Untargeted HPLC-MS-based metabolomics approach to reveal cocoa powder adulterations.

Cocoa powder is a highly consumed product all over the world which could be substituted by cheaper raw materials resulting in food fraud. In this work, a non-targeted metabolomics approach based on the use of reversed-phase liquid chromatography coupled to high-resolution mass spectrometry was developed to carry out the characterization of cocoa powder samples adulterated, at two different levels, with carob flour, soy flour, and chicory. The sample preparation protocol and the chromatographic parameters were optimized to extract and detect the highest number of molecular features. Both non-supervised and supervised statistical methods were employed to analyze the most significant variables that gave rise to group discrimination. From the 21 and 37 significant variables analyzed in positive and negative ionization modes, respectively, a total of 20 were tentatively identified. Different families of compounds including flavonoids, fatty acids, terpenoids, lysophospholipids, and a galactolipid could be pointed out as cocoa adulteration markers.

A sarabande of tropical fruit proteomics: Avocado, banana, and mango.

The present review highlights the progress made in plant proteomics via the introduction of combinatorial peptide ligand libraries (CPLL) for detecting low-abundance species. Thanks to a novel approach to the CPLL methodology, namely, that of performing the capture both under native and denaturing conditions, identifying plant species in the order of thousands, rather than hundreds, is now possible. We report here data on a trio of tropical fruits, namely, banana, avocado, and mango. The first two are classified as "recalcitrant" tissues since minute amounts of proteins (in the order of 1%) are embedded on a very large matrix of plant-specific material (e.g., polysaccharides and other plant polymers). Yet, even under these adverse conditions we could report, in a single sweep, from 1000 to 3000 unique gene products. In the case of mango the investigation has been extended to the peel too, since this skin is popularly used to flavor dishes in Far East cuisine. Even in this tough peel 330 proteins could be identified, whereas in soft peels, such as in lemons, one thousand unique species could be detected.

Analysis of glycerophospho- and sphingolipids by CE.

Glycerophospholipids are amphiphilic molecules possessing polar head groups with a glycerol backbone and nonpolar variable long-chain fatty acids. Numerous molecular species are found in a single class of glycerophospholipid, conferring to these lipids a high structural diversity. They are major components of biological membranes and participate in important activities involving cell signaling and substrate transport. Sphingolipids consist of long-chain bases linked by an amide bond to a fatty acid and via the terminal hydroxyl group to complex carbohydrate or phosphorus moieties, constituting a complex family of compounds that also present an enormous structural variability. As important component of neuronal membranes, sphingolipids contribute to cellular diversity and functions and are associated with several neurodegenerative disorders. Moreover, they were studied in several foods due to their sensorial, reological, and antioxidant characteristics. In this work, the most relevant information available on glycerophospholipid and sphingolipid analysis by CE is reviewed. CE is a very promising analytical technique in polar lipid analysis, which provides high efficiency, relatively high resolution, and enormous versatility and requires small amounts of sample and solvent. MEKC and NACE methodologies have been developed as the most useful alternatives for these analyses by CE. Very interesting LODs have been achieved enabling the application of CE to the determination of glycerophospholipids and sphingolipids in several food and biological matrices.

Determination of betaines in vegetable oils by capillary electrophoresis tandem mass spectrometry--application to the detection of olive oil adulteration with seed oils.

A CE-tandem mass spectrometry (MS²) methodology enabling the simultaneous determination of betaines (glycine betaine, trigonelline, proline betaine and total content of carnitines) in vegetable oils was developed. Betaines were derivatized with butanol previous to their baseline separation in 10 min using a 0.1 M formic acid buffer at pH 2.0. Ion trap conditions were optimized in order to maximize the selectivity and sensitivity. Analytical characteristics of the proposed method were established by evaluating its selectivity, linearity, precision (RSDs ranged from 4.8 to 10.7% for corrected peak areas) and accuracy by means of recovery studies (from 80 to 99%) and LODs and LOQs at 0.1 ppb level. The method was applied for the determination of the selected betaines in seed oils and extra virgin olive oils. MS² experiments provided the fingerprint fragmentation for the betaines identified in vegetable oils. In extra virgin olive oils, carnitines were not detected, making it possible to propose them as a feasible novel marker for the detection of adulterations of olive oils. Application of the developed method for the analysis of different mixtures of extra virgin olive oil with seed oil (between 2 and 10%) enabled the detection and quantitation of the total content of carnitines. The results obtained show the high potential of the developed method for the authentication and quality control of olive oils.

Recent approaches for enhancing sensitivity in enantioseparations by CE.

This article reviews the latest methodological and instrumental improvements for enhancing sensitivity in chiral analysis by CE. The review covers literature from March 2007 until May 2009, that is, the works published after the appearance of the latest review article on the same topic by Sánchez-Hernández et al. [Electrophoresis 2008, 29, 237-251]. Off-line and on-line sample treatment techniques, on-line sample preconcentration strategies based on electrophoretic and chromatographic principles, and alternative detection systems to the widely employed UV/Vis detection in CE are the most relevant approaches discussed for improving sensitivity. Microchip technologies are also included since they can open up great possibilities to achieve sensitive and fast enantiomeric separations.