Proanthocyanidins in Cacao - Natural Antioxidants and Biocides from Wild Medicinal Plants - page 38

appropriate during fermentation. Conditions
during drying are more appropriate for this
decrease (Wollgast and Anklam, 2000).
The amount of epicatechin decreases by
about 90% and that of procyanidins by
10-50% during fermentation (Kim and
Keeney, 1984; Camu et al. , 2008). The amount
of catechin and of the associated dimer
epicatechin-(4b→8)-catechin increases, how-
ever, during this process (Porter et al. , 1991).
Cyanidin 3- O -glycosides disappear rapidly
during the fermentation process (Camu et al. ,
2008). Fully fermented cacao seeds when cut
have a brown coloration, whereas inad-
equately fermented beans have a violet col-
our (Rohsius et al. , 2010).
Other changes in phenolic content
occur during the drying process. During dry-
ing, the water content is reduced from about
45% to 7% (Camu et al. , 2008). Pyrazines
are usually produced during the drying
process. These components of the odour
complement result from reactions of amino
acids and reducing sugars (Jinap et al. , 2008).
Methylpyrazine compounds constitute one
of the important groups of cocoa flavours,
representing about 40% of the compounds
identified from the cocoa aroma fraction
(Jinap et al. , 2008).
During fermentation and drying, the
level of (−)-epicatechin decreased to
2615 mg/kg, about 8% of the level of unpro-
cessed seed (Criollo type) (Elwers et al. ,
2009). The level of (+)-catechin decreased to
7.2 mg/kg, about 1% of its former level.
Caffeic acid aspartate is more resistant to
drying and about 33% of the original amount
remains (Elwers et al. , 2009).
There is also a decrease in the amount
of phenolic compounds that cannot be
explained only by enzymatic oxidation dur-
ing fermentation because the conditions for
polyphenol oxidase activity are not appro-
priate during that process. Conditions
during drying are more appropriate for the
loss of proanthocyanidins (Wollgast and
Anklam, 2000). A decrease in the amount of
these polyphenolic compounds during dry-
ing has been attributed to enzymatic brown-
ing followed by non-enzymatic browning
from quinone polymerization. Additionally,
polyphenols form complexes with the

proteins and polysaccharides that are
present (Niemenak et al. , 2006). The combi-
nation of these processes reduces both the
solubility and astringency of the proan-
thocyanidins, modifying the bitterness and
astringency of the seeds at this stage
(Nazaruddin et al. , 2006).

3.4 Roasted Cacao Beans

After cacao beans are dried, they are often
stored for a period of time and shipped to
various places in the world where they are
consumed. The processing includes the
roasting of cocoa nibs at about 120-140°C
for 10-20 min. In the course of roasting, up
to 20% of the total phenolic compounds
can be degraded.
Proteolysis in cacao beans during fer-
mentation gives rise to amino acids and
peptides (Biehl and Passern, 1982) that are
responsible for the development of cocoa
aroma in the subsequent roasting process.
The reactions of polyphenols, sugars and
amino acids are responsible for much of the
flavour and colour of the roasted cacao beans
(Luna et al. , 2002; Redovniković et al. , 2009).
Roasting leads to the development of spe-
cific aromas via the Maillard reaction, cara-
melization of sugars, degradation of proteins
and formation of volatile compounds such
as pyrazines (Luna et al. , 2002). On fer-
mentation and roasting, a major portion of
the proanthocyanidins is converted to
largely insoluble red-brown material result-
ing in the characteristic colour of chocolate
(Porter et al. , 1991). Although the amount of
polyphenols is substantially reduced by
enzymatic browning during fermentation
(Redovniković et al. , 2009), only small addi-
tional changes occur during the roasting
process (14%) (Nazaruddin et al. , 2006;
Jolić et al. , 2011). Maillard compounds are
primarily affected by the temperature and
time of roasting (Camu et al. , 2008).
Although proanthocyanidin with epicate-
chin units are the major components in
unprocessed cacao, epimerization of (−)-epi-
catechin to (+)-catechin in cocoa procyani-
dins has been observed (Prior and Gu, 2005).