A confocal microscope showing the structure of the molten chocolate mixed with saliva after it has experienced forces that mimic the eating. Credit: Siavash Soltanahmadi
Key points:
- A new study takes an in-depth look, through engineering principles and in situ imaging, at the physical process that takes place in the mouth when eating chocolate.
- With a better understanding of the friction, lubrication and fat involved in the process, researchers believe they can design healthier chocolate that still tastes good.
- The analytical techniques used can apply to other foodstuffs that go through phase changes.
Scientists have decoded the physical process that takes place in the mouth when a piece of chocolate is eaten. The research team at the University of Leeds hope it will lead to the development of a new generation of chocolates that have the same feel and texture, but are healthier.
The study, published in ACS Applied Materials and Interface, used analytical techniques from a field of engineering called tribology, which examines how surfaces and fluids interact, to examine the interplay of chocolate and saliva.
The team noted that when chocolate is in contact with the tongue, it releases a fatty film that coats the tongue and other surfaces in the mouth. Once chocolate is in contact with the tongue, solid cocoa particles are released and they become important in terms of the tactile sensation. It is this fatty film that makes the chocolate feel smooth throughout the entire time it is in the mouth.
“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,” said Anwesha Sarkar, professor of colloids and surfaces at Leeds. “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.”
Equipped with a much better understanding of the physical mechanisms that occur as people eat chocolate, the scientists believe a “next generation of chocolate” can be developed—one that offers the feel and sensation of high-fat chocolate, but is a healthier choice.
“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 researcher Siavash Soltanahmadi, also a professor at Leeds.
Additionally, the team believes the physical techniques used in this study could be applied to the investigation of other foodstuffs that undergo a phase change, such as ice cream, margarine and cheese.
Information provided by University of Leeds.