Distribution and Quantification of Flavan-3-ols and Procyanidins with Low Degree of Polymerization in Nuts, Cereals, and Legumes

The monomeric flavan-3-ols catechin and epicatechin as well as procyanidins are of great interest due to their potential beneficial health effects observed in epidemiological studies. However, the occurrence and concentration of these compounds is not well-known due to the fact that reference compounds are not commercially available. In this study we determined the pattern and concentration of catechin, epicatechin, and different dimeric and trimeric procyanidins in 38 food samples (nuts, cereals, legumes) using a reversed phase high-performance liquid chromatography electrospray ionization tandem mass spectrometry (RP-HPLC-ESI-MS/MS) approach based on isolated authentic reference compounds. Of the analyzed food samples 21 were found to contain dimeric and trimeric procyanidins and their monomeric building units catechin and epicatechin. Mainly the monitored nut samples contained the analyzed procyanidins as well as catechin and epicatechin whereas only 3 cereals were identified as sources of the analyzed compounds. The concentration ranged from 148 mu g/100 g in macadamia nut to 55 mg/100 g in pinto bean. Catechin and procyanidin B-3 were found to be the most abundant analytes. The only A-type procyanidin that could be identified was procyanidin A2, which was found in peanut. The achieved data could be used for authenticity control and furthermore in combination with dietary studies to calculate the daily intake of monomeric flavan-3-ols and procyanidins. To our knowledge this is the first detailed study quantifying monomeric flavan-3-ols and dimeric and trimeric procyanidins in various nuts, cereals, and legumes.