María J. Manzanos

Study of the volatile composition of an aqueous oak smoke preparation

An aqueous smoke flavouring from oak (Quercus sp.) sawdust was obtained on the laboratory scale. Its qualitative and quantitative composition was studied by gas chromatography after previous extraction. A high number of compounds (215) was detected. In addition to the well-known smoke components, others, only recently described as smoke components, were also detected. In the first group there are aldehydes, ketones, diketones, esters, alcohols, acids, furan and pyran derivatives, syringol, guaiacol, phenol and pyrocatechol derivatives, alkyl and aryl ethers; in the second group the presence of some furan and pyran derivatives is noteworthy, as well as a significant number of lignin dimers in low proportion, a considerable number of anhydrosugars in very high proportion and some nitrogenated derivatives in low proportions. Differences between this oak aqueous liquid smoke and others previously obtained from several woods, under similar operative conditions, are due, not only to the absence or presence of some compounds, but also to the proportions of the different groups of components present in the preparation.

Study of the composition of the different parts of a Spanish Thymus vulgaris L. plant

Abstract The yield and composition of the dichloromethane extracts of leaves, flowers and stems of Thymus vulgaris L. growing in northeastern Spain have been studied. The yield obtained from leaves and flowers is much higher than that obtained from stems. This plant has a chemotype different from those previously known for Thymus vulgaris L. The fraction of the dichloromethane extract from leaves and flowers, studied by gas chromatography/mass spectrometry, shows that these tissues have higher concentrations of terpene hydrocarbons, oxygen terpene derivatives, sesquiterpene hydrocarbons, oxygen sesquiterpene derivatives, saturated aliphatic hydrocarbons and phytosterol derivatives than the stems. However, aldehydes with large number of carbon atoms have been found in higher concentrations in stems than in flowers and leaves. These extracts from different parts of Thymus vulgaris L. also show the presence of a large number of flavonoids and vitamin E, compounds of great interest in food industry for their antioxidant activity. Leaves and flowers of this plant are of interest as flavourings, as well as being natural antioxidants for the food industry.

Study of the components of a solid smoke flavouring preparation

The study of the components of a solid smoke flavouring preparation was carried out using several techniques. The sample was extracted by means of an ultrasonic bath and by successively using dichloromethane and water as solvents. Observation by microscope, of the initial sample and the residues of extractions, indicate that the carrier of this preparation consists of two components insoluble in dichloromethane. One of these consist of small transparent globular particles, and the other of irregular particles of a gold colour, the latter is soluble in water. Fourier Transform infra-red spectra of the solid smoke flavouring preparation, its extracts and residues, were obtained and studied. From these it can be concluded that the two components of the carrier are saccharides, one of them similar to starch and the other with reducing ability owing to the presence of carbonyl groups. Also, from the infra-red spectrum of the flavouring mixture extracted with dichloromethane, ratios between the absorbances of carbonyl and phenol functional groups are obtained, and compared with those of an aqueous smoke flavouring. Finally, the composition of the volatile fraction of the extract in dichloromethane was studied by gas chromatography-mass spectrometry and gas chromatography techniques. Carbonyl compounds, namely ketones, aldehydes, and furan and pyran derivatives, are the major components and constitute approximately 60% of the volatile fraction of the extract. Also, phenol derivatives are present in the sample. Guaiacol and syringol derivatives constitute approximately 25% of the volatile fraction. Some compounds, not previously detected in wood smoke, were identified in this flavouring. However, polycyclic aromatic hydrocarbons were not detected in the sample. Quantitative data from gas chromatography and infrared spectroscopy agree, and show the close relationship between the composition of the soluble fraction in dichloromethane and the odour of the sample.

Quality of farmed and wild sea bass lipids studied by 1H NMR: Usefulness of this technique for differentiation on a qualitative and a quantitative basis

Proton Nuclear Magnetic Resonance ((1)H NMR) spectroscopy was employed to study the lipids of farmed and wild European sea bass (Dicentrarchus labrax). This technique provided a great deal of detailed information on sea bass lipids composition and, once the spectra signals have been assigned, the simple observation of the spectra enables one to distinguish cultured from wild fish. This distinction is possible due to the presence in the former of high proportions of diunsaturated acyl groups, mainly linoleic. Furthermore, new approaches for quantitative characterization of sea bass lipids were developed. For the same season wild sea bass lipids contain not only higher molar percentages of omega-3 and of docosahexaenoic (DHA), but also higher concentrations of phosphatidylcholine and of cholesterol than farmed ones. However, in general, the absolute content of DHA and of eicosapentaenoic plus arachidonic (EPA+ARA) acyl groups as well as of phosphatidylcholine and cholesterol, were reasonably higher in farmed than in wild sea bass fillets, due to the higher total lipid content of the former. The presence of omega-1 acyl groups in all farmed samples and in some of the wild specimens was shown. As far as we know, this is the first time that omega-1 acyl groups have been identified and quantified in fish lipids by (1)H NMR.

A study of several parts of the plant Foeniculum vulgare as a source of compounds with industrial interest

Abstract The yield and composition of the volatile fraction of the pentane extracts of leaves, stems and seeds of Foeniculum vulgare Mill, have been studied. The yield obtained from seeds was much higher than that obtained from leaves and stems. The volatile fraction of the pentane extract of the latter two has a higher concentration of terpene hydrocarbons and a smaller concentration of oxygenated terpene hydrocarbons than that of the seeds. Sesquiterpenes have been detected in the leaves, as has petroselinic acid in the seeds. Saturated aliphatic hydrocarbons with 25 or more carbon atoms have been found in all of the parts. The pentane extract of the leaves also contains the antioxidant vitamin E. These extracts from different parts of fennel show not only the proportion of their volatile flavour components, but also the concentration of fatty acids and antioxidant compounds (such as vitamin E), if any.

Smoke and liquid smoke. Study of an aqueous smoke flavouring from the aromatic plant Thymus vulgaris L

An aqueous smoke flavouring from Thymus vulgaris L was obtained. The qualitative and quantitative composition of its dichloromethane extract was studied by gas chromatography and gas chromatography/mass spectrometry. In addition to the common smoke components such as aldehydes, ketones, diketones, esters, acids, furan and pyran derivatives, alkyl aryl ethers, phenol, guaiacol and syringol derivatives, some terpenic compounds were detected. Differences between this aqueous liquid smoke and others from various kinds of wood are due not only to the absence or presence of some compounds but also to the proportions of the different groups of components present in the mixture. Some aldehydes, esters, guaiacol and its derivatives and terpenic compounds contribute to the overall odour of this liquid smoke more significantly than the ketones, furan and pyran derivatives, acids, phenol and its derivatives and syringol. The yield in smoke components obtained from the pyrolysis of Thymus vulgaris L at 488 °C is of a similar order to that obtained from other woods. © 1999 Society of Chemical Industry

2,6-Di-Tert-Butyl-Hydroxytoluene and Its Metabolites in Foods

2,6-Di-tert-butyl-hydroxytoluene (BHT, E-321) is a synthetic phenolic antioxidant which has been widely used as an additive in the food, cosmetic, and plastic industries for the last 70 y. Although it is considered safe for human health at authorized levels, its ubiquitous presence and the controversial toxicological data reported are of great concern for consumers. In recent years, special attention has been paid to these 14 metabolites or degradation products: BHT-CH2 OH, BHT-CHO, BHT-COOH, BHT-Q, BHT-QM, DBP, BHT-OH, BHT-OOH, TBP, BHQ, BHT-OH(t), BHT-OH(t)QM, 2-BHT, and 2-BHT-QM. These derived compounds could pose a human health risk from a food safety point of view, but they have been little studied. In this context, this review deals with the occurrence, origin, and fate of BHT in foodstuffs, its biotransformation into metabolites, their toxicological implications, their antioxidant and prooxidant properties, the analytical determination of metabolites in foods, and human dietary exposure. Moreover, noncontrolled additional sources of exposure to BHT and its metabolites are highlighted. These include their carryover from feed to fish, poultry and eggs, their presence in smoke flavorings, their migration from plastic pipelines and packaging to water and food, and their presence in natural environments, from which they can reach the food chain.

Characterization of the components of a salty smoke flavouring preparation

Abstract A solid smoke flavouring preparation had a heterogeneous appearance and microscopy revealed transparent crystalline particles, vegetable matter, irregular brown particles and dark brown globular particles. A quantity of globular particles was separated from a fraction of the total sample. Fourier Transform infrared spectra of the total sample and of the globular particles, as well as of their residues and extracts in dichloromethane were studied. The insoluble fraction of the flavouring preparation in dichloromethane was again extracted with distilled water and infrared spectra of its residue and extract were also studied. It was inferred that, in addition to compounds responsible for the flavour, vegetable matter, NaCl, fatty acids and fatty esters and a carrier (presumably made of saccharides) were used in the manufacture of this flavouring preparation. Globular particles of the flavouring preparation were composed of fatty acids and fatty esters, carrier and flavour compounds. Gas chromatography/mass spectrometry and gas chromatography with flame ionization detection techniques were used to study the soluble fraction (in dichloromethane) of the flavouring preparation. Phenol derivatives were the main components responsible for the smoke flavour. In addition to the flavouring compounds arising from wood pyrolysis, flavouring compounds derived from plants were also found. Fatty acids and fatty esters, detected by infrared spectroscopy were shown to be the main components of the soluble fraction.

Usefulness of 1H NMR in assessing the extent of lipid digestion

Proton Nuclear Magnetic Resonance ((1)H NMR) is proved to be, for the first time, a very useful technique in monitoring the extent of lipid hydrolysis in digestion processes. Sunflower oil and minced fish flesh, as model foods, were subjected to different in vitro digestion experiments and the lipolysis levels reached were evaluated using (1)H NMR spectral data. Simple observation of the spectra gives very valuable information about the extent of the lipolysis and enables a rapid discrimination among samples having different hydrolysis degree. Equations were developed to quantify all the lipolytic products, and either referred to acyl groups plus fatty acids, or to glyceryl structures. The main hydrolysis products were 1,2-diglycerides, 2-monoglycerides, glycerol and fatty acids, although small proportions of 1,3-diglycerides and of 1-monoglycerides were also found. With this methodology, determination of the extent of lipid digestion in its different definitions can be made. It has been shown that these definitions are not equivalent, which is evidence for the need for a consensus in this regard.

A study by 1H NMR on the influence of some factors affecting lipid in vitro digestion

This article focuses on the impact of several experimental factors, including gastric acidification, intestinal transit time, presence of gastric lipase, sample/digestive fluids ratio, concentration and nature of the enzymes in intestinal juice, and bile concentration, on the extent of in vitro lipolysis when using a static model that simulates human digestion processes in mouth, stomach and small intestine. The study was carried out by Proton Nuclear Magnetic Resonance ((1)H NMR). This technique provides a complete molecular picture of lipolysis, evidencing for the first time, whether preferential hydrolysis of certain glycerides over others occurs. A lipolysis degree similar to that reported in vivo was reached by varying certain variables within a physiological range; among them, bile concentration was found to be crucial. The holistic view of this (1)H NMR study provides information of paramount importance to design sound in vitro digestion models to determine the bioaccessibility and bioavailability of lipophilic compounds.