title: Analysis of Cocoa Proanthocyanidins Using Reversed Phase High-Performance Liquid Chromatography and Electrochemical Detection: Application to Studies on the Effect of Alkaline Processing.
abstract: Flavan-3-ols and proanthocyanidins play a key role in the health beneficial effects of cocoa. Here, we developed a new reversed phased high-performance liquid chromatography-electrochemical detection (HPLC-ECD) method for the analysis of flavan-3-ols and proanthocyanidins of degree of polymerization (DP) 2-7. We used this method to examine the effect of alkalization on polyphenol composition of cocoa powder. Treatment of cocoa powder with NaOH (final pH 8.0) at 92 °C for up to 1 h increased catechin content by 40%, but reduced epicatechin and proanthocyanidins by 23-66%. Proanthocyanidin loss could be modeled using a two-phase exponential decay model (R(2) > 0.7 for epicatchin and proanthocyanidins of odd DP). Alkalization resulted in a significant color change and 20% loss of total polyphenols. The present work demonstrates the first use of HPLC-ECD for the detection of proanthocyanidins up to DP 7 and provides an initial predictive model for the effect of alkali treatment on cocoa polyphenols.
authors.affiliation: †Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Todd H
authors.initials: TH
authors.lastname: Stanley
authors.affiliation: ‡Department of Food Science and Technology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24060, United States.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Smithson
authors.affiliation: ‡Department of Food Science and Technology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24060, United States.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Neilson
authors.affiliation: †Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Ramaswamy C
authors.initials: RC
authors.lastname: Anantheswaran
authors.affiliation: †Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.|§Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Lambert
mesh_terms: D000468:Alkalies / Q000737:chemistry; D002099:Cacao / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods; D056148:Chromatography, Reverse-Phase / Q000295:instrumentation / Q000379:methods*; D005511:Food Handling / Q000379:methods; D006358:Hot Temperature; D010936:Plant Extracts / Q000032:analysis* / Q000302:isolation & purification; D044945:Proanthocyanidins / Q000032:analysis* / Q000302:isolation & purification
chemical_list: D000468:Alkalies; D010936:Plant Extracts; D044945:Proanthocyanidins; C013221:proanthocyanidin
keywords: Theobroma cacao; alkalization; cocoa; electrochemical detection; proanthocyanidins