Scientists at the School of Food Science and Nutrition at the University of Leeds in the UK have discovered why chocolate is so irresistible, and that it’s not just down to the taste, but has to do with the process by which it’s made, which passes in the mouth from a solid emulsion to a smooth emulsion due to its own ingredients and the combination with saliva.
The study, whose findings are published this week in the journal Applied Materials and ACS Interface, analyzes in depth the physical process that occurs in the mouth when eating a piece of chocolate and the pleasure that its touch and texture produce. Specifically, the lubrication behavior of this phase change material (PCM).
Chocolate seems irresistible to us not only because of its flavor, but also because of the process it goes through in the mouth from a solid emulsion to a smooth emulsion, due to its own ingredients and the combination with saliva.
Fat plays a key role the moment a piece of chocolate comes into contact with the tongue, after which solid cocoa particles are released and become important in terms of tactile sensation.
Research with an artificial language
Tests were carried out using a luxury brand of dark chocolate on a surface similar to an artificial tongue. The researchers used analytical techniques from a field of engineering called “tribology“, which studies the friction, wear and lubrication that occur during contact between solid surfaces in motion.
In this case, they verified this interaction between the ingredients of the chocolate itself and the saliva. In the taste buds, “the determining mechanisms were the formation of cocoa butter bridges between the particles of this substance and the fatty material of the emulsion droplets”, according to the study.
The authors also verified that the product, when in contact with the tongue, releases a film of fat that covers this organ and other surfaces of the mouth. That film is what makes this product feel smooth all the time in the mouth.
Search charts. / Siavash Soltanahmadi et al./ACS Applied materials and interface
“The unpublished results of this study, supported by long-range lubrication theories, reveal how the tribological mechanism of licking changed from solid fat-dominated lubrication (saliva-poor regime) to aqueous lubrication (saliva-dominated regime), which gave rise to an increase in the coefficient of friction”, point out the authors in their study, where they also highlight “the formation of the distinctive hydrodynamic viscous film” on the tongue.
Remove the fat but not the flavor
The researchers also note that the deeper fatty material in chocolate plays a very limited role, so it can be reduced without affecting the feeling of pleasure from consumption.
The team believes that this work can contribute to the development of a new generation of chocolates with the same taste and texture, but healthier for consumption.
This work could help develop a new generation of chocolates with the same taste and texture, but healthier to eat.
In addition, the physical techniques used could be applied to investigate other foods that undergo a phase change, where a substance changes from a solid to a liquid state, such as ice cream, margarine or cheese.
The project in which this work is part received funding from the European Research Council under the Horizon 2020 research and innovation program of the European Union.