Chocolate. The quality side.

QC of cocoa & chocolate using NIR

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Last week the BUCHI Group gathered in the mountains of Pennsylvania for our annual national meeting. Jerry Richardson, our Product Manager for BUCHI Kjeldahl, Dumas and Extraction, decided to lure the sales group in with a session modeled around a topic near and dear to so many – chocolate.

Chocolate

Being a Swiss company, you know we have had our hands in the chocolate industry. In fact, one of the largest Swiss chocolate makers has been using BUCHI NIR in their quality control program for years. (If you aren’t familiar with NIR yet, please start here!)

Quality

Just as is echoed across most of the food industry, cocoa and chocolate manufacturers rely on analytical methods to monitor and control quality parameters such as moisture, fat, protein and sugar content of their incoming, in-process and finished products. These critical quality parameters impact the taste, texture, shelf-life and cost of our beloved confections.

So, we circle back to the obvious question – how would NIR support the quality and profitability of a cocoa or chocolate manufacturer?

It starts with the bean

Cocoa beans of course are the most important ingredient in chocolate, but the imported bean quality will vary depending on the – sometimes dynamic – environmental conditions of the region where they were grown. Quantification of the fat content in the beans and intermediate products can help ensure consistency in final products. Another important quality parameter is moisture content, which can be used to monitor the roasting process.

The reference method for fat is the Weibull-Stoldt method, a traditional acid hydrolysis followed by Soxhlet extraction in ether; the reference method for moisture is Karl Fischer titration. Both methods require sample preparation, chemical reagents, skilled technicians and extended analysis time. In contrast, beans can be placed in a sample cup on the NIR and both fat and moisture can be measured simultaneously in as little as 30 seconds. The non-destructive, rapid NIR method can be used to make decisions regarding cocoa bean processing – for example, whether or not roasting is complete.

While it’s easy to think of the NIR as a magical black-box, these measurements are based on the interaction of light with your sample. The carbon-hydrogen and hydrogen-oxygen functional groups representative of the sample fat and water content, respectively, are readily measured using NIR spectroscopy. Applying a calibration model, we can quickly relate the sample spectra back to its composition (e.g. fat and moisture). Of course, the calibration model is based on samples of known composition, and the primary reference methods (Weibull-Stoldt, Karl Fischer) need to be employed to generate and validate the relationship between spectra and the quality parameter of interest.

Cocoa Mass, Cocoa Butter and Cocoa Powder

The theme of quick, non-destructive measurements doesn’t end with the bean. NIR has also been applied to measure moisture and fat in nibs and cocoa mass, free fatty acids and iodine value in cocoa butter, and moisture and fat in cocoa powder. These measurements can be used to maximize the cocoa butter yield from the cocoa liquor, ensure the standard of identity specifications are met without excess addition of expensive ingredients like cocoa butter, and to determine the fat content on which the products should be sold; these applications could have a significant impact on production efficiency and profitability.

Confectionery products

Calibration models using NIR have also been developed for key confectionery product categories, including: milk and dark chocolate. Parameters include: moisture, fat (including solid fat at room temperature), lactose, sucrose and theobromine.

As it turns out, the session’s brainchild, Jerry, was himself a closet chocolatier. He built his own chocolate lab in his home. I have yet to quality-check his product portfolio, though I’ve heard good reviews. After hearing him talk about chocolate, I can at least vouch for his devotion to his craft.

Additional information

For additional information, take a look at the BUCHI Application Finder to see what we have published in way of chocolate analysis. You’ll find applications using extraction and hydrolysis, speed extraction, Kjeldahl and NIR. Please note that not all applications are published; if you have an application in mind, consult a BUCHI representative to see if we have experience within our local or global network!

 

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