USING SCIENCE TO ANALYSE THE SMELL OF COCOA

Last Updated on June 13, 2021 by Nick Baskett

Chocolate is big business, and separating the good beans from the bad is a critical first stage for chocolate companies. Cocoa beans are dried and fermented to kill bacteria and bring out the flavour, but the process is not always perfect and beans can be ruined, mouldy, or have other undesirable characteristics.

Transporting beans that get discarded at the processing plant is a costly mistake buyers want to avoid. To help mitigate this risk, expert tasters are employed to quality check the bags before they’re purchased or shipped, but this, some in the industry claim, is not an infallible exercise.

The Leibniz Institute for Food Systems Biology at the Technical University of Munich in Germany has issued a research paper in which they claim there is a way to avoid mistakes and apply science to quantify the test results.

A smell is our brain’s interpretation of a chemical molecule that our sensitive noses can detect, so the challenge is to identify the elements that are associated with bad beans. This is what the team of researchers think they have achieved.

The presence of two metabolites including a chemical compound, geosmin, were named as the key indicators of a mouldy-tasting bean.

Our approach really was the first one to definitely show that it’s the key compound – Martin Steinhaus, head of the sensory systems chemistry unit at TU Munich, Head Researcher

The hope is that this discovery lays the foundation for a number of applications in the industry, including widespread screening prior to shipping. The system would need to be commercialised at a low enough cost to be deployed in the country of origin, but the benefits could be to determine the degree to which unattractive compounds existed and thereby grade the bean before a price is set.

The market for technology to grade commodities seems to be a hot area of research. Demetria, a company based out of Israel has developed technology for a similar purpose in coffee beans but using cheap light refractometry, and a mobile app. The company hopes to bring their technology to the cocoa sector next.

As the CEO of Demetria told Nick Baskett during a Bartalks interview the technology can also be used to inform the farmers when they are doing something that gets good results and help them avoid the actions that result in negative outcomes.

In the cocoa sector, some approaches taken by farmers will result in poor outcomes. Cocoa has a lot of fat in the bean, about 50%, which the plant naturally develops to help it sustain growth in a thick shady landscape. That fat easily absorbs flavours from its environment, and beans that are not carefully stored and managed can easily absorb unattractive flavours.

The challenge isn’t only with the farmers, however. Flavour profiling cocoa is more of an art than a science, and what is considered perfect for one company, may get rejected by another. Bringing some empirical data to the process may remove some of the art of tasting, but also perhaps some of the cost.

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