An HPLC method, using detection after postcolumn derivatization with p-dimethylaminocynnamaldehyde
(DMACA), was developed for the quantitative analysis of individual flavanols in food.
This method was applied to flavanol determination in 56 different kinds of Spanish
food products, including fruit, vegetables, legumes, beverages (cider, coffee, beer,
tea, and wine), and chocolate. The determined compounds corresponded to the catechins
and proanthocyanidin dimers and trimers usually present in food and, therefore, they
were representative of the flavanols of low degree of polymerization consumed with
the diet. The data generated could be used for calculation of the dietary intake of
either individual or total flavanols, which would allow the further establishment
of epidemiological correlations with the incidence of chronic diseases. Similar flavanol
profiles were found in the different samples of a similar type of product, even though
important variations could exist in the concentrations of total and individual flavanols
among them. This was attributed to factors such as sample origin, stage of ripeness,
post-harvesting conservation, and processing. Total flavanol contents varied from
nondetectable in most of the vegetables to 184 mg/100 g found in a sample of broad
bean. Substantial amounts were also found in some fruits, such as plum and apple,
as well as in tea and red wine. Epicatechin was the most abundant flavanol, followed
by catechin and procyanidin B2. In general, catechins were found in all the flavanol-containing
products, but the presence of gallocatechins was only relevant in pomegranate, broad
bean, lentil, grape, wine, beer, and tea, and most of the berries. Galloyled flavanols
were only detected in strawberry, medlar, grape, and tea.