Great chocolate is a complex mix of science, physicists reveal
The science of what makes good chocolate has been revealed by researchers studying a 140-year-old mixing technique.
Scientists have uncovered the physics behind the process – known as conching – which is responsible for creating modern chocolate’s distinctive smooth texture.
A team led by the School of Physics and Astronomy studied mixtures resembling liquid chocolate created using the conching process, which was developed by Swiss confectioner Rodolphe Lindt in 1879. Their analysis, which involved measuring the density and flow properties of mixtures at various stages of the process, suggests how conching may have altered the physical properties of the microscopic sugar crystals and other granular ingredients of chocolate. Until now, the science behind the process was poorly understood.
The new research reveals that conching – which involves mixing ingredients for several hours – produces smooth molten chocolate by breaking down lumps of ingredients into finer grains and reducing friction between particles. Before the invention of conching, chocolate had a gritty texture. This is because the ingredients form rough, irregular clumps that do not flow smoothly when mixed with cocoa butter.
The findings may hold the key to producing confectionery with lower fat content, and could help make chocolate manufacturing more energy efficient. Their insights could also help improve processes used in other sectors that rely on the mixing of powders and liquids, such as ceramics manufacturing and cement production.
The study, published in Proceedings of the National Academy of Sciences, involved a collaboration with researchers from New York University. The work received funding from Mars Chocolate UK and the Engineering and Physical Sciences Research Council.
Professor Wilson Poon, of the School of Physics and Astronomy, who led the study, said:
Conching consumes a significant amount of energy. We hope that our work can help reduce this consumption and lead to greener manufacturing of the most popular confectionary product in the world. It is also interesting that by studying a subject as practical as chocolate making, we have been able to derive new insights into the fundamental physics of how complex mixtures flow, and then use these insights to help industries very far removed from chocolate manufacturing. It is a great example of how physics can build bridges between disciplines and sectors.