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Big differences in cocoa flavanol losses during roasting

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By Oliver Nieburg+

31-Jul-2013
Last updated on 01-Aug-2013 at 13:49 GMT2013-08-01T13:49:57Z

Cocoa flavanol losses during roasting higher for certain bean origins and varieties
Cocoa flavanol losses during roasting higher for certain bean origins and varieties

A study has found stark differences in the amount of cocoa flavanols preserved after cocoa beans from different origins have been roasted.

Flavanols from Ivory Coast beans were found to increase by 30% after roasting, while Java beans decreased by half, despite being roasted under the same conditions.

The discovery was made by Kothe et al. and results were published in the journal Food Chemistry.

Method: Indonesian and Ivorian beans

The researchers compared the impact of roasting on three bean varieties: one from the Ivory Coast and two from Indonesia (Java 1 and 2).

The scientists used pilot plant scale equipment to roast 5 kg of cocoa beans from each origin at multiple temperatures and measured flavanol monomers including, epicatechin and catechin as well as five procyanidin dimers.

Fermented Java 1 beans had the highest concentration of polyphenols before roasting, followed by Java 2 and Ivorian beans respectively.

Fact Box: Cocoa flavanols and health benefits

Cocoa flavanols have been associated with a string of positive health benefits including improved mood, cognition and cardiovascular health. The only health claim approved to date by the European Food Safety Authority (EFSA) is for “maintenance of the elasticity of blood vessels.” (i.e. blood flow), following an application from Barry Callebaut.

The unroasted beans from all origins had an average of 4.82 mg/g epicatechin and 0.26 mg/g catechin.

Epicatechin goes down; catechin goes up

The researchers found that roasting lowered the epicatechin content in all bean origins analysed, but increased the catechin content.

For example, at the strongest roasting temperature (160°C for 30 mins), the epicatechin content in Java 1 beans  fell 68%, but the catechin content grew 240%. Certain procyanidin dimers also rose, while others fell.

Ivorian beans registered even larger increases in catechin content with a 836% rise on average across all temperatures measured.

Roast below 140°C to preserve flavanols

Higher temperatures were also said to cause loss of flavanols.

“According to our results, temperature should be kept below 140 °C in order to preserve most of the initial flavanol concentration and to obtain almost unaffected flavanol composition,” said the researchers.

Other cocoa flavanol research

An earlier study by Crozier et al. showed that dry fermented cocoa beans contain 6-7% of polyphenolic content by weight.

Previous research by Elwers et al. found that cocoa bean fermenting reduced the initial concentration of flavanols by around 90%.

During a site visit earlier this year, Barry Callebaut revealed that the presence of cocoa flavanols varied depending on the origin of the bean - with Central and South American origins having the highest concentrations due to the soil, the climate and the strain of beans

Source:
Food Chemistry, Vol. 141, Issue 4, p 3656–3663
http://dx.doi.org/10.1016/j.foodchem.2013.06.049
‘Temperature influences epimerization and composition of flavanol monomers, dimers and trimers during cocoa bean roasting’
Authors: Lisa Kothe, Benno F. Zimmermann, Rudolf Galensa

1 comment (Comments are now closed)

high catechin v epicatechin good or bad?

I don't see why roasting under 140C is considered optimal when at 160C there is an big rise in catechins in most beans...is there proof that catechins are inferior to epicatechins?

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Posted by chris aylmer
14 August 2013 | 13h202013-08-14T13:20:58Z

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