New trends in beer flavour compound analysis

As the beer market is steadily expanding, it is important for the brewing industry to offer consumers a product with the best organoleptic characteristics, flavour being one of the key characteristics of beer. New trends in instrumental methods of beer flavour analysis are described. In addition to successfully applied methods in beer analysis such as chromatography, spectroscopy, nuclear magnetic resonance, mass spectrometry or electronic nose and tongue techniques, among others, sample extraction and preparation such as derivatization or microextraction methods are also reviewed.

Recent trends in the advanced analysis of bioactive fatty acids

The consumption of dietary fats have been long associated to chronic diseases such as obesity, diabetes, cancer, arthritis, asthma, and cardiovascular disease; although some controversy still exists in the role of dietary fats in human health, certain fats have demonstrated their positive effect in the modulation of abnormal fatty acid and eicosanoid metabolism, both of them associated to chronic diseases. Among the different fats, some fatty acids can be used as functional ingredients such as alpha-linolenic acid (ALA), arachidonic acid (AA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), gamma-linolenic acid (GLA), stearidonic acid (STA) and conjugated linoleic acid (CLA), among others. The present review is focused on recent developments in FAs analysis, covering sample preparation methods such as extraction, fractionation and derivatization as well as new advances in chromatographic methods such as GC and HPLC. Special attention is paid to trans fatty acids due its increasing interest for the food industry.

Ion-pair dynamic liquid-phase microextraction combined with injection-port derivatization for the determination of long-chain fatty acids in water samples

Ion-pair dynamic liquid-phase microextraction coupled to injection-port derivatization has been developed for the determination of long-chain fatty acids in water samples by gas chromatography-mass spectrometry (GC-MS). In this procedure, long-chain fatty acids (C(14), C(16) and C(18)) were converted into their ion-pair complexes with tetrabutylammonium hydrogen sulfate and then extracted by organic solvent (1-octanol) impregnated in the hollow fiber. The dynamic nature of the extraction was represented by the repeated movement of the acceptor phase (organic solvent) in the hollow fiber that was controlled by a syringe pump. Ion pairs of fatty acids quantitatively formed butyl esters in the injection-port of the gas chromatography. Several parameters such as injection temperature, purge-off time, organic solvent, ion-pair reagent, pH, agitation speed, extraction time and the syringe pump parameters (plunger speed and dwell time) have been optimized. The limits of detection were in the range 0.0093-0.015 ng mL(-1) (at a signal-to-noise ratio of 3) under GC-MS-selected ion monitoring mode and the relative standard deviations were between 7.7% and 11.5%. The method was successfully applied to measure long-chain fatty acids in real water samples.