I loved this article reported by researchers in Belgium and Switzerland, published in the journal Applied and Environmental Microbiology as it is about chocolate! If you don’t know as I didn’t, fermentation is the first step in chocolate making. Inside the pod the bitter cocoa beans remain covered with a white gluey moist pulp composed of sugar and protein. The beans are piled together and covered with banana leaves. In this manner they are left for around one week with occasional aeration allowing microorganisms to grow initiating fermentation. This casts the heavenly spell. During fermentation, the pulp around the beans eventually drains out but leaves behind the characteristic flavors and aroma we are mad about. The microbes in the environment orchestrating the fermentation actually hold the magic wand. This microbial composition varies greatly with farms, seasons and beans. Of course, that’s why there are so many flavors to delight us. Among the fungi, yeast play a prominent role here. They produce enzyme that degrades the gluey pulp around the beans. Fermentation mediated by yeast converts the moist pulp sugar into ethanol, bacteria then oxidizes ethanol to acetic acid. The acid together with high heat kills the beans initiating chemical reactions which generate aromatic compounds that give chocolate its characteristic taste and flavor.
Yeasts as used in making bread and beer, is a standard commercial culture to ensure reliable, reproducible fermentation and production. Cocoa industry however, does not do that. They depend on natural fermentation. This leads to inconsistency and economic loss. The recent research done by the same research groups in Belgium and Switzerland, reports several experimentally proven efficient yeast cultures they have created to use in cocoa fermentation. The work was challenging as the environmentally selected microbial culture consists of a complex combination of yeast, lactic acid and acetic acid bacteria acting behind cocoa bean metamorphosis. Interestingly the bacterial diversity is much lower and more or less similar compared to fungal ones here. This led them to exclude the bacteria from the culture. Among the fungal crowd, luckily they found very familiar yeast Saccharomyces cerevisiae to be the dominant one. In the first place, to get rid of the complexity and uncertainty in the fungal part, they developed heat tolerant aggressive hybrids of S. cerevisiae strains that can outcompete the wild contaminant fungal strains favored by the high temperature tolerance and killer activity of hybrid yeasts. Killer activity means an ability to produce toxic products that is detrimental to the growth of the competitors. Additionally they showed that the aromatic profiles of the resultant chocolates using these novel cultures differed significantly. This arsenal of cocoa-fermenting yeast cultures with signature flavoring ability is a privilege for the chocolate industry to play with the flavors.
Are you ready to move on?
This work is really noteworthy in terms of technical advancement for standardizing cocoa fermentation. This promises reproducible and quality chocolate without a miss. The bread and beer industry have already refined their way regarding this issue. Cocoa industry can now move on as well. We are yet to know their say. Of course on the way we will have to leave behind some fungi (working in natural fermentation along with S. cerevisiae), we are not sure about. I think there should be enough discussion about those unsung fungi before any decision. If you are missing any fungus in your chocolate then that is another twist in this story. May be designer chocolate (with fungi of your choice) will be the next innovation granting your wish!..