Chocolate Education: A Note on Taste Part 2
Let’s talk about cacao fermentation and how this step can make or break good flavor. Poor quality fermentation=poor quality cacao. Different parts of the world seem to have different fermentation characteristics, and Hawaii is unique in that our ferments here seems to behave in a different way from anywhere else in the chocolate world. The regional variability of fermentation and its impact on flavor potential are not fully understood, but I’ll do my best to explain some of what we know here.
Yes, chocolate is a fermented food! Most cacao growers use wild yeasts for fermentation, these microorganisms are everywhere and find their way naturally into the process. This stands in stark contrast to the wine industry where standardized yeast strains are used. At Lydgate fermentation happens right here on the farm, and most cacao farmers have a fermentation facility close to their farm. This is because fermentation is a time sensitive process that must be started a short time after harvest. Wild yeasts from the farm mean that cacao has fermentation terroir — as balance and types of local microorganisms are site specific. This is on top of the terroir or place based growing conditions of the farm discussed in our last newsletter. This means our Lydgate Farms bars are unique not just in growing conditions, but also in the microorganism balance of the fermentation process.
It bears mention that not everyone in the chocolate world is in agreement on the variability of cacao fermentation — some say flavor is all genetics and that the fermentation merely potentiates those genetics. But, as someone who is working with this process month in and month out, I can tell you that not every ferment tastes, or behaves, the same.
The basic process of cacao bean fermentation involves a large amount of wet cacao seeds – perhaps 40,000 of those slimy seeds covered in sweet white pulp with the purple bitter insides you ate on the tour. This wet seed is loaded into a vessel or box of some kind (we use 2’x2’ untreated maple plywood boxes here at Lydgate). Wild yeasts along with lactic acid bacteria and acetobacter have already inoculated the mass through environmental exposure during harvest. Oncein the box will begin their magic process. During the 5-7 days of fermentation there are two main phases. In the first anaerobic phase the sugar in the pulp of the cacao seed is converted to ethyl alcohol by yeasts. During the second aerobic phase alcohol is converted to acetic acid by acetobacter which is aided by increased turning of the mass to introduce oxygen. It is during this second phase when the beans can get really hot! The exothermic reaction (internally generated temperature) can get as high as 126º F in the later stages of our ferments. That is hotter than a hot tub folks! This hot acetic acid (vinegar) permeates the cacao seed and begins a series of wonderful metabolic changes and flavor improvements and gives off a pungent smell of fruit vinegar, delightful!
This acetic acid denatures the proteins of the cacao seed, (similar to what happens to fish soaked in lime juice for all you ceviche fans) and causes chemical changes that turn simple bitter flavors into the fine flavors we associate with great tasting dark chocolate. Knowing when to turn the cacao boxes to mix and add oxygen is a decision that is influenced by sight, smell, and by temperature readings that track to various fermentation phases. It is a fine art that takes patience and practice to master.
How the flavor of chocolate is affected by fermentation and all the microbial changes that occur are complex topics that I will attempt to cover in the next Chocolate Education post! Anything else you’re curious to learn about? Please let me know.