Making Great Chocolate Relies on Cocoa Fermentation and Processing
The flavor arms race has begun in the world of chocolate, as researchers aim to mine more exotic and complex flavors for commercial products. Dennis Sandris Nielsen, Professor with Special Responsibilities at the Department of Food Science at the University of Copenhagen (UCPH FOOD), states:
"In this study, we have, together with colleagues from Belgium and Nicaragua, examined for the first time how different conditions during fermentation affect the composition and activity of the microorganisms naturally present on the Criollo beans and how this affects the flavor of the finished fermented beans.”
A cocoa fruit contains 30-40 cocoa beans, which are surrounded by a fleshy pulp. If you take raw cocoa beans and try to make chocolate from it, it lacks the flavor complexity needed to make delicious cocoa products. Fermentation is essential to release the peak flavor potential of the cocoa beans.
Fermentation is accomplished by separating the beans from the cocoa fruit and allowing them to ferment. The pulp surrounding the bean, along with the processing equipment, carry the necessary microorganisms to begin the fermentation. The pulp also acts as the perfect fermentation environment with an acidic ph (3-3.5) and high sugar concentration (10%), allowing a narrow selection of microorganisms to thrive. Yeast starts the fermentation process producing alcohol. At the same time, lactic acid bacteria consume the naturally present citric acid causing a rise in the pH.
This increasing pH makes the environment more favorable for acetic acid bacteria, which converts some of the alcohol present into vinegar. The alcohol and vinegar penetrate the beans and destroy the germ in the cocoa beans preventing germination. The cell walls are broken down, removing the natural barriers within the bean. This allows a variety of substances to react with each other, developing even more flavor. Drying the beans in the sun produces additional flavor complexity while stabilizing the microbial activity and ending the fermentation process. Roasting encourages the products of the fermentation and drying process to react, producing the recognizable flavor of cocoa.
In the study, fermentations from different parts of Nicaragua, including highlands and lowlands, as well as fermentations with a variety of oxygen availability were analyzed.
"By using a combination of high throughput sequencing, chromatography, and sensory analysis, we can get an understanding of the quality of the cocoa, particularly in relation to the processing. Overall, our findings show that the treatment the cocoa receives after the harvest is at least as important for the quality and flavor as the genetics of the cocoa. Where the cocoa was grown also has some significance. By varying the conditions during fermentation, we can therefore also reasonably predict the final taste, which provides good opportunities for high-end producers, in particular, to develop chocolate with different flavors and scents," says Dennis Sandris Nielsen.