Why Chocolate is so Delicious, according to Science

Washington Post photo by Salwan Georges
A variety of chocolates on display inside Pierre Marcolini, a luxury chocolate shop in Brussels, in 2019.

Chocolate is delicious – that’s a fact backed up by research. The question, really, is why a bite into its scrumptious goodness is enough to send a person into an utter state of bliss.

Enter science.

After conducting a study that included four types of dark chocolate and a 3D-printed tongue, a team of researchers in the United Kingdom found that it all comes down to chocolate’s slick outer layer – a.k.a. its fat.

“Our main finding out of this is that fat matters a lot,” Anwesha Sarkar, a professor of colloids and surfaces at the University of Leeds, told The Washington Post.

The research paper, published this month in the American Chemical Society’s Applied Materials and Interfaces journal, details how the team of scientists analyzed chocolate’s journey from aluminum wrapper to a tongue’s papillae – replicating each step with a humanlike model of the organ, which they used instead of an actual human tester to eliminate as many variables as possible.

The process of eating chocolate begins with what Sarkar called the “licking phase,” or when chocolate first comes in contact with the tongue. This is when the smooth “chocolate sensation” is set into motion, Sarkar said. Then, as it starts melting and saliva enters the mix, solid cocoa particles in the chocolate are released, along with a rush of happiness-boosting endorphins.

After conducting the experiment, the scientists concluded that chocolate’s much-cherished silky sensation is a product of its fat droplets making cocoa’s otherwise gritty particles go down smoothly inside the mouth. But does this mean chocolate has to be high in fat to be enjoyed?

Not quite, Sarkar said. If the chocolate is coated in fat, it doesn’t necessarily matter whether the chocolate itself contains much fat.

“In the licking phase, fat is absolutely important for the sensation that lubrication creates,” she said. “But as you go down into the chocolate’s inner contents and its core, and this all starts mixing with saliva, the amount of fat doesn’t matter. So, you should have enough fat to coat the cocoa particles initially, but you don’t need too much fat after.”

In other words, the researchers found that the amount of fat isn’t nearly as important as its location – a discovery that could pave the way for a new generation of chocolates that aren’t only tasty but also healthier and more sustainable, Sarkar said.

“The biggest bottleneck in designing food is the taste and texture,” she said. “If we understand the mechanics of why something is delicious, it’s easier to re-create more healthy and sustainable versions. We can also better design food for vulnerable populations, people who have swallowing disorders or who need energy-dense products.”

“I mean, imagine if we could make broccoli taste as good as chocolate,” added Sarkar, a self-described chocolate lover. “Or, at least make something like a zero-calorie chocolate have the same creaminess and silkiness of a normal one.”

Sarkar said her team’s findings could apply to other beloved foods, like cheese. The goal, she said, is to have a better understanding of how food texture plays a role in people’s tasting experience.

“Our inclinations and aversion to food really come from its texture, not the taste,” she said. “So, for example, many things people love contain sugar; but, you know, an orange isn’t the same as a piece of chocolate. So it’s not the sweetness, it’s the texture.”

When it comes to food, other studies suggest that texture and deliciousness are tied together. According to one published in 2015, people’s texture preferences fall into four groups: chewers, who love chewy food; crunchers, who like crispiness; suckers, who prefer items that dissolve; and smooshers, who want nothing more than food to spread around in their mouths.

“Texture can be a major reason for rejection of foods,” said Melissa Jeltema, who co-authored the study with Jacqueline Beckley and Jennifer Vahalik from U&I Collaboration, a strategic business development and products research technology firm. “Individuals have a preferred way of eating foods, so foods that most easily align with that preferred way of eating will be preferred – assuming taste is also liked.”

Jeltema said chocolate is an example of a food item that’s able to bend texture preferences – it can be enjoyed by anyone who likes its taste. For chewers, there are brownies and chocolate-covered raisins; for crunchers, chocolates with nuts; for suckers, hard chocolate candies; and for smooshers, something like a Nutella spread or chocolate ice cream.

That’s the magic of chocolate – according to science.