Hanne Bertram - Academia.edu (original) (raw)

Papers by Hanne Bertram

Magnetic Resonance in Food Science, 2011

RSC Publishing Logo. ...

Molecular Nutrition & Food Research, 2017

This is the peer reviewed version of the following article: B.

Nutrients, Jan 23, 2016

We investigated the effect of a 24-week energy-restricted intervention with low or high dairy int... more We investigated the effect of a 24-week energy-restricted intervention with low or high dairy intake (LD or HD) on the metabolic profiles of urine, blood and feces in overweight/obese women by NMR spectroscopy combined with ANOVA-simultaneous component analysis (ASCA). A significant effect of dairy intake was found on the urine metabolome. HD intake increased urinary citrate, creatinine and urea excretion, and decreased urinary excretion of trimethylamine-N-oxide (TMAO) and hippurate relative to the LD intake, suggesting that HD intake was associated with alterations in protein catabolism, energy metabolism and gut microbial activity. In addition, a significant time effect on the blood metabolome was attributed to a decrease in blood lipid and lipoprotein levels due to the energy restriction. For the fecal metabolome, a trend for a diet effect was found and a series of metabolites, such as acetate, butyrate, propionate, malonate, cholesterol and glycerol tended to be affected. Overa...

Molecular Nutrition & Food Research, 2016

Proteins constitute an important part of the human diet, but understanding of the effects of diff... more Proteins constitute an important part of the human diet, but understanding of the effects of different dietary protein sources on human metabolism is sparse. We aimed to elucidate diet-induced metabolic changes through untargeted urinary metabolomics after four weeks of intervention with lean-seafood or nonseafood diets. It is shown that lean-seafood intake reduces urinary excretion of metabolites involved in mitochondrial lipid and energy metabolism possibly facilitating a higher lipid catabolism in healthy subjects. Methods: In a randomized controlled trial with crossover design, 20 healthy subjects consumed two balanced diets that varied in main protein sources for 4 weeks. Morning spot urine samples were collected before and after each intervention period. Untargeted metabolomics based on 1 H NMR spectroscopy and LC-MS analyses were applied to characterize the urinary metabolic response to the interventions. Results: The lean-seafood diet period reduced the urinary level of L-carnitine, 2,6dimethylheptanoylcarnitine, and N-methyl-2-pyridone-5-carboxamide, relative to the nonseafood period. The dietary analysis revealed that the higher urinary level of trimethylamine-N-oxide after the lean-seafood diet period and guanidinoacetate and 3-methylhistidine after the nonseafood diet period was related to the endogenous content of these compounds in the diets. Conclusions: Our data reveal that 4 weeks of lean-seafood intake reduces urinary excretion of metabolites involved in mitochondrial lipid and energy metabolism possibly facilitating a higher lipid catabolism in healthy subjects after the lean-seafood intake.

INTRODUCTION Dairy foods comprise a range of different products with varying nutritional componen... more INTRODUCTION Dairy foods comprise a range of different products with varying nutritional components. They contain a large amount of long-chain saturated fat, which traditionally has been linked to obesity and increased risk of cardiovascular diseases (CVD). However, preliminary results have indicated that short-chain fatty acids may have an effect on the so-called fasting-induced adipose factor (FIAF; also known as Angptl4). Increased levels of FIAF in circulation have been shown to inhibit the active form of lipoprotein lipase (LPL) and thereby reduce lipid uptake in target organs, which may have a positive impact in relation to reducing obesity. MATERIALS & METHODS Free fatty acids (FFA) in milk were quantified after homogenization and LPL-activation of milk, and milk’s potential as regulator of FIAF was investigated in vitro using the human colon cell line, HCT116. Rt-PCR was applied to measure the FIAF mRNA abundance. Ultrasound sonication was used to homogenize the milk samples...

European Food Research and Technology, 2015

Journal of agricultural and food chemistry, Jan 6, 2014

The enzymatic hydrolysis of lactose to glucose and galactose gives rise to reactions that change ... more The enzymatic hydrolysis of lactose to glucose and galactose gives rise to reactions that change the chemistry and quality of ambient-stored lactose-hydrolyzed ultra-high-temperature (UHT) milk. The aim of the present study was to investigate and compare chemical changes in lactose-hydrolyzed and conventional UHT milk during a 9 month ambient storage period. Several complementary analyses of volatiles, free amino acids, acetate, furosine, and level of free amino terminals were concluded. The analyses revealed an increased level of free amino acids and an increased formation rate of specific compounds such as furosine and 2-methylbutanal in lactose-hydrolyzed UHT milk compared to conventional UHT milk during storage. These observations indicate more favorable conditions for Maillard and subsequent reactions in lactose-hydrolyzed milk compared to conventional UHT milk stored at ambient temperature. Furthermore, it is postulated that proteolytic activity from the lactase-enzyme prepara...

Meat Science, 2010

Nuclear magnetic resonance (NMR)-based metabonomics was applied to investigate the effects of pre... more Nuclear magnetic resonance (NMR)-based metabonomics was applied to investigate the effects of preslaughter exercise stress on the plasma metabolite profile at time of slaughter. The study included a total of 40 slaughter pigs, which were exposed to one of the following treatments: No pre-slaughter stress (control treatment), pre-slaughter exercise on a treadmill and subsequently 0, 1, or 3 h rest prior to slaughter. NMR-based metabonomics revealed a clear difference in the plasma metabolite profile at time of slaughter between control pigs and pigs exercised without rest, which mainly could be ascribed to increased plasma lactate due to exercise. A resting period of 1 or 3 h prior to slaughter reversed the stress-induced perturbations in the plasma metabolite profile. The plasma metabolite profile at time of slaughter was highly correlated with muscle temperature 1 min post-mortem, and a correlation to WHC was also demonstrated. Lactate was found to be the metabolite of importance for the association between the plasma metabolome and pH, temperature and WHC.

LWT - Food Science and Technology, 2005

Newly developed ultrasound equipment was tested for on-line determination of water-holding capaci... more Newly developed ultrasound equipment was tested for on-line determination of water-holding capacity (WHC) early post mortem (p.m.). The experiment was based on measurements of m. longissimus dorsi (LD) from 10 pigs, five of which were treated to result in pork with high WHC and five to result in pork with low WHC. Ultrasound measurements were carried out on the carcass of each pig every ten minutes from 15 to 85 min p.m. at three locations of the LD. Low field nuclear magnetic resonance (NMR) measurements were performed on excised samples simultaneously with the ultrasound measurements and at 24 h p.m. Drip loss was measured by Honikel's bag method. The ultrasound experiment demonstrated that classification of meat with high and low WHC was possible, but only at 85 min p.m., and only by the measurements obtained at the posterior end of the LD. NMR measurements underlined that there are structural differences in meat influenced by pre-slaughter treatment prior to 85 min p.m. However, meat properties that determine WHC were apparently not expressed sufficiently to be registered by the applied pragmatic handheld ultrasound equipment before 85 min p.m.

Journal of Proteome Research, 2014

Urinary loss of tricarboxylic acid cycle intermediates as revealed by metabolomics studies: an un... more Urinary loss of tricarboxylic acid cycle intermediates as revealed by metabolomics studies: an underlying mechanism to reduce lipid accretion by whey protein ingestion?

Journal of Agricultural and Food Chemistry, 2007

Water-binding properties of myofibrils extracted from porcine muscle, and added hemoglobin with a... more Water-binding properties of myofibrils extracted from porcine muscle, and added hemoglobin with and without exposure to H2O2, were characterized using low-field proton NMR T2 relaxometry. The effects of pH and ionic strength in the samples were investigated as pH was adjusted to 5.4, 6.2, and 7.0 and ionic strength was adjusted to 0.29, 0.46, and 0.71 M, respectively. The formation of dityrosine as a measure of oxidative protein cross-linking revealed a significant increase in dityrosine concentrations upon H2O2 activation. The formation of dityrosine was strongly pH-dependent and increased with decreasing pH. In addition, increased levels of thiobarbituric acid reactive substances were observed upon addition of H2O2, implying that lipid oxidation was enhanced, however, with a different oxidation pattern as compared to the myofibrillar proteins. Low-field NMR relaxation measurements revealed reduced T2 relaxation times upon H2O2 activation, which corresponds to reduced water-holding capacity upon oxidation. However, a direct relationship between degree of oxidation and T2 relaxation time was not observed with various pH values and ionic strengths, and further studies are needed for a complete understanding of the effect of oxidation on myofibrillar functionality.

Analytical Chemistry, 2013

We describe a time-saving protocol for the processing of LC-MS-based metabolomics data by optimiz... more We describe a time-saving protocol for the processing of LC-MS-based metabolomics data by optimizing parameter settings in XCMS and threshold settings for removing noisy and low-intensity peaks using design of experiment (DoE) approaches including Plackett-Burman design (PBD) for screening and central composite design (CCD) for optimization. A reliability index, which is based on evaluation of the linear response to a dilution series, was used as a parameter for the assessment of data quality. After identifying the significant parameters in the XCMS software by PBD, CCD was applied to determine their values by maximizing the reliability and group indexes. Optimal settings by DoE resulted in improvements of 19.4% and 54.7% in the reliability index for a standard mixture and human urine, respectively, as compared with the default setting, and a total of 38 h was required to complete the optimization. Moreover, threshold settings were optimized by using CCD for further improvement. The approach combining optimal parameter setting and the threshold method improved the reliability index about 9.5 times for a standards mixture and 14.5 times for human urine data, which required a total of 41 h. Validation results also showed improvements in the reliability index of about 5−7 times even for urine samples from different subjects. It is concluded that the proposed methodology can be used as a time-saving approach for improving the processing of LC-MS-based metabolomics data.

Molecular Nutrition & Food Research, 2016

The scope of the present study was to investigate the effects of red versus white meat intake on ... more The scope of the present study was to investigate the effects of red versus white meat intake on the metabolome of rats. Methods and results Twenty-four male Sprague-Dawley rats were randomly assigned to 15 days of ad libitum feeding of one of four experimental diets: 1) lean chicken, 2) chicken with lard, 3) lean beef, and 4) beef with lard. Urine, feces, plasma and colon tissue samples were analyzed using 1 H NMR-based metabolomics and real-time PCR was performed on colon tissue to examine the expression of specific genes. Urinary excretion of acetate and anserine was higher after chicken intake, while carnosine, fumarate and trimethylamine N-oxide excretion were higher after beef intake. In colon tissue, higher choline levels and lower lipid levels were found after intake of chicken compared to beef. Expression of the apc gene was higher in response to the lean chicken and beef with lard diets. Correlation analysis revealed that intestinal apc gene expression was correlated with fecal lactate content (R 2 =0.65). Conclusions This study is the first to identify specific differences in the metabolome related to the intake of red and white meat. These differences may reflect perturbations in endogenous metabolism that can be linked to the proposed harmful effects associated with intake of red meat. Meat from different sources (e.g. beef or chicken) is composed of different structural components, which might give rise to differences in the nutritional impact of the meat as evidenced from

Meat Science, 2004

The water characteristics in cooked pressure-heat treated (45 C for 45 min prior to pressurisatio... more The water characteristics in cooked pressure-heat treated (45 C for 45 min prior to pressurisation at 150 MPa for 30 min) and non-pressurised, cooked (control) samples of beef Longissimus aged for 1, 3, 8 or 16 days were studied by nuclear magnetic resonance microscopy. A multi-echo sequence was used to obtain T2 images, and independent of ageing period, the T2 values were found to be lower in pressure-heat treated meat revealing alterations in water characteristics of pressure-treated, cooked meat compared with cooked meat. With increasing ageing duration, the T2 values in both pressure-treated, cooked and cooked meat decreased indicating that the water became more tightly trapped in the protein network. In addition, independent of length of ageing period the relationship between cooking loss in the cooked meat and transverse relaxation differed between non-pressurised and pressuretreated meat, which reveals that the mechanisms changing the water properties in beef during ageing are different from those occuring during pressure-heat treatment of meat. #

Meat Science, 2004

Using low-field NMR transverse relaxation measurements, the physico-chemical state of water in me... more Using low-field NMR transverse relaxation measurements, the physico-chemical state of water in meat was followed continuously during cooking of 20 uncured and 20 cured pork samples from RN-carriers (n=20) and non-carriers (n=20). The obtained relaxation data were analysed using (i) distributed exponential fitting, and (ii) principal component analysis (PCA). Distributed exponential fitting revealed transition from a system with relatively well-separated components to a less well-defined system with a wide distribution of relaxation times and merged components during cooking. In addition, distributed exponential fitting analysis implied changes in relaxation characteristics that are tentatively ascribed to denaturation of myosin and subsequent shrinkage of the myofibrillar structures. The results are further suggested to reflect formation of new compartments in the myofibrillar lattice during the shrinkage of the existing structures with a succeeding redistribution of water. Nitrite curing was found to affect the distribution of water as well as the progress in the different water populations during cooking. PCA revealed two major shifts in relaxation characteristics around 43 and 56 C in uncured samples and around 43 and 63 C in cured samples, and the shift around 43 C was found to be significantly affected by RN-genotype. The strong shift in water properties around 43 C is suggested to be a result of myosin denaturation, and thus the results imply differences in myosin denaturation in meat from RN-carriers compared with meat from non-carriers. The second shift in water properties is suggested to reflect the onset of collagen shrinkage causing longitudinal shrinkage of meat, and accordingly the shift from 56 to 63 C in the presence of salt points towards an effect of curing on structural alterations during cooking. #

Journal of Agricultural and Food Chemistry, 2008

Independently of the marinade used, the water-binding capacity was improved, cooking loss was red... more Independently of the marinade used, the water-binding capacity was improved, cooking loss was reduced, and the yield was enhanced compared with nonmarinated pork samples. This was also reflected in the water mobility within the samples measured by proton NMR relaxometry. Visualization of samples by confocal laser scanning microscopy (CLSM) revealed salt-dependent microstructural changes in the green pork samples treated with NaHCO 3 , giving rise to nearly complete disintegration of overall structures. High-resolution visualization by atomic force microscopy (AFM) further suggested that a higher cooking loss in sodium chloride-enhanced samples could be ascribed to less solubilization and higher heat-induced protein denaturation compared with phosphate-and bicarbonate-enhanced samples.

Journal of Agricultural and Food Chemistry, 2006

Low-field NMR T 2 and Fourier transform infrared (FT-IR) measurements were performed on meat samp... more Low-field NMR T 2 and Fourier transform infrared (FT-IR) measurements were performed on meat samples of two qualities (normal and high ultimate pH) during cooking from 28°C to 81°C. Pronounced changes in both T 2 relaxation data and FT-IR spectroscopic data were observed during cooking, revealing severe changes in the water properties and structural organization of proteins. The FT-IR data revealed major changes in bands in the amide I region (1700-1600 cm -1 ), and a tentative assignment of these is discussed. Distributed NMR T 2 relaxation data and FT-IR spectra were compared by partial least-squares regression. This revealed a correlation between the FT-IR peaks reflecting -sheet and R-helix structures and the NMR relaxation populations reflecting hydration water (T 2B ∼ 0-10 ms), myofibrillar water (T 21 ∼ 35-50 ms), and also expelled "bulk" water (T 2 relaxation times >1000 ms). Accordingly, the present study demonstrates that definite structural changes in proteins during cooking of meat are associated with simultaneous alterations in the chemical-physical properties of the water within the meat.

Food Quality and Preference, 2003

The study comprised two experiments with the aim to investigate the influence of raw meat quality... more The study comprised two experiments with the aim to investigate the influence of raw meat quality and cooking procedure on cooking loss and juiciness of pork. The first experiment determined the cooking loss at 60, 70 and 80 C centre temperature of 10 raw meat qualities (defined according to ultimate pH, drip loss, breed and rearing conditions) when cooked as steaks on a pan or as a roast in oven at a oven temperature of 90 or 190 C. The differences in cooking loss between the raw meat qualities and the cooking procedures did decrease as the centre temperature increased and were almost negligble at 80 C. Low water holding capacity (WHC) and low pH resulted in high cooking loss while no difference in cooking loss was observed between meat having medium or high WHC and pH. In the second experiment four raw meat qualities (standard, Duroc, low pH and heavy carcass weight) chosen from the first experiment to ensure a wide variation in cooking loss, were cooked in oven at 90 or 190 C oven temperature. Juiciness was assessed three times during the chewing process. The results suggested that juiciness experienced initially in the chewing process depended only on the water content of the meat, whereas juiciness experienced later in the chewing process was determined by a combination of the water and intramuscular fat contents and the saliva production during chewing. #

Journal of Agricultural and Food Chemistry, 2005

This study introduces the use of combined 23Na magnetic resonance imaging (MRI) and 23Na NMR rela... more This study introduces the use of combined 23Na magnetic resonance imaging (MRI) and 23Na NMR relaxometry for the study of meat curing. The diffusion of sodium ions into the meat was measured using 23Na MRI on a 1 kg meat sample brined in 10% w/w NaCl for 3-100 h. Calculations revealed a diffusion coefficient of 1 x 10(-5) cm2/s after 3 h of curing and subsequently decreasing to 8 x 10(-6) cm2/s at longer curing times, suggesting that changes occur in the microscopic structure of the meat during curing. The microscopic mobility and distribution of sodium was measured using 23Na relaxometry. Two sodium populations were observed, and with increasing length of curing time the relaxation times of these changed, reflecting a salt-induced swelling and increase in myofibrillar pore sizes. Accordingly, the present study demonstrated that pore size and thereby salt-induced swelling in meat can be assessed using 23Na relaxometry.

Magnetic Resonance in Food Science, 2011

RSC Publishing Logo. ...

Molecular Nutrition & Food Research, 2017

This is the peer reviewed version of the following article: B.

Nutrients, Jan 23, 2016

We investigated the effect of a 24-week energy-restricted intervention with low or high dairy int... more We investigated the effect of a 24-week energy-restricted intervention with low or high dairy intake (LD or HD) on the metabolic profiles of urine, blood and feces in overweight/obese women by NMR spectroscopy combined with ANOVA-simultaneous component analysis (ASCA). A significant effect of dairy intake was found on the urine metabolome. HD intake increased urinary citrate, creatinine and urea excretion, and decreased urinary excretion of trimethylamine-N-oxide (TMAO) and hippurate relative to the LD intake, suggesting that HD intake was associated with alterations in protein catabolism, energy metabolism and gut microbial activity. In addition, a significant time effect on the blood metabolome was attributed to a decrease in blood lipid and lipoprotein levels due to the energy restriction. For the fecal metabolome, a trend for a diet effect was found and a series of metabolites, such as acetate, butyrate, propionate, malonate, cholesterol and glycerol tended to be affected. Overa...

Molecular Nutrition & Food Research, 2016

Proteins constitute an important part of the human diet, but understanding of the effects of diff... more Proteins constitute an important part of the human diet, but understanding of the effects of different dietary protein sources on human metabolism is sparse. We aimed to elucidate diet-induced metabolic changes through untargeted urinary metabolomics after four weeks of intervention with lean-seafood or nonseafood diets. It is shown that lean-seafood intake reduces urinary excretion of metabolites involved in mitochondrial lipid and energy metabolism possibly facilitating a higher lipid catabolism in healthy subjects. Methods: In a randomized controlled trial with crossover design, 20 healthy subjects consumed two balanced diets that varied in main protein sources for 4 weeks. Morning spot urine samples were collected before and after each intervention period. Untargeted metabolomics based on 1 H NMR spectroscopy and LC-MS analyses were applied to characterize the urinary metabolic response to the interventions. Results: The lean-seafood diet period reduced the urinary level of L-carnitine, 2,6dimethylheptanoylcarnitine, and N-methyl-2-pyridone-5-carboxamide, relative to the nonseafood period. The dietary analysis revealed that the higher urinary level of trimethylamine-N-oxide after the lean-seafood diet period and guanidinoacetate and 3-methylhistidine after the nonseafood diet period was related to the endogenous content of these compounds in the diets. Conclusions: Our data reveal that 4 weeks of lean-seafood intake reduces urinary excretion of metabolites involved in mitochondrial lipid and energy metabolism possibly facilitating a higher lipid catabolism in healthy subjects after the lean-seafood intake.

INTRODUCTION Dairy foods comprise a range of different products with varying nutritional componen... more INTRODUCTION Dairy foods comprise a range of different products with varying nutritional components. They contain a large amount of long-chain saturated fat, which traditionally has been linked to obesity and increased risk of cardiovascular diseases (CVD). However, preliminary results have indicated that short-chain fatty acids may have an effect on the so-called fasting-induced adipose factor (FIAF; also known as Angptl4). Increased levels of FIAF in circulation have been shown to inhibit the active form of lipoprotein lipase (LPL) and thereby reduce lipid uptake in target organs, which may have a positive impact in relation to reducing obesity. MATERIALS & METHODS Free fatty acids (FFA) in milk were quantified after homogenization and LPL-activation of milk, and milk’s potential as regulator of FIAF was investigated in vitro using the human colon cell line, HCT116. Rt-PCR was applied to measure the FIAF mRNA abundance. Ultrasound sonication was used to homogenize the milk samples...

European Food Research and Technology, 2015

Journal of agricultural and food chemistry, Jan 6, 2014

The enzymatic hydrolysis of lactose to glucose and galactose gives rise to reactions that change ... more The enzymatic hydrolysis of lactose to glucose and galactose gives rise to reactions that change the chemistry and quality of ambient-stored lactose-hydrolyzed ultra-high-temperature (UHT) milk. The aim of the present study was to investigate and compare chemical changes in lactose-hydrolyzed and conventional UHT milk during a 9 month ambient storage period. Several complementary analyses of volatiles, free amino acids, acetate, furosine, and level of free amino terminals were concluded. The analyses revealed an increased level of free amino acids and an increased formation rate of specific compounds such as furosine and 2-methylbutanal in lactose-hydrolyzed UHT milk compared to conventional UHT milk during storage. These observations indicate more favorable conditions for Maillard and subsequent reactions in lactose-hydrolyzed milk compared to conventional UHT milk stored at ambient temperature. Furthermore, it is postulated that proteolytic activity from the lactase-enzyme prepara...

Meat Science, 2010

Nuclear magnetic resonance (NMR)-based metabonomics was applied to investigate the effects of pre... more Nuclear magnetic resonance (NMR)-based metabonomics was applied to investigate the effects of preslaughter exercise stress on the plasma metabolite profile at time of slaughter. The study included a total of 40 slaughter pigs, which were exposed to one of the following treatments: No pre-slaughter stress (control treatment), pre-slaughter exercise on a treadmill and subsequently 0, 1, or 3 h rest prior to slaughter. NMR-based metabonomics revealed a clear difference in the plasma metabolite profile at time of slaughter between control pigs and pigs exercised without rest, which mainly could be ascribed to increased plasma lactate due to exercise. A resting period of 1 or 3 h prior to slaughter reversed the stress-induced perturbations in the plasma metabolite profile. The plasma metabolite profile at time of slaughter was highly correlated with muscle temperature 1 min post-mortem, and a correlation to WHC was also demonstrated. Lactate was found to be the metabolite of importance for the association between the plasma metabolome and pH, temperature and WHC.

LWT - Food Science and Technology, 2005

Newly developed ultrasound equipment was tested for on-line determination of water-holding capaci... more Newly developed ultrasound equipment was tested for on-line determination of water-holding capacity (WHC) early post mortem (p.m.). The experiment was based on measurements of m. longissimus dorsi (LD) from 10 pigs, five of which were treated to result in pork with high WHC and five to result in pork with low WHC. Ultrasound measurements were carried out on the carcass of each pig every ten minutes from 15 to 85 min p.m. at three locations of the LD. Low field nuclear magnetic resonance (NMR) measurements were performed on excised samples simultaneously with the ultrasound measurements and at 24 h p.m. Drip loss was measured by Honikel's bag method. The ultrasound experiment demonstrated that classification of meat with high and low WHC was possible, but only at 85 min p.m., and only by the measurements obtained at the posterior end of the LD. NMR measurements underlined that there are structural differences in meat influenced by pre-slaughter treatment prior to 85 min p.m. However, meat properties that determine WHC were apparently not expressed sufficiently to be registered by the applied pragmatic handheld ultrasound equipment before 85 min p.m.

Journal of Proteome Research, 2014

Urinary loss of tricarboxylic acid cycle intermediates as revealed by metabolomics studies: an un... more Urinary loss of tricarboxylic acid cycle intermediates as revealed by metabolomics studies: an underlying mechanism to reduce lipid accretion by whey protein ingestion?

Journal of Agricultural and Food Chemistry, 2007

Water-binding properties of myofibrils extracted from porcine muscle, and added hemoglobin with a... more Water-binding properties of myofibrils extracted from porcine muscle, and added hemoglobin with and without exposure to H2O2, were characterized using low-field proton NMR T2 relaxometry. The effects of pH and ionic strength in the samples were investigated as pH was adjusted to 5.4, 6.2, and 7.0 and ionic strength was adjusted to 0.29, 0.46, and 0.71 M, respectively. The formation of dityrosine as a measure of oxidative protein cross-linking revealed a significant increase in dityrosine concentrations upon H2O2 activation. The formation of dityrosine was strongly pH-dependent and increased with decreasing pH. In addition, increased levels of thiobarbituric acid reactive substances were observed upon addition of H2O2, implying that lipid oxidation was enhanced, however, with a different oxidation pattern as compared to the myofibrillar proteins. Low-field NMR relaxation measurements revealed reduced T2 relaxation times upon H2O2 activation, which corresponds to reduced water-holding capacity upon oxidation. However, a direct relationship between degree of oxidation and T2 relaxation time was not observed with various pH values and ionic strengths, and further studies are needed for a complete understanding of the effect of oxidation on myofibrillar functionality.

Analytical Chemistry, 2013

We describe a time-saving protocol for the processing of LC-MS-based metabolomics data by optimiz... more We describe a time-saving protocol for the processing of LC-MS-based metabolomics data by optimizing parameter settings in XCMS and threshold settings for removing noisy and low-intensity peaks using design of experiment (DoE) approaches including Plackett-Burman design (PBD) for screening and central composite design (CCD) for optimization. A reliability index, which is based on evaluation of the linear response to a dilution series, was used as a parameter for the assessment of data quality. After identifying the significant parameters in the XCMS software by PBD, CCD was applied to determine their values by maximizing the reliability and group indexes. Optimal settings by DoE resulted in improvements of 19.4% and 54.7% in the reliability index for a standard mixture and human urine, respectively, as compared with the default setting, and a total of 38 h was required to complete the optimization. Moreover, threshold settings were optimized by using CCD for further improvement. The approach combining optimal parameter setting and the threshold method improved the reliability index about 9.5 times for a standards mixture and 14.5 times for human urine data, which required a total of 41 h. Validation results also showed improvements in the reliability index of about 5−7 times even for urine samples from different subjects. It is concluded that the proposed methodology can be used as a time-saving approach for improving the processing of LC-MS-based metabolomics data.

Molecular Nutrition & Food Research, 2016

The scope of the present study was to investigate the effects of red versus white meat intake on ... more The scope of the present study was to investigate the effects of red versus white meat intake on the metabolome of rats. Methods and results Twenty-four male Sprague-Dawley rats were randomly assigned to 15 days of ad libitum feeding of one of four experimental diets: 1) lean chicken, 2) chicken with lard, 3) lean beef, and 4) beef with lard. Urine, feces, plasma and colon tissue samples were analyzed using 1 H NMR-based metabolomics and real-time PCR was performed on colon tissue to examine the expression of specific genes. Urinary excretion of acetate and anserine was higher after chicken intake, while carnosine, fumarate and trimethylamine N-oxide excretion were higher after beef intake. In colon tissue, higher choline levels and lower lipid levels were found after intake of chicken compared to beef. Expression of the apc gene was higher in response to the lean chicken and beef with lard diets. Correlation analysis revealed that intestinal apc gene expression was correlated with fecal lactate content (R 2 =0.65). Conclusions This study is the first to identify specific differences in the metabolome related to the intake of red and white meat. These differences may reflect perturbations in endogenous metabolism that can be linked to the proposed harmful effects associated with intake of red meat. Meat from different sources (e.g. beef or chicken) is composed of different structural components, which might give rise to differences in the nutritional impact of the meat as evidenced from

Meat Science, 2004

The water characteristics in cooked pressure-heat treated (45 C for 45 min prior to pressurisatio... more The water characteristics in cooked pressure-heat treated (45 C for 45 min prior to pressurisation at 150 MPa for 30 min) and non-pressurised, cooked (control) samples of beef Longissimus aged for 1, 3, 8 or 16 days were studied by nuclear magnetic resonance microscopy. A multi-echo sequence was used to obtain T2 images, and independent of ageing period, the T2 values were found to be lower in pressure-heat treated meat revealing alterations in water characteristics of pressure-treated, cooked meat compared with cooked meat. With increasing ageing duration, the T2 values in both pressure-treated, cooked and cooked meat decreased indicating that the water became more tightly trapped in the protein network. In addition, independent of length of ageing period the relationship between cooking loss in the cooked meat and transverse relaxation differed between non-pressurised and pressuretreated meat, which reveals that the mechanisms changing the water properties in beef during ageing are different from those occuring during pressure-heat treatment of meat. #

Meat Science, 2004

Using low-field NMR transverse relaxation measurements, the physico-chemical state of water in me... more Using low-field NMR transverse relaxation measurements, the physico-chemical state of water in meat was followed continuously during cooking of 20 uncured and 20 cured pork samples from RN-carriers (n=20) and non-carriers (n=20). The obtained relaxation data were analysed using (i) distributed exponential fitting, and (ii) principal component analysis (PCA). Distributed exponential fitting revealed transition from a system with relatively well-separated components to a less well-defined system with a wide distribution of relaxation times and merged components during cooking. In addition, distributed exponential fitting analysis implied changes in relaxation characteristics that are tentatively ascribed to denaturation of myosin and subsequent shrinkage of the myofibrillar structures. The results are further suggested to reflect formation of new compartments in the myofibrillar lattice during the shrinkage of the existing structures with a succeeding redistribution of water. Nitrite curing was found to affect the distribution of water as well as the progress in the different water populations during cooking. PCA revealed two major shifts in relaxation characteristics around 43 and 56 C in uncured samples and around 43 and 63 C in cured samples, and the shift around 43 C was found to be significantly affected by RN-genotype. The strong shift in water properties around 43 C is suggested to be a result of myosin denaturation, and thus the results imply differences in myosin denaturation in meat from RN-carriers compared with meat from non-carriers. The second shift in water properties is suggested to reflect the onset of collagen shrinkage causing longitudinal shrinkage of meat, and accordingly the shift from 56 to 63 C in the presence of salt points towards an effect of curing on structural alterations during cooking. #

Journal of Agricultural and Food Chemistry, 2008

Independently of the marinade used, the water-binding capacity was improved, cooking loss was red... more Independently of the marinade used, the water-binding capacity was improved, cooking loss was reduced, and the yield was enhanced compared with nonmarinated pork samples. This was also reflected in the water mobility within the samples measured by proton NMR relaxometry. Visualization of samples by confocal laser scanning microscopy (CLSM) revealed salt-dependent microstructural changes in the green pork samples treated with NaHCO 3 , giving rise to nearly complete disintegration of overall structures. High-resolution visualization by atomic force microscopy (AFM) further suggested that a higher cooking loss in sodium chloride-enhanced samples could be ascribed to less solubilization and higher heat-induced protein denaturation compared with phosphate-and bicarbonate-enhanced samples.

Journal of Agricultural and Food Chemistry, 2006

Low-field NMR T 2 and Fourier transform infrared (FT-IR) measurements were performed on meat samp... more Low-field NMR T 2 and Fourier transform infrared (FT-IR) measurements were performed on meat samples of two qualities (normal and high ultimate pH) during cooking from 28°C to 81°C. Pronounced changes in both T 2 relaxation data and FT-IR spectroscopic data were observed during cooking, revealing severe changes in the water properties and structural organization of proteins. The FT-IR data revealed major changes in bands in the amide I region (1700-1600 cm -1 ), and a tentative assignment of these is discussed. Distributed NMR T 2 relaxation data and FT-IR spectra were compared by partial least-squares regression. This revealed a correlation between the FT-IR peaks reflecting -sheet and R-helix structures and the NMR relaxation populations reflecting hydration water (T 2B ∼ 0-10 ms), myofibrillar water (T 21 ∼ 35-50 ms), and also expelled "bulk" water (T 2 relaxation times >1000 ms). Accordingly, the present study demonstrates that definite structural changes in proteins during cooking of meat are associated with simultaneous alterations in the chemical-physical properties of the water within the meat.

Food Quality and Preference, 2003

The study comprised two experiments with the aim to investigate the influence of raw meat quality... more The study comprised two experiments with the aim to investigate the influence of raw meat quality and cooking procedure on cooking loss and juiciness of pork. The first experiment determined the cooking loss at 60, 70 and 80 C centre temperature of 10 raw meat qualities (defined according to ultimate pH, drip loss, breed and rearing conditions) when cooked as steaks on a pan or as a roast in oven at a oven temperature of 90 or 190 C. The differences in cooking loss between the raw meat qualities and the cooking procedures did decrease as the centre temperature increased and were almost negligble at 80 C. Low water holding capacity (WHC) and low pH resulted in high cooking loss while no difference in cooking loss was observed between meat having medium or high WHC and pH. In the second experiment four raw meat qualities (standard, Duroc, low pH and heavy carcass weight) chosen from the first experiment to ensure a wide variation in cooking loss, were cooked in oven at 90 or 190 C oven temperature. Juiciness was assessed three times during the chewing process. The results suggested that juiciness experienced initially in the chewing process depended only on the water content of the meat, whereas juiciness experienced later in the chewing process was determined by a combination of the water and intramuscular fat contents and the saliva production during chewing. #

Journal of Agricultural and Food Chemistry, 2005

This study introduces the use of combined 23Na magnetic resonance imaging (MRI) and 23Na NMR rela... more This study introduces the use of combined 23Na magnetic resonance imaging (MRI) and 23Na NMR relaxometry for the study of meat curing. The diffusion of sodium ions into the meat was measured using 23Na MRI on a 1 kg meat sample brined in 10% w/w NaCl for 3-100 h. Calculations revealed a diffusion coefficient of 1 x 10(-5) cm2/s after 3 h of curing and subsequently decreasing to 8 x 10(-6) cm2/s at longer curing times, suggesting that changes occur in the microscopic structure of the meat during curing. The microscopic mobility and distribution of sodium was measured using 23Na relaxometry. Two sodium populations were observed, and with increasing length of curing time the relaxation times of these changed, reflecting a salt-induced swelling and increase in myofibrillar pore sizes. Accordingly, the present study demonstrated that pore size and thereby salt-induced swelling in meat can be assessed using 23Na relaxometry.