The key role of ovalbumin in lipid bioaccessibility and oxidation product profile during the in vitro digestion of slightly oxidized soybean oil.

The behaviour of slightly oxidized virgin and refined soybean oils during in vitro digestion was studied by 1H nuclear magnetic resonance (1H NMR) and solid phase microextraction-gas chromatography/mass spectrometry. The main objectives were to analyze lipolysis extent and oxidation during digestion, and to assess the impact of two different proportions of ovalbumin on both processes. At the same time γ-tocopherol fate was monitored, when possible, by 1H NMR. The results reveal that the initial oxidation degree of the oils negatively influences the lipolysis extent, reducing the bioaccessibility of the major oil components, which include some essential fatty acids. Although the low ovalbumin proportion tested does not significantly affect lipolysis, this is greatly enhanced when ovalbumin is added at a high level, improving lipid bioaccessibility. It has also been shown that oxidation does not seem to have occurred to a great enough extent during digestion for it to be detected from polyunsaturated acyl group degradation. Moreover, the changes observed in the oxidation product profile of the starting oils after digestion can be considered to be due mainly to the transformation of the initially present hydroperoxides, whose concentration diminishes in the digested samples to give hydroxy-dienes, epoxides and aldehydes. In presence of a high ovalbumin proportion, hydroperoxide reduction to hydroxy-dienes is favoured and lower levels of aldehydes and epoxides are observed. This latter could be due to a diminution in their generation and/or to their reaction with ovalbumin. A high proportion of this protein in the system also increases γ-tocopherol bioaccessibility.

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.

Diagnóstico perinatal de rabdomiomas intracardiacos y esclerosis tuberosa / Perinatal diagnosis of cardiac rhabdomyomas and tuberous sclerosis

Los tumores cardiacos son poco comunes, y los más frecuentes son los rabdomiomas. Su diagnóstico puede realizarse durante la época fetal. La evolución es variable: algunos son asintomáticos y otros se manifiestan por una obstrucción al flujo o en forma de arritmia. Este tipo de tumores puede ser la clave diagnóstica de una esclerosis tuberosa. Dado el amplio espectro en su presentación, mostramos dos casos, uno de diagnóstico prenatal y otro a partir de un hallazgo en la ecocardiografía(AU)

Primary cardiac tumors are not very common. Rhabdomyomas are those most frequently reported during childhood. They can be diagnosed as early as the fetal period. The course varies; in some cases, there are no symptoms, while in others, the diagnosis is based on the presence of an obstruction to the flow or an arrhythmia. Tumors of this type can be the clue to the diagnosis of tuberous sclerosis. Because of the wide variety of presenting features, we describe two cases, one diagnosed prenatally and the other through a finding on echocardiography(AU)

Occurrence of polycyclic aromatic hydrocarbons in artisanal Palmero cheese smoked with two types of vegetable matter.

Palmero cheese is a fresh smoked cheese from the Isle of Palma (Canary Islands), manufactured with goat's milk. To guarantee its safety, the occurrence of polycyclic aromatic hydrocarbons (PAH) in artisanal Palmero cheese smoked with 2 types of vegetable matter (almond shells and dry prickly pear) was studied. The determination of PAH includes extraction and clean-up steps, followed by separation, identification, and quantification of PAH by gas chromatography-mass spectrometry in selected ion-monitoring mode. The most abundant PAH are those with 2 and 3 aromatic rings. Although the highest total PAH concentrations corresponded to the cheeses smoked with almond shells, the degree of PAH contamination of the cheeses studied was lower than that found in other cheeses smoked in the traditional way. The nature of the vegetable material used for smoking seemed to have an influence on the type of PAH formed, especially on alkylderivatives and some light PAH. However, despite the artisanal, and consequently variable, production process of these cheeses, many similarities have been found among their PAH profiles. In fact, relatively constant relationships are observed between the concentrations of certain pairs of PAH. Benzo(a)pyrene was only present in 2 samples, and in much lower concentrations than the maximum allowed legal limits. Therefore, according to the results obtained, it appears that it is possible to obtain a safe product without renouncing the artisanal character or the sensory properties of this type of cheese.

Headspace solid-phase microextraction as a tool to estimate the contamination of smoked cheeses by polycyclic aromatic hydrocarbons.

Headspace solid-phase microextraction (HS-SPME) was used to study polycyclic aromatic hydrocarbons (PAH) in smoked cheeses. Two types of fiber coatings and different extraction conditions were tested. The results reveal that the use of an 85-microm polyacrylate fiber immersed in the headspace of the samples at 70 degrees C for 60 min is suitable for the detection of PAH with no more than 4 aromatic rings. To determine if a relationship can be established between the results obtained using a solvent extraction technique and HS-SPME, 6 samples of smoked cheese previously studied by a solvent extraction method were analyzed by HS-SPME, and the results obtained by both methodologies were compared. Polycyclic aromatic hydrocarbons were identified and quantified by gas chromatography-mass spectrometry operating in selective ion monitoring mode. Among the PAH determined by the solvent extraction method, only those with 4 aromatic rings or less were detected by HS-SPME and, consequently, this technique does not allow one to determine the PAH content of smoked cheese samples under the conditions of the study. Nevertheless, the relationship between the results obtained by both techniques for some PAH revealed that HS-SPME could be useful as a screening method to distinguish among samples with different degrees of PAH contamination.

Components detected by means of solid-phase microextraction and gas chromatography/mass spectrometry in the headspace of artisan fresh goat cheese smoked by traditional methods.

The study of the headspace components of fresh smoked goat cheese, was carried out by means of solid-phase microextraction using a polyacrylate fiber followed by gas chromatography/mass spectrometry. The samples studied were six artisan Palmero cheeses manufactured following traditional methods and smoked using pine needles. The cheese regions studied were exterior, interior, and a cross section. In total, more than 320 components were detected, the exterior region being the richest in components, among which were acids, alcohols, esters, hydrocarbons, aldehydes, ketones, furan and pyran derivatives, terpenes and sesquiterpenes, nitrogen derivatives, phenol, guaiacol and syringol derivatives, ethers, and others. In addition to typical cheese components, typical smoke components were also detected; these latter were present especially in the headspace of the exterior region and only those in significant concentrations in the exterior region were also detected in the interior. The main components were acids and phenolic derivatives. These latter compounds play an important role in the flavor of this cheese, and their relative proportions together with the presence of specific smoke components derived from pine leaves may be considered of interest in order to distinguish this cheese from others smoked with different vegetable matter.

Study of the effects of smoke flavourings on the oxidative stability of the lipids of pork adipose tissue by means of Fourier transform infrared spectroscopy.

Pork adipose tissue was dry-salted for 24 h and then smoked by immersion in two liquid smoke flavourings for 1, 2 or 3 min. Both unsmoked and smoked pork adipose tissue samples were submitted to oxidative conditions at 70 °C in a convection oven with circulating air. Melted lipids of both samples were studied by Fourier transform infrared spectroscopy. Duplicate spectra were collected each day of the experiment by applying a film of melted lipids between two KBr disks. Changes in frequency values of different bands and in ratios between absorbances of some bands allow oxidation degree and oxidative stability of the samples to be determined. The usefulness of this technique for monitoring the oxidation process of pork adipose tissue lipids is shown. The greater oxidative stability of smoked pork adipose tissue samples in comparison with unsmoked samples is proved.

Carbohydrate and nitrogenated compounds in liquid smoke flavorings.

Commercial smoke flavorings were extracted with dichloromethane and the remaining aqueous phase was evaporated at room temperature; the residues obtained were dissolved in methanol and studied by gas chromatography/mass spectrometry. The composition of these residues was totally different from that of the dichloromethane extracts, constituting a small number of compounds that were also detected in the dichloromethane extract, as well as a large number of compounds not described before as components of either smoke for food smoking or smoke flavorings. Among those compounds not previously described there are some furan, pyran, and phenolic derivatives, as well as some pyridine and carbohydrate derivatives. The main component of these fractions is 1,6-anhydro-beta-D-glucopyranose, or levoglucosan. Likewise, aqueous residues of liquid smoke flavorings, prepared at a laboratory scale from beech, vine shoots, thyme, and sage, were studied in the same way. These contained compounds of the same groups cited above, but showed clear differences. The aqueous residue of beech smoke flavoring was the most similar to that of the commercial smoke flavorings. The aqueous residues of vine shoots, thyme, and sage smoke flavorings contained a lower number of furan, pyran, and carbohydrate derivatives and a higher number of nitrogenated derivatives. Instead of levoglucosan, the main component was an unidentified compound, present in all samples, included in the carbohydrate derivatives group. In the samples studied, the influence of the vegetal source on the composition of the aqueous fraction has been shown. In the future, attention must be paid to the functionality of these smoke components.

Polycyclic aromatic hydrocarbons in liquid smoke flavorings obtained from different types of wood. Effect of storage in polyethylene flasks on their concentrations.

Smoke flavorings are widely used as an alternative to the traditional smoking techniques. Smoke generation conditions can determine the level of polycyclic aromatic hydrocarbons (PAHs) in the smoke and, consequently, in these preparations. In this paper, the influence of the wood source on the formation of PAHs is studied. For this purpose, five liquid smoke flavorings, obtained from different types of wood, were used. Sample aliquots, including deuterated internal standards, were subjected to an alkaline treatment, extracted by liquid-liquid partition and cleaned up by means of silica tubes, followed by gas chromatography-mass spectrometry analysis. The results reveal that the flavoring obtained from poplar wood presents the highest number and concentrations of both total and carcinogenic PAHs, even though the levels of these latter are very low. It has also been observed that the storage of smoke flavorings in polyethylene flasks reduces the concentration of some PAHs.

Study of several aspects of a general method for the determination of polycyclic aromatic hydrocarbons in liquid smoke flavourings by gas chromatography-mass spectrometry.

The effectiveness of the steps of a general method, which includes alkaline treatment of the samples, extraction, clean-up and analysis, for the determination of polycyclic aromatic hydrocarbons in liquid smoke flavourings and smoked foods have been studied, by using mixtures of pure polycyclic aromatic hydrocarbons and of smoke flavouring compounds. All these products were applied to samples of liquid smoke flavourings in order to test the effectiveness of each step of the method, as well as to investigate its effect on real samples, and thus obtain a suitable procedure for the study of polycyclic aromatic hydrocarbons in liquid smoke flavourings. The alkaline treatment has been proved to be necessary because of its capability for removing some smoke components. Both cyclohexane and dichloromethane are able to extract polycyclic aromatic hydrocarbons with high recovery percentages; however, cyclohexane is more adequate due to its lower ability to extract other smoke flavourings components. It is important to note that the elution sequence of polycyclic aromatic hydrocarbons during the clean-up step is quite different depending on the solvent used to dissolve the extract, which determines the ability of this process to isolate polycyclic aromatic hydrocarbons for their accurate identification and quantification by gas chromatography-mass spectrometry in selected ion monitoring mode. Finally, the PAHs present in a liquid smoke flavouring and their concentrations were determined; it was observed that, despite the different extraction solvents and clean-up procedures used, the results were very similar.

Determination of polycyclic aromatic hydrocarbons in commercial liquid smoke flavorings of different compositions by gas chromatography-mass spectrometry.

The presence of polycyclic aromatic hydrocarbons (PAHs) in five commercial liquid smoke flavorings, used in the European food industry, was studied. The samples were subjected to an alkaline treatment, extracted with cyclohexane, cleaned up by means of solid-phase extraction tubes, and analyzed by gas chromatography-mass spectrometry. Three different procedures for the cleanup were tested. The results revealed the presence of 34 PAHs, some of them with methyl substituents. In all cases, the concentrations of compounds of low molecular weight were much higher than those of high molecular weight. Relationships between smoke flavoring compositions and PAH levels were also studied. Three of the samples contained high levels of both total and carcinogenic PAHs. Benzo[a]pyrene was also detected in these three samples, but its concentration did not exceed the 10 microg/kg level fixed by the FAO/WHO. Finally, a relation was found, first between the concentrations of total carcinogenic PAHs and benzo[a]pyrene and also between the concentrations of pyrene and benzo[a]pyrene. The latter ratio reveals that pyrene concentration could be very useful in predicting the level of benzo[a]pyrene and, consequently, in estimating the carcinogenicity arising from the presence of benzo[a]pyrene and other carcinogenic PAHs.

Influence of the moisture content on the composition of the liquid smoke produced in the pyrolysis process of Fagus sylvatica L. wood.

The pyrolysis of several samples of sawdust of Fagus sylvatica L. wood with different moisture contents was carried out, keeping all other smoke generation parameters constant. However, parameters such as smoke production length and maximum temperature reached were affected by the moisture content of the sample and varied in the different pyrolytic runs. The acidity and the composition of the liquid smokes obtained were determined, this latter by means of gas chromatography/mass spectrometry and gas chromatography with flame ionization detection. The acidity and composition of the liquid smoke produced were affected not only by the moisture content of the sawdust sample but also by the smoke generation length and by the temperature of the process. The highest yields in components were produced from samples with low moisture content that underwent a short pyrolytic process. Some compounds, with important properties from an organoleptic and preservative point of view, were not generated from samples with high moisture content. Equations that closely relate yield of the total components or of groups of components or of individual components with parameters such as moisture content, length of the process, and temperature were obtained; these equations predict yield data of liquid smoke components with a satisfactory degree of approximation.

Extractable components of the aerial parts of Salvia lavandulifolia and composition of the liquid smoke flavoring obtained from them.

The fraction extractable with dichloromethane of the aerial parts of sage (Salvia lavandulifolia) and the liquid smoke obtained from this plant are studied by means of gas chromatography/mass spectrometry and gas chromatography. The extract of the aerial parts of the sage plant contains not only terpene, sesquiterpene hydrocarbons, and their oxygenated derivatives, which are interesting compounds both for their organoleptic properties and for their antioxidant activity, but also a large group of phenolic compounds with abietatriene or related structure, the mass spectra of which are given, many of them having antioxidant, antiviral, and antibacterial properties. The liquid sage smoke obtained is slightly acidic and contains common smoke components in specific proportions, and a large group of aromatic nitrogenated derivatives such as pyrazine and pyridine derivatives in small proportions, together with the main oxygenated terpene derivatives present in the plant; some of the compounds detected in this liquid smoke have not been described as smoke components before.

Usefulness of the frequency data of the fourier transform infrared spectra to evaluate the degree of oxidation of edible oils.

The oxidation process of 13 edible oil samples with different proportions of oleic, linoleic, and linolenic acyl groups has been studied using Fourier transform infrared spectroscopy. The oxidation experiments were carried out by heating the samples in a convection oven at 70 degrees C. Duplicate spectra were recorded from a film of pure oil between two disks of KBr for each sample every day during the course of the oxidation, and frequency data of each band of the spectrum were collected automatically. Changes in the values of the frequency of most of the bands of the spectra were observed. The shiftings of the frequency value of specific bands allowed one to distinguish between the different stages of the oxidation process and to establish the oxidation degree of each oil sample. This methodology could be useful to evaluate the oxidative stability of edible oils in a simple, fast, and accurate way.

Food as a source of polycyclic aromatic carcinogens.

Polycyclic aromatic hydrocarbons (PAH) belong to a large chemical family comprising many different compounds with important biological activity in mutagenic and carcinogenic processes. PAH have been detected in both raw and processed foods. The presence of PAH in non-processed foods is associated with environmental pollution from both human and industrial activities, whereas contamination of processed foods can be caused by certain preservation and processing procedures. Both toxicological and epidemiological studies have shown a relation between such compounds and tumor development. The data indicate that PAH must undergo a biotransformation process that causes the formation of biologically active metabolites. In this process, the presence of an enzyme complex that is induced by different xenobiotics is implied, making the toxicity of such compounds hard to predict. As setting a threshold limit below which toxicity could be considered negligible is difficult, the presence of PAH in foodstuffs should be reduced to as low as possible by controlling environmental contamination and all procedures that could cause PAH contamination during food processing, preserving, and packaging.

Polycyclic aromatic compounds: extraction and determination in food.

Polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic compounds (PACs) in general, comprise the largest class of known environmental carcinogens. Reports of some studies of total diet in a number of developed countries indicate that food constitutes an important source of exposure of man to PACs, although other authors have shown the need to develop accurate data, in order that the overall public health hazard may be effectively evaluated and controlled. In this context, this review aims to give an overview of methods used to determine the PAC content of foodstuffs. At first, the nature, classification and derived compounds of PAHs are considered. Likewise, the occurrence of PAHs in processed and in non-processed foods is shown. The main causes are environmental contamination and the utilization of procedures which give rise to the presence of PACs during the processing, preservation, and packaging of foods. Octanol: water partition coefficients of PACs and their relationships with some properties, such as aqueous solubility and bioaccumulation, are considered. The solubility of complex mixtures of PACs in several organic solvents and the different methods for extraction and isolation of the PAC-fraction from foodstuffs are reviewed. The methodologies used for the separation, identification and quantitative determination also are briefly considered.