Chocolate Maker's Journal
Markham Valley Part 2: Large-Scale Fermentation & Drying
Posted on 11/29/2011 by Ray Major
After a difficult journey over the mountains of Papua New Guinea, Lech Moonsbourgh and I drove across the Markham River Valley. We finally located Markham Farm, where a burly security guard directed us to the fermentary.
We drove around and parked beside what looked like an airplane hangar. It was the Markham fermentary and it was enormous. Outside of the Dominican Republic it was the largest single unit I had ever seen.
The building was open in the back showing the sixteen sets of fermentation boxes, six each arranged stair-step up to a height of almost 8 meters. In the center was a belt conveyor feeding a bucket elevator that ran up to a platform on top. The foreman informed me that the cocoa pods were broken in the field and the wet cacao was brought to the fermentation center in bags. They dumped the wet cacao onto the belt and it was carried by the bucket elevator up to fill the first box eight meters above.
There were five fermentation boxes. The cacao was fermented for two days in the first box and then one day in each of the subsequent four boxes for a total of six days. The first two days were an anaerobic fermentation where the sugars in the pulp were fermented to ethanol by yeasts. This is also where a good deal of the fruity flavor develops. Transferring the cacao to the second box aerates the mass and allows lactic acid bacteria to take over generating heat and organic acids that eventually kill the bean and trigger a series of enzymatic reactions. These reactions can be measured by a color change in the cacao and are responsible for the reduced astringency and pleasant chocolate flavor characteristic of well fermented cacao beans.
The last series of fermentation boxes emptied directly onto the driers. After the fermentation process is complete the cacao is still very wet and needs to be dried down to stable moisture content, usually less than 7.5%. As the beans dry the fermentation process stops, although some enzymatic reactions continue and these play a role in flavor development. The trick is not to dry the cacao too fast and to avoid locking the acidity inside. If that happens the beans will be too sour and that will hide all the uniqueness of their flavor. Normally this is best done in the sun, but in areas where rainfall is heavy, like Papua New Guinea, cacao farmers must resort to artificial drying.
Like everything else, the Markham dryers were huge. They were beds of steel with tiny perforations through which hot air flowed up through the cacao and carried off the moisture. As it dries the cacao needs to be turned and mixed and the Markham crew did this by hand with wooden rakes especially designed not to damage the beans. One advantage to drying cacao indoors is it keeps the livestock off the beans. On many farms you can see chickens and dogs walking through drying cacao. Any contamination from this is of course removed in the process, but it makes me shudder every time I hear an advocate for eating raw cacao.
As we stood talking around the dryers, Mr. Singh arrived. He was a tall thin man, with hawkish features and his hair was wrapped up in a dark blue turban. He was a Malaysian and had only recently assumed responsibility for the plantation, but he was confident and knowledgeable. We walked around the fermentary together and I took some pictures that tried to capture the scale of the operation. It was enormous, but despite its size there was careful attention to quality at each step in the process. Much of the cacao was hand sorted after drying. A group of women were working at this as we passed by and we were greeted by waves and smiles. We stopped by some bags that had just come off the cleaner and sampled the cacao. It smelled clean and fruity. Most of Markham Farm's cacao went to Europe and had already been featured by some fine chocolate makers like Michel Cluizel, but I was sure that the Scharffen Berger team chocolatiers could do it one better.
At the edge of one dryer I started cutting beans. I always do this to judge the fermentation quality. The inside or cotyledon of most cacao beans is purple or violet before fermentation and turns brown as the enzymatic changes occur that signal fermentation is complete. I typically look for somewhere between 85% and 95% fermented or brown beans. This tells me the lot has been well fermented, but not over fermented; undesirable because of the off flavors created as the microorganisms begin to break down the cocoa butter in the bean.
As I cut these beans I was astonished to find that about 25% of them were white inside. Most fine flavored cacao today belong to a type we call Trinitario. Trinitario is a cross between Criollo, a delicately flavored variety with white or pale violet beans and Forastero, a bolder, stronger flavored cacao with dark purple beans. In hybrids the cross is often better than either of the parents and Trinitario is the best combination of flavor and vigor. Because it is a cross, Trinitario beans will often show a certain percentage — usually five to ten percent of white beans and in general the more white beans the more Criollo character in the flavor and in my opinion the more interesting the chocolate. Twenty-five percent of white beans in a small grab sample from the edge of the dryer was quite remarkable. The original cacao planted in Papua New Guinea came from Samoa and was planted by the Germans in the 1890s and early 1900s. This first cacao was a Criollo type and it could be that at Markham Farm they still had some of this original planting material. It gave me a shiver of excitement to think what we could do with it.
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