Aided by the high fat content of chocolate, which traps all but the most volatile of compounds, researchers from the Laboratoire de Chimie Analytique et Sciences de l'Aliment (IPHC-UMR 7178) in Illkirch report that identification of seven compounds that can be used as chemical tracers.
“The method described in this work (hydrodistillation, GC analysis, and statistic treatment) may improve the control of the geographical origin of chocolate during its long production process,” wrote the researchers, led by Christophe Marcic.
The analtical technique is said to integrate the entire production process for chocolate – from bean to processing to final product – and distinguishes between chocolate originating from the Caribbean, Madagascar, Africa, and South America.
“Consumers have no way of tracing the origin of the cocoa used to produce their chocolate to a particular country, much less a particular site of agricultural production,” explained the researchers.
“To determine the quality of chocolate and the veracity of labelling, consumers need to be informed of the cocoa production site’s country, even more with the rising market of ‘healthy chocolate’,” they added.
Marcic and his co-workers chose hydrodistillation for its simplicity, and combined this with separation by gas chromatography andmass spectrometry (GC-MS) detection or flame ionization detection (GC-FID). The researchers tested 51 commercial dark chocolates from eight countries, provided by French luxury chocolate company Valrhona.
“The analysis of the volatile content and their statistical processing by multivariate analyses tended to form independent groups for both Africa and Madagascar, even if some of the chocolate samples analyzed appeared in a mixed zone together with those from America,” wrote the researchers.
“This analysis also allowed a clear separation between Caribbean chocolates and those from other origins.”
The French researchers also identified seven compounds, which they proposed as tracers, including linalool and (E,E)-2,4-decadienal), for complete characterisation of the chocolate's geographical origin.
Source: Journal of Agricultural and Food Chemistry
2010, Volume 58, Issue 3, Pages 1478–1483, doi: 10.1021/jf903471e
“Differentiation of Chocolates According to the Cocoa’s Geographical Origin Using Chemometrics”
Authors: A. Cambrai, C. Marcic, S. Morville, P. Sau Houer, F. Bindler, E. Marchioni