María L. Ibargoitia

Volatile components of aqueous liquid smokes from Vitis vinifera L shoots and Fagus sylvatica L wood

Vitis vinifera L shoots and Fagus sylvatica L wood were used to obtain aqueous smoke flavouring preparations. Both flavourings have a gold colour and pleasant odour. The flavour components of both samples are extracted with dichloromethane. The identification and quantitation of the components of the extracts are carried out by means of gas chromatography/mass spectrometry, and gas chromatography with flame ionisation detection. In both preparations carbonyl derivatives are in higher concentrations than phenol derivatives. Compounds that confer sweet, burnt and pungent flavours are in higher concentrations in the Vitis vinifera L shoots smoke flavouring, and compounds that give smoky flavours are in higher concentrations in the Fagus sylvatica L wood smoke flavouring. Ratios between the concentrations of the main components are proposed as parameters in order to characterise smoke and smoke flavourings, manufactured under specific conditions, from a specific wood. Finally, the yield of some components from a fixed amount of wood is also given.

GC/MS analysis of lignin monomers, dimers and trimers in liquid smoke flavourings

The common components found in smoke flavourings are carbonyl derivatives, acids, esters and lignin monomers such as alkyl-aryl ethers and phenol derivatives. Recently the presence of lignin dimers has been noted. In addition to these compounds, lignin trimers and new lignin dimers have been detected in the brown layer left by a smoke flavouring on the wall of the receptacle in which it was contained; these compounds tend to migrate towards the wall of the container and have not been previously described as smoke or smoke flavouring components. Lignin trimers and dimers are important in the preservation of smoked foods for their known high antioxidant activity, even higher than that of the lignin monomers. The mass spectral data of a large number of lignin trimers and dimers are given and can be useful for future studies of smoke flavourings and smoked food as well as in beverage studies and for the characterisation of woods to be used in the beverage industry. © 1999 Society of Chemical Industry

Characterisation of the lipidic components of margarines by 1H Nuclear Magnetic Resonance.

In this work, (1)H Nuclear Magnetic Resonance ((1)H NMR) has been used to study the lipidic fraction of margarines of different compositions, determining simultaneously both major components, which is to say triglycerides, and other minor ones, such as 1- and 2-monoglycerides, 1,2-diglycerides, vegetable stanols and sterols, and sorbic acid. The results show a wide variety of acyl group compositions, with polyunsaturated groups ranging from 22% to 50%, monounsaturated from 23% to 50%, and saturated from 21% to 55%. 1,2-Diglycerides and vegetable stanols and/or sterols have been detected in all the studied margarines, in concentrations varying between 2.73 and 26.06 mmol/kg, and between 3.40 and 240.01 mmol/kg, respectively. A good agreement has been found between the results obtained by (1)H NMR and some composition data of these margarines, showing the usefulness of this technique to analyse the lipidic composition of margarine in a quick and easy way.

Contamination of cheese by polycyclic aromatic hydrocarbons in traditional smoking. Influence of the position in the smokehouse on the contamination level of smoked cheese

This paper sets out to determine the polycyclic aromatic hydrocarbon (PAH) contamination degree of a traditionally smoked cheese: Herreño cheese, which comes from one of the Canary Islands. Its PAH profile is thoroughly studied by means of gas chromatography-mass spectrometry in SIM mode, and compared with that of an unsmoked cheese. Furthermore, a parameter not previously studied is evaluated, namely the influence of the position of the individual cheeses in the smokehouse on their PAH contamination level. Heavy PAH, among which are included most of the carcinogens, are very scarce and their concentrations low. In fact, benz[a]anthracene, together with chrysene+triphenylene, are the only heavy PAH detected in all of the smoked samples studied. The concentration of benzo[a]pyrene, detected only in 1 of the samples, is below the limit established in Spain for the rind of smoked cheese. In contrast, high concentrations of light PAH have been found, especially of naphthalene and its alkyl derivatives, whose effect on human health is not yet well established. The results derived from the analysis of the PAH profile suggest the potential usefulness of certain ratios between some pairs of PAH (phenanthrene/anthracene, naphthalene/acenaphthylene) to provide information on the PAH contamination source. Furthermore, differences have been found, depending on the position of the cheeses in the smokehouse, those placed in the path followed by the smoke being more contaminated. Therefore, the findings of this study could help in improving the design of smokehouses, to decrease the PAH contamination degree of smoked cheese.

Volatile components obtained from the leaves of Jasonia glutinosa

The components of the essential oil and of the pentane extract of the leaves of Spanish wild growing Jasonia glutinosa were studied for the first time by GC-MS and GC with FID detector. The leaves of Jasonia glutinosa are poor in terpene and sesquiterpene hydrocarbons, and rich in their oxygen derivatives. The principal identified components of the essential oil are camphor (42.4%), endo-borneol (17.8%), α-terpineol (1.0%), nerolidol (4.2%) and T-cadinol (2.3%), and the principal identified components of the pentane extract are α-pinene (3.5%), camphor (38.3%), endo-borneol (12.1%), γ-selinene (1.0%), nerolidol (4.6%), bornyl formate (1.2%), nonacosane (1.0%) and hentriacontane (1.2%). The method used to extract these components from the plant affects the nature of the components obtained and their relative proportions.

1H Nuclear Magnetic Resonance monitoring of the degradation of margarines of varied compositions when heated to high temperature

In this study, (1)H Nuclear Magnetic Resonance was used to monitor the evolution of three margarines of varied compositions when submitted to heating at 180°C in an oven with aeration. Heating causes degradation of polyunsaturated acyl groups and this depends not only on their unsaturation degree, but also on the concentration of the different acyl groups. The evolution of monounsaturated groups varies depending on the disappearance rate of the groups with higher unsaturation degree. Heat treatment also causes hydrolysis reactions that lead to a reduction in 1-monoglycerides and an increase in 1,2-diglycerides, especially in the margarines with higher water content, as well as degradation of some vegetable sterols. Different types of aldehydes and epoxides were identified and quantified, above all in the margarine with the highest proportion of polyunsaturated groups, especially linoleic; some of these are toxic, such as 4-hydroxy- and 4,5-epoxy-2-alkenals.

A new methodology capable of characterizing most volatile and less volatile minor edible oils components in a single chromatographic run without solvents or reagents. Detection of new components

The possibilities offered by a new methodology to determine minor components in edible oils are described. This is based on immersion of a solid-phase microextraction fiber of PDMS/DVB into the oil matrix, followed by Gas Chromatography/Mass Spectrometry. It enables characterization and differentiation of edible oils in a simple way, without either solvents or sample modification. This methodology allows simultaneous identification and quantification of sterols, tocols, hydrocarbons of different natures, fatty acids, esters, monoglycerides, fatty amides, aldehydes, ketones, alcohols, epoxides, furans, pyrans and terpenic oxygenated derivatives. The broad information provided by this methodology is useful for different areas of interest such as nutritional value, oxidative stability, technological performance, quality, processing, safety and even the prevention of fraudulent practices. Furthermore, for the first time, certain fatty amides, gamma- and delta-lactones of high molecular weight, and other aromatic compounds such as some esters derived from cinnamic acid have been detected in edible oils.

Prooxidant effect of α-tocopherol on soybean oil. Global monitoring of its oxidation process under accelerated storage conditions by 1H nuclear magnetic resonance

The effect of adding α-tocopherol in proportions ranging from 0.002 to 5% in weight on the oxidative stability of soybean oil was studied. For the first time, the oxidation process under accelerated storage conditions including evolution of the molar percentages of the several types of oil acyl groups, and formation and evolution of various kinds of oxidation products comprising hydroperoxides, hydroxy-dienes and other alcohols, epoxides, aldehydes and keto-dienes, was followed by 1H nuclear magnetic resonance. It is proved that, except in the lowest proportion, α-tocopherol not only exerts a prooxidant effect on soybean oil but also modifies its oxidation pathway, affecting the oxidation products generation rate, their nature, relative proportions and concentrations. It is noticeable that the highest α-tocopherol concentrations induce the generation of some toxic compounds at earlier stages of the thermoxidation process and sometimes in higher concentration, such as certain oxygenated α,β-unsaturated aldehydes and monoepoxides derived from linoleic groups.

Influence of fat and phytosterols concentration in margarines on their degradation at high temperature. A study by 1H Nuclear Magnetic Resonance

The objective of this work was to study the influence of several factors, especially fat and phytosterols concentration, on the behavior of margarine under thermo-oxidative conditions. For this purpose, margarines with similar compositions in acyl groups, but differing in the concentration of both fat and phytosterols, were heated at 180°C. The changes in the main components of margarine lipids and the formation of new compounds throughout the thermal treatment were monitored by (1)H Nuclear Magnetic Resonance. The results show that the presence of high concentrations of phytosterols seems to have an antioxidant effect, since it slows down the thermo-oxidation rate of margarine and, consequently, the generation rate and concentrations of secondary oxidation products such as some aldehydes, epoxides and alcohols. The oil-water ratio also seems to have an important effect on margarine behavior, in such a way that the lower the fat concentration is, the higher its thermo-oxidation rate.

Complexity and uniqueness of the aromatic profile of smoked and unsmoked Herreño cheese.

In this work, the volatile fraction of unsmoked and smoked Herreño cheese, a type of soft cheese from the Canary Islands, has been characterized for the first time. In order to evaluate if the position in the smokehouse could influence the volatile profile of the smoked variety, cheeses smoked at two different heights were studied. The volatile components were extracted by Solid Phase Microextraction using a divinylbenzene/carboxen/polydimethylsiloxane fiber, followed by Gas Chromatography/Mass Spectrometry. In total, 228 components were detected. The most numerous groups of components in the unsmoked Herreño cheese were hydrocarbons, followed by terpenes and sesquiterpenes, whereas acids and ketones were the most abundant. It is worth noticing the high number of aldehydes and ketones, and the low number of alcohols and esters in this cheese in relation to others, as well as the presence of some specific unsaturated hydrocarbons, terpenes, sesquiterpenes and nitrogenated derivatives. The smoking process enriches the volatile profile of Herreño cheese with ketones and diketones, methyl esters, aliphatic and aromatic aldehydes, hydrocarbons, terpenes, nitrogenated compounds, and especially with ethers and phenolic derivatives. Among these, methylindanones or certain terpenes like α-terpinolene, have not been detected previously in other types of smoked cheese. Lastly, the results obtained suggest a slightly higher smoking degree in the cheeses smoked at a greater height.