Everything that I have read on the fermentation process for wet cocoa beans indicates that the liquid be allowed to drain off. The fermentation boxes have slits and the heaps on banana leaves allow the liquid to run off. When you make a mash for fermentating grain, the liquid is not drained and the grain ferments OK. Some of the old Japanese here [ed: the big island of Hawaii] will actually add water to a tub of beans and allow fermentation to occur. They don't seem to feel that it affects the beans and provides a better fermentation. Any thoughts on the correct method of fermentation and whether the liquid helps or hinders the process?
Good question. I will attempt a wet fermentation (fully soaked in liquid) and report on my findings. I drain the liquid from my micro-batches to separately ferment into cacao wine.
What's better, fermenting a zinfandel on the skins, or fermenting it off of them? Neither, it all depends on what type of wine you're making.
Same with cocoa. Depending on what type of chocolate you want, you tailor your fermentation. Think about what happens in fermentation. You're going to start by inverting the sugars and forming alcohol (ethanol to be precise). that ethanol is then further metabolized into organic acid (mostly acetic). if you don't allow those materials an out, your beans will soak in them and take on their characteristics, and allow them to affect other cellular chemistry.
If you do allow them an out, you can end up with a vastly different flavor profile.
Of course, there are a thousand additional variables you can manipulate to change the outcome as well. Net/Net - there's no one right way.
sebastian is right based on my experience (as he should be as he is vastly more knowledgeable than me). I have run 2 trials on fermentation while not allowing as much of the "miel" or sugary liquid in the pulp to run off. you can't keep it all in but we kept more of it than normal. this miel also ferments, almost immediately upon liberation from the cacao pod. our results were a faster, hotter (relative to our standard fermenting profile) ferment. at the first turn, 48 hours in, we noted a stronger than normal alcohol production. at the following 24 hour interval turns we noted higher faster temps than usual (around 48C in much of the box by the 2nd turn, and 52C thereafter) and vinegar fumes that caused us to wear respirators to be able to breathe while working the beans (which sometimes happens anyway). there was visible vapor rising out of the box for a while.
the heat and acetic acid production caused some of the skins of the beans to kind of slough off by the 4th turn and by the end the beans were overfermented and too strongly acidic for our purposes. the over-fermentation can be remedied and probably the other problems too if it were really desirable to do it this way. summary: its totally possible to do and may be advisable for someone who wants that flavor profile.
re: water tub fermenting, that's how coffee is fermented, at least here, in ceramic lined concrete water tubs, for 24 hours, were they adapting a coffee procedure to cacao? how did it work? how long did they leave it in?
Remember that oxygen is the fuel for your aerobic fermentations, so the more you turn your fermentations, the more fuel you put on that fire. LAB are aerobic buggers (or facultative aerobes in some cases), so the more O2 you feed them, the hotter, faster, and more acid they're going to generate. Had you done a fermentation for the exact same duration, but not turned it, or only turned it 1x, you'd find a very, very different flavor and chemical profile (for example, after your 4th turn, the heart healthy bits of your cocoa beans are going to be all but wiped out).