Characterization and quantification of 4-methylsterols and 4,4-dimethylsterols from Iberian pig subcutaneous fat by gas chromatography-mass spectrometry and gas chromatography-flame ionization detector and their use to authenticate the fattening systems.

4-Methylsterols and 4,4-dimethylsterols of 47 samples of subcutaneous fat from Iberian pigs reared on two different fattening systems, "Extensive" and "Intensive", have been analyzed by GC-MS and GC-FID. The lipids were extracted by melting the subcutaneous fat in a microwave oven. The unsaponifiable matter was fractionated by thin layer chromatography. Then, the analysis was performed on a capillary SPB-5 column (30 m × 0.25 mm i.d., 0.15 µm film thickness), with hydrogen as a carrier gas and using a flame ionization detector. n-eicosanol was used as internal standard for quantification of individual methylsterols. These compounds have been analyzed by GC-MS for their identification. The full scan of free and trimethyl silyl ethers was used as acquisition mode. Six compounds have been identified for the first time in this type of samples: (3ß,4α,5α)-4-methyl-cholesta-7-en-3-ol, (3ß,4α,5α)-4-methyl-cholesta-8(14)-en-3-ol, (3ß,5α)-4,4-dimethyl-cholesta-8(14),24-dien-3-ol, (3ß)-lanosta-8,24-dien-3-ol, (3ß, 5α)-4,4-dimethyl-cholesta-8,14-dien-3-ol and (3ß)-lanost-9(11),24-dien-3-ol. The samples were derivatized as trimethyl silyl ethers before their analysis by GC-FID. By using these compounds as chemical descriptors, pattern recognition techniques were applied to differentiate between extensive and intensive fattening systems of Iberian pig. Several pattern recognition techniques, such as principal component analysis, linear discriminant analysis, support vector machines, artificial neural networks, soft independent modeling of class analogy and k nearest neighbors, have been used in order to find out a suitable classification model. A multilayer perceptron artificial neural network based on the contents of the above mentioned compounds allowed the differentiation of the two fattening systems with an overall classification performance of 91.7%.

Authentication of fattening diet of Iberian pigs according to their volatile compounds profile from raw subcutaneous fat.

The composition of volatile components of subcutaneous fat from Iberian pig has been studied. Purge and trap gas chromatography-mass spectrometry has been used. The composition of the volatile fraction of subcutaneous fat has been used for authentication purposes of different types of Iberian pig fat. Three types of this product have been considered, montanera, extensive cebo and intensive cebo. With classification purposes, several pattern recognition techniques have been applied. In order to find out possible tendencies in the sample distribution as well as the discriminant power of the variables, principal component analysis was applied as visualisation technique. Linear discriminant analysis (LDA) and soft independent modelling by class analogy (SIMCA) were used to obtain suitable classification models. LDA and SIMCA allowed the differentiation of three fattening diets by using the contents in 2,2,4,6,6-pentamethyl-heptane, m-xylene, 2,4-dimethyl-heptane, 6-methyl-tridecane, 1-methoxy-2-propanol, isopropyl alcohol, o-xylene, 3-ethyl-2,2-dimethyl-oxirane, 2,6-dimethyl-undecane, 3-methyl-3-pentanol and limonene.

Authentication of fattening diet of Iberian pig according to their triacylglycerols profile from subcutaneous fat.

Triacylglycerols of 50 samples of subcutaneous fat of Iberian pigs reared extensively on two different feeding systems: montanera (M) and cebo (C) have been analysed by gas chromatography flame ionization detector. The lipids were extracted by melting from subcutaneous fat into microwave oven. The fat was then filtered and dissolved in hexane. This analysis was performed on a column (30 m x 0.25 mm i.d.) coated with a bonded stationary phase DB-17HT (50% phenyl-50% methylpolysiloxane; 0.15 microm film thickness) with hydrogen (2.1 mL min(-1)) as a carrier gas, programmed temperature was kept at 320 degrees C, and was then raised to 350 degrees C at a rate of 2.0 degrees C min(-1) and flame ionization detector. By using the triacylglycerols as chemical descriptors, pattern recognition techniques were applied to differentiate between montanera and cebo fattening diet of Iberian pig. Triolein, palmitoyl-stearyl-oleoyl glycerol and di-oleoyl-linoleoyl glycerol were found to be the most differentiating variables.

Characterization and quantification of the hydrocarbons fraction of the subcutaneous fresh fat of Iberian pig by off-line combination of high performance liquid chromatography and gas chromatography.

Hydrocarbons in fresh subcutaneous fat of Iberian pig have been analyzed by GC-MS after fractionation of the unsaponifiable fraction with a new off-line combination of HPLC and GC method. The new method proposed improves the recovery and simultaneous quantification of terpenic hydrocarbons in comparison to the traditional LC method. When necessary and for identification purposes, selective ion monitoring (SIM) was used as acquisition mode in GC-MS. To determine the position of the double bonds in the unsaturated hydrocarbon chain the dimethyl disulfide derivatives (DMDS) were obtained. To elucidate the structure of the branched 1-alkenes the hydrocarbon fraction was submitted to hydrogenation. Thirty-five compounds have been identified, including n-alkanes, n-alkenes, branched (n-1,n-2-dimethyl-1-alkenes) and terpenic hydrocarbons, being the most abundant n-alkenes and n-alkanes of even chain of n-C12-n-C26. Besides the hydrocarbons already described in bibliography, a new diterpenic hydrocarbon, ent-kaurene, have been identified for the first time. The compound reported as Neophytadiene by other authors, has been identified as a 20 atoms hydrocarbon with two double bonds, the 7,11,15-trimethyl-heptadeca-1,4-diene.

Eritema exudativo multiforme asociado a nódulo de Orf / Erythema exsudativum multiforme in association to Orf nodule

Varón de 16 años que consultó por presentar una erupción cutánea de aparición brusca, constituida por lesiones con morfología típica de diana o escarapela de Bateman, cuyo estudio dermatopatológico confirmó el diagnóstico de eritema exudativo multiforme (EEM). Tras una exploración detenida se observó que además presentaba en el tercerdedo de la mano derecha una lesión de aspecto diferente, que al estudio dermatopatológico permitió observar algunas células con núcleo y citoplasma modificados que sugerían inclusiones virales, todo ello compatible con nódulo de Orf. La causa más frecuente de EEM es el virus del herpes simples, seguida de mycoplasma pneumoniae y de algunos fármacos, pero su asociación con parapoxvirus es excepcional y sólo se han recogido algo más de 20 casos en la literatura de nódulos Orf asociados a EEM, que se caracteriza por comencar de 10 a 14 días después de aparecer el nódulo de Orf y desaparecen en el plazo de una semana y media, aunque en nuestro caso las lesiones de EEM se iniciaron a las 48 horas de comenzar el Orf. En España no tenemos información de que se haya observado ningún caso de esta asociación, aunque sí se han descrito varios casos asociados a nódulos de los ordeñadores. En definitiva, se trata de un caso de nódulo de Orf adquirido a través del contacto con un animal enfermo, que posteriormente desarrolló un EEM y aunque los parapoxvirus pueden ser una causa poco frecuente de EEM, el nódulo de Orf debe ser tenido en cuenta en el diagnóstico etiológico del EEM en poblaciones de riesgo (AU)

Determination of phenols, flavones, and lignans in virgin olive oils by solid-phase extraction and high-performance liquid chromatography with diode array ultraviolet detection.

A simple analytical method for the quantitative determination of phenols, flavones, and lignans in virgin olive oils was developed. The polar fraction was isolated from small amounts of oil sample (2.5 g) by solid-phase extraction (SPE) using diol-phase cartridges, and the extract was analyzed by reversed-phase HPLC coupled with diode array UV detection. Chromatographic separation of pinoresinol, cinnamic acid, and 1-acetoxypinoresinol was achieved. Repeatability (RSD < 6.5%), recovery (> 90%), and response factors for each identified component were determined. SPE on amino-phase cartridges was used for isolating acidic phenols and as an aid for phenol identification. For the first time, 2-(4-hydroxyphenyl)ethyl acetate was detected in olive oils. The aldehydic structure of the ligstroside aglycon was confirmed by NMR spectroscopy. The colorimetric determination of total o-diphenolic compounds by reaction with molybdate was consistent with their HPLC determination. Differences between results obtained by liquid-liquid extraction and SPE were not statistically significant.

Fatty acid profiles as discriminant parameters for coffee varieties differentiation.

The fatty acid contents of coffee lipid extracts have been determined by capillary gas chromatography. Ten fatty acids were considered: myristic (C14:0), palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), linolenic (C18:3), arachidic (C20:0), eicosenoic (C20:1) and behenic acid (C22:0). The analyzed coffee samples belonged to arabica and robusta varieties and were either green or roasted coffee beans. The lipids were Soxhlet extracted from ground coffee beans with hexane, and the fatty acids were determined as their corresponding methyl esters. Fatty acids contents were considered as chemical descriptors to differentiate coffee varieties. Several Pattern Recognition methods, Principal Component Analysis and Linear Discriminant Analysis allowed discrimination between green and roasted arabica and robusta coffees.