Alkaline processing reduces cocoa's flavanol content, study
The researchers from the Hershey Center for Health and Nutrition published their findings in The Journal of Agriculture and Food Chemistry.
“The data reported here are, to our knowledge, the first comprehensive report on the changes in the monomeric flavan-3-ols, namely, epicatechin and catechin, in cocoa beans ranging from unripe to ripe, dried, fermented, roasted, and Dutch processed powders," said the team.
The majority of science into the potential benefits of cocoa have revolved around cardiovascular benefits of the flavanols (also known as flavan-3-ols or catechins), and particularly the monomeric flavanol (-)epicatechin.
The authors point out that common cocoa processing steps such as fermentation, roasting, alkaline treatment (Dutch processing) and baking processes that use baking soda all have been shown to reduce both the level of total procyanidins and the level of low molecular weight flavanols.
The levels of epicatechin and catechin were determined in raw (from USDA office in Puerto Rico) and conventionally fermented Ivory Coast and Papua New Guinea beans cacao beans and during conventional processing, which included drying, roasting, and Dutch (alkali) processing.
Unripe cacao beans had 29 per cent higher levels of epicatechin and the same level of catechin compared to fully ripe beans, noted the researchers.
Levels of epicatechin and catechin were compared in beans that were unfermented and in beans that underwent medium (about 5 days) and long fermentation (about 10 days), they explained.
Long fermentation previously has been shown to impact the level of epicatechin in cocoa beans, and the authors reported loss of both flavanols as fermentation time increased.
Beans were roasted to temperatures of 120°C and the researchers found that temperatures of 70°C or higher caused some loss (up to 88 per cent at 120°C) of epicatechin.
Catechin levels, however, increased as roasting temperature increased, found the researchers.
Additionally, natural cocoa powders and powders that had been treated with different levels of alkali also were measured.
The authors reported that in terms of the epi/cat ratio, the highest were found in unripe and ripe, unfermented dried beans. Fermentation and roasting lowered the epi/cat ratio further, with the lowest ratios found in Dutch-processed cocoa powders.
"We found that the processing step which causes the most loss in the flavanol epicatechin is the alkali processing step. Here the epicatechin, which is thought to be most beneficial, appears to be converted to catechin which has been shown to be less active in the body,” said Dr Mark Payne, lead author of the paper.
Source: The Journal of Agriculture and Food Chemistry
Title: Impact of Fermentation, Drying, Roasting, and Dutch Processing on Epicatechin and Catechin Content of Cacao Beans and Cocoa Ingredients
Authors: M.J Payne, W. J. Hurst, K. B. Miller, C. Rank, D. A. Stuart