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Publications (188)
The aim of this study is to analyze in depth, by means of proton nuclear magnetic resonance, 1H NMR, the changes caused by nixtamalization and tortilla making in the lipid composition of two corn varieties. This technique permits the characterization of not only main but also minor lipid components of both corn and tortilla. Ferulates have been fou...
Little is still known about both the effect of amino acids on the oxidation course of edible oils and the modifications that the former may undergo during this process. Bearing this in mind, the objective of this work was to study the evolution of a system consisting of soybean oil with 2% of l-lysine under heating at 70 °C and stirring conditions,...
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 propor...
Few in vitro studies have tackled the effect of alpha-tocopherol on lipid oxidation during digestion, and discrepant results have been reported. As a result, the aim of this study was to elucidate whether the addition of alpha-tocopherol enhances or slows down the advance of oxidation that occurs during in vitro gastrointestinal digestion of polyun...
The effect of the enrichment of sunflower oil with γ‐tocopherol on the evolution of its oxidation is the subject of this study. Sunflower oil and samples of this oil enriched with different γ‐tocopherol concentrations are submitted to accelerated storage conditions and their evolution, until total polymerization is monitored by ¹H NMR spectroscopy....
The aim of this study is to shed light on the evolution of the minor compounds in the corn oil oxidation process, through the information provided by direct immersion-microextraction in solid phase followed by gas chromatography/mass spectrometry (DI-SPME-GC/MS). This methodology enables one, in a single run, to establish the identity and abundance...
BACKGROUND
Minor components of edible oils could influence their evolution during in vitro digestion. This might affect the bioaccessibility of lipid nutrients and the safety of the ingested food. Bearing this in mind, the evolution of virgin and refined soybean oils, very similar in acyl group composition, throughout in vitro digestion has been st...
Unravelling the relationship between food and health requires a more in-depth knowledge of the various changes occurring in the gastrointestinal tract during digestion and which may ultimately affect the nutritional quality and safety of ingested food lipids before absorption into the bloodstream. In this context, this review deals with the oxidati...
European sea bass is very popular in the Mediterranean area, although very little is known about the possible different behaviours of farmed and wild samples during cooking. This study addresses the effect of microwave cooking, salt-crusted and conventional oven baking on the lipids and volatile profile of farmed and wild sea bass. Proton Nuclear M...
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 o...
Fresh and partially oxidized flaxseed oil, as models of omega-3 rich lipids, were submitted to in vitro gastrointestinal digestion. Hydrolysis level, lipid composition and oxidative status of the samples before and after digestion were studied by Proton Nuclear Magnetic Resonance (¹H NMR) and Solid Phase Microextraction-Gas Chromatography/Mass Spec...
Eleven edible oils, namely extra virgin olive, virgin olive, olive, sunflower, virgin soybean, refined soybean, linseed and four corn oils were studied in order to analyze the occurrence in them of minor nitrogenated components. The study was carried out by using Solid Phase Microextraction (SPME) followed by Gas Chromatography/Mass Spectrometry (G...
This study aims to shed light on the changes provoked by boiling, steaming and sous-vide cooking on the lipids and volatile profile of farmed and wild European sea bass meat. None of the cooking techniques provoked changes due to hydrolytic or oxidation processes detectable by ¹H NMR on sea bass lipids. The lipid profile of main and minor lipidic c...
The effect of the presence of ovalbumin and soy protein isolate on lipolysis and oxidation taking place during in vitro gastrointestinal digestion of slightly oxidized sunflower and flaxseed oils was addressed. The extent of lipolysis, the molar proportions of acyl groups/fatty acids after digestion, and the oxidation products formed were studied b...
The extent of cod liver oil hydrolysis and oxidation during in vitro gastrointestinal digestion was investigated by Proton Nuclear Magnetic Resonance (¹H NMR) and Solid Phase Microextraction-Gas Chromatography/ Mass Spectrometry (SPME-GC/MS). These techniques evidenced the degradation of polyunsaturated ω-3 and ω-6 lipids and, for the first time, t...
The effect of smoking using liquid smoke flavourings on the hydrolysis and oxidation of European sea bass lipids during in vitro digestion was investigated. The techniques used were ¹H NMR and SPME-GC/MS. The former proved that liquid smoking does not influence the extent of lipolysis, but prevents those lipid oxidation reactions that occur during...
Proton Nuclear Magnetic Resonance (1H NMR) was employed to study monovarietal commercial Spanish extra-virgin olive oils (EVOO) (Arbequina, Arroniz, Cornicabra, Hojiblanca and Picual). Each sample was analyzed by a standard pulse and by an experiment suppressing the main lipid signals, enabling the detection of signals of minor components. The aim...
A study of the various chemical reactions which take place during fish in vitro digestion and the potential effect of fish salting on their extent is addressed for the first time. Farmed European sea bass fillets, raw, brine-salted or dry-salted, were digested using a gastrointestinal in vitro model. Fish lipid extracts before and after digestion w...
This article gives an overview of margarine, its composition, and analysis. Some of the factors influencing its composition, as well as its major and minor components, are addressed; their importance and concentrations are also commented on. Special attention is paid to those components for which health-giving properties have been suggested, such a...
Both fresh and slightly oxidized sunflower oils, as models of omega-6 rich lipids, were submitted to in vitro gastrointestinal digestion and studied by ¹H NMR and SPME-GC/MS. Changes in lipolysis degree, lipid composition and oxidative level were studied by ¹H NMR. Three quantitative approaches were used and several equations were newly developed....
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...
Farmed European sea bass (Dicentrarchus labrax) fillets were smoked with three commercial smoke flavourings. Unsmoked and smoked fillets were submitted to oxidative conditions to study their oxidative stability. To this aim, at regular intervals of time under oxidative conditions, their lipids were extracted and studied by Fourier Transform Mid-Inf...
Background:
Fish shelf-life extension is a topic of great interest. In this study the behaviour of salted and unsalted farmed and wild European sea bass (Dicentrarchus labrax) fillets during storage was analyzed through the evolution of their volatile metabolites. Farmed and wild sea bass fillets were brine-salted for 15 or 75 min, or dry-salted,...
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 hum...
Farmed sea bass (Dicentrarchus labrax) fillets were smoked using one oil-based and two aqueous smoke flavorings. The headspace of the smoked products was studied by solid-phase microextraction followed by gas chromatography/mass spectrometry (SPME-GC/MS). The effect of smoking on several quality and safety characteristics of the fillets and on thei...
Fillets of farmed gilthead sea bream (Sparus aurata) and European sea bass (Dicentrarchus labrax) were pan- and microwave-fried using extra-virgin olive and sunflower oils. Moreover, both oils were heated under the same conditions in the absence of food. Proton Nuclear Magnetic Resonance spectroscopy (1H NMR) was employed to study the changes occur...
From the beginning of the process, heating an oil at frying temperature brings about its degradation, generating aldehydes and many other compounds. The aldehydes formed can be small molecules or can be supported on truncated acyl groups of triglycerides. Both kinds can also have other functional groups, for which reason some of these aldehydes are...
This review deals with the oxidation products generated in corn oil samples stored at room temperature. During this slow process, free radicals react with the fatty acyl chains, especially linoleic ones, generating new compounds. Some of these oxidation products remain joined to the triglyceride structure and others break down, giving rise to compo...
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 cha...
The evolution of the composition of three sunflower oils submitted to frying temperatures over a prolonged period of time was carried out by means of 1H nuclear magnetic resonance. Using the same technique, the evolution of the composition of three sunflower oils derived frying media, formed throughout 14 deep-frying experiments of three different...
Farmed and wild European sea bass (Dicentrarchus labrax) could be distinguished by its volatile metabolites, an issue not addressed until now. The aim of this work was to study these metabolites by Solid Phase Microextraction followed by Gas Chromatography /Mass Spectrometry (SPME-GC/MS).
Both farmed and wild sea bass have a great number of volatil...
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...
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 conc...
In this study, 1H 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...
A new approach is reported, based on Proton Nuclear Magnetic Resonance (1H NMR) spectral data, to study qualitatively and quantitatively the hydrolysis level in complex lipid mixtures. It is based on a detailed study of the spectra of tri-, di-, mono-glycerides and fatty acids. It has been validated by using mixtures of standard compounds which sim...
Farmed European sea bass (Dicentrarchus labrax) fillets were salted by two methods, brine‐ and dry‐salting. Both salted and unsalted fillets were submitted to thermo‐oxidative conditions in order to study the evolution of their lipids and their oxidative stability. Lipids were extracted and studied by proton nuclear magnetic resonance (1H NMR). Thi...
This review summarizes present-day knowledge provided by proton nuclear magnetic resonance (1H NMR) concerning food lipid thermo-oxidative degradation. The food lipids considered include edible oils and fats of animal and vegetable origin. The thermo-oxidation processes of food lipids of very different composition, occurring at low, intermediate, o...
Extra virgin olive, soybean and sunflower oils were used in three different series of fourteen experiments to deep-fry three foods of very different lipidic content and composition. The aim of this study was toanalyze how much the composition of the frying medium influenced the lipidic composition of the fried food. To achieve this, the composition...
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 com...
Three series of fourteen deep-frying experiments on three foods of very different compositions were carried out using extra virgin olive oil as the original frying medium. The aim of the study was to establish how the nature of the food being fried influences the composition of the frying medium. The changes in the composition of the frying media r...
BACKGROUND
The lipids of 16 farmed and wild European sea bass (Dicentrarchus labrax) samples were studied by Fourier transform infrared (FTIR) spectroscopy. The spectroscopic parameters which would be useful when distinguishing between both fish origins were analysed.RESULTSIt was shown, for the first time, that the frequency and the ratio between...
Solid Phase Microextraction (SPME) followed by Gas Chromatography/Mass Spectrometry (GC/MS) was employed to study the headspace composition of corn oil (maize oil) samples stored at room temperature in closed receptacles with limited amounts of air for different periods of time. Samples with a high oxidation level showed the presence of typical sec...
A study of the evolution of the composition of both soybean oil submitted to heating at frying temperature for a prolonged period of time, as well as of soybean oil-frying media used in three different series of deep-frying experiments is carried out by means of 1H nuclear magnetic resonance. The foods involved in the deep-frying processes have ver...
This chapter focusses on the usefulness of Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy in the study of edible oils and fats, and of food lipids in general, not only from a qualitative but also from a quantitative point of view. As far as compositional studies are concerned, it has been evidenced by several authors that this technique pr...
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 re...
The evolution of the molar percentage of several kinds of acyl groups of extra virgin olive, sunflower and virgin linseed oils was monitored throughout heating at frying temperature by means of (1)H nuclear magnetic resonance. Likewise, the evolution of the percentage in weight of the polar compounds of the same oils under the same heating conditio...
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 dis...
Linseed oil was heated at frying temperature in an industrial fryer for 20 h. The evolution of its composition was monitored by 1H Nuclear magnetic resonance. The composition parameters determined simultaneously were: the molar percentage of the different acyl groups, the Iodine Value, the concentration of the total aldehydes as well as of the diff...
Extra virgin olive oil was heated at 190 °C in a discontinuous industrial fryer for 40 h. The evolution during heating of the acyl group proportions and of the iodine value was monitored by 1H nuclear magnetic resonance. Monounsaturated acyl groups degraded at faster rates than linoleic and linolenic groups. The formation of primary oxidation compo...
The effect of salting method, dry salting (DS), brine salting (BS), brine salting with sucrose addition (BSS) or dry salting with sucrose addition (DSS) on the quality of Atlantic salmon treated with a liquid smoke flavouring was investigated over a 45‐day storage period. Sugar‐added samples were the ones with the significantly lowest values for TB...
The evolution of the abundance of the different types of aldehydes, including those that are genotoxic and cytotoxic, oxygenated α,β unsaturated, in the headspace of extra virgin olive, sunflower and virgin linseed oils, submitted to frying temperature for prolonged periods of time, in a discontinuous industrial fryer, was analysed. Very close rela...
Sunflower oil was heated at 190 °C in a discontinuous industrial fryer for 32 h. The simultaneous monitoring during heating of the Iodine Value, acyl groups proportions and aldehydes concentrations was carried out by 1H Nuclear Magnetic Resonance; at the same time the percentage in weight of Polar Compounds was also controlled by an instrumental te...
The distribution of the volatile components in four regions, Rind, Exterior, Intermediate, and Interior, of hand-made Idiazabal cheese which had been ripened for two months was studied in detail. It is proved that the headspace of this ripened sheep cheese is non-homogeneous in the different cheese regions. The Rind is the richest region in volatil...
The use of smoke flavourings for the processing of salmon has begun to substitute traditional smoking methods. This review examines the quality issues associated with salted salmon 'smoked' by this technique along the salting and smoking steps. Firstly, the evidence is examined to determine whether dry or brine salting is better for salmon flesh de...
The volatile components of virgin and refined oils whose compositions were very different in terms of oleic, linoleic and linolenic acyl groups were studied by solid phase microextraction (SPME) followed by gas chromatography/mass spectrometry (GC/MS), and their composition of acyl groups was determined by proton nuclear magnetic resonance (1) H NM...
Relationships between the time at which edible oils reach 25% in weight of polar compounds and their original composition, expressed as molar percentage of their acyl groups, were tested; the aim was to analyze the influence of oil composition on its performance at high temperature. Likewise, relationships between the composition of the oils and th...
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...
The influence of oil composition in the main components and of heating time at frying temperature on the formation of toxic alkylated monoaromatic hydrocarbons in oils is studied. Oils of very different compositions such as extra virgin olive, sunflower and virgin linseed oils were submitted to frying temperature in an industrial fryer for prolonge...
In this study it was proved the formation of oxygenated alpha,beta-unsaturated aldehydes (OαβUAs) of 6, 7, 9 and 10 carbon atoms during the thermal treatment (190°C with aeration) of a commercial vegetable oil rich in omega-3 and omega-6 acyl groups, which also contained small amounts of added proteins and carbohydrates to produce barbecue aroma wh...
This study reports the effect of different refrigeration/freezing treatments on the physicochemical, textural and sensorial properties of farmed Atlantic salmon (Salmo salar) treated with a commercial liquid smoke flavouring. Observations were made on three groups of fillets – group RFS: salted, smoked and stored at 4 °C; group BFS: frozen at −25 °...
A global study of sunflower oil oxidation at two different temperatures (100 and 70 degrees C) with aeration was carried out by (1)H nuclear magnetic resonance ((1)H NMR), paying attention not only to the degradation of the main components but also to the formation of others. The functional groups of compounds monitored simultaneously during the ox...
Sunflower oil at a specific oxidation stage (when several oxygenated alpha,beta-unsaturated aldehydes are generated, mainly 4-hydroperoxy-trans-2-alkenals and 4-hydroxy-trans-2-alkenals), caused at 70 degrees C with aeration for 7 days, was administered intraperitoneally to rats. This oil was studied by means of solid phase micro-extraction followe...
The oil liquid matrix of several corn oil samples that have been stored at room temperature in closed receptacles for different periods of time is studied by means of 1H nuclear magnetic resonance (1H NMR), in order to further knowledge about this type of edible oil oxidation. As expected, the degradation of linoleic acyl groups predominates. In sa...
A study is made of the evolution of the composition of sunflower oil kept over prolonged periods of time at high temperature (190 degrees C) in a domestic fryer. The technique used is (1)H NMR spectroscopy. The degradation rate of linoleic acyl groups is determined in this process, as well as the proportions of monounsaturated, of saturated plus mo...
The headspaces of two samples of cod liver oil, when recently acquired, after five and after fifteen months from opening, were studied by solid phase microextraction, followed by gas chromatography/mass spectrometry. Nearly one hundred compounds were found, some of them identified for the first time as cod liver oil components. In both samples, the...
The study of the volatile components presents in the headspace of 27 sunflower oil samples, stored over different periods of time, at room temperature in closed receptacles, in presence of limited amounts of air, has been carried out by solid phase microextraction (SPME) followed by gas chromatography/mass spectrometry (GC/MS). The composition of t...
Six samples of cod liver oil were studied using Fourier transform infrared (FTIR) spectroscopy and (1)H nuclear magnetic resonance ((1)H NMR). These techniques provide information simply and rapidly about the global features of the cod liver oil main components, showing their potential as routine techniques for evaluating certain parameters of the...
Mixtures of either sunflower oil or thermodegraded sunflower oil and a standard meal were submitted to an in vitro digestion model. The same experiment was carried out with fluid deep-frying fat and thermodegraded fluid deep-frying fat. The thermodegradation of the oil and fat was provoked by submitting them to 190 degrees C with aeration in a conv...
Solid phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) of the headspace composition of two sunflower oil samples was carried out; both samples were taken from the same original oil, stored for a prolonged time (112 months) in closed containers at room temperature under different air/oil volume ratios. Great diff...
The oxidation of lipids containing polyunsaturated omega-3 or omega-6 acyl groups, such as docosahexenoic, eicosapentenoic, linolenic, arachidonic, or linoleic groups, and of the corresponding fatty acids, generates among other compounds alpha,beta -unsaturated aldehydes supporting different functional groups containing oxygen, which can be named o...
The degradation process of edible oils of very different nature, submitted to 190 °C with aeration, is studied by means of 1H nuclear magnetic resonance (NMR). In this study, no primary oxidation products, such as hydroperoxides, are detected, the signals of aldehydes being the first to be observed in the 1H NMR spectra. Differences between this de...
The oxidation of sunflower oil, stored in closed receptacles at room temperature for a period of 10 years, was monitored using Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (NMR). The objective was to understand the evolution of the oxidation process in sunflower oil under the conditions above mentioned. These tec...
The textural and physicochemical properties of fillets of farmed Atlantic salmon (Salmo salar) treated with two commercial liquid smoke flavourings (LS1 and LS2) were examined after 15, 30 and 45 days of storage at 2 °C in oxygen impermeable bags. Salmon flesh treated with LS1 was characterized by high water-soluble protein, fat and moisture conten...
This study compares the effects of four different smoking processes on the sensorial and physicochemical characteristics of Atlantic salmon (Salmo salar) fillets. Two commercial liquid smoke flavourings (FA and FB) and two types of wood used for cold-smoking wood smoke generation (BS: Beech wood and OS: Oak wood) are investigated. Comparisons were...
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 extr...
Approximate solubility parameters of monomeric stationary phases can be calculated from gas chromatographic retention volumes of aliphatic saturated hydrocarbons; and some other properties, such as the molar volume and the latent heat of vaporization, by applying the regular solution model to the chromatographic process. By including data of aromat...
By applying the regular solution model to the solution processes that take place in gas chromatography, equations are obtained, which relate the retention volume of solutes with their molar volume and latent heat of vaporization. From these equations, solubility parameters of monomeric stationary phases are obtained and their values compared with t...
The textural properties of raw Atlantic salmon (Salmo salar) were measured at three different points along the fillet using different instrumental methods employing blade, sphere and cylinder probes. The variables examined were the force, energy and the slope of the force–deformation curve. Texture profile analysis (TPA test) was also undertaken. T...
The oxidation processes of virgin olive, corn and linseed oils, repeatedly submitted to the effect of microwave heating until the temperature reached 190 °C, have been studied by means of 1H nuclear magnetic resonance. These oxidation processes are very different to those produced at 70 °C with aeration; differences have been found not only in the...
A study of the headspace of smoked swordfish and cod was carried out by means of Solid Phase Microextraction followed by gas chromatography–mass spectrometry. The headspace of both smoked fish species contains ketones, aldehydes, alcohols, acids, esters, hydrocarbons, ethers, nitrogen derivatives, phenol, guaiacol, and syringol derivatives, as well...
Two aqueous smoke flavourings were obtained, on a laboratory scale, from mixtures of oak wood sawdust (Quercus sp.) and sawdust of the aerial parts of thyme (Thymus vulgaris L.) or sage (Salvia lavandulifolia Vahl.) (8:2, w[sol ]w, respectively). The acidity and composition of these preparations were determined in this study. The presence of thyme...
The oxidation process of sunflower and corn oils at 70 °C with circulating air has been studied by means of 1H nuclear magnetic resonance (NMR). The changes produced in the two oils are compared not only in relation to the rate of degradation of acyl groups but also with reference to both the rate of formation and degradation of primary oxidation p...
The oxidation process of olive, hazelnut, and peanut oils at 70°C with circulating air has been studied by means of 1H NMR. The evolution of the process, including the rate of degradation of the acyl groups and of formation and degradation
of primary oxidation products, as well as the rate of formation of secondary oxidation products such as aldehy...
The static headspace composition of sunflower oil throughout the oxidation process at 70 degrees C with circulating air is studied by means of solid-phase microextraction followed by gas chromatography-mass spectrometry (SPME-GC-MS); at the same time the liquid phase of the same oil is studied by means of Fourier transform infrared (FTIR) spectrosc...
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 fo...
The oxidation process of rapeseed, walnut and linseed oils, rich sources of linolenic acyl groups, was studied by means of 1H nuclear magnetic resonance spectroscopy. The visible changes in some spectrum signals, especially in those of methylic, allylic and bis-allylic hydrogen atoms, provide information about the degradation of the different acyl...
The usefulness of 1H nuclear magnetic resonance (NMR) for studying oil oxidation processes was tested. Refined sesame oil was submitted to oxidative conditions at 70 °C with circulating air, and the status of the sample was studied daily by 1H NMR. This technique permits the determination of the proportions of the acyl groups in the oil throughout...
The presence of polycyclic aromatic hydrocarbons (PAHs) has been studied in different samples of olive oil, extra virgin olive oil, and refined seed oils. A high number of PAHs have been found, with a wide range of molecular weights and in concentrations that are high or even very high compared with the data obtained by other authors, especially in...
The texture of two meat products (salted pork loin and salted bacon) treated with two commercial liquid smoke flavourings (immersion for 30 s in either F1 or F2) was examined by instrumental texture profile analysis after 15, 30 and 90 days of storage. The two flavourings caused changes to the texture parameters of the products. Smoke flavouring F1...
Farmed salmon fillets were dry-salted for 24 h. Both salted and unsalted samples were submitted to oxidative conditions at 50 °C in an oven with circulating air. Lipids of both samples were extracted daily from aliquots and studied by Fourier transform infrared spectroscopy. The infrared spectra of salmon lipids are similar to those of vegetable ed...
Polycyclic aromatic hydrocarbons (PAHs) are a family of toxicants that are ubiquitous in the environment. These contaminants generate considerable interest, because some of them are highly carcinogenic in laboratory animals and have been implicated in breast, lung, and colon cancers in humans. These chemicals commonly enter the human body through i...
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