ABSTRACT
Vinson et al. (1999) investigated in detail the antioxidant properties of polyphenols in cocoa and two types of chocolate using an
in vitro
model of heart disease. These authors found that
epicatechin
and
catechin
were found in all of the six samples analyzed by high-performance liquid chromatography (HPLC). These two monomeric polyphenols were minor components of the chocolates, ranging from 1.97 to 2.76 mol% of the phenols in the milk chocolate, from 2.98 to 5.48 mol%
in the dark chocolate, and from 5.45 to 6.11 mol% in the cocoa powder. Assuming a 35% content of fat and moisture, the concentrations of the catechins are 15 to 16 mg/100 g in milk chocolate, 48 to 137 mg/100 g in dark chocolate, and 296 to 327 mg/100 g in cocoa powder. A recent HPLC analysis of single samples of European chocolate found 16 mg/100 g in milk chocolate and 54 mg/100 g in dark chocolate. Another report found 300 mg/100 g in cocoa powder, which also agrees well with these results. The total concentration of the two catechins in chocolate correlates well with the total polyphenols as measured by the Folin method, with a Pearson correlation coefficient of 0.9326,
p
< 0.01. The quality of the phenol antioxidants was assessed by Vinson et al. (1999)
using the IC
for LDL + VLDL (very low density lipoprotein) oxidation, with smaller values indicating a higher quality. Quality of the antioxidants was due to free radical-scavenging activity and not chelation as the concentration of polyphenols for 50% inhibition was < l µ
M
and cupric ion 25 µ
M
in the oxidation medium. There was less percent variation within the groups for this parameter than for the total polyphenol content. The quality order was dark chocolate > cocoa > milk chocolate. The dark chocolate and cocoa were significantly different from the milk chocolate (
p
< 0.05), but not from each other. There was no correlation between the quantity of phenolic antioxidants in the chocolate and the quality as measured by IC
,
p
> 0.05. There was also no correlation between the amount of
epicatechin
and
catechin
in the chocolates and the IC
.
