title: Degradation of (-)-epicatechin and procyanidin B2 in aqueous and lipidic model systems. first evidence of "chemical" flavan-3-ol oligomers in processed cocoa.
abstract: Despite the key role of flavan-3-ols in many foods, very little is yet known concerning the modification of their chemical structures through food processes. Degradation of model media containing (-)-epicatechin and procyanidin B2, either separately or together, was monitored by RP-HPLC-DAD-ESI(-)-MS/MS. Medium composition (aqueous or lipidic) and temperature (60 and 90 °C) were studied. In aqueous medium at 60 °C, (-)-epicatechin was mainly epimerized to (-)-catechin, but it was also oxidized to "chemical" dimers, a "chemical" trimer, and dehydrodi(epi)catechin A. Unlike oxidation, epimerization was enhanced at 90 °C. In lipidic medium, epimerization proved slow but degradation was faster. Procyanidin B2 likewise proved able to epimerize, especially at 90 °C and in aqueous medium. At high temperature only, the interflavan linkage was cleaved, yielding the same compounds as those found in the monomer-containing model medium. Oxidation to procyanidin A2 was also evidenced. With little epimerization and slow oxidation even at 90 °C, procyanidin B2 proved more stable in lipidic medium. Synergy was also observed: in the presence of the monomer, the dimer degradation rate increased 2-fold at 60 °C. This work states for the first time the presence of newly formed flavan-3-ol oligomers in processed cocoa.
authors.affiliation: Unité de Brasserie et des Industries Alimentaires, Earth and Life Institute, ELIM, Faculté d'Ingénierie Biologique, Agronomique et Environnementale, Université catholique de Louvain , Croix du Sud, 2 bte L07.05.07, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Cédric
authors.initials: C
authors.lastname: De Taeye
authors.forename: Marie-Lucie Kankolongo
authors.initials: ML
authors.lastname: Cibaka
authors.forename: Vesna
authors.initials: V
authors.lastname: Jerkovic
authors.forename: Sonia
authors.initials: S
authors.lastname: Collin
mesh_terms: D044946:Biflavonoids / Q000032:analysis / Q000737:chemistry*; D002099:Cacao / Q000737:chemistry*; D002392:Catechin / Q000032:analysis / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D019281:Dimerization; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry; D005511:Food Handling / Q000379:methods; D006358:Hot Temperature; D059808:Polyphenols / Q000032:analysis; D044945:Proanthocyanidins / Q000032:analysis / Q000737:chemistry*; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D014867:Water
chemical_list: D044946:Biflavonoids; D005419:Flavonoids; D059808:Polyphenols; D044945:Proanthocyanidins; D012996:Solutions; D014867:Water; C479580:procyanidin B2; C404987:flavan-3-ol; D002392:Catechin
keywords: chocolate; cocoa; conching; flavan-3-ol; lipidic medium; polyphenol