Marit Aursand

Effects of dietary marine oils and olive oil on fatty acid composition, platelet membrane fluidity, platelet responses, and serum lipids in healthy humans

The influence of various dietary marine oils and olive oil on fatty acid composition of serum and platelets and effects on platelets and serum lipids were investigated as part of an extensive study of the effects of these oils on parameters associated with cardiovascular/thrombotic diseases. Healthy volunteers (266) consumed 15 mL/d of cod liver oil (CLO); whale blubber oil (refined or unrefined); mixtures of seal blubber oil and CLO; or olive oil/CLO for 12 wk. In the CLO, seal oil/CLO, and whale oil groups, serum levels of eicosapentaenoic acid (EPA) were increased. In platelets, EPA was increased in the CLO, seal/CLO, and olive oil/CLO groups. The localization of n-3 polyunsaturated fatty acids in the triacylglycerols did not seem to influence their absorption. Intake of oleic acid is poorly reflected in serum and platelets. No significant differences in triacylglycerols (IG), total cholesterol, or high density lipoprotein cholesterol were observed, even though TG were reduced in the CLO, CLO/seal oil, and whale oil groups. Mean platelet volume increased significantly in both whale oil groups and the CLO/olive oil group. Platelet count was significantly reduced in the refined whale oil group only. Lipopolysaccharide-stimulated blood tended to generate less thromboxane B2 in CLO, CLO/seal, and CLO/olive groups. The whale oils tended to reduce in vivo release of β-thromboglobulin. In conclusion, intake of various marine oils causes changes in platelet membranes that are favorably antithrombotic. The combination of CLO and olive oil may produce better effects than these oils given separately. The changes in platelet function are directly associated with alterations of fatty acid composition in platelet membranes.

Positional distribution of ω3 Fatty acids in marine lipid triacylglycerols by high-resolution13C nuclear magnetic resonance spectroscopy

The positional distribution [α(1,3)-acyl and ß(2)-acyl] of ω3 fatty acids [18:4(n-3), 20:4(n-3), 20:5(n-3), 22:5(n-3) and 22:6(n-3)] in depot fat of Atlantic salmon (Salmo salar), harp seal oil and cod liver oil triacylglycerols has been examined by13C nuclear magnetic resonance (NMR) spectroscopy. The positional distribution data can be defined from the spectrum of the carbonyl (C1 carbon) and the methylene (C2 and glyceryl carbon) regions. In depot fat of Atlantic salmon and cod liver oil, docosahexaenoic acid (DHA) was concentrated in the ß-position of the triacylglycerides with 72.6 and 74.4%, respectively. Only 3.2% of DHA and 4.6% of eicosapentaenoic acid (EPA) were esterified to the ß-position of the triacylglycerides in harp seal oil. EPA is nearly randomly distributed in cod liver oil and muscle lipids of Atlantic salmon, with 37.8 and 39.7%, respectively, in the ß-position. In general, the13C NMR-derived data were in accordance with corresponding data reported in the literature obtained by conventional techniques.

13C NMR pattern recognition techniques for the classification of Atlantic salmon (Salmo salar L.) according to their wild, farmed, and geographical origin.

(13)C nuclear magnetic resonance (NMR) in combination with multivariate data analysis was used to (1) discriminate between farmed and wild Atlantic salmon ( Salmo salar L.), (2) discriminate between different geographical origins, and (3) verify the origin of market samples. Muscle lipids from 195 Atlantic salmon of known origin (wild and farmed salmon from Norway, Scotland, Canada, Iceland, Ireland, the Faroes, and Tasmania) in addition to market samples were analyzed by (13)C NMR spectroscopy and multivariate analysis. Both probabilistic neural networks (PNN) and support vector machines (SVM) provided excellent discrimination (98.5 and 100.0%, respectively) between wild and farmed salmon. Discrimination with respect to geographical origin was somewhat more difficult, with correct classification rates ranging from 82.2 to 99.3% by PNN and SVM, respectively. In the analysis of market samples, five fish labeled and purchased as wild salmon were classified as farmed salmon (indicating mislabeling), and there were also some discrepancies between the classification and the product declaration with regard to geographical origin.

Use of NMR in fish processing optimization: a review of recent progress

The goal of this review is to give an overview of general trends in the application of the NMR related to fish processing and quality and to provide some viewpoints on the current situation. Three novel examples of the application of the methodologies magnetic resonance spectroscopy, magnetic resonance imaging, and low‐field NMR are also presented. The capability of these techniques to be utilized as a tool to optimize fish processing, and thereby improving product quality, as well as to confirm labelling information, are demonstrated. Copyright

Determination of origin of Atlantic salmon (Salmo salar): the use of multiprobe and multielement isotopic analyses in combination with fatty acid composition to assess wild or farmed origin.

Variability within the stable isotope ratios in various lipidic fractions and the fatty acid composition of muscle oil has been analyzed for a large sample (171 fish) of wild and farmed Atlantic salmon ( Salmo salar) from 32 origins within Europe, North America, and Tasmania. Sampling was extended over all seasons in 2 consecutive years and included fish raised by different practices, in order to maximize the range of variation present. It is shown that two readily measured parameters, delta 15N measured on choline and delta18 O measured on total oil, can be successfully used to discriminate between fish of authentic wild and farmed origin. However, the certainty of identification of mislabeling in market-derived fish is strengthened by including the percentage of linoleic acid C18:2n-6 in the lipidic fraction. Thus, several apparent misidentifications were found. The combination of these three analytical parameters and the size of the database generated makes the method practical for implementation in official laboratories as a tool of labeling verification.

High‐resolution 1H and 2H NMR spectroscopy of pure essential fatty acids for plants and animals

High‐resolution 1H and 2H NMR spectroscopy were used to study the most important saturated (C14:0, C16:0, C18:0), monounsaturated (C16:1n‐7, C18:1n‐7, C18:1n‐9, C20:1n‐9, C22:1n‐9) and polyunsaturated [C18:3n‐3, C20:5n‐3 (EPA), C22:6n‐3 (DHA)] fatty acids which may be found in fish lipids, in order to prepare the tools for a subsequent study of the recognition of the origin of fish oils by isotopic analysis. The interpretation of the 1H and 2H NMR spectra of the different acids is reported. Additionally, the overall D/H and the 13C/12C isotope ratios are given. The overall D/H ratio ranges from 114.0 to 137.2 ppm/V.SMOW (V.SMOW=water standard) and the 13C/12C ratio from ‐23.5 to ‐33.2‰. From the 2H NMR spectra, an investigation of the internal deuterium distribution in the saturated and mono‐ and polyunsaturated fatty acids was made. The deuterium distribution can be given for nearly all the chemical sites, except for the different double bonds, in EPA and DHA. The precision of the measurements was of the order of 0.5–4% depending on the nature of the cluster considered.

Classification of Wild and Farmed Salmon Using Bayesian Belief Networks and Gas Chromatography-Derived Fatty Acid Distributions

In this study, we present the use of Bayesian Belief Networks (BBN) for the classification of wild versus farmed Atlantic salmon (Salmo salar L.). Using a data set of 131 salmon samples from several geographical origins and the gas chromatography-derived distributions of 12 fatty acids (FAs), a Bayesian Belief Network was constructed, ultimately using only the three most important FAs (16:1n-7, 18:2n-6, and 22:5n-3). The training data set yielded a prediction error of 0% (68/68 farmed; 20/20 wild correct) while the validation data set prediction error was 4.65% (32/32 farmed; 9/11 wild correct). Different randomly chosen validation sets yielded similar prediction accuracies. This model was then applied to 30 market (store-bought) samples where predictions were compared with the product labels.

Quality Evaluation of Atlantic Halibut (Hippoglossus Hippoglossus L) During Ice Storage Using 1H NMR Spectroscopy

1 ABSTRACT 1H nuclear magnetic resonance (NMR) spectroscopy has been investigated as a possible tool for quality evaluation of Atlantic halibut (Hipoglossus hipoglossus L). Perchloric acid extracts of muscle samples, taken from chill-stored fish over a period of three weeks, were analysed with NMR. TMAO was not found to change notably with storage time, whereas phosphocreatine was only detectable in samples taken at the day of slaughter. NADP+ was detectable in samples up to two days after slaughter. ATP and its degradation products were monitored during the whole experiment, which enabled calculations of K-values. K-values derived fiom NMR data was compared to K-value measurements with Fresh Tester. The K-values found in the NMR analyses were low during the whole period. These experiments have proven that Nh4R is a possible method for studying ATP degradation of Atlantic halibut, with the potential of monitoring several metabolites simultaneously.

Quantitative high-resolution 13C nuclear magnetic resonance of anserine and lactate in white muscle of Atlantic salmon (Salmo salar)

Quantitative 13C nuclear magnetic resonance (NMR) spectra of minced white muscle of Atlantic salmon (Salmo salar) were obtained without chemical pretreatment of the sample. The carbon in the metabolites anserine and lactate gave rise to sufficiently resolved signals in the 13C spectrum to permit estimation of the total concentration of these muscle constituents. The NMR data are in good agreement with corresponding data reported in the literature obtained by conventional methods, indicating that all of these metabolites are NMR visible. Information about the muscle pH was obtained from the pH-dependent 13C chemical shift of C14 and C16 in the histidine ring of anserine. Well-resolved 13C NMR spectra obtained from intact muscle of Atlantic salmon demonstrate that NMR will be a useful method to study postmortem changes occurring during storage of fish.

Omega-3 Fatty Add Content of Intact Muscle of Farmed Atlantic Salmon (Salmo salar) Examined by 1H MAS NMR Spectroscopy

The nutritional benefits of fish and fish oils have resulted in an increasing interest in seafoods and derived products generally focused on the level of omega-3 (n-3) fatty acids (FAs). In particular 20:5 n-3 (EPA) and 22:6 n-3 (DHA) are believed to play a natural, preventive role in cardiovascular diseases, and alleviation of other health problems [1,2]. Aquaculture opens up interesting possibilities for exerting a control over factors affecting the nutritional and sensory attributes of fish as food such as the quantitative and qualitative content of fat in the edible tissues. About 20% of the muscle lipids of farmed Atlantic salmon are n-3 FAs, with some variation due to the FA composition of the fish feed. The content of EPA and DHA in muscle of farmed Atlantic salmon has been found to be approximately 0.6 and 0.8 g/100 g of fillet, respectively [3]. Traditionally, gas chromatography (GC) has been used to obtain the FAs profile of lipids. This technique requires that the sample is pretreated, extraction and methylation of the lipids have to be included as part of the analysis [3]. Recently it has been demonstrated that high-resolution nuclear magnetic resonance (NMR) spectroscopy can be used to provide insight into the nature of lipid mixtures and offers the opportunity to study hetereogeneous lipid mixtures, oils and fat deposits without being destructive [4–7]. NMR measurements can be performed on intact muscle and allows the identification and quantification of muscle metabolites [4,7,8] addition to lipid fluidity studies in fish muscle stored at low temperatures [9]. In preliminary studies 13C NMR has been used to obtain the n-3 FA content of intact fish muscle [7,10]. The 13C NMR experiment on intact muscle is very time consuming and it would be an advantage to detect on 1H instead of 13C due to the facts that 1H NMR has the highest NMR sensitivity of any stable nucleus, and it has nearly 100% natural abundance. In our preliminary research it has been shown that high-resolution 1H NMR is a unique and rapid technique to quantify the total n-3 acid content of the lipid extracted from muscle of Atlantic salmon [5,7]. A traditional 1H spectrum of intact muscle will only result in broad signals containing fat/water proton resonances and individual FAs or groups of lipids are not observed. However, recent research indicates that magic angle spinning (MAS) NMR spectroscopy offers the opportunity to study intact tissue non-destructively to quantify components of the tissues. Ni and Eads [11,12] have studied fruit tissue and they have shown that low-speed MAS simultaneously relieves susceptibility broadening, improves resolution, produces accurate chemical shifts, and increases signal-to-noise ratio. In the present study, we have obtained 1H MAS NMR spectra of intact salmon muscle and quantified the total n-3 acid content from the spectra. The data from the MAS NMR analyses were compared to those obtained by estimating the fat content in extracts from equivalent muscle samples by 1H NMR and by GC. The results from MAS NMR and from 1H NMR were usually in good agreement, while the content of n-3 estimated by GC was in general higher than if estimated by the NMR techniques.