Improving chocolate production: Researchers check quality of cocoa butter with ultrasound

Researchers found that by using the ultrasound technique they can detect differences in the crystallization behavior of cocoa butter induced by changing the process conditions - temperature and stirring rate - or altering the composition by adding minor components to cocoa butter, Professors Imogen Foubert, who specializes in fat crystallization, told ConfectioneryNews.

Cocoa crystallization detection via ultrasonic waves

When liquid cocoa butter forms into solid cocoa butter five types of crystals are formed, each with its own size, shape, and melting point. Out of those five types, only the beta V crystal type is desirable for use in chocolate, Foubert explained. The size and number of the crystals and how the crystals grow together also influence the properties of the chocolate.

“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,”​ Professor Koen Van Den Abeele, an expert in the use of ultrasound for non-destructive testing of materials, said.

This process enabled Professors Foubert and Van Den Abeele to see how the different crystals stick together, an important aspect for the ultimate properties of the chocolate.

Online vs. offline​

Chocolate manufacturers currently check the quality of their chocolate “offline,”​ in which a sample is taken from the production line to be analysed in a lab. This method is time-consuming and costly, especially when something needs to be corrected. As a result, a large amount of chocolate is destroyed or re-processed.

With the ultrasonic method, the chocolate can be checked “online” ​while it is still on the production line.

“The main advantage of ultrasound is that it is a non-destructive technique that can be used online, so that it can be seen immediately if something is wrong with the crystallization,”​ Foubert said.

‘From cocoa butter to chocolate’​​

Researchers at the University of Leuven want to keep building on the discovery that ultrasonic waves can be used to detect various types of cocoa crystallization while the cocoa butter is still on the production line.

“We have to make the step from cocoa butter to chocolate,”​ Foubert said. “We have to get even more insight into what the technique actually measures and make a prototype that can be built in in a chocolate production line.”​

One company has already expressed interest in collaborating with the research team, according to Foubert.

“Hopefully more will follow, and we will have the financial resources to build this into a working sensor in a chocolate production company,”​ Foubert added.