Scientists have uncovered what makes chocolate so popular, as they advised confectioners how to keep its beloved texture while making it healthier.
The researchers decoded the physical process that takes place in the mouth as a piece of chocolate melts from a solid into a smooth emulsion.
They claim that a fatty film coating the harder centre, which helps it cover all parts of the mouth, makes chocolate's texture so appealing.
The University of Leeds scientists hope their findings will lead to the development of healthier luxury chocolate, maintaining the mouth feel while being better for us.
'The chocolate sensation'
According to the study, the smooth sensation that arises in our mouth comes from the way the chocolate is lubricated, either from ingredients in the treat itself, from saliva, or a combination of the two.
Almost as soon as chocolate comes into contact with the tongue, fat has a key role to play.
Solid cocoa particles are released, and they become important in terms of the tactile sensation.
Fat deeper inside the chocolate could be reduced without the feel or sensation of chocolate being affected.
Anwesha Sarkar, professor of colloids and surfaces in the School of Food Science and Nutrition at Leeds, said: "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."
First chocolate, next…. cheese?
The study published in the ACS Applied Materials and Interfaces journal did not look at how chocolate tastes, instead focusing on feel and texture.
Tests were conducted using a luxury brand of dark chocolate on an artificial 3D tongue-like surface, which was designed at the university.
Lead researcher Dr Siavash Soltanahmadi said: "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.
"Our research opens the possibility that manufacturers can intelligently design dark chocolate to reduce the overall fat content."
The researchers believe the techniques used could also be applied to ice cream, margarine, and cheese.