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

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.

A Rapid Method for Determination of the Main Conjugated Linoleic Acid Precursors (C18:2 n-6 and C18:3 n-3) in Forage by Capillary Zone Electrophoresis with Ultraviolet Detection Using Gas Chromatography with Flame Ionization Detection as a Comparative Method.

A rapid method has been proposed for determination of the main conjugated linoleic acid precursors such as linoleic (C18:2 n-6) and linolenic (C18:3 n-3) acids in forages by capillary zone electrophoresis (CZE) with direct UV detection at 200 nm. Among the fatty acids found in forages, C18:2 n-6 and C18:3 n-3 have received particular attention due to their roles as precursors for the synthesis of conjugated linoleic acid, a class of health-enhancing compounds that is predominantly found in dairy products. The electrolyte background consisted of 12.0 mmol/L tetraborate buffer (pH 9.2) added to 12.0 mmol/L Brij 35®, 17% acetonitrile, and 33% methanol. Under the optimized conditions, the baseline separation of C18:2 n-6 and C18:3 n-3 was achieved within 4 min. The CZE-UV method was compared to GC with a flame ionization detector, which is the American Oil Chemists' Society (AOCS 996.06) official method for fatty acid analysis. The methods did not show any evidence of significant differences within 95% confidence interval (P>0.05). The CZE-UV method was successfully applied to the analysis of 80 genotypes of Brachiaria ruzizienses clones submitted to a genetic improvement program in agricultural research.

20 years of fatty acid analysis by capillary electrophoresis.

A review taking into account the literature reports covering 20 years of fatty acid analysis by capillary electrophoresis is presented. This paper describes the evolution of fatty acid analysis using different CE modes such as capillary zone electrophoresis, non-aqueous capillary electrophoresis, micellar electrokinetic capillary chromatography and microemulsion electrokinetic chromatography employing different detection systems, such as ultraviolet-visible, capacitively coupled contactless conductivity, laser-induced fluorescence and mass spectrometry. In summary, the present review signals that CE seems to be an interesting analytical separation technique that is very useful for screening analysis or quantification of the usual fatty acids present in different matrices, offering short analysis times and a simple sample preparation step as inherent advantages in comparison with the classical methodology, making it a separation technique that is very attractive for quality control in industry and government agencies.

Rapid separation of free fatty acids in vegetable oils by capillary zone electrophoresis.

INTRODUCTION: Olive oil is a very important product to human health since it inhibits formation of free radicals, tumour growth, lesions and inflammatory substances. High concentrations of free fatty acids in olive oils results in lipid deterioration due to oxidative or hydrolytic rancidity. OBJECTIVE: To optimise an alternative capillary zone electrophoresis methodology, under ultraviolet indirect detection and to determine free fatty acids in edible vegetable oils without derivatisation steps in sample preparation. METHODS: The condition used consisted of 15 mm NaH2 PO4 -Na2 HPO4 at pH ~6.86, 4.0 mm of sodium dodecybenzenesulphonate, 8.3 mm of Brij 35®, 45% v/v of acetonitrile and 2.1% of 1-octanol, injection at 12.0 mbar of pressure for 4 s, +19 kV of applied voltage and indirect detection at 224 nm, within an analysis time of 11 min. RESULTS: The capillary zone electrophoresis method was successfully applied to determination of free fatty acids in extra virgin olive oil, virgin olive oil and soybean oil samples. The comparison with the official volumetric titration method showed no significant difference within the 95% confidence interval. CONCLUSION: The main advantage to the proposed method is the possibility to observe the individual amount of the free fatty acids, which would be useful for researchers interested in studying the effect of the free fatty acids profile on oxidative process in food.