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The aim of this work was to provide recent fatty acid (FA) profiling of chocolates and chocolate products, principally C18:1 trans FAs (TFAs). Thirty-two samples were analyzed by gas chromatography and FAs were quantified. The total TFA content declared in chocolate labeling and the real TFA content were compared. The TFA content ranged from 0.04 to 2.51 g/100 g of sample, and it was noticed that several manufacturers were underestimating the total TFA content in their labeling. The main TFA isomers quantified were C18:1 trans-9 (0.006-0.244%), C18:1 trans-10 (0.009-0.392%), and C18:1 trans-11 (0.013-0.464%), expressed in g/100 g of sample. Principal component analysis was used to discriminate industrial fats from natural trans fats based on the isomeric TFA profile and dairy fat (DF) biomarkers allowing to group samples in four clusters: high TFA content and high DF content, high TFA content and low DF content, low TFA content and high DF content, and low TFA content and low DF content.

The worldwide advent of concentrated supplements containing omega-3 fatty acids (FA) in the form of triacylglycerols (TAG) or ethyl esters (EE) has increased the interest in developing methods to classify these products. The quality control based on their lipid composition has become necessary since EE bioavailability has been proved to be lower when compared to the TAG. In this preliminary study, eight models based on 1H NMR and supervised discriminant analysis (PLS-DA/OPLS-DA) were applied to classify omega-3 fish oil in TAG or EE forms. The 4.0–4.5 ppm region was selected for modeling since it bracketed spectral features to discriminate TAG and EE. The non-supervised principal component analysis was employed to visually evaluate the distribution of samples and revealed a clear separation of TAG from EE marine oils along PC1. In addition, representative TAG and EE samples were 100 % correctly classified using any of the eight supervised models studied. The developed models resulted in high R2Y (≥ 0.977) and Q2 (≥ 0.953), and low root mean square error for prediction (≤ 0.009), which demonstrates the high potential of this rapid and straightforward procedure to evaluate the lipid form of supplements and mislabeling.

Omega-3 fatty acids (FAs) are mainly available as triacylglycerols (TAGs) and ethyl esters (EEs) in fish oil supplements, and it is known that EEs are less bioavailable than TAGs in the human body. This study applied attenuated total reflectance with Fourier transform infrared (ATR-FTIR) and Raman spectroscopies associated with chemometrics to evaluate the supplements’ lipid form. Representative products were first characterized by reference chromatographic methods. Subsequently, principal component analysis (PCA) and partial least square discriminant analysis were performed in the spectral wavenumber ranges 1700–1780 (ATR-FTIR) and 1720–1770 cm–1 (Raman). TAGs and EEs were clearly distinguished along PC1 by employing both techniques, but a higher explained variance was obtained by ATR-FTIR. The prediction of TAG and EE fish oil samples was also better using ATR-FTIR (R2 = 0.99 versus 0.95 for Raman). However, both models correctly classified 100% of the samples, which indicates the suitability of these approaches to be used in quality control laboratories aiming for fish oil lipid form evaluation.

The regulations established worldwide, restricting trans fatty acids (TFA) from industrial origin in foods, encourage the development of rapid methods to verify the quality of food products. A simple and rapid procedure based on 1H NMR combined with multivariate calibration was developed to quantify C18:1 TFA isomers in chocolate fat. Thirty chocolate samples (milk, dark and white chocolates) were analyzed by 1H NMR, and also by a reference gas chromatographic method. Then, partial least squares regression was used for model development. The most important 1H NMR signals for the modeling comprised the 5.25–5.45 ppm region, corresponding to CH (double bonds and glycerol backbone), and the 1.94–1.99 ppm region, characteristic of CH2 allylic to trans double bonds. Good predictive qualities for all TFA isomers were obtained. Coefficient of correlation for prediction was 0.967 for C18:1 trans 6–8; 0.981 for C18:1 trans 9; 0.987 for C18:1 trans 10; 0.941 for C18:1 trans 11; 0.983 for C18:1 trans 12 and 0.977 for total TFA. This study demonstrates the potential of 1H NMR to be applied in food industries in order to perform TFA control analysis as well as to investigate food fraud.

This work aimed to predict C18:1 TFA isomers as well as other groups of fatty acids (saturated, monounsaturated, polyunsaturated, and total TFA) in chocolates by ATR-FTIR and partial least square regression. The quantification of fatty acids in representative samples (white, dark, and milk chocolates) was rapid (<30 s) and did not require derivatization. The optimized models showed satisfactory linear correlations compared to a reference gas chromatographic method. Coefficients of correlation for prediction considering C18:1 positional isomers were 0.973 (trans 6–8), 0.991 (trans 9), 0.991 (trans 10), 0.988 (trans 11), and 0.998 (trans 12). When considering fatty acids groups, these coefficients ranged from 0.965 to 0.999. The obtained results indicate that this straightforward procedure is suitable for chocolate analysis, for determining its general lipid composition and TFA isomeric profile, which would be of great interest for quality control programs in the face of the new TFA regulations.

Fish oils (FO) omega-3 supplements containing eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids are extensively consumed due to their beneficial health effects. Fatty acids (FA) are mainly available as triacylglycerols (TAG) and ethyl esters (EE) in FO supplements, and EE is known to be less bioavailable. Then, the evaluation of FA in FO should comprise not only omega-3 content but also the delivered form. This research aimed to approach in detail a set of chromatographic analytical methods employing TLC, GC-FID, and GC-MS for FO quality control, considering both FA contents and form. TAG and EE FA were differentiated by GC-FID, due to the difference in the retention times of compounds, and also by GC-MS, as a result of the different m/z spectra observed. TLC also distinguished both FA forms, but a mixture of TAG and EE in FO concentrates was not observed, as evidenced by GC techniques. Ten FO supplements available in the Brazilian market were analyzed, and the FA profiles of natural and concentrated FO were compared. EPA + DHA label claim compliance was also accessed. Their contents varied from 78 to 113% of labeled content, and only one supplement had FA in EE form. Brazilian FO supplements analyzed were a source of EPA and DHA and most products (except one sample) were accurately labeled according to current Brazilian regulation, which permits a variation in 20% of the declared content. Furthermore, the methodologies approached can be used in future researches considering FO analyses and bioavailability studies approaching the different FA forms.

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are essential omega-3 fatty acids (FA) in human nutrition. Dietary supplements containing these FA are available in the market and there is a need to assess their quality to prevent frauds. The purpose of this work was to optimize and validate a fast capillary electrophoresis (CE) method to determine EPA and DHA content in marine oils omega-3 supplements. Sample preparation comprised only a saponification step and analysis time was 8 min. Validation was performed according to limits of detection and quantification, linearity, accuracy and repeatability. Ten real samples of marine oil supplements were analyzed by CE and compared to conventional gas chromatography method. No significant differences between both methods were found within 95% confidence interval. Overall, CE method was successful to FA quantification and it could be used for fast FA monitoring during omega-3 supplement manufacture, final product quality assurance and labelling.