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.

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The anthocyanin composition was analysed in strawberry fruits from five different cultivars (cv. Eris, Oso Grande, Carisma, Tudnew and Camarosa). Twenty-five defined anthocyanin pigments were detected, most of them containing Pelargonidin (Pg) as aglycone; some cyanidin (Cy) derivatives were also found. Glucose and rutinose were the usual substituting sugars, although arabinose and rhamnose were also tentatively identified; some minor anthocyanins showed acylation with aliphatic acids. A relevant aspect was the detection of anthocyanin-derived pigments, namely 5-carboxypyranopelargonidin-3-glucoside and four condensed pigments containing C-C linked anthocyanin (Pg) and flavanol (catechin and afzelechin) residues. Total anthocyanin content ranged between 200 and 600 mg kg À1 , with Pg 3-gluc constituting 77-90% of the anthocyanins in the strawberry extracts followed by Pg 3-rut (6-11%) and Cy 3-gluc (3-10%). A notable variability was found among the anthocyanin concentrations in samples of a same variety and harvest, indicating a strongly influence of the degree of maturity, edaphic-climatic factors and post-harvest storage.

The formation of three major pigments has been detected in model solutions imitating wine containing malvidin 3-monoglucoside (Mv-3-glu) and procyanidin B2 in the presence of acetaldehyde. Two of them were reddish-blue compounds whose visible spectra are bathochromically shifted with regard to that of Mv-3-glu. They were assigned to two enantiomers containing Mv-3-glu and B2 moieties linked across their C-8 by an ethyl bridge. A molecular ion at m/z 1097, consistent with such a structure, has been established by LC/MS for both of them. The third majority pigment was an orange-red product possessing a spectrum with a maximum wavelength in the visible region at 511 nm and a molecular ion at m/z 1093. A possible structure containing two flavylium mesomeric forms, corresponding to malvidin and to pelargonidin, has been suggested for this compound. This pigment proved to be more stable than the first two, as well as more resistant to discoloration by increased pH values and SO 2 . Similar pigments, whose spectra possess maximum wavelengths in the visible region between 490 and 511 nm, have also been found in equivalent solutions containing other flavan-3-ols [(+)-catechin, (-)-epicatechin, or procyanidin B3]. Evidence for the formation in red wine of pigments with similar spectral characteristics is also contributed.

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