Dag Ekeberg | Norwegian University of Life Sciences (original) (raw)
Papers by Dag Ekeberg
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Esterification and transesterification of lipids using boron trifluoride in methanol is widely us... more Esterification and transesterification of lipids using boron trifluoride in methanol is widely used in lipid chemistry to study fatty acid (FA) profiles of various lipids by GC‐MS. Transesterification of the FAs in sphingolipids is a difficult and time-consuming task. A rapid and convenient method for preparation of FAMEs from sphingomyelin (SM) using microwaves (MWs) was developed for GC‐MS analysis. Experiments with three levels of power were performed and the yields were compared at regular time intervals. The maximum yields for all power levels were the same, but the time to reach these yields varied with the power. It was found that at a power of 70 W the maximum yield was reached after 27 min having a stable time window of 8 min for this yield. Practical applications: The technique presented here enables a rapid and easy method for preparing FAMEs from SM by the use of a MW reactor. The reaction time has been reduced from several hours down to only 27 min, with excellent yields.
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Journal of Chromatography A, 2006
A method for quantitative determination of extractives from heartwood of Scots pine (Pinus sylves... more A method for quantitative determination of extractives from heartwood of Scots pine (Pinus sylvestris L.) using gas chromatography (GC) with flame ionization detection (FID) was developed. The limit of detection (LOD) was 0.03 mg/g wood and the linear range (r = 0.9994) was up to 10 mg/g with accuracy within ±10% and precision of 18% relative standard deviation. The identification of the extractives was performed using gas chromatography combined with mass spectrometry (GC-MS). The yields of extraction by Soxhlet were tested for solid wood, small particles and fine powder. Small particles were chosen for further analysis. This treatment gave good yields of the most important extractives: pinosylvin, pinosylvin monomethyl ether, resin acids and free fatty acids. The method is used to demonstrate the variation of these extractives across stems and differences in north-south direction.
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Food Science & Nutrition, 2021
The Atlantic salmon (Salmo salar) is a fish rich in lipids, in particular both eicosapentaenoic a... more The Atlantic salmon (Salmo salar) is a fish rich in lipids, in particular both eicosapentaenoic acid (EPA; C20:5n-3c) and docosahexaenoic acid (DHA; C22:6n-3c), and is one of the most important species in aquaculture in Europe, where Norway is the world's largest producer (Asche et al., 2019). However, there has been reported a decreased concentration of n-3 fatty acids (FAs) in farmed salmon compared to the level in previous years (Aas et al., 2019). Due to the scarcity and increasing price of marine oils, the feed that previously consisted of 90% fish meal and fish oils have been reduced to 25%, while the rest has been substituted with plant-based ingredients (Aas et al., 2019; Sprague et al., 2016). This substitution enabled a growth of 5.8% per annum in aquaculture production without a considerable increase in fish meal and fish oil consumption (Hamilton et al., 2020). In recent years in Norway, the proportion of plant-based ingredients like plant oil and plant protein in the feed have increased. Recently, up to 2/3 of the lipid fraction in salmon feed is of rapeseed oil origin. In Norway today, the feed consists of 70% plant-based ingredients
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International Dairy Journal, Feb 1, 2017
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Journal of Analytical and Applied Pyrolysis, Sep 1, 2017
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Food Science and Nutrition, Apr 28, 2022
The fatty acid profiles of wild and farmed Atlantic salmon (Salmo salar) and salmon feed was eluc... more The fatty acid profiles of wild and farmed Atlantic salmon (Salmo salar) and salmon feed was elucidated and quantitated. Due to the increasing proportion of vegetable oils in salmon feed, it was of interest to evaluate the effects on the farmed salmon fatty acid profile. There was found to be four times more fat in the muscle in farmed compared to wild salmon, 8.97 ± 0.63% and 2.14 ± 0.32%, respectively. The contents of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids were 15.0%, 55.4%, and 29.6%, respectively, in farmed salmon, while 26.3%, 47.4%, and 26.3% in wild salmon. The lipids were also fractioned into neutral lipids, free fatty acids, and polar lipids by solid‐phase extraction. Both wild and farmed salmon contained approximately equal amount of eicosapentaenoic acid and docosahexaenoic acid with 520 and 523 mg/100 g fish muscle, respectively. The salmons of both kinds were evaluated from a health perspective by discussing the contents of n‐3 and n‐6 fatty acids, saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids together with nutritional quality indices. In conjunction with a lower fat intake by consumption, the wild Atlantic salmon displayed the most nutritionally beneficial profile.
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Journal of Lipids, 2017
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ACS omega, May 4, 2018
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Journal of Lipids, 2018
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A method for separation of triacylglycerol (TAG), diacylglycerol (DAG), and monoacylglycerol (MAG... more A method for separation of triacylglycerol (TAG), diacylglycerol (DAG), and monoacylglycerol (MAG) was developed and used to separate and analyse the neutral lipids (NL) from digested cow milk by solid-phase extraction (SPE) and GC-MS. The lipids used were extracted from ex vivo digested full fat milk by Devle et al. (2014), who separated neutral lipids, free fatty acids (FFA), and phospholipids (PL) to study the interacting effect of ex vivo protein- and lipid digestion of milk with different fat content. The NLs were first separated from the FFAs and PLs by SPE on a NH2 column as described by Devle et al. (2014). Further separation into TAG-, DAG-, and MAG fractions was accomplished by applying the NLs in a small volume on a new NH2 column. TAG was eluted with 1 mL heptane:diethyl ether (93:7), DAG with 3 mL heptane:diethyl ether (93:7), and MAG with 3 mL chloroform:methanol (2:1).
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Nature Communications
Lytic polysaccharide monooxygenases (LPMOs) catalyze oxidative cleavage of crystalline polysaccha... more Lytic polysaccharide monooxygenases (LPMOs) catalyze oxidative cleavage of crystalline polysaccharides such as cellulose and are crucial for the conversion of plant biomass in Nature and in industrial applications. Sunlight promotes microbial conversion of plant litter; this effect has been attributed to photochemical degradation of lignin, a major redox-active component of secondary plant cell walls that limits enzyme access to the cell wall carbohydrates. Here, we show that exposing lignin to visible light facilitates cellulose solubilization by promoting formation of H2O2 that fuels LPMO catalysis. Light-driven H2O2 formation is accompanied by oxidation of ring-conjugated olefins in the lignin, while LPMO-catalyzed oxidation of phenolic hydroxyls leads to the required priming reduction of the enzyme. The discovery that light-driven abiotic reactions in Nature can fuel H2O2-dependent redox enzymes involved in deconstructing lignocellulose may offer opportunities for bioprocessing ...
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Journal of Clinical Pathology-molecular Pathology, Aug 1, 2003
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Additional file 2. Â GC-FID and GC-MS fatty acid analysis results.
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International Journal of Food Science & Technology, 2015
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Journal of Applied Phycology, 2020
The fatty acid profiles of the three lipid fractions, neutral lipids (NL), free fatty acids and p... more The fatty acid profiles of the three lipid fractions, neutral lipids (NL), free fatty acids and polar lipids (PL), from the macroalgaePalmaria palmata(wild),Alaria esculenta(cultivated) andSaccharina latissima(cultivated) were studied in light of dietary important fatty acids. Blade and stipe from the macroalgae were collected at the end of the growth season (May/June) at Frøya (Trøndelag, Norway). A total of 51 fatty acids were identified in the algae, including several fatty acids novel to one or more of the algae. The NL and PL fractions ofP. palmatawere the most promising from a health perspective, due to a high content of eicosapentaenoic acid (10.1 ± 0.5% and 6.6 ± 0.1%, respectively) and notrans-fatty acids. In addition, these fractions had very low omega-6/omega-3 ratios (< 0.1) and can therefore be beneficial for balancing the omega-6/omega-3 ratio in the diet. The NL fraction ofA. esculentahad the highest content of monounsaturated- and polyunsaturated fatty acids (20.9...
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Journal of Lipids
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AppliedChem
Laminaria hyperborea (Gunnerus) Foslie 1885 is a seaweed native to the North Atlantic, which is u... more Laminaria hyperborea (Gunnerus) Foslie 1885 is a seaweed native to the North Atlantic, which is utilized in the production of alginate. Its potential as a source of bioactive lipids remains unexplored. In this study, mono- and digalactosyldiacylglycerols (MGDG and DGDG) were identified in stipe and blade from L. hyperborea for the first time. Samples were harvested off the west coast of Norway in May 2018. Lipids were extracted with chloroform:methanol (2:1, v/v) and fractionated using solid phase extraction, whereupon the fatty acid content was determined by gas chromatography-mass spectrometry. The fatty acid profile was used to predict the mass of the glyceroglycolipids. A total of 103 and 161 molecular species of MGDG, and 66 and 136 molecular species of DGDG were identified in blade and stipe, respectively, by HPLC-ESI-MS/MS. The most abundant molecular species were identified from the total ion chromatograms. According to these, MGDG(20:5/18:4, 18:4/18:4, 16:0/18:1, 14:0/18:2,...
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Bookmarks Related papers MentionsView impact
Esterification and transesterification of lipids using boron trifluoride in methanol is widely us... more Esterification and transesterification of lipids using boron trifluoride in methanol is widely used in lipid chemistry to study fatty acid (FA) profiles of various lipids by GC‐MS. Transesterification of the FAs in sphingolipids is a difficult and time-consuming task. A rapid and convenient method for preparation of FAMEs from sphingomyelin (SM) using microwaves (MWs) was developed for GC‐MS analysis. Experiments with three levels of power were performed and the yields were compared at regular time intervals. The maximum yields for all power levels were the same, but the time to reach these yields varied with the power. It was found that at a power of 70 W the maximum yield was reached after 27 min having a stable time window of 8 min for this yield. Practical applications: The technique presented here enables a rapid and easy method for preparing FAMEs from SM by the use of a MW reactor. The reaction time has been reduced from several hours down to only 27 min, with excellent yields.
Bookmarks Related papers MentionsView impact
Journal of Chromatography A, 2006
A method for quantitative determination of extractives from heartwood of Scots pine (Pinus sylves... more A method for quantitative determination of extractives from heartwood of Scots pine (Pinus sylvestris L.) using gas chromatography (GC) with flame ionization detection (FID) was developed. The limit of detection (LOD) was 0.03 mg/g wood and the linear range (r = 0.9994) was up to 10 mg/g with accuracy within ±10% and precision of 18% relative standard deviation. The identification of the extractives was performed using gas chromatography combined with mass spectrometry (GC-MS). The yields of extraction by Soxhlet were tested for solid wood, small particles and fine powder. Small particles were chosen for further analysis. This treatment gave good yields of the most important extractives: pinosylvin, pinosylvin monomethyl ether, resin acids and free fatty acids. The method is used to demonstrate the variation of these extractives across stems and differences in north-south direction.
Bookmarks Related papers MentionsView impact
Food Science & Nutrition, 2021
The Atlantic salmon (Salmo salar) is a fish rich in lipids, in particular both eicosapentaenoic a... more The Atlantic salmon (Salmo salar) is a fish rich in lipids, in particular both eicosapentaenoic acid (EPA; C20:5n-3c) and docosahexaenoic acid (DHA; C22:6n-3c), and is one of the most important species in aquaculture in Europe, where Norway is the world's largest producer (Asche et al., 2019). However, there has been reported a decreased concentration of n-3 fatty acids (FAs) in farmed salmon compared to the level in previous years (Aas et al., 2019). Due to the scarcity and increasing price of marine oils, the feed that previously consisted of 90% fish meal and fish oils have been reduced to 25%, while the rest has been substituted with plant-based ingredients (Aas et al., 2019; Sprague et al., 2016). This substitution enabled a growth of 5.8% per annum in aquaculture production without a considerable increase in fish meal and fish oil consumption (Hamilton et al., 2020). In recent years in Norway, the proportion of plant-based ingredients like plant oil and plant protein in the feed have increased. Recently, up to 2/3 of the lipid fraction in salmon feed is of rapeseed oil origin. In Norway today, the feed consists of 70% plant-based ingredients
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International Dairy Journal, Feb 1, 2017
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Bookmarks Related papers MentionsView impact
Journal of Analytical and Applied Pyrolysis, Sep 1, 2017
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Food Science and Nutrition, Apr 28, 2022
The fatty acid profiles of wild and farmed Atlantic salmon (Salmo salar) and salmon feed was eluc... more The fatty acid profiles of wild and farmed Atlantic salmon (Salmo salar) and salmon feed was elucidated and quantitated. Due to the increasing proportion of vegetable oils in salmon feed, it was of interest to evaluate the effects on the farmed salmon fatty acid profile. There was found to be four times more fat in the muscle in farmed compared to wild salmon, 8.97 ± 0.63% and 2.14 ± 0.32%, respectively. The contents of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids were 15.0%, 55.4%, and 29.6%, respectively, in farmed salmon, while 26.3%, 47.4%, and 26.3% in wild salmon. The lipids were also fractioned into neutral lipids, free fatty acids, and polar lipids by solid‐phase extraction. Both wild and farmed salmon contained approximately equal amount of eicosapentaenoic acid and docosahexaenoic acid with 520 and 523 mg/100 g fish muscle, respectively. The salmons of both kinds were evaluated from a health perspective by discussing the contents of n‐3 and n‐6 fatty acids, saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids together with nutritional quality indices. In conjunction with a lower fat intake by consumption, the wild Atlantic salmon displayed the most nutritionally beneficial profile.
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Journal of Lipids, 2017
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ACS omega, May 4, 2018
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Journal of Lipids, 2018
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A method for separation of triacylglycerol (TAG), diacylglycerol (DAG), and monoacylglycerol (MAG... more A method for separation of triacylglycerol (TAG), diacylglycerol (DAG), and monoacylglycerol (MAG) was developed and used to separate and analyse the neutral lipids (NL) from digested cow milk by solid-phase extraction (SPE) and GC-MS. The lipids used were extracted from ex vivo digested full fat milk by Devle et al. (2014), who separated neutral lipids, free fatty acids (FFA), and phospholipids (PL) to study the interacting effect of ex vivo protein- and lipid digestion of milk with different fat content. The NLs were first separated from the FFAs and PLs by SPE on a NH2 column as described by Devle et al. (2014). Further separation into TAG-, DAG-, and MAG fractions was accomplished by applying the NLs in a small volume on a new NH2 column. TAG was eluted with 1 mL heptane:diethyl ether (93:7), DAG with 3 mL heptane:diethyl ether (93:7), and MAG with 3 mL chloroform:methanol (2:1).
Bookmarks Related papers MentionsView impact
Nature Communications
Lytic polysaccharide monooxygenases (LPMOs) catalyze oxidative cleavage of crystalline polysaccha... more Lytic polysaccharide monooxygenases (LPMOs) catalyze oxidative cleavage of crystalline polysaccharides such as cellulose and are crucial for the conversion of plant biomass in Nature and in industrial applications. Sunlight promotes microbial conversion of plant litter; this effect has been attributed to photochemical degradation of lignin, a major redox-active component of secondary plant cell walls that limits enzyme access to the cell wall carbohydrates. Here, we show that exposing lignin to visible light facilitates cellulose solubilization by promoting formation of H2O2 that fuels LPMO catalysis. Light-driven H2O2 formation is accompanied by oxidation of ring-conjugated olefins in the lignin, while LPMO-catalyzed oxidation of phenolic hydroxyls leads to the required priming reduction of the enzyme. The discovery that light-driven abiotic reactions in Nature can fuel H2O2-dependent redox enzymes involved in deconstructing lignocellulose may offer opportunities for bioprocessing ...
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Journal of Clinical Pathology-molecular Pathology, Aug 1, 2003
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Additional file 2. Â GC-FID and GC-MS fatty acid analysis results.
Bookmarks Related papers MentionsView impact
International Journal of Food Science & Technology, 2015
Bookmarks Related papers MentionsView impact
Journal of Applied Phycology, 2020
The fatty acid profiles of the three lipid fractions, neutral lipids (NL), free fatty acids and p... more The fatty acid profiles of the three lipid fractions, neutral lipids (NL), free fatty acids and polar lipids (PL), from the macroalgaePalmaria palmata(wild),Alaria esculenta(cultivated) andSaccharina latissima(cultivated) were studied in light of dietary important fatty acids. Blade and stipe from the macroalgae were collected at the end of the growth season (May/June) at Frøya (Trøndelag, Norway). A total of 51 fatty acids were identified in the algae, including several fatty acids novel to one or more of the algae. The NL and PL fractions ofP. palmatawere the most promising from a health perspective, due to a high content of eicosapentaenoic acid (10.1 ± 0.5% and 6.6 ± 0.1%, respectively) and notrans-fatty acids. In addition, these fractions had very low omega-6/omega-3 ratios (< 0.1) and can therefore be beneficial for balancing the omega-6/omega-3 ratio in the diet. The NL fraction ofA. esculentahad the highest content of monounsaturated- and polyunsaturated fatty acids (20.9...
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Journal of Lipids
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AppliedChem
Laminaria hyperborea (Gunnerus) Foslie 1885 is a seaweed native to the North Atlantic, which is u... more Laminaria hyperborea (Gunnerus) Foslie 1885 is a seaweed native to the North Atlantic, which is utilized in the production of alginate. Its potential as a source of bioactive lipids remains unexplored. In this study, mono- and digalactosyldiacylglycerols (MGDG and DGDG) were identified in stipe and blade from L. hyperborea for the first time. Samples were harvested off the west coast of Norway in May 2018. Lipids were extracted with chloroform:methanol (2:1, v/v) and fractionated using solid phase extraction, whereupon the fatty acid content was determined by gas chromatography-mass spectrometry. The fatty acid profile was used to predict the mass of the glyceroglycolipids. A total of 103 and 161 molecular species of MGDG, and 66 and 136 molecular species of DGDG were identified in blade and stipe, respectively, by HPLC-ESI-MS/MS. The most abundant molecular species were identified from the total ion chromatograms. According to these, MGDG(20:5/18:4, 18:4/18:4, 16:0/18:1, 14:0/18:2,...
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