09-04 chocolate

[Image above] Who knew chocolate was hiding so much delicious science? Credit: Charisse Kenion on Unsplash

If I take any lessons away from 2020, a year of life defined by the global COVID-19 pandemic, it’s that I’ve learned to better appreciate the little things in life. A homemade meal that not only tastes great but fills my home with fantastic aromas; the warmth of chatting with a familiar face, even if only via my computer screen; a book that transports me to faraway places in my imagination. 

While those may have once been small things appreciated throughout my day, now they are often hallmarks of another day of life enjoyed, savored, appreciated.

For many people around the globe, especially in Europe and the United States, one of the simple pleasures of life to savor and enjoy is chocolate—global chocolate consumption in 2019 alone is estimated to have reached 7.7 million metric tons. That roughly comes out to 2.2 pounds of chocolate per year for every person on this planet.

Although chocolate is a simple pleasure, the science behind chocolate as a food and as a material is deliciously complex.

There is a lot of complex biology behind the process of eating chocolate—compounds within chocolate actually cause release of neurotransmitters in your brain, signaling activity that leads to feelings of happiness and satisfaction.

But there is also a lot of materials science to consider at a chocolate’s surface that affects how we experience eating it, including crystallization and the dynamics of fat migration. And we can’t forget the importance of a chocolate’s visual appearance, as demonstrated by recent efforts to engineer structural color that gives chocolates a shimmery surface.

Arguably, however, taste is the most important sensory experience when it comes to eating chocolate. And a lot of that taste comes down to how chocolate melts on our tongue.

You know how some chocolates feel grainy as they melt, while other chocolates seem lusciously smooth? The structure of chocolate affects how we perceive that texture—it affects how the chocolate melts, and thus how we experience tasting the chocolate in our mouth.

As such, chocolatiers work hard to control structure. They do so through a complex process called tempering that uses temperature changes to align the crystals within chocolate. There are actually six different ways that chocolate can crystallize, and getting this structure right is the key to really good chocolate. 

In addition to the alignment of the crystals, another important aspect of chocolate’s structure is its pores, according to a series of studies in 2019 at Argonne National Lab that used X-rays to investigate the nanostructure of chocolate.

“Our tongues are actually pretty good detectors at this length scale,” ANL X-ray physicist Jan Ilavsky says in the ANL press release. ​“Based on how compact or how open the structure is, that can possibly have an impact on how fast or how slowly the chocolate melts.” And that affects our experience of eating and tasting chocolate. 

So far we’ve talked a lot about the microstructure of chocolate, but a chocolate’s macrostructure is yet another key component to the experience of tasting chocolate. In other words, shape is important because it affects how easily a piece of chocolate melts in your mouth. Yet the shape of one of the most commonly encountered forms of chocolate, in turns out, was designed more for convenience than taste.

“The shape of a typical store-bought chocolate chip is an arbitrary result of the industrial manufacturing process used to make it,” according to industrial designer Remy Labesque. “As you might expect, a drop of molten chocolate is deposited onto a flat surface and left to cool. Chocolate chip taste varies widely by brand, but the shape of the chips does not.”

Which is precisely why artisanal company Dandelion Chocolate enlisted Labesque’s help to entirely rethink the chocolate chip.

Labesque, who is now senior industrial designer at Tesla, engineered Dandelion’s chocolate chip to maximize taste and texture, giving it optimal surface area. Dandelion wanted the chips to work well in large chocolate chip cookies, but also be perfectly suited to sneak a few into your mouth while you’re mixing up that cookie batter as well.

Labesque’s resulting design is drastic—the chocolate chip swapped its curves for angles, taking on a flattened diamond shape. The angular chips have two thick points and two thin, with a straight ridge across the top.

“The shape of our chip is faceted: The edges of a Dandelion Chocolate chip taper to thin-as-we could-make-’em without compromising structure,” Labesque explains in a story on Dandelion’s website. “This is because the thermal mass of a thin piece of chocolate melts more quickly on the palate. So when you put a Dandelion chip on your tongue, the thin, chiseled edges warm-to-melt nearly instantly.”

“The 3D shape, while simple, we believe is also novel,” he continues. “And this is noteworthy because the world of industrial design is running out of simple forms that haven’t been claimed for something already. Beyond that we’re proud to have optimized the chocolate chip eating experience as a result of rethinking the humble shape itself.”

Although Dandelion’s chocolate chips are optimized to melt in the mouth, the chips’ edges are still designed with the practicality of manufacturing in mind, too. Dandelion mass produces the chips in molds, so although the chips’ edges are thin, they are still thick enough to hold up in production as well as in baking.

So eating chocolate is not only a simple pleasure of life, it’s also a great demonstration of the science and engineering that’s all around us every day (and thus an excellent teaching tool!). 

But don’t take my word for it. Science teaches us to be skeptical and gather our own data. So conduct your own delicious experiment—you know, in the name of science. Dandelion sells its faceted chips on its website, although good design and good chocolate are not cheap—a 17.6-oz. bag of these beauties costs $30.