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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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).

6 thoughts on “A Tricky Treat

  1. Hey Liz,

    Thanks for the post. It is always interesting to learn where different foods originated and their other mysterious facts, especially when it comes to chocolate. I am actually eating chocolate cake as I write this : )
    I think this was a good and interesting topic for you particularly looking at how its production might have consequences due to climate changes. I went and looked up some more interesting facts to see if there was anything you might have missed but that was still interesting. I came across a few facts.
    1. Consumers spend more than $20 billion annually on chocolate
    2. Chocolate manufacturers use around 40% of the world’s almonds and around 20% of the world’s peanuts.
    3. The shelf life of a bar of chocolate is a year, but freezing extends this.
    4. The melting point of chocolate is just below the human body temperature. This is why chocolate easily melts in your mouth!
    Finally my two favorite facts:
    5. For chocolate to be lethal, a person has to consume 22lbs!!
    6. There are no allergies caused by chocolates!

    I just thought those were also interesting. Thanks for making me curious about the secrets of chocolate! It makes me wonder what other secrets other foods hold!…

    1. http://www.tiptoptens.com/2011/05/13/10-most-interesting-facts-about-chocolate/

    2. http://www.allchocolate.com/understanding/

  2. This was a tasteful post 🙂

    One thing that might be interesting to include is chocolate’s effect on our body. I’ve always heard that dark chocolate is actually good for you (in moderation of course) but never taken the time to look anything up. Turns out that this is true, but dark chocolate is the best because it has more cocoa than the other varieties. My favorite quote from the article that I looked at was “Many people don’t realize that chocolate is plant-derived, as are the fruits and vegetables recommended for a healthy heart.” So I guess it counts as my vegetable and dessert! If only…
    Another article claims that “If you want to reduce your heart disease risk, there are much better places to start than at the bottom of a box of chocolates. You can still eat chocolate as part of a balanced diet but moderation is key because this sweet treat is usually packed with saturated fat and calories.”


  3. This was a very interesting post! One aspect of chocolate in which I have always been interested (besides the health side) was the reported “feel good” side of chocolate. You always hear about how it stimulates something in your brain to make you happier and I looked into why that may be.

    Scientists are still isolating the chemicals and chemical combinations in chocolate; it contains over 300! One well-known ingredient possibly responsible for “lift” felt after eating chocolate is caffeine. Although it is present in small quantities, it may react with other stimulants (like theobromine, the chemical Liz mentioned above, or phenylethylamine, which is related to amphetamines).

    Another possibility that scientists are looking into is the introduction of a chemical that reacts with the brain similarly to THC (tetrahydrocannabinol) in marijuana. This would explain the cravings that people get for chocolate and the satisfaction that comes with eating it. A possible chemical that could do this is anandamide, a neurotransmitter that is also naturally produced in the brain. However, the scientists did stress that chocolate will not get you high, but just give you a good feeling. More research is currently being done on the chemical composition of chocolate and how it affects brains. I thought this was interesting because I had always heard that chocolate was kind of addictive and appeased a reward section of your brain and these were some reasons why this might occur.


  4. Great post! Several topics have been interesting to read so far..but this chocolate one surpasses them all. In reading this post, I began questions certain “myths” about chocolate…wondering if there was any scientific basis. Interestingly, as Jon Cripe mentioned, chocolate may have beneficial effects on the heart. Chocolate apparently causes increased blood flow, less platelet stickiness and clotting, and improved bad cholesterol. In fact, I found a study that was literally published three days ago in the European Health Journal. This study looked at using flavanol-rich chocolate (FRC) as a treatment for patients with congestive heart failure (CHF) and found that it acutely improves vascular function (1). Patients with CHF have impaired endothelial and increased platelet reactivity. FRC is beneficial for vascular and platelet function by increasing nitric oside bioavailability and decreasing oxidative stress. The researchers found that administering only FRC in normal patients inhibits platelet function. So, they suggest that congestive heart failure can be acutely treated with FRC, primarily due to its ability to inhibit platelet buildup.

    Some other topics concerning chocolate that seemed to pop in my head as I read along were chocolate and its effects on the brain (which kgagesch touched upon), its potential capability as an aphrodisiac, its ability to promote healthy skin, and…the use of chocolate milk as a post-workout recovery drink. I’m not going to comment on chocolate’s aphrodisiac capacities…but I did find some interesting information regarding its effects on skin. Researchers in Germany noticed that the skin of women who were given daily “doses” of extra-flavonoid-enriched cocoa for three months was moister, smoother and red (when exposed to ultraviolet light). The researchers believe that the flavonoids (which absorb UV light) can help protect the skin and can increase blood flow to the skin, thus improving its appearance (2).

    I also looked into the myth about chocolate milk…for a good reason, too. At my fraternity, chocolate milk is always out-of-stock because my brothers believe it is one of the best post-work recovery drinks. Well, a study conducted in the Kinesiology Department at Indiana University–Bloomington suggests that chocolate milk may serve as an effective recovery aid for exhausting exercises (3). Although there study only involved nine male, endurance-trained cyclists, the researchers found that the time to exhaustion and total work were both greater for “chocolate milk” patients than for patients who had drank a carbohydrate replacement drink for their recovery.

    In the end, lizanichini, this was a great topic to post about. It really got me thinking about all the different myths about chocolate…and really to better understand it at a scientific level. Thanks!

    1. Flammer, A.J.; Sudano, I.; Wolfrum, M. et al. Cardiovascular effects in flavanol-rish chocolate in patients with heart failure. Eur Heart J. 2011, n/a
    2. Ingall, M. Chocolate can do good things for your heart, skin, and brain. CNN.com, 2006(Dec 22). http://www.cnn.com/2006/HEALTH/12/20/
    3. Karp, J.R.; Johnston, J.D.; Tecklenburn, S. et al. Chocolate milk as a post-exercise recovery aid. Int J Sport Nutr Exerc Metab. 2006, 16(1): 78-91.

  5. This is such an interesting post. It is always a lot of fun to know about facts about food. Reading this post makes me want to have some chocolate now. I like the fact that you mentioned about climate change here since it is a key factor for future developments now, but people tend to forget about it.
    The picture of cacao pod is great! I love how you said “Seen in its natural form, many may swear they’ve never tried the fruit pictured below.” It is true. I remember seeing it in Ecuador and just could not belive that this actually makes chocolate. Interestingly enough, the natural form of the cacao pod fruit actually doesn’t taste that good and that is probably why people cannot link it and chocolate together.
    I found it interesting to learn about that chocolate is dangerous to dog and did some research. I found that caffeine and all its relatives are poisoned to dogs and that includes coffee, tea, cocoa, chocolate, colas, stimulant drinks such as Red Bull and also some cold medicines and pain killers. Dogs become restless, breath rapids, have heart palpitations and muscle tremors, and even are bleeding when they have caffeine poisoning. There is also no antidote for caffeine. But that reminds me that when I was little, I used to have slight bloody nose when I ate too much chocolate. I wonder whether this has similar mechanism as the poisoning as dogs and cats. Even if human metabolize theobromine much faster than dogs and cats, would it still be dangerous for us when we have a lot of chocolate? Considering kids are smaller in size and about the same size as dogs, I cannot stop wondering. However, I wasn’t able to find much information on this. I am not sure whether it was because this was just a coincidence or even if caffeine can cause damage to human, it has to be an excess amount that normal people can hardly reach.
    I also thought of the story of a friend’s dog. He had some grapes one day and got really sick. Apparently grapes and raisins are bad for dogs as well since they can cause kidney failure in dogs. After eating grapes and raisin, dog will first have repeated vomiting, and then become lethargic and depressed within a day. What we regards as great food is poisoned to our pets and thus when we think we are doing out best to love and take care of them, we might be hurting them. It is actually kind of scary to think about that.
    Coming off the craving of chocolate and its relationship to brain that kgagesch talks about, I found that phenylethylamine, a substance of chocolate, is a chemical found in the body that is similar to amphetamine and it causes the brain to release mesolimbic dopamine in the pleasure centers of the brain to helps mediate feelings of giddiness, attraction, euphoria and excitement. Since the release peaks during an orgasm, researches believe that this might be the reason that women prefer chocolate to sex. I also find out why that women like to eat chocolate prior to menstruation. It is because chocolate contains high levels of magnesium, which runs low during this period.
    Overall, this is an interesting post with a lot of fun facts about chocolate, and I definitely know much more about chocolate now.


  6. First of all I liked the first picture in this article because I actually picked that exact fruit from a tree in Ecuador and we got to taste the seeds in side. They are really bizarre; they melt in your mouth and are sort of gummy, but taste like chocolate. So I thought I’d share a few facts about this plant.

    The plant is found predominantly in the Amazon Basin (where I was in January) and near the foothills of the Andes (also another location were in in Ecuador). Each seed of the plant contains a significant amount of fat (40-50%) also known as cocoa butter, which is helpful in removing stretch-marks on pregnant women. An active ingredient in the plant, “thermobromide” is a compound similar to caffeine. The name of the plant comes from the Greek phrase “food of the gods.” Ironic seeing as it has become such a staple in our obesity-prone Western world. Trees that produce this fruit can be 12-15 feet high. However the one that we stumbled across in someone’s backyard in the Amazon basin was tall enough to reach without climbing the tree.


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