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The Choba Choba Blog

5 questions for Dr Silke Elwers

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Dr. Silke Elwers is an expert on cacao and co-publisher of “Cocoa Atlas” (2009), a comprehensive comparison of international cacao qualities. From 1998 to 2009 she worked as a biologist in cacao research at the University of Hamburg, where she did her doctorate on cacao quality parameters depending on geographic and genetic origin. Silke has many years of experience in cultivating cacao, including the selection of suitable land, plants, systems, cacao varieties and adjusted post-harvest procedures in Brazil, Panama, Peru and Southeast Asia. She works as a scientific consultant and gives lectures, workshops and conferences about cacao all over the world.

The geographic origin of cacao has always been quite a controversial and complex topic. Can you tell us more about it?

When Columbus reached Central America in the 15th century, he came into contact with cacao on one of his trips. The Maya and other indigenous people of Central America already started to cultivate cacao a several thousand years ago. However, the center of origin of the species Theobroma cacao is not Central America, to where it was brought by pre-Columbian traders. In fact, the genetic origin of cacao is in the so-called Upper Amazon. Thus, the Amazonian regions of Peru belong to the center of origin of cacao.

We commonly talk about three “groups” when dealing with cacao: Trinitario, Forastero and Criollo. This distinction is not very accurate as the diversity of cacaos is way more complex. Can you tell us a bit more about the classification of cacao?

Cacao was brought to Central America and the Caribbean around 2000 B.C. and thus has a long cultivation history in this area. The corresponding varieties are categorized under the name “Criollo” or “native” cacao. When the Europeans discovered the Amazonian region, they found out that wild cacao was growing in this area. They started to install cacao plantations in the Bahia region and also introduced some of the Amazonian varieties to Central America. Thus the name “Forastero” or “foreign” was formed for Amazonian cocoa varieties. Hybrids between Forastero and Criollo form the third group, the so-called Trinitarios (also because the first large scale cultivation took place on the island of Trinidad).

However, this classification is much more related to the historical development of cacao farming and trading than based on genetics reality. In fact, the gene pool of the Criollo group is rather small as all Criollo varieties originate from ancient indigenous cultivars. In contrast, the Forastero group is extremely diverse, with disconnected wild populations alongside all of the many rivers of the Amazon basin. Thus, this so-called Forastero group is very inhomogeneous and many unknown varieties with unique flavours are still waiting to be discovered.

Among the many cacao varieties, there are some that are very interesting in terms of their flavor potential and others not. How can we identify great cacao?

“Fine or flavor” cacaos are the varieties that possess characteristic flavor notes besides the basic cocoa flavour. These can be fruity, floral and also nutty aroma notes. Current studies show that many of these very characteristic components come from the cacao fruit pulp which surrounds the fresh cacao seeds. During fermentation, these compounds infiltrate the cacao seeds and thus form the unique flavor profile of a fine or flavor cacao variety.

Fermenting cacao is a critical step in order to obtain a high quality. Can you explain to us why the fermentation process is key and what happens at this stage ?

During fermentation, the key compounds are formed which is crucial for the development of the cocoa aroma. This happens when the cacao seed tissue is macerated by the infiltration of the acetic acid that is formed during fermentation. The maceration leads to a partial decomposition of the seed proteins, thus forming the so-called cocoa aroma precursors. There is no chocolate flavor without fermentation!

Besides, polyphenols and other very bitter and astringent components are leaking from the seeds during fermentation so that the fermented seeds lose a part of their bitterness. Also, fine or flavour compounds of the fruit pulp invade the seeds, as said above.

Apart from progressively reducing the humidity in the bean, what are other purposes of slowly drying the cacao?

Drying slowly allows the conclusion of the aroma formation within the cacao seeds. This cannot take place if the seeds are drying too quickly, especially in the first three days of drying. Thus cacao seeds should dry at least for seven days. After drying, cacao can be stored and transported safely (without the risk of mould ingression) from the warehouse to the chocolate maker where the magic continues!

The Choba Choba Team wishes to thank Dr. Silke Elwers very much for her kindness and expertise in answering our questions. More expert interviews can soon be found on our Blog … Stay connected!