Manuel León-Camacho

HPLC analysis of tocopherols and triglycerides in coffee and their use as authentication parameters

The triglyceride and tocopherol contents of green and roasted coffee beans belonging to the arabica and robusta varieties were determined by reversed phase and normal phase high resolution liquid chromatography, respectively. Refractive index detector was used in the case of the triglycerides and fluorescence for tocopherols. Coffee oil was Soxhlet extracted with hexane. By considering the triglyceride and tocopherol profiles as chemical descriptors, a chemometric study with authentication purposes was performed to differentiate coffee varieties. Pattern recognition techniques like principal component analysis and linear discriminant analysis were carried out. Discrimination between arabica and robusta coffees was achieved with both profiles, but only tocopherols also allow the differentiation between green and roasted coffees.

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.

Determination of the arabica/robusta composition of roasted coffee according to their sterolic content

A method for the determination of the percentage of the arabica coffee in mixtures of roasted coffee is proposed. The sterol content of roasted coffee blends was determined by extracting the coffee oil, saponifying the lipids and the sterols present in the unsaponifiable fraction were separated by thin layer chromatography. Then, they were converted into trimethyl silyl derivatives and analysed by gas chromatography. Twelve sterols were determined in roasted coffee samples which were mixtures of the arabica and robusta classes. Considering the sterols as chemical descriptors, principal component regression was applied. Δ5avenasterol was found to be a very adequate variable to establish the arabica percentage in roasted coffee blends. The method was applied to the determination of the arabica–robusta composition of commercial roasted coffee samples.

A new high-performance liquid chromatographic method with evaporative light scattering detector for the analysis of phospholipids. Application to Iberian pig subcutaneous fat

A new method for the analysis of phospholipids by normal-phase HPLC is described using a silica column. Addition of ammonia and triethylamine to a gradient based on chloroform/methanol/water promoted a good and rapid separation of phospholipid classes (20 min run). The use of an evaporative light scattering detector permitted an accurate analysis of a mixture of phospholipids. Calibration curves were linear within different range for each phospholipid class. The LOD and LOQ obtained were below 0.03 and 0.05 mg kg⁻¹ for all cases, respectively. Besides, a new method for the separation of phospholipids from total lipids before HPLC analysis by a solid-phase extraction (SPE) with Si cartridges has been developed. This methodology gave a good recovery ranging from 97 to 117%. The method was validated with a standard mixture of phospholipids. This method has been applied to characterize the phospholipid fraction of subcutaneous fat from Iberian pig. Cardiolipin, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylcholine, and sphingomyelin have been described for first time in these samples. The fatty acid composition of the different phospholipid classes and their HPLC electrospray ionization mass spectrometry have been used for characterizing the molecular species present in each one.

Gas and Liquid Chromatography: Methodology Applied to Olive Oil

Olive oil, like other oils and fats (Karleskind & Wolff 1996), consists of a large number of compounds, which results in a highly complex matrix. When studying its composition in order to typify it or to verify its quality, the analytical chemist finds a powerful tool in chromatographic methods, which are mainly separative techniques that also can be used for quantification. In current regulations (EC 1991; Codex Alimentarius 1993; IOOC 1997), most of the techniques applied to the analysis of fats and oils, with the aim of defining and characterizing them, are liquid or gas chromatographic techniques.

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

AbstractThe 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. FigureIberian pigs in outdoor rearing system (Montanera)

Changes in the Fatty Acid and Triacylglycerol Profiles in the Subcutaneous Fat of Iberian Ham during the Dry-Curing Process

In this study, we have evaluated the changes that occur in the profiles of total fatty acids and triacylglycerols during the dry-curing process (730 days) of Iberian ham. The subcutaneous adipose tissues of six hams obtained from three Iberian pigs fed on acorns were analyzed periodically during the processing time (from the raw to the dry-cured samples), including postsalting, drying, and ripening stages. The environmental conditions were also registered. The curing process significantly decreased (p < 0.01) the relative percentages of total polyunsaturated fatty acids, including C18:2n-6 and C18:3n-3 and, therefore, significantly increased (p < 0.05) the level of monounsaturated fatty acids. The triglycerides containing 0-2 double bonds showed an increase during the curing process. On the contrary, the more unsaturated ones (3-5 double bonds) suffered a significant decrease. We have postulated that these changes could also be due to polymerization and oxidation reactions that affect the triacylglycerols and besides the fatty acids. In general, most fatty acids and triacylglycerols reversed the trend by about 500-600 days of processing.

Olive oil normalizes the altered distribution of membrane cholesterol and Na+-Li+ countertransport activity in erythrocyte of hypertensive patients

Abstract The effects of olive oil (OO)- and high-oleic sunflower oil (HOSO)-enriched diets on erythrocyte membrane cholesterol distribution (by means of cholesterol oxidation after continuous cholesterol oxidase treatment) and Na + Li + countertransport activity in control subjects and patients with untreated essential hypertension (with or without concomitant hypercholesterolemia) have been examined. The participants were 12 normotensive and sixteen hypertensive women who consumed in randomized order the two monosaturated fatty acid (MUFA) diets over 4-week periods separated by a 4-week washout period. The half-times for cholesterol oxidation were significantly higher in hypertensive women, ranging from an increase of 38 to 57% in the normo-(20.6 ± 2.8 min; P P + Li + countertransport was found to be significantly higher in hypertensive women, ranging the increase from 22 to 57% in the normo-(0.314 ± 0.043 mmol × [h × liter cell] −1 ; P −1 ; P + Li + countertransport in erythrocyte of hypertensive patients. This action of OO also indicates that alterations in membrane cholesterol distribution may be relevants for the pathogenesis of hypertension. The effects, however, cannot be exclusively attributed to the content of MUFAs (mainly oleic acid) in the diet, as HOSO was unable to induce favorable changes.

Determination of ent-kaurene in subcutaneous fat of Iberian pigs by gas chromatography multi-stage mass spectrometry with the aim to differentiate between intensive and extensive fattening systems

This work presents a gas chromatography multi-stage mass spectrometry (GC-MS(3)) method for the determination of ent-kaurene in subcutaneous fat of Iberian pig, present in adipose tissue of animals due to pasture ingestion (extensive fattening system). The method comprises a saponification and a liquid-liquid extraction of the unsaponifiable fraction, followed by an isolation of the hydrocarbon fraction by high performance liquid chromatography (HPLC) and analysis by GC-MS(3) (ion trap) with electronic ionization. The GC-MS(3) analysis allows the isolation and characterization of specific fragments from the original (MS(1)) molecular structure, and particularly, those fragments originated from the precursor ion (m/z=229) characteristic of ent-kaurene. The MS/MS product fragment m/z=213 is used as a further precursor fragment giving rise to a MS(3) spectrum specific for ent-kaurene. The limit of detection of the MS(3) technique is lower than 0.2 microg kg(-1) and a linear regression has been found between 0.2 and 112 microg kg(-1). This method is applicable for the determination of the fattening system of the Iberian pig.

Isomerization of fatty acids during deodorization and physical refining — stripping with nitrogen

A gas-liquid chromatography study has been carried out on the methyl esters of trans fatty acids formed by isomerization of the corresponding cis fatty acids during the deodorization of olive, soybean, and sunflower oils. The results expressed as molar fraction are coherent. They enable comparison of the behaviour of the unsaturated fatty acids of several oils in this type of isomerization during this process, using nitrogen as stripping gas. Isomerisierung von Fettsauren wahrend der Desodorierung und physikalischen Raffination — Stickstoff als Trenngas.Es wurde eine Gas-Flussigkeitschromatographische Studie der Methylester der trans-Fettsauren erstellt, die durch Isomerisierung der entsprechenden cis-Fettsauren wahrend der Desodorierung bzw. physikalischen Raffination von Oliven-, Soja- und Sonnenblumenol entstehen. Die Ergebnisse, dargestellt als Molenbruch, sind in sich schlussig und erlauben einen Vergleich mit dem Isomerisierungsverhalten ungesattigter Fettsauren verschiedener Ole bei der Desodorierung mit Stickstoff als Trenngas.