Scientists have figured out why good chocolates feel delightful when you bite into them, settling smooth and warm upon the tongue. And they think the discovery will lead to creation of chocolates that are healthier, without sacrificing either texture or taste.
Interestingly, the high-tech discovery relied on creation of a 3D printed artificial tongue.
“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.
But fat’s only important in the outer layer of the morsel, where it first meets the tongue and is lubricated. That means the inner piece of candy could be made healthier and still provide the “chocolate sensation,” say the researchers from the School of Food Science and Nutrition and the School of Mechanical Engineering at the University of Leeds in England.
In a news release, the team said that it had “decoded the physical process that takes place in the mouth when chocolate is eaten, as it changes from a solid into a smooth emulsion that many people find totally irresistible.”
The research, published in the American Chemical Society’s journal, Applied Materials and Interfaces, considered texture, not taste.
The “sensation” of chocolate comes from how it’s lubricated by the chocolate’s ingredients, saliva or a combination. The analysis showed that “fat plays a key function almost immediately when a piece of chocolate is in contact with the tongue. After that, solid cocoa particles are released and they become important in terms of the tactile sensation, so fat deeper inside the chocolate plays a rather limited role and could be reduced without having an impact on the feel or sensation of chocolate.”
Why build a tongue?
The tests used Lindt Excellence bars, a luxury brand of dark chocolate, and an artificial 3D “tongue” surface designed at the University of Leeds. The artificial tongue was used “instead of an actual human tester to eliminate as many variables as possible,” according to The Washington Post.
The news release said that the “researchers used analytical techniques from a field of engineering called tribology” for the study, including imaging.
Tribology looks at how surfaces and fluids interact, friction levels and the role of lubrication.
In 2020, University of Leeds created “for the first time, a 3D soft biomimetic surface that replicates the topography and wettability of a real human tongue. The 3D-printed fabrication contains a Poisson point process-based random papillae (tastebud) distribution and is employed to micromold soft silicone surfaces with wettability modifications.”
“Lubrication science” helped the Leeds researchers analyze what happens when chocolate first meets the tongue and tastebuds. Sarkar said that provides “mechanistic insights into how food actually feels in the mouth.”
Knowing that helps companies ”design food with better taste, texture or health benefits,” she said.
As long as chocolate has some fat, it forms droplets in the mouth that help create a smooth, creamy sensation. But the researchers said the fat needs to be on the outer surface of the chocolate. Fat inside doesn’t contribute to that.
“We believe dark chocolate can be produced in a gradient-layered architecture with fat covering the surface of chocolates and particles to offer the sought after self-indulging experience without adding too much fat inside the body of the chocolate,” said lead author Siavash Soltanahmadi.
The research team said similar techniques could be applied to other foods that change when they meet the tongue, including cheese and ice cream.
Building healthier treats
Sarkar said the study findings could change how manufacturers look at other foods, as well. The key is learning about the role texture plays in what people like to eat.
“Our inclinations and aversion to food really come from its texture, not the taste,” she told The Washington Post. “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.”
The Post article noted another study on how texture and taste mesh. The 2015 research, published in Food Science and Nutrition, focused on the different ways that people “manipulate food in their mouths” and how that drives what foods they like to eat.
The study authors, from The Understanding & Insight Group LLC, said there are four basic “mouth behavior” groups: crunchers, chewers, smooshers and suckers. While most of those categories are self-explanatory, it’s worth noting that smoosher food favorites include custards, oatmeal, candies that melt in the mouth, ripe bananas and soft fries, among others.
Those researchers noted that “individuals are not aware of how they use food in their mouths.”