Total polyphenol content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC), and proanthocyanidin (PAC) content were determined in fruit from three tropical Vaccinium species (Vaccinium consanguineum, Vaccinium floribundum, and Vaccinium poasanum) from Costa Rica sampled at three stages of fruit development. Results show that TAC increased as the fruit developed, while TPC, TFC, and PAC content decreased. Anthocyanin profiles were evaluated using electrospray ionization tandem mass spectrometry. Cyanidin and delphinidin glycosides were the predominant anthocyanins for the three tropical Vaccinium species. Proanthocyanidins were characterized using attenuated total reflection Fourier transform infrared spectroscopy, nuclear magnetic resonance, and matrix-assisted laser desorption/ionization time-offlight mass spectrometry. The presence of procyanidin structures with B-type interflavan bonds were observed, but deconvolution of mass spectrometry isotope patterns indicated that PACs with one or more A-type interflavan bonds accounted for more than 74% of the oligomers at each degree of polymerization. KEYWORDS: proanthocyanidins, anthocyanin, A-type interflavan bonds, MALDI−TOF MS of the National Fruit Growing Program by the Costa Rican Department of Agriculture. 1,4,8 Polyphenols found in Vaccinium species, such as cranberry, contain hydroxycinnamic acids, flavonols, anthocyanins, and proanthocyanidins, among others. 9,10 Anthocyanins are watersoluble pigments that vary by the number of methyl, methoxy, or hydroxyl group, the nature and number of sugars attached to the molecule, and the nature and number of aliphatic or aromatic acids attached to sugars in the molecule. 11,12 Proanthocyanidins (PACs) are oligomers of flavan-3-ols. PAC structures vary by the nature of the monomer unit, interflavan linkage, and degree of polymerization (DP). 13 PACs are classified by the type of flavan-3-ol monomers, such as properlagonidins, which are oligomers of (epi)afzelechin, procyanidins, which are oligomers of (epi)catechin, and prodelphinidins, which are oligomers of (epi)gallocatechin. 14 However, many types of PACs contain more than one type of monomeric flavan-3-ols, such as PACs in grape seeds. PACs can have B-and A-type bonds. B-type bonds are defined by the presence of C 4 −C 8 or C 4 −C 6 interflavan bonds, whereas Atype bonds have C 4 −C 8 bonds but also have an additional interflavan bond between C 2 −O−C 7 or C 2 −O−C 5 . 9,13,15
