What makes chocolate so good? The secret lies in the way it lubricates our tongues, scientists say

LEEDS, United Kingdom — Ever wonder what makes chocolate so much better than just about any other sweet treat? Science now has the answer. The mouthwatering attraction of chocolate comes down to how it lubricates our tongues, a delicious new study reveals.

Scientists from the University of Leeds have decoded exactly what takes place when someone eats the sweet treat, as it changes from a solid into a smooth emulsion. Many people find the physical process totally irresistible, and now British experts have worked out why.

By analyzing each of the steps, the study opens the door to developing luxury chocolates with superior mouthfeel and texture. During the moments chocolate enters the mouth, the sensation arises from the way the chocolate is lubricated, either from other ingredients in the treat, saliva, or a combination of the two.

“Lubrication science gives mechanistic insights into how food actually feels in the mouth. You can use that knowledge to design food with better taste, texture or health benefits, says Anwesha Sarkar, Professor of Colloids and Surfaces in the School of Food Science and Nutrition, in a media release.

What role does fat play in chocolate’s feel?

Fat plays a key function almost immediately when chocolate is in contact with the tongue. After that, the chocolatey food releases solid cocoa particles. They become important in terms of the tactile sensation. Fat deeper inside a chocolate bar plays a rather limited role. Researchers say fat content could be reduced without having an impact on the feel or sensation of chocolate.

“If a chocolate has 5% fat or 50% fat it will still form droplets in the mouth and that gives you the chocolate sensation. However, it is the location of the fat in the make-up of the chocolate which matters in each stage of lubrication, and that has been rarely researched,” Prof. Sarkar continues.

“We are showing that the fat layer needs to be on the outer layer of the chocolate, this matters the most, followed by effective coating of the cocoa particles by fat, these help to make chocolate feel so good.”

The study, published in the journal ACS Applied Materials and Interface, focused on feel and texture by testing a luxury brand of dark chocolate on an artificial 3D tongue-like surface. Findings were based on analytical techniques from a field of engineering called tribology, which includes in situ imaging.

Tribology focuses on how surfaces and fluids interact, as well as the levels of friction between them and the role of lubrication. In this case, it’s saliva or liquids from the chocolate.

Those mechanisms are all happening in the mouth when people eat chocolate, Prof. Sarkar says. It releases a fatty film that coats the tongue and other surfaces, creating smoothness throughout the entire time it is in the mouth.

Microscopic image of molten chocolate mixed with saliva.
A confocal microscope showing the structure of the molten chocolate mixed with saliva after it has experienced forces that mimic the eating. (Photo credit: Dr Siavash Soltanahmadi)

Scientists may be able to make chocolate healthier

“With the understanding of the physical mechanisms that happen as people eat chocolate, we believe that a next generation of chocolate can be developed that offers the feel and sensation of high-fat chocolate yet is a healthier choice,” says lead author Dr. Siavash Soltanahmadi. “Our research opens the possibility that manufacturers can intelligently design dark chocolate to reduce the overall fat content.”

“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.”

Chocolate is made from cocoa beans, the seeds of the cacao tree. However, they have to be processed to bring out their characteristic flavor. This starts with fermentation, in which the moist seeds sit for days in baskets covered with banana leaves while yeasts and bacteria grow on the beans and alter their nature.

The beans are dried in the sun and then roasted. Worldwide, about three million tons of cocoa are produced each year. Cocoa production developed over the years by trial and error, not by scientific analysis, so the secrets to chocolate’s global were largely unknown. Techniques used in the study could be applied to other foods that transform from a solid to a liquid, such as ice-cream or cheese, the researchers note.

South West News Service writer Mark Waghorn contributed to this report.

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  1. And of course, fat is BAD for you but all the sugar in the chocolate is good.
    Totally backwards. Cut down the sugar and leave the fat alone!

  2. Uh… I could be wrong, I often am.
    But I thought it was theobromine
    (the food of the gods)
    in the cacao beans
    that made chocolate so good.

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