“Life is like a box of chocolates. You never know what you’re gonna get.” Forrest Gump

akira yamada via Wikimedia commons

As you’re peering into your heart-shaped box of chocolates this Valentine’s Day, you may have questions. Which one will have the caramel? Which one has almonds? Coconut? How do I avoid that weird fruity ganache I hate? Well, trial and error is always a strategic possibility, but if you’d prefer fewer surprises those boxes usually have a key of some sort to tell you which flavor corresponds to which confection. It’s probably in that paper layer that you tossed aside as soon as you opened the box.

But these can’t be your only questions. I know you come here for the plant science. So let’s explore the tree behind the treats.

Theobroma cacao with fruit Credit: Luisovalles via Wikipedia

Chocolate is prepared from the seeds of the tree Theobroma cacao. This small, shade-loving tree is native to the rainforests of Central and South America. It prefers a tropical environment and is cultivated in areas located within 20 degrees of the equator. Flowers develop on the trunk of the tree and once pollinated, they develop into yellow-orange oblong fruits that look more like Nerf footballs than anything you might want to try to eat.* Each pod contains between 20 and 60 seeds. The seeds are high in fat and contain a variety of aromatic chemicals that provide the beloved flavor. Check out the videos below that take you from the tropical tree to the treats in your Valentine’s Day box.

Theobroma cacao flowers Credit: Kurt Stuber via Wikipedia

Now, I could stop writing this post at this point because I’m sure the majority of my readers have already learned more than they thought they possibly could about cocoa trees (unless of course you are a plant scientist or chocolatier). However, in my opinion, chocolate is all about over-the-top decadence. So prepare to overindulge in the next level of chocolate science.

Cross-section of cacao fruit Credit: Keith Weller, USDA ARS via Wikipedia

There are three main cultivars of Theobroma cacao used for chocolate production. The vast majority of commercial chocolate production (80 – 90%) uses ‘Forastero,’ which provides high yields and disease resistance. It’s not the highest quality, but can be produced in large quantities and blended with other varieties to improve flavor. The ‘Crillo’ variety produces the finest quality chocolate, but is the rarest comprising only 5-10% of world production because of low yields and less robust trees. The ‘Trinitero’ variety accounts for 10 – 15% of world production and is a hybrid of the other two varieties. Clearly, these different varieties will command different prices in the world chocolate trade. However, the seeds have indistinguishable appearances. Given the large number of small stakeholder farmers and the middlemen of the cocoa trade, it can be a problem for chocolate producers to know what they are getting (or how much they should pay for it). Researchers have recently developed a genetic test that can be performed on cocoa bean samples to establish their true identity and value. This type of testing has clear benefits to chocolate producers in terms of quality control and financial savings and it may be implemented as standard practice someday soon. Consumers, like Forrest Gump, may still be wondering about the contents of their holiday confections, but nanofluidic single nucleotide polymorphism (SNP) genotyping will ensure that chocolatiers know exactly what they’re getting.

Cacao Beans Credit: David Monniaux via Wikipedia

Hungry for more chocolate trivia?

Theobroma cacao may be native to Central America, but the Ivory Coast is the world’s leading cocoa producer yielding more than 1.6 million tons annually. West Africa dominates cocoa production for the world.

Valentine’s Day is a popular day for chocolate and the highest single day for chocolate sales is February 13th. We purchase around 60 million pounds of chocolate worth about $350 million in the days surrounding Valentine’s Day. This includes about 36 million heart-shaped boxes filled with chocolate candies. Impressive to be sure, but Easter and Halloween still trump V-Day for holiday sales of chocolate.

Each American eats about 10 – 12 pounds of chocolate every year. We may be accused of many excesses compared to the rest of the world, but we are not superlative at chocolate consumption. The world leader- the Swiss consume an average of 21 pounds of chocolate annually.

If you still need more Valentine’s Day plant science, check out yesterday’s post Roses are red or the V-Day edition of Plants in Pop Culture by Postdoc Street or Say it with flowers by Malcolm Campbell. If you’re more in the mood for scary and unsettling chocolate-related news, read Ed Yong’s Ant farm from Aeon magazine. OK, that’s enough reading. For crying out loud, go tell someone you love them (with plants).


*Thankfully, the ancient Olmecs were gustatory adventurers and developed a way to enjoy the chocolate flavor. Needless to say, Columbus liked the drink and there was no keeping it a secret from Europe. Check out the links below for more on the fascinating history of chocolate.

References and Links:


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