Different Effects of Vitamin C-Based Supplements on the Advance of Linseed Oil Component Oxidation and Lipolysis during In Vitro Gastrointestinal Digestion.

Although widely consumed, dietary supplements based on Vitamin C contain high doses of this compound, whose impact on lipid oxidation during digestion needs to be addressed. Therefore, the effect of seven commercial supplements and of pure l-ascorbic acid and ascorbyl palmitate on linseed oil during in vitro gastrointestinal digestion was tackled. The advance of lipid oxidation was studied through the generation of oxidation compounds, the degradation of polyunsaturated fatty acyl chains and of gamma-tocopherol, by employing Proton Nuclear Magnetic Resonance.

Oxidative stability of extra-virgin olive oil enriched or not with lycopene. Importance of the initial quality of the oil for its performance during in vitro gastrointestinal digestion.

The performance of commercial non-enriched and lycopene-enriched extra-virgin olive oils (EVOO) during in vitro gastrointestinal digestion was studied in order to elucidate potential benefits of lycopene addition. Samples were analyzed before and after digestion by Proton Nuclear Magnetic Resonance (H NMR) and Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS). EVOO samples differed in both main (oleic and linoleic acyl groups) and minor components (phenolic and oxidation compounds).

Effect of adding alpha-tocopherol on the oxidation advance during in vitro gastrointestinal digestion of sunflower and flaxseed oils.

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 polyunsaturated lipids. For this purpose, commercial sunflower and flaxseed oils (as models of omega-6 and omega-3 rich lipid systems, respectively) were in vitro digested in the absence or in the presence of this tocol at different concentrations (0.

Food lipid oxidation under gastrointestinal digestion conditions: A review.

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 oxidation process of food lipids under digestive conditions and the studies carried out on this topic using different digestion models: , or static or dynamic, and including one, two and/or three digestive phases (oral, gastric and duodenal). These studies have contributed to clarifying the occurrence and extent of lipid degradation under such a particular environment, many of them also highlighting the factors affecting the advance or delay of the oxidation of dietary lipids during digestion, like: food lipid content, unsaturation degree and initial oxidative status; the presence in the food bolus of compounds showing antioxidant activity (polyphenols, tocopherols…) either added or naturally present; the presence in the food bolus of proteins (including iron or not); food technological or culinary processings (salting, smoking, cooking…), among others.

Effects of different cooking methods on the lipids and volatile components of farmed and wild European sea bass (Dicentrarchus labrax).

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 Magnetic Resonance did not detect that hydrolysis or oxidation of lipidic components had taken place.

Changes provoked by boiling, steaming and sous-vide cooking in the lipid and volatile profile of European sea bass.

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 H NMR on sea bass lipids. The lipid profile of main and minor lipidic components was maintained after cooking.

Effect of liquid smoking on lipid hydrolysis and oxidation reactions during in vitro gastrointestinal digestion of European sea bass.

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 H 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 in vitro digestion of unsmoked samples, giving rise to cis,trans-conjugated dienes associated with hydroperoxy/hydroxy groups.

Behaviour of non-oxidized and oxidized flaxseed oils, as models of omega-3 rich lipids, during in vitro digestion. Occurrence of epoxidation reactions.

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 (H NMR) and Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS). Although a great degree of lipolysis was reached in both kinds of samples after digestion, it was somewhat lower in the digests of oxidized flaxseed oil.

Effect of the presence of protein on lipolysis and lipid oxidation occurring during in vitro digestion of highly unsaturated oils.

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 by Proton Nuclear Magnetic Resonance. The presence of proteins provoked a higher hydrolysis in triglycerides, a lower decrease of polyunsaturated chains, and a lower generation of oxidation compounds (conjugated dienes in chains having also hydroperoxy/hydroxy groups, epoxides and aldehydes); the formation of hydroxides was clearly favoured over that of hydroperoxides.

Polyunsaturated lipids and vitamin A oxidation during cod liver oil in vitro gastrointestinal digestion. Antioxidant effect of added BHT.

The extent of cod liver oil hydrolysis and oxidation during in vitro gastrointestinal digestion was investigated by Proton Nuclear Magnetic Resonance (H 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, that of vitamin A, naturally present in cod liver oil. Cis,trans-conjugated dienes associated with hydroperoxides, as well as monoepoxides, cis,trans-2,4-alkadienals, 4-hydroperoxy- and 4-hydroxy-2-alkenals, and several vitamin A derived metabolites were generated.

Direct study of minor extra-virgin olive oil components without any sample modification. H NMR multisupression experiment: A powerful tool.

Proton Nuclear Magnetic Resonance (H 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 was to determine the possibilities of both H NMR approaches to characterize EVOO composition, focusing on acyl groups, squalene, sterols, triterpene acids/esters, fatty alcohols, wax esters and phenols (lignans, tyrosol, hydroxytyrosol, oleocanthal, oleacein, oleokoronal, oleomissional, ligstrodials and oleuropeindials), and to determine hydrolysis and oxidation levels.

H NMR and SPME-GC/MS study of hydrolysis, oxidation and other reactions occurring during in vitro digestion of non-oxidized and oxidized sunflower oil. Formation of hydroxy-octadecadienoates.

Both fresh and slightly oxidized sunflower oils, as models of omega-6 rich lipids, were submitted to in vitro gastrointestinal digestion and studied by H NMR and SPME-GC/MS. Changes in lipolysis degree, lipid composition and oxidative level were studied by H NMR. Three quantitative approaches were used and several equations were newly developed.

Fish in Vitro Digestion: Influence of Fish Salting on the Extent of Lipolysis, Oxidation, and Other Reactions.

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 were analyzed by H NMR, and the headspace composition of the digestates was investigated by SPME-GC/MS.

A study by (1)H 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.

Influence of different salting processes on the evolution of the volatile metabolites of vacuum-packed fillets of farmed and wild sea bass (Dicentrarchus labrax) stored under refrigeration conditions: a study by SPME-GC/MS.

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 analysed through the evolution of their volatile metabolites. Farmed and wild sea bass fillets were brine-salted for 15 or 75 min, or dry-salted, vacuum-packed and stored at 4 °C for up to 1 month, and their headspaces were studied by Solid Phase Micro extraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS).

Farmed and wild sea bass (Dicentrarchus labrax) volatile metabolites: a comparative study by SPME-GC/MS.

Background: 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).

Results: Both farmed and wild sea bass have a great number of volatile metabolites, most of them being in low concentrations.

Usefulness of (1)H 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.

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-CH 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.

Fourier transform infrared spectroscopy as a tool to study farmed and wild sea bass lipid composition.

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.

Results: It was shown, for the first time, that the frequency and the ratio between the absorbance of certain bands are efficient and reliable authentication tools for the origin of sea bass.

Quality of farmed and wild sea bass lipids studied by (1)H 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.

Volatile components of several virgin and refined oils differing in their botanical origin.

Background: 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 NMR. The virgin oils studied were olive, linseed and walnut oils, while the refined oils were sunflower and rapeseed oils.

Results: Large differences were found among the headspace compositions of the virgin oils.

Fate in digestion in vitro of several food components, including some toxic compounds coming from omega-3 and omega-6 lipids.

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 when heated. The OαβUAs detected by Solid Phase Microextraction (SPME) followed by Gas Chromatography/Mass Spectrometry (GC/MS) were: 4-hydroxy-2-hexenal, 4-oxo-2-hexenal and 4,5-epoxy-2-heptenals, coming from omega-3 acyl groups; and 4-hydroxy-2-nonenal, 4-oxo-2-nonenal and 4,5-epoxy-2-decenals, coming from omega-6 acyl groups. Mixtures of this oil, either thermodegraded or not, with standard food were submitted to an in vitro digestion model.

Analysis of hydroperoxides, aldehydes and epoxides by 1H nuclear magnetic resonance in sunflower oil oxidized at 70 and 100 degrees C.

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 oxidation were, in addition to acyl groups, the following: hydroperoxides, conjugated dienic systems of hydroperoxy acyl groups, aldehydes including the genotoxic and cytotoxic oxygenated alpha,beta-unsaturated aldehydes, and mono- and diepoxides. Chemical shifts of protons of all mentioned groups were given.

A study of the toxic effect of oxidized sunflower oil containing 4-hydroperoxy-2-nonenal and 4-hydroxy-2-nonenal on cortical TrkA receptor expression in rats.

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 followed by gas chromatography/mass spectrometry (SPME-GC/MS) and by proton nuclear magnetic resonance ((1)H-NMR). Oxidized sunflower oil (3 ml/kg/day) was administered to male Sprague-Dawley rats for 21 days.

Characterization of cod liver oil by spectroscopic techniques. New approaches for the determination of compositional parameters, acyl groups, and cholesterol from 1h nuclear magnetic resonance and Fourier transform infrared spectral data.

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 quality of the cod liver oil. FTIR spectroscopy provides information about the molar percentage of polyunsaturated acyl groups in the sample and also about the ratio between unsaturated and saturated structures.