Why Are Chocolates Irresistible? Study Finds Reasons, Provides Clues To New Generation Of Luxury Chocolates

Not only has the study described the physical process occurring in the mouth when chocolate is consumed, but also provided clues to the development of a new generation of luxury chocolates.

The way the chocolate is lubricated when it is inside the mouth determines what kind of sensation arises upon its consumption. This feeling could either be the result of the ingredients present inside the chocolate, or from the saliva inside the mouth, or both. 

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Everyone loves chocolates, and the feeling when the confection melts inside the mouth is out of this world. A piece of chocolate is solid, but changes into a smooth emulsion inside the mouth as it is eaten. This is a feeling many find irresistible. 

A new study led by researchers at the University of Leeds has found the reason behind chocolates being irresistible. Not only has the study described the physical process occurring in the mouth when chocolate is consumed, but also provided clues to the development of a new generation of luxury chocolates. The researchers believe these luxury chocolates will not only give a rich feel inside the mouth upon consumption, but will be healthier. 

The study describing the findings was recently published in the journal ACS Applied Materials & Interfaces. According to the study, the way the chocolate is lubricated when it is inside the mouth determines what kind of sensation arises upon its consumption. This feeling could either be the result of the ingredients present inside the chocolate, or from the saliva inside the mouth, or both. 

What happens after chocolate is inside the mouth?

Almost immediately after a piece of chocolate is in contact with the tongue, fat plays an important function. Soon, solid cocoa particles are released, which become important in terms of the tactile (relating to the sense of touch) sensation. Therefore, the fat deeper inside the chocolate plays a limited role in the sensation arising in the mouth. This means that the amount of fat deep inside the chocolate could be reduced, without having an impact on the sensation of chocolate. 

In a statement released by University of Leeds, Anwesha Sarkar, one of the authors on the paper, said lubrication science gives mechanistic insights into how food actually feels inside the mouth, and one can use that knowledge to design food with better taste, texture or health benefits. 

She added that irrespective of whether a chocolate has five per cent fat or 50 per cent fat, it will form droplets inside the mouth. And this is what gives one the chocolate sensation. 

Sarkar explained that it is the location of the fat in the make-up of the chocolate which matters in each stage of lubrication, and this is what has rarely been researched. 

She said the researchers are showing that the fat layer needs to be on the outer layer of the chocolate, and that this matters the most, followed by effective coating of the cocoa particles by fat. All these help to make chocolate feel extremely good. 

Instead of focusing on the question of how chocolate tastes, the study investigated the confection's feel and texture. 

How the study was conducted

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

According to the University of Leeds, tribology is about how surfaces and fluids interact, the levels of friction between them, and the role of lubrication, and the mechanisms occurring inside the mouth when chocolate is consumed simulate this process. When chocolate is eaten, the saliva or liquids from the confection could fulfil the role of lubrication. 

Mechanism of lubrication inside the mouth when chocolate is consumed

Chocolate releases a fatty film upon coming in contact with the tongue. This film coats the tongue and other surfaces in the mouth. According to the study, the fatty film makes the chocolate feel smooth throughout the entire time it is in the mouth. 

Significance of the study

In the statement, Dr Siavash Soltanahmadi, the lead researcher in the study, said with the understanding of the physical mechanisms that happen as people eat chocolate, the authors believe that a next generation of chocolate can be developed that offers the feel and sensation of high-fat chocolate, yet is a healthier choice.

He added that the research opens the possibility that manufacturers can intelligently design dark chocolate to reduce the overall fat content, and the authors 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. 

According to the researchers, the physical techniques used in the study could be applied to the investigation of other foodstuffs that undergo a phase change, where a substance transforms from a solid to a liquid. Some such foods are ice cream, margarine and cheese.