In-line crystallisation quality check for chocolate
06 June 2016
Researchers from KU Leuven, Belgium, have developed a quick solution to identify whether cocoa butter is crystallising correctly during the chocolate hardening process.
Professor Imogen Foubert from the KU Leuven Department of Microbial and Molecular Systems explains more about the development “Cocoa butter crystallises as the liquid chocolate hardens. Five types of crystals can be formed during this process, but only one of these has the qualities we want. The number, size, shape, and the way in which the crystals stick together play an important role as well.” It is therefore crucial to monitor the crystallisation of the cocoa butter during the chocolate production process.
“We have discovered that we can detect differences in the crystallisation of cocoa butter with ultrasonic waves,” said Professor Koen Van Den Abeele from the KU Leuven Department of Physics and Astronomy. The new technique involves sending transversal ultrasonic waves through the cocoa butter. The reflection of these waves is measured and this can provide information about the structure of the butter. “When the cocoa butter is liquid, the ultrasonic wave is reflected in its entirety. As soon as the butter crystallises, part of the sound wave penetrates the cocoa butter, so the amount of reflection we measure changes. This enables us to see how the different crystals stick together, which is important for the ultimate properties of the chocolate.”
Traditionally, chocolate manufacturers have analysed the quality of their chocolate in a laboratory, using a sample from the production line. However, this is time-consuming and means that it is not possible to intervene quickly if something is wrong. As a result, a large amount of chocolate is wasted or needs to be re-processed. The novel technique can be used ‘online’ to check the chocolate while it’s still on the production line.
The researchers designed a lab prototype, which now needs to be turned into a prototype for use in real chocolate production lines. The current results were obtained with cocoa butter and need to be confirmed for actual chocolate.
The findings are the result of Annelien Rigolle’s interdisciplinary doctoral research, supervised by Professor Imogen Foubert , who specialises in fat crystallisation, and Professor Koen Van Den Abeele, who’s an expert in the use of ultrasound for non-destructive testing of materials such as composites, metals, and concrete.
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