The authors of a study, published in Food Research International,
maintain that the health benefits of cocoa
polyphenols as reported in recent studies have increased the interest
in obtaining products from cocoa beans not only with high polyphenol,
but also with a high flavan-3-ol content.
They report that the main flavan-3-ol compounds present in cocoa are the
monomers catechin and epicatechin, and the dimer procyanidin B2, but
during the processing of cocoa, significant degradations of these
compounds take place due to fermentation and the high roasting
“In the aerobic fermentation of cocoa, (-)-epicatechin,
(+)-catechin and anthocyanidin molecules are oxidized and polymerized
in the presence of the polyphenol
oxydase (PPO) enzyme.
These high molecular weight polymers (tannins) have less
bioavailability than their precursors,” they report.
In recent years, said the researchers, studies have focused on ways to
mitigate or suspend the PPO enzyme activity in cocoa in order to avoid
polyphenol oxidation reactions and polymerization.
And they said the objective of their research thus was the study of the
antioxidant capacity and the flavan-3-ol content of polyphenol-rich
cocoa products obtained through an unconventional cocoa processing
They said that fresh cocoa pods from the Quevedo region in Ecuador were
purchased, with the fresh pulp removed manually from the pods in situ.
Batches of 136 kg of depulped beans were thermally treated with water
vapour at an internal bean temperature of 95ºC for five minutes by
immersing the beans in 2,500 litres of water to inactivate the enzyme
The beans were then dried at a controlled temperature of 45ºC until a
moisture content of seven per cent was reached. The dried beans were
cleaned and deshelled with the aid of aspiration to obtain the nibs,
which were then partially defatted through physical pressing at a
temperature of 55 ºC, said the team.
Upon completion of this process, a natural polyphenol-rich cocoa cake
with a butter content of 12 per cent was obtained. The polyphenol-rich
cocoa cake was then used as a raw material to obtain a cocoa powder
(sample A) and two polyphenol-rich cocoa extracts (samples B and C),
The authors said that for the cocoa powder production, the cake was
thermally treated in an autoclave with a saturated flash steam at 121 ºC
for one minute. After the heat treatment, the cake was milled and
sieved to obtain a cocoa powder they referred to as sample A.
In a small trial, they added, the defatted cocoa cake obtained in the
industrial process was extracted by means of a solid-liquid extraction
process with a hydro-alcoholic mixture consisting of 70 per cent
ethanol. The cocoa cake was extracted at 70 ºC for two hours under
mechanical stirring, the solid was filtered, and the liquid fraction was
This fraction was then distilled under reduced pressure to remove the
solvent, affording an aqueous extract. After drying the liquid extract, a
polyphenol-rich cocoa extract was obtained to give sample B.
The remaining liquid aqueous extract was then subjected to an additional
step, said the authors, consisting of a liquid-liquid extraction with
ethyl acetate at a temperature of 50 ºC.
The aqueous and organic fractions were separated by means of decantation
and the organic phase was recovered. After distillation to remove the
organic solvent, the product was dried to obtain a purified cocoa
extract deemed as sample C.
“Sample A was thus a natural polyphenol-rich cocoa powder while
samples B and C were polyphenol-rich cocoa extracts obtained from
the natural-rich cocoa cake, with sample C resulting from a
purification of sample B. This procedure was expanded to an industrial
scale to obtain a range of cocoa products,” added the researchers.
They said that their results showed that total polyphenols and flavanols
quantified in the cocoa powder rich in polyphenols (sample A) were much
higher than the control cocoa powder, but similar to those found in
another previously reported cocoa polyphenol (Cienfuegos-Jovellanos et
Furthermore, after the extraction process, the cocoa extract (sample B)
contained three times more epicatechin and five times more procyanidin
B2 than its respective control, they found.
And they said the purification step resulted in a concentration of
epicatechin monomer of 300 mg/g, and the researchers added that the heat
treatment of 121 ºC for one minute did not result in any loss of total
monomers and dimers.
“The results confirm that the wet heat treatment produces
polyphenol-rich cocoa powder that meets the microbiological standards
for its commercialization without altering the phenolic composition,”
said the authors.
Source: Food Research International
Published online ahead of print
Title: Antioxidant properties of polyphenol-rich cocoa products
Authors: G. Schinella, S. Mosca, E. Cienfuegos-Jovellanos, M.Ángeles Pasamar, B. Mugerza, D. Ramón, J. Luis