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 interestin 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 themonomers catechin and epicatechin, and the dimer procyanidin B2, butduring the processing of cocoa, significant degradations of thesecompounds take place due to fermentation and the high roasting temperatures.

In the aerobic fermentation of cocoa, ( - )-epicatechin,(+)-catechin and anthocyanidin molecules are oxidized and polymerizedin the presence of the polyphenol oxydase (PPO) enzyme.

These high molecular weight polymers (tannins) have lessbioavailability than their precursors, they report.

In recent years, said the researchers, studies have focused on ways tomitigate or suspend the PPO enzyme activity in cocoa in order to avoidpolyphenol oxidation reactions and polymerization.

And they said the objective of their research thus was the study of theantioxidant capacity and the flavan-3-ol content of polyphenol-richcocoa products obtained through an unconventional cocoa processingtechnique.

Method

They said that fresh cocoa pods from the Quevedo region in Ecuador werepurchased, with the fresh pulp removed manually from the pods in situ.Batches of 136 kg of depulped beans were thermally treated with watervapour at an internal bean temperature of 95C for five minutes byimmersing the beans in 2,500 litres of water to inactivate the enzymePPO.

The beans were then dried at a controlled temperature of 45C until amoisture content of seven per cent was reached. The dried beans werecleaned and deshelled with the aid of aspiration to obtain the nibs,which were then partially defatted through physical pressing at atemperature of 55 C, said the team.

Upon completion of this process, a natural polyphenol-rich cocoa cakewith a butter content of 12 per cent was obtained. The polyphenol-richcocoa 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),they added.

The authors said that for the cocoa powder production, the cake wasthermally treated in an autoclave with a saturated flash steam at 121 Cfor one minute. After the heat treatment, the cake was milled andsieved to obtain a cocoa powder they referred to as sample A.

In a small trial, they added, the defatted cocoa cake obtained in theindustrial process was extracted by means of a solid-liquid extractionprocess with a hydro-alcoholic mixture consisting of 70 per centethanol. The cocoa cake was extracted at 70 C for two hours undermechanical stirring, the solid was filtered, and the liquid fraction wasrecovered.

This fraction was then distilled under reduced pressure to remove thesolvent, affording an aqueous extract. After drying the liquid extract, apolyphenol-rich cocoa extract was obtained to give sample B.

The remaining liquid aqueous extract was then subjected to an additional purification step, said the authors, consisting of a liquid-liquid extraction withethyl acetate at a temperature of 50 C.

The aqueous and organic fractions were separated by means of decantationand the organic phase was recovered. After distillation to remove theorganic solvent, the product was dried to obtain a purified cocoaextract deemed as sample C.

Sample A was thus a natural polyphenol-rich cocoa powder whilesamples B and C were polyphenol-rich cocoa extracts obtained fromthe natural-rich cocoa cake, with sample C resulting from apurification of sample B. This procedure was expanded to an industrialscale to obtain a range of cocoa products, added the researchers.

Findings

They said that their results showed that total polyphenols and flavanolsquantified in the cocoa powder rich in polyphenols (sample A) were muchhigher than the control cocoa powder, but similar to those found inanother previously reported cocoa polyphenol (Cienfuegos-Jovellanos etal., 2009).

Furthermore, after the extraction process, the cocoa extract (sample B)contained three times more epicatechin and five times more procyanidinB2 than its respective control, they found.

And they said the purification step resulted in a concentration ofepicatechin monomer of 300 mg/g, and the researchers added that the heattreatment of 121 C for one minute did not result in any loss of totalmonomers and dimers.

The results confirm that the wet heat treatment producespolyphenol-rich cocoa powder that meets the microbiological standardsfor 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 productsindustrially processed
Authors: G. Schinella, S. Mosca, E.Cienfuegos-Jovellanos, M.ngeles Pasamar, B. Mugerza, D. Ramn, J. LuisRos