Summary: Researchers have decoded the sensory processing mechanisms that make the feeling of eating chocolate so irresistible to most people.
Source: University of Leeds
Scientists have decoded the physical process that takes place in the mouth when a piece of chocolate is eaten, when it changes from a solid to a smooth emulsion that many people find completely irresistible.
By analyzing each of the steps, the interdisciplinary research team from the University of Leeds hopes this will lead to the development of a new generation of luxury chocolates that will have the same feel and texture but be healthier to consume.
During the times it is in the mouth, the chocolate sensation comes from the way the chocolate is lubricated, either from ingredients in the chocolate itself, from saliva, or a combination of both.
The fat plays a key role almost immediately when a piece of chocolate is in contact with the tongue. After that, solid cocoa particles are released and they become important in terms of tactile sensation, so the fat deeper inside the chocolate plays a rather limited role and could be reduced without impacting the sensation. or the sensation of chocolate.
Anwesha Sarkar, Professor of Colloids and Surfaces at the School of Food Science and Nutrition in Leeds, said: “The science of lubrication provides mechanistic insight into how food actually feels in the mouth. You can use this knowledge to design foods with better taste, texture, or health benefits.
“If a chocolate is 5% fat or 50% fat, it will always form droplets in the mouth and that will give you the sensation of chocolate. However, it is the location of the fat in the composition of the chocolate which matters at each stage of lubrication, and which has rarely been studied.
“We show that the layer of fat has to be on the outer layer of the chocolate, that’s what matters the most, followed by an effective coating of the cocoa particles by the fat, these help make the chocolate so good .”
The study – published in the scientific journal Applied materials and ACS interface – did not study the question of the taste of chocolate. Instead, the survey focused on its feel and texture.
Tests were carried out using a luxury brand of dark chocolate on an artificial 3D tongue-shaped surface designed at the University of Leeds. The researchers used analytical techniques from a field of engineering called tribology to conduct the study, which included in situ imaging.
Tribology is about how surfaces and fluids interact, the levels of friction between them, and the role of lubrication: in this case, saliva or chocolate liquids. These mechanisms all occur in the mouth when chocolate is eaten.
When chocolate comes into contact with the tongue, it releases a greasy film that coats the tongue and other surfaces of the mouth. It is this fatty film that makes the chocolate creamy throughout its passage in the mouth.
Dr Siavash Soltanahmadi, from the Leeds School of Food Science and Nutrition and lead researcher on the study, said: “With the understanding of the physical mechanisms that occur when people eat chocolate, we believe that a next generation can be developed which provides the feel and feel of full fat chocolate while being a healthier choice.
“Our research opens up the possibility for manufacturers to intelligently design dark chocolate to reduce overall fat content.
“We believe that dark chocolate can be produced in a gradient layered architecture with fat covering the surface of the chocolates and particles to deliver the desired pleasure experience without adding too much fat inside the body of the chocolate. ”
Revenue from chocolate sales in the UK is set to rise over the next five years, according to research by business intelligence agency MINTEL. Sales are expected to increase 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 study other foodstuffs that undergo a phase change, where a substance is transformed from a solid to a liquid, such as ice cream, margarine or cheese.
Funding: This project has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme.
About this sensory neuroscience research news
Author: David Lewis
Source: University of Leeds
Contact: David Lewis – University of Leeds
Picture: Image is in public domain
Original research: Open access.
“An overview of the multiscale lubrication mechanism of edible phase change materials” by Anwesha Sarkar et al. Applied materials and ACS interfaces
Overview of multiscale lubrication mechanism of edible phase change materials
Studying the lubrication behavior of phase change materials (PCMs) can be challenging in applications involving relative motion, for examplesports (ice skating), food (chocolates), energy (thermal storage), clothing (textiles with PCM), etc.
In oral tribology, a phase change often occurs in a sequence of dynamic interactions between ingested PCM and the oral surfaces of a lick scene at one mixed with saliva stage at contact scales covering the micro- (cellular), meso- (papillae) and macro-scales.
Often, lubrication performance and correlations between length scales and different stages remain poorly understood due to the lack of test setups that mimic real human tissue.
Here, we provide new insights into PCM lubrication mechanisms using dark chocolate as an example at a single papilla (meso) and whole tongue (macro) scale spanning solid states, melted and mixed with saliva, strongly uniting sophisticated biomimetic oral surfaces with on the spot tribomicroscopy for the first time.
The unprecedented results of this study, supported by transcendent lubrication theories, reveal how the tribological mechanism of licking shifted from solid fat-dominant lubrication (saliva-poor diet) to watery lubrication (saliva-dominant diet), the latter having resulted in an increase in the coefficient of friction of at least threefold.
At the mesoscale, the governing mechanisms were the bridging of cocoa butter between confined cocoa particles and the fatty coalescence of emulsion droplets for the melted and saliva-mixed states, respectively.
At the macro scale, a distinctive hydrodynamic viscous film formed at the interface governing the velocity-dependent lubrication behavior indicates the striking importance of multi-scale analyses.
New tribological insights into different phase transition steps and scales from this study will inspire the rational design of the next generation of PCMs and materials containing solid particles.
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