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.
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SPOTSHOT & Carpet Removers: How do they work?!

                             

Have you ever been in a situation in your house, bedroom,…perhaps , dorm room…and someone accidentally spills something on the carpet?  I mean how many countless times does your “responsible” mother spill her red wine everywhere during one of her shows (Dancing with the Stars, Desperate Housewives, The Bachelor, etc.)?  Or how about the number of times you return home and see that your loveable golden retriever puppy left you a “treat” on your new Kerastan carpet?  Or even more likely (and surely more applicable to you fratstar college kids)—the number of occasions your college roommate had a bit too much to drink and, well, couldn’t find the trash can quick enough?  Lucky you, there is a quick remedy to save your carpet: SpotShot Carpet Stain Remover.

But seriously, have you ever thought how this magic potion remover actually works?!  Yeah, me neither….until now.  Here’s how:

Most cleaning agents work according to one of four mechanisms.  These mechanisms employ either “like” solvents, surfactants, oxidizing agents, or “whiteners.”  First, the stain remover may contain a certain solvent capable of dissolving the stain, which is based on the popular solubility aphorism “like dissolves like.”  For instance, if your child accidentally wipes his greasy hands all over your carpet, the resulting grease stain will contain a bunch of hydrocarbons.  In order to dissolve this grease stain, you would remove it by using an inorganic solvent containing hydrocarbons, since like dissolves like.  On the other hand, you might have a stain as a result of, say, butter, which is an organic substance.  As a result, you would want to remove the stain using an organic solvent, such as tetrachloroethylene.  This technique, based on picking a solvent similar to your stain, is the same technique implored in dry cleaning.

Sulfunate ion

A second approach—and the most frequently used in stain removers—employs surfactants, such as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.  Soap is a common surfactant, but stain removers often use sulfonates (pictured left), which are salts of sulfonic acid.  Surfactants are usually organic, amphiphilic compounds.  Amphiphilic molecules contain both hydrophobic groups and hydrophilic tails, so that they contain both a water-insoluble and a water-soluble component.  Thus, a surfactant molecule contains a long, hydrophobic tail with a small, polar head.  The hydrocarbon tail can surround (i.e. dissolve) the grease stain, and the polar ends dissolve in water.  As a result, these surfactant molecules can interact with each other, forming a micelle around a “stain” molecule (pictured below).  This micelle is water-soluble and gets washed away.  In this process, which is called emulsification, stains are thus removed via the formation of micelles by surfactant molecules around inorganic (or organic) stain molecules.

Micelle

A third mechanism stain removers might use involves “eating the stain.”  By using oxidizing agents, such as chlorine bleach or peroxides, stain removers can break the bonds holding the long-chain stain molecules together.  The products of this oxidation reaction are water-soluble and can be washed away more easily by the solvent.  In food-related stains, biological and enzyme detergents work well since they release enzymes that act as catalysts to speed up the chemical digestion of the proteins and fats in these stains.

Lastly, the fourth approach (and certainly a “shortcut” or “last resort” for stain removers) essentially hides the stain from eyesight.  They employ detergents like bleach that disrupt the bonds between chromophore molecules, which absorb light at specific wavelengths, re-emitting it as visible light to produce “color.”  In this case, the optical properties of the stain molecule are changed and seem to be “colorless.”  So with this technique, although we may say that the stain left from dog doo on your living room carpet has been “removed,” the dog doo is actually still there: it just is no longer visible.  Comforting…it makes you think twice about lying down on that carpet of yours, huh?

In sharing these stain-removing properties with you, I hope you have had some sort of “common sense science” revelation.  We often overlook simple everyday items and how they might function.  However, it is important to realize that these seemingly simple items function scientifically—whether chemically, biologically, physiologically, or physically—and that we can benefit from understanding the scientific principles that they employ, no matter how basic or how intricate they may seem.

http://antoine.frostburg.edu/chem/senese/101/consumer/faq/stain-removers.shtml

http://www.cip.ukcentre.com/soap1.htm

http://en.wikipedia.org/wiki/Sulfonate

http://www.youtube.com/watch?v=y3AdOsRAipU&feature=related