Candida rugosa
Kelly Hummingbird

It is no wonder that chocolate comes from a tree appropriately named Theobroma cacao, which is Greek for “food of the gods.” Who would have actually thought that such a delicious treat could only be made possible by such a tiny organism – a unicellular organism at that? One of the organisms I’m speaking of is called Candida rugosa, a yeast which helps make chocolate so sinfully delicious.

C. rugosa comes from the genus Candida, which includes around 154 species (Dr. Fungus). It is a spherical-shaped unicellular microfungi that is more beneficial than it is harmful. While it is a nosocomial bloodstream pathogen, it very rarely causes infection – unlike its cousin, C. albicans, which is known to cause yeast infections.

In a colony, C. rugosa is white to cream in color and the cells look spherical, but wrinkled (Dr. Fungus). Like most yeasts, it is eukaryotic and unicellular, and grows best in temperatures ranging from 20-30?C. It requires macronutrient sources (carbon, nitrogen, sulfur, etc), and high water concentrations (Desk Encyclopedia of Microbiology).

In my opinion, the main reason that this simple little yeast is so important is that it helps prevent bitter chocolate. The seeds from the Cacao tree must be fermented, dried and roasted to produce a good chocolate flavor. The seeds have a high sugar content that the yeasts favor. The yeasts then ferment the sugars to ethyl alcohol and hydrolyze the pectin that covers the seeds. If the yeasts did not do this, the final product would be bitter. Eventually, the yeasts die from the alcohol they produce and other bacteria grow. After a few days, the beans are dried, bagged, sold, and roasted (Case, date unknown).

Although C. rugosa’s cousins are harmful, I am quite fond of this species of Candida.

References:

Case, Christine L. The Microbiology of Chocolate. http://smccd.net/accounts/case/chocolate.html

Desk Encyclopedia of Microbiology, 2003

Dr. Fungus - http://www.doctorfungus.org/thefungi/Candida_spp.htm

*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.

 

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