Triglycerides of cacao butter can form six different crystal structures named ß(I) through ß(VI). Each crystal structure is characterized by a distinct melting point, increasing from the lowest melting point, ß(I), to the highest, ß(VI). Most commercial chocolates available contain ß(V) crystal structures, which have a melting point of about 88°F. At temperatures higher than this, chocolate will melt (like the one you left in your pocket), and if not cooled at a slow enough rate, ß(V) crystals will not be able to form properly. The result is a “fat bloom” or a “sugar bloom” which is recognizable in the form of a light colored coating on the chocolate’s surface. In the case of a “fat bloom” cacao butter is separating near the surface, while a “sugar bloom” contains microscopic sugar crystals on the chocolate’s surface. Both blooms result from poor tempering, the process used to make sure chocolate’s temperature throughout its solidification to allow ß(V) crystals to form.

Figure 3. Chocolate that has developed a “fat bloom” due to melting and recrystalizing improperly or an extended shelf life.

Could climate change affect chocolate?

As if the predications of global warming aren’t scare enough, a study published this past September found that climate change in West Africa could actually reduce the suitability of cacao cultivation there [4]. Figure 4 shows all of the locations globally where chocolate is grown, but over half of the world’s chocolate supply is cultivated in Ghana and Ivory Coast. The study looks at climate conditions such as altitude, precipitation and temperature. Ideal cacao-growing temperatures are between 22-25°C globally. At this temperature most cacao can currently be grown between 100-250 meters above sea lever, but increasing temperatures will change the appropriate altitude to 450-500 meters above seal level by 2050. Some environmentalists worry that this shift will increase pressure on endangered forests.

Figure 4: Countries where Chocolate is Grown. Many countries with tropical climates are suitable for growing chocolate.

Figure 5. Change in Land Suitability for Cacao Cultivation Due To Climate Change. A few green regions show prospect for improved suitably as the appropriate growing altitude increases with temperature hikes. However, the overall trend for nearly all of the current growing area is a decrease in suitability.

Works Cited

  1. Arnold, Carrie. “The Sweet Smell of Chocolate: Sweat, Cabbage and Beef: Scientific American.” Science News, Articles and Information | Scientific American. 31 Oct. 2011.
  2. Grassi, Davide, Christina Lippi, Stefano Necozione, and Claudia Ferri. “Short-term Administration of Dark Chocolate Is Followed by a Significant Increase in Insulin Sensitivity and a Decrease in Blood Pressure in Healthy Persons.” American Journal of Clinical Nutrition 81.3 (2005): 611-14.
  3. Hurst, W. Jeffrey, Stanley M. Tarka, Terry G. Powis, Fred Valdez, and Thomas R. Hester. “Archaeology: Cacao Usage by the Earliest Maya Civilization.” Nature. 418.6895 (2002): 289-90.
  4. Läderach, Peter, ed. Predicting the Impact of Climate Change on the CocoaGrowing Regions in Ghana and Cote D’Ivoire. Rep. Managua: International Center for Tropical Agriculture, 2011.
  5. Schenk, H. “Understanding the Structure of Chocolate.” Radiation Physics and Chemistry 71.3-4 (2004): 829-35. Print.
  6. Snyder, Alison. “Fact or Fiction: Chocolate Is Poisonous to Dogs: Scientific American.”Scientific American. 2 Feb. 2007.
  7. Stecker, Tiffany. “Climate Change Could Melt Chocolate Production: Scientific American.” Scientific American. 3 Oct. 2011.