Fermentation is a crucial step in the transformation of cacao beans to
what we know as chocolate. Without fermentation cacao beans yield little
or no chocolate flavor. The principal effect of fermentation is to eliminate
or, at least, drastically reduce astringency and to develop the full cacao
flavor. Because fermentation plays such a critical role in final chocolate
flavor and quality, SCHARFFEN BERGER has strict requirements on which beans
are acceptable.
Astringency is the drying sensation in the mouth. This is the effect
you get when chewing on grape skins or eating a bit of the interior skin of
an underripe banana. Astringency is reduced by adequate fermentation. Astringency
should not be confused with bitterness which is associated more with the
caffeine-like chemical in chocolate called "theobromine".
Fermentation must be carried out on or near the farm. It involves
removing the cacao seeds and the pulp that surrounds them from the protective
pod shortly after the harvest. The pulp and the forty or so seeds are then
placed on the ground or in a wooden bin and covered with banana leaves. Yeast
in the environment settles on the pulp and ferments natural sugars in it to
alcohol, at which point acetic acid (vinegar)-producing bacteria, as well as
bacteria that produce lactic acid from residual sugar, take over. As acids are
produced during this procedure the pH of the seeds decreases and the temperature
rises as high as 140 F. The combined effects of the acidity and alcohol production
in the fermentation process acts to kill the cacao seed. When the seed dies,
internal structures break down and allow previously segregated compounds to
combine with one another. This results in a host of new compounds (and a marked
increase in flavor complexity) and a decrease in the concentration of the small
polyphenol molecules most responsible for astringency.
It takes from between four and seven days to complete fermentation. But
it is not a matter of simply leaving the beans alone for that period of time.
In order to properly ferment, the farmer must either have knowledge based on
experience or have the ability to measure a variety of parameters that govern
timing of tasks such as turning the mass of cacao beans.
The final step before the cacao is ready to be sold, is drying. The
drying process can take up to seven days, drying in the sun. Because cacao
dried in a dryer powered by wood, diesel, or propane fired driers can often
cause off-flavors, sun-dried cacao is preferred. Sun drying reduces the danger
of the exterior of the bean hardening before the moisture in the interior can
evaporate.
