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What makes chocolate so irresistible?

Scientists from the University of Leeds have now cracked the mystery behind what happens when chocolate melts in your mouth. (Image for representation) | photo credit: Reuters

The sweet, rich taste of chocolate is a sensory treat that many enjoy, but is that all that makes chocolate irresistible?

Scientists from the University of Leeds have now cracked the mystery behind what happens when chocolate melts in your mouth.

By studying the gradual dissolution of chocolate pieces, scientists have discovered that the sensation of chocolate melting on the tongue comes from the lubrication provided by saliva as it dissolves the sugar particles, or the ingredients used to make the chocolate.

Posted in Applied materials and ACS interfaces, the study saw researchers focus on the texture and feel of the chocolate rather than its taste. They used techniques employed in tribology – the study of friction, lubrication and the interaction between surfaces – to test a luxury brand chocolate on an artificial tongue-like structure. Four different samples of dark chocolate were used.

By analyzing the different stages of chocolate sensation, from the first contact with the tongue to mixing with saliva, scientists have discovered that a fatty layer of film covers the tongue and the mouth. The smoothness provided by the film between the surface of the mouth and the chocolate is what gives the rich, melt-in-the-mouth feel.

“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 “, Anwesha Sarkar, study co-author and professor at the University of Leeds, said in a press release.

She pointed out that the location of fat matters more than the amount of fat. “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 that counts at each stage of lubrication, and this has rarely been studied.

Although there have been many studies on the oral perception of chocolate when bitten, the perception of chocolate when licked has not been sufficiently explored.

The melting property of chocolate also depends on a number of factors such as the concentration of its constituents, the size and shape of solid particles such as sugar crystals and cocoa solids, and the amount of emulsifier. These factors affect the flow characteristics, the primary taste perception and the behavior of the chocolate in the mouth.

The study of edible phase change materials (PCMs) such as chocolate can be extremely beneficial as it can help design healthier foods as well as design foods for vulnerable populations. The new study opens up many avenues for food science and engineering, because understanding the physical mechanics behind what makes food taste good can help provide healthier options while retaining the qualities that make it palatable. These results can also be used to study other foods that convert from solids to liquids, such as ice cream, margarine and cheese.

Siavash Soltanahmadi, the lead researcher, said the 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 degraded layer 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” , did he declare.