April 19, 2024

I, Science

The science magazine of Imperial College

by Gabriella Sotelo (14 February 2023)

Scientists have worked out the physical process that occurs in your mouth when chocolate is eaten. Specifically they explored that solid to smooth emulsion that occurs which makes chocolate so good, and what exactly was the key player. The result: the fat. 

When you eat chocolate, your oral perception, or loosely, your mouth’s ability to recognize texture, usually begins with biting or licking. Biting is usually most involved with most properties of the chocolate and is tooth-chocolate contact. According to researchers, this is well studied. But what is not as well studied is what happens between the tongue and chocolate. This licking process, and the lubrication behavior of chocolates has been unexplored, until last month when researchers released an insight to this process in the scientific journal ACS Applied Material and Interfaces.

The scientists created a 3D biomimetic tongue-like surface which can emulate the functions of a real human tongue. To decipher the lubrication method of specifically dark chocolate, there was a multistage approach that was taken with the tongue to represent licking and saliva stages. 

The 3D tongue, designed by the University of Leeds,  tested luxury chocolate bars with four different sugar, fat, and cocoa compositions, with cocoa content ranging from 70% to 99%. The analytical technique the researchers used to conduct the study is called tribology. Tribology regards how liquids and surfaces interact, their level of friction, and the role of lubrication, so the saliva or liquids from the chocolate. 

They found what coated the tongue most was chocolates with a higher fat content! Though the 3D tongue may have limitations, the researchers think that the more fat that is in a chocolate bar, the more likely it is to stick to your tongue and mouth in pure deliciousness. 

“If a chocolate has 5% fat or 50% fat it will still form droplets in the mouth and that gives you the chocolate sensation.” Anwesha Sarkar, Professor of Colloids and Surfaces in the School of Food Science and Nutrition at Leeds, stated in a release. Sarkar continued to say “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.”  

Fat is then a key factor in how your tongue feels when chocolate is in contact with it, and knowing that means scientists can then play around with the content to create a so-called healthier bar without impacting the feel of the chocolate in your mouth. The authors of the study are actually hoping for this, so we may hopefully taste the smooth, delicious chocolate with less fat.