Analysis of Cocoa Proanthocyanidins Using Reversed Phase High-Performance Liquid Chromatography and Electrochemical Detection: Application to Studies on the Effect of Alkaline Processing

作者：Stanley Todd H; Smithson Andrew T; Neilson Andrew P; Anantheswaran Rarnaswamy C; Lambert Joshua D^*

来源：Journal of Agricultural and Food Chemistry, 2015, 63(25): 5970-5975.

DOI：10.1021/acs.jafc.5b02661

• cocoa
• Theobroma cacao
• alkalization
• proanthocyanidins
• electrochemical detection

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 chromatographyelectrochemical detection (HPLC-ECD) method for the analysis of flavan-3-ols and proanthocyanidins of degree of polymerization (DP) 27. 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 degrees C for up to 1 h increased catechin content by 40%, but reduced epicatechin and proanthocyanidins by 2366%. 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.

• 出版日期2015-7-1