Scientists from the School of Food Science and Nutrition at the University of Leeds in the United Kingdom have discovered why chocolate is so irresistible, and it’s not just because of its flavor. According to the study, the key lies in the process in which chocolate goes from being solid to a smooth emulsion in the mouth, influenced by both its own ingredients and its interaction with saliva.
The study, whose conclusions are published this week in the journal ACS Applied Materials and Interface, delves into the physical process that occurs when consuming a piece of chocolate and the pleasure generated by its texture and feel. In particular, the study examines the lubrication behavior of this phase change material. The results indicate that fat plays a key role when chocolate comes into contact with the tongue. At that moment, solid cocoa particles are released and are crucial for the tactile sensation.
The study was conducted using a luxury brand of dark chocolate and a tongue-like surface. Researchers applied analytical techniques from the field of tribology, which studies friction, wear, and lubrication between moving solid surfaces. They examined how chocolate ingredients interact with saliva and found that “the determining mechanisms were the formation of cocoa butter bridges between the particles of this substance and the fatty material of the emulsion droplets.”
Through this work, researchers observed that upon contact with the tongue, chocolate releases a layer of fat that coats this organ and other surfaces in the mouth, resulting in a sensation of smoothness that persists while the chocolate is in the mouth. The authors also highlight “the formation of a distinctive hydrodynamic viscous film” on the tongue, which contributes to the pleasure of consuming chocolate.
They also point out that the deeper fat within chocolate has a fairly limited role, opening up the possibility of reducing it without affecting the feeling of pleasure during consumption. This could lead to the development of a new generation of chocolates that maintain the same sensation and texture but are healthier.
The research team believes that the techniques used in this study could also be applied to other foods that experience phase changes, such as ice cream, margarine, or cheese. This work was funded by the European Research Council under the Horizon 2020 research and innovation program of the European Union.
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