Scientists discover the secret behind chocolate’s irresistible texture – paving the way for luxurious, healthy chocolate

Happy woman eating a large chocolate bar

Scientists at the University of Leeds have deciphered the physical process of melting chocolate in the mouth, and hope that by understanding the different steps involved, they can develop a new generation of fine chocolate that has the same texture and feel but is healthier for consumption.

Scientists have deciphered the physical process that takes place in the mouth when eating a piece of chocolate, as it transforms from a solid into a smooth emulsion that many people find completely irresistible.

By analyzing each step, the interdisciplinary research team at the University of Leeds hope this will lead to the development of a new generation of fine chocolate that will have the same feel and texture but will be healthier for consumption.

During its moments in the mouth, the sensation of the chocolate arises from the way the chocolate is lubricated, either from ingredients in the chocolate itself, from saliva, or a combination of the two.

Molten dark chocolate microscope

Confocal micrograph of molten dark chocolate. credit: dr. Siavash Sultan Ahmadi

Fat comes into play a major function almost immediately when a piece of chocolate comes into contact with the tongue. Then, the cocoa solids are released and become important in terms of tactile sensations, so the fats deep within the chocolate play a somewhat limited role and can be reduced without affecting the texture or feel of the chocolate.

Anwesha Sarkar, Professor of Colloids and Surfaces at the School of Food and Nutrition Sciences in Leeds, said: “Lubricity gives mechanistic insights into how food feels in the mouth. You can use this knowledge to design food with better taste, texture or health benefits.

“If the chocolate has 5% fat or 50% fat, it will still form droplets in the mouth and that gives you a chocolatey sensation. However, it is the location of the fat in the chocolate’s makeup that is important at each stage of the lubrication, and this has rarely been researched.”

“We’re showing that the layer of fat should be on the outside of the chocolate, and that’s what’s most important, followed by an effective coating of the cocoa particles with the fat, which helps make the chocolate feel good.”

Chocolate mixed with saliva

Confocal microscopy showing the structure of molten chocolate mixed with saliva after it was subjected to forces mimicking eating. credit: dr. Siavash Sultan Ahmadi

Study – published in the scientific journal Applied materials and interface He did not investigate the chocolate taste. Instead, the investigation focused on its texture and feel.

The tests were carried out using a luxury brand of dark chocolate on a three-dimensional tongue-like artificial surface designed at the University of Leeds. The researchers used analytical techniques from an engineering field called tribology to conduct the study, which included in situ imaging.

Tribology is about how surfaces and liquids interact, the levels of friction between them and the role of lubrication: in this case, saliva or liquids from chocolate. All of these mechanisms occur in the mouth when eating chocolate.

When the chocolate comes into contact with the tongue, it releases a fatty film that covers the tongue and other surfaces in the mouth. It is this fatty film that keeps the chocolate soft throughout its time in the mouth.

Dr Siavash Sultan Ahmadi, from the School of Food Science and Nutrition in Leeds and lead researcher on the study, said: “By understanding the physical mechanisms that occur when people eat chocolate, we believe that the next generation of chocolate could be developed to provide the feel and feel of chocolate that is rich in fat but is an option.” More healthy.

“Our research opens up the possibility that manufacturers can intelligently design dark chocolate to reduce the total fat content.

“We believe that dark chocolate can be produced in a layered, graduated structure with the fat covering the surface of the chocolate and the particles to deliver the desired self-indulging experience without adding too much fat inside the body of the chocolate.”

Revenue from chocolate sales in the UK is expected to grow over the next five years, according to research by business intelligence agency MINTEL. Sales are expected to grow by 13% between 2022 and 2027, to reach £6.6 billion.

The researchers believe that the physical techniques used in the study could be applied to the investigation of other foodstuffs that undergo a phase change, in which matter changes from a solid to a liquid, such as ice cream, margarine, or cheese.

Reference: “Insights into the Multiscale Lubrication Mechanism of Food Phase Change Materials” By Siavash Sultan Ahmadi, Michael Bryant and Anwesha Sarkar, Jan. 12, 2023, Available Here. Applied materials and interface.
DOI: 10.1021/acsami.2c13017

This project has received funding from the European Research Council under the European Union’s Research and Innovation Program Horizon 2020.

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