Lipid Characterization of White, Dark, and Milk Chocolates by FT-Raman Spectroscopy and Capillary Zone Electrophoresis.

Abstract

There are few studies about different types of chocolate and their chemical characterization by Fourier transform (FT)-Raman spectroscopy and capillary zone electrophoresis (CZE). The aim of this study was to evaluate the lipid profile of different types of Brazilian chocolate through characterization by FT-Raman spectroscopy and identification and quantification of major fatty acids (FAs) by CZE to confirm FT-Raman spectrometry results. It was found that the main spectroscopic profile difference of the chocolate samples analyzed was related to the presence of saturated or unsaturated FAs. Well defined bands at approximately 1660, 1267, and 1274 cm(-1) corresponding to vibrational modes of unsaturated FAs (UnFAs) were found only in the spectra of samples with cocoa butter in their composition according to label specifications, mainly in dark chocolate samples. The FA identification and quantification by CZE found the presence of stearic (18:0) and palmitic (16:0) acids as the major saturated FAs in all chocolate samples. Dark chocolate samples showed the highest levels of oleic (cis-9 18:1) and linoleic (cis, cis -9,12 18:2) UnFAs monitored and the lowest levels of 14:0 in their chemical composition. Samples coded as 02 (with not only cocoa butter in their composition according to label) had the highest levels of 14:0 (FA not present in cocoa butter composition) corresponding to label information and inferring the presence of other fat sources, called cocoa butter substitutes, mainly for milk and white chocolate samples. This study suggests FT-Raman spectroscopy is a powerful technique that can be used to chemically characterize the chocolate lipid fraction, and CZE is a tool able to confirm Raman spectroscopy results and identify and quantify the major FAs in chocolate samples.