Science Explains Why Chocolate Should be Savored, Not Scarfed

Cocoa beans are made up of nibs and cocoa butter, roughly 50 percent of each. The butter is a fat that’s stable at room temperature, which is why it is popular not only in chocolate and baked goods, but also in beauty products. When used in the latter, the cocoa butter is typically deodorized, stripped of some or all of its aromas. But these aromas are essential to chocolate.  

Flavor is primarily an expression of smell, not taste—which is why it’s so hard to discern what you’re eating when you have a cold. In chocolate, the molecules that make up these aromas are suspended in the butter (or fat) and released slowly into our mouth and retronasal passage as the glorious substance starts to melt on our tongue.

Chocolate’s high concentration of fat, coupled with a melting point just below human body temperature, allows for maximum flavor dispersal. That’s why, according to food chemist Peter Schieberle, chocolate should be savored, not scarfed.

“When you put chocolate in your mouth, a chemical reaction happens,” Schieberle explained to his colleagues at the meeting of the American Chemical Society before being presented with the 2011 ACS Award for the Advancement of Application of Agricultural and Food Chemistry. “Some people just bite and swallow chocolate. If you do that, the reaction doesn’t have time to happen, and you lose a lot of flavor.”

Every smell is made up of multiple aroma compounds that come together to register in our brains as a distinct scent. While cocoa contains over 600 of these volatile, or airborne, aroma compounds, most of what registers to us as a chocolate smell comes from compounds that, surprisingly, smell nothing like cocoa. Instead, these compounds have aromas ranging from peaches and potato chips to cooked meat that transform when they are combined.

When sharing his team’s findings, Schieberle asserted: “To make a very good cocoa aroma, you need only 25 of the nearly 600 volatile compounds present in the beans.” 

Before the development of advanced genetic testing, early botanists grouped cacao into three categories: Criollo (“native”), Forastero (“stranger”) and Trinitario (“native of Trinidad”)—vague designations based on a combination of geography and plant morphology that didn’t reflect a comprehensive genetic assessment of the plant.

Expanded classifications were published in a 2008 study by Juan Carlos Motamayor and a team of researchers who extracted DNA from cacao leaves and clustered the crop into 10 genetic groupings. These new groupings were organized by geographical location or the traditional variety most represented in the particular cluster. As chocolate reviewer Mark Christian summed up when I interviewed him for my book on diversity in bread, wine, coffee, chocolate, and beer: “I am glad the reclassification happened. It was a f-cking insult to nature to think there were only three [groupings] of cacao.”

By recognizing this diversity, we can preserve it. Motamayor and others have already identified additional cacao groupings. This expansion helps plant geneticists know what material they have to work with so they can utilize diverse traits when breeding new varieties for disease resistance, drought tolerance, and more. Plus, some of the diverse varieties offer an incredible range of tastes—similar to the range found in coffee.

The Heirloom Cacao Preservation Fund (HCP), an initiative co-founded with the Fine Chocolate Industry Association, is trying to increase the profile of traditional varieties of cacao in hopes that farmers will see higher profitability from these diverse offerings. “The HCP mission is driven by flavor,” explains HCP Board President Dan Pearson. “We work with the U.S Department of Agriculture Agricultural Research Service to identify heirloom cacao and link flavor to genetics.”

On its website, HCP asserts it is “the first initiative to connect flavor and genetics with an end goal of rewarding growers by helping them achieve the same or even greater income than they would by selling ordinary or bulk cacao.”

Terroir, most associated with wine, is typically defined as the combination of environmental factors that impart flavor and other characteristics to certain crops. This includes climate, geography and soil quality, as well as farming and processing methods. But terroir also impacts the flavor of cacao, which is grown in a thin belt 10 degrees north and south of the equator.

Senior research fellow Darin Sukha and his colleagues at the Cocoa Research Centre at the University of West Indies assessed how processing location and growing environment impact cocoa flavor in a 2014 study. “When the influence of different processing locations and growing environments on the flavor and other quality attributes of cacao were systematically investigated,” Sukha explained, “there were significant effects on sensory attributes.”

Floral flavors in cocoa, they discovered, were largely a reflection of the genetics of the plant, while fruity flavors varied from location to location and seemed to be influenced by where the cocoa was processed—quite possibly due to the microorganisms found in the soil, on equipment, in fermentation boxes and on the hands of those handling the crop.

So the next time you tuck into a square of chocolate, remember that the factors that make it so delicious start long before it reaches the hands of makers, with cacao genetics, plus the yeast and bacteria that help draw out the taste of place.  

While so-called raw and virgin chocolates are all the rage, there's a reason chocolate typically relies on roasted beans. Roasting is one of the most important ways of heightening flavor: through the non-enzymatic browning process known as the Maillard reaction, the aroma precursors in amino acids attack sugars to create cocoa compounds associated with sweet, nutty, caramel, and chocolate flavors.

The process was identified over 100 years ago by French chemist Louis-Camille Maillard, but was overlooked for many years because the science was so complicated. This changed in 1953 when African-American chemist John Edward Hodge published research that organized Maillard’s discovery into clear, distinct steps.

The Maillard reaction not only generates flavors. It transforms the color and, occasionally, the texture of foods—think of a seared steak or piece of toast. In cocoa, it also facilitates the release of select neurotransmitters, chemicals that transmit signals between nerve cells. In their 2014 study, food scientists Joanna Oracz and Ewa Nebesny of Poland’s Lodz University of Technology found that roasting helped boost levels of dopamine, serotonin and other chemicals found in unroasted cocoa beans.

Dopamine helps modulate blood flow, contributes to cognitive functioning, and regulates motor activity—and its release is associated with feelings of reward and pleasure. Serotonin helps regulate physical and mental processes, including those related to our moods, sexual desire and appetite. 

Smell and taste are experiences we identify with our nose and mouth, but they manifest in the brain. Our first taste buds develop in utero and our mother’s taste preferences help shape our own. These buds hold clusters of receptor cells that recognize five primary tastes—sweet, sour, salty, bitter and umami—plus the presence of fat. Microscopic hairs extend up through the taste receptors to connect with food molecules. These cells communicate with each other and transmit electrical impulses that are carried to the part of the brain where they become taste.

Every flavor outside of primary tastes and the detection of fat is actually a smell. These aromas are triggered by airborne molecules that waft into our nose and the retronasal passage in the back of our mouth. They stimulate smell receptors in the upper nasal cavity that work together in what’s called a “binding pocket” to catch odor molecules and carry messages into the olfactory cortex in the front of the brain. This is where they become what we know as smell.

The olfactory cortex is the same region of the brain associated with memory, which is why smells so often trigger associations that other senses don’t seem to conjure. Familiar smells—those chocolate chip cookies grandma used to bake or a particular brand of chocolate bar that reminds you of your childhood—often take us back to moments that feel safe and happy. Dark chocolate in particular has been shown to decrease stress levels in the human brain, further contributing to psychological health.

“Flavor,” Harold McGee reminds us in his essay "Perception vs. Reality," “is a perception, an experience that’s constructed in the brain.” It is an experience that is uniquely our own, shaped by personal memory and experience. Which is why you might want to keep your next chocolate indulgence all to yourself—to savor slowly, on account of science.