Chocolate Making Series Part 1 – The Art of Cocoa Fermentation
April 7, 2017
When we think of chocolate, what comes to mind is usually the rich, roasty, and creamy flavors of a dark chocolate bar, or the buttery sweetness of milk chocolate. But chocolate doesn’t start out tasting like ambrosia, on the contrary, as a cacao bean, actually a seed, it is unbearably astringent and bitter - good for defending against hungry forest crawlers, but not for chocolate making. To get the chocolatey flavor we all know and love the cacao seeds must first undergo a process called fermentation. That’s right, like pickles and wine, chocolate is a fermented food.
The cacao bean’s long road to chocolate begins in either a heap covered with banana leaves, a wicker basket or tray, or some other container in which to hold the pulpy seeds. But here is where things get a little complicated. A variety of variables are at play - the type of cacao, the season, and how the farmer chooses to ferment his or her beans - that all contribute to how long it will take the beans to reach optimal fermentation, usually somewhere between three to eight days. And this fermentation, it turns out, would not be possible without the help of nature’s greatest instigator - the microorganism.
As beans are being pulled from their pods and prepared for fermentation they touch a variety of surfaces, from hands to banana leaves to the tiny feet of fruit flies, that all provide microorganisms, such as yeasts and bacteria. The yeast organisms feast on leftover pulp from the cacao bean, turning its sugars into ethanol, while bacteria generates lactic and acetic acids that essentially break down the bean. It is this arduous process of fermentation in which beans must be sorted and stirred and carefully monitored for temperature (they must reach 43 degrees Celsius to kill the bean) that breaks down the cellular structure of cacao and unlocks its infamous flavor.
Hitting the sweet spot of a perfectly fermented bean is difficult, timing is crucial. An under fermented bean will still taste astringent and bitter, or will have off-flavors due to the presence of acids that were not eliminated during the fermentation process. On the other hand, there is such a thing as over fermentation. Leave the beans too long and they taste putrid, and are susceptible to mold or infestations. To check beans for quality, a cut test is used in which a bean is split lengthwise to see the inside of the bean. Here is where fermentation comes into full view. Whether or not a bean is over or under fermented becomes apparent in the way it looks - under fermented ones look purple while over fermented look slate-like.
A properly fermented bean will have not only changed its color from a slight purple to a darker brown, but its own chemical structure will have changed as well. No longer is the bean bitter and distasteful, instead via its own death and deconstruction it has become even more valuable. As author Simran Sethi perfectly sums it up, “the death of the bean begets flavor.”
Sethi, Simran. Bread, Wine, Chocolate: The Slow Loss of Foods We Love. New York, NY: HarperCollins Publishers, 2015. Print.
Crit Rev Food Sci Nutr. 2004;44(4):205-21.The microbiology of cocoa fermentation and its role in chocolate quality.Schwan RF1, Wheals AE.Department of Biology, Federal University of Lavras, Lavras, Brazil. email@example.com
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