Phenolic content and oxidative stability of chocolates produced with roasted and unroasted cocoa beans.

Abstract

The aim of this study was to produce chocolate using roasted (RB) and unroasted cocoa beans (URB). The effect of roasting on the total phenolic content (TPC), antioxidant activity [2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, ferric reducing antioxidant power (FRAP), and cupric ion reducing antioxidant capacity (CUPRAC) values], phenolic compounds, caffeine, oxidative stability [free fatty acid, peroxide, conjugated dienes, conjugated trienes, and thiobarbituric acid reactive substances (TBARS)], Fourier transform infrared (FTIR), and differential scanning colorimetry (DSC) analysis of both cocoa beans and chocolate samples were analyzed. According to the results, the TPC of URB (24.96 mg gallic acid equivalent (GAE)/g sample) was higher than roasted beans (21.32 mg GAE/g sample). Similar results were also seen in the TPC of chocolate samples. Although roasting did not affect the DPPH scavenging activity and caffeine content of cocoa beans, it decreased FRAP and CUPRAC values. (-)-Epicatechin and chlorogenic acid values were higher in unroasted bean and chocolate samples, but the amount of gallic acid increased with the roasting process. Free fatty acid, peroxide, conjugated dienes, conjugated trienes, and TBARS results of unroasted samples were lower than roasted ones, indicating better oxidative stability. The melting temperatures of cocoa beans changed with roasting while it was similar between chocolate samples. Composition of the beans and the chocolate samples were qualitatively determined with FTIR.