Nitrite and nitrate content in meat products and estimated intake in Denmark from 1998 to 2006

The content of nitrite and nitrate in cured meat products has been monitored in Denmark seven times between 1995 and 2006. The maximum permitted added amounts of sodium nitrite in Denmark (60 mg kg(-1) for most products up to 150 mg kg(-1) for special products) have not been exceeded, except for a few samples back in 2002. The intake, mean and intake distribution of sodium nitrite have been calculated from 1998 to 2006 with data from the Danish dietary survey conducted in 2000-02 on Danes from four to 75 years of age. The amounts used by industry have been relatively stable through the whole period with levels varying between 6 and 20 mg sodium nitrite kg(-1) with sausages, meat for open sandwiches and salami-type sausages being the greatest contributors. The mean intake of sodium nitrate was around 1 mg day(-1), which is very low compared with the total intake of 61 mg day(-1). The mean intake of sodium nitrite was 0.017 and 0.014, 0.009 and 0.008, and 0.007 and 0.003 mg kg(-1) body weight day(-1) for men and women in the age groups 4-5, 6-14 and 15-75 years, respectively, which was much lower than the acceptable daily intake (ADI) of 0.09 mg kg(-1) body weight day(-1). The 99th percentile for the group of 4-year-olds was 0.107 and 0.123 mg kg(-1) body weight day(-1) for boys and girls, respectively, and the 95th percentile was 0.057 and 0.073 mg kg(-1) body weight day(-1) for boys and girls, respectively, highest for the girls. With fewer than 100 boys and girls in the 4-5-year age group, only very few persons were responsible for the high intake. The conversion of nitrate to nitrite in the saliva and the degradation of nitrite during production and storage must also be considered when evaluating the intake of nitrite.     

Characterization of volatiles from cultured dairy spreads during storage by dynamic headspace GC/MS

The effect of storage time and storage temperature on the formation of volatile compounds in dairy spreads was investigated. Dairy spreads were stored for 10 weeks at -18, 5 and 20 °C, respectively, and analyzed after 0, 38, 54 and 67 days of storage. By means of a dynamic headspace GC/MS method using Tenax traps the dairy spreads were analyzed for volatile aromatic compounds. 61 components were identified and their relative content was followed during the storage period. Among these were four alcohols, 17 aldehydes, four esters, ten alkanes, 11 ketones and six lactones. A general increase in the concentration of most of the volatile compounds during storage was found. The content of volatile compounds in dairy spreads stored at -18 °C was nearly constant or showed a rather low increase in the content during the storage period. Storage at higher temperatures (5 and 20 °C) resulted in an increase in the content of most of the volatiles after 40 days of storage. The profiles obtained were subjected to multivariate data analysis to determine the volatiles potentially responsible for oxidized off-flavors in dairy spread. The volatiles were divided into three groups: one correlated with storage temperature and 5 °C, one with storage time and 20 °C and the last with storage time alone. Most of the volatiles were found in the highest concentration after storage at 20 °C, but the content of some volatiles was highest after storage at 5 °C.     

A longitudinal observational study of the dynamics of Mycoplasma bovis antibodies in naturally exposed and diseased dairy cows

Mycoplasma bovis is an important pathogen causing disease and substantial economic losses in cattle. However, knowledge of the dynamics of antibody responses in individual cows in the face of an outbreak is currently extremely limited. The use of commercial antibody tests to support clinical decision-making and for surveillance purposes is therefore challenging. Our objective was to describe the dynamics of M. bovis antibody responses in 4 Danish dairy herds experiencing an acute outbreak of M. bovis-associated disease, and to compare the antibody dynamics between dairy cows with different disease manifestations. A total of 120 cows were examined using a standardized clinical protocol and categorized into 4 disease groups: “mastitis,” “systemic,” “nonspecific,” and “none.” Paired blood and milk samples were collected and tested using a commercial M. bovis antibody–detecting ELISA. Plots of raw data and generalized additive mixed models with cow and herd as random effects were used to describe serum and milk antibody dynamics relative to the estimated time of onset of clinical disease. Cows with mastitis had high optical density measurement (ODC%) of antibodies in both milk and serum at disease onset. The estimated mean ODC% in milk was below the manufacturer's cut-off for the other groups for the entire study period. The estimated mean serum ODC% in the “systemic” group was high at onset of disease and stayed above the cut-off until 65 d after disease onset. However, the lower 95% confidence interval (CI) for the mean ODC% was only above the manufacturer's cut-off between 7 and 17 d after onset of disease. The CI of the “systemic” and “none” groups did not overlap at any time between the day of disease onset and 65 d after disease onset, and the estimated mean ODC% for both the “nonspecific” and “none” groups were generally below the cut-off for the majority of the study period. In conclusion, the serum antibody responses were highly dynamic and showed a high level of variation between individual cows. This strongly suggests that serology is unlikely to be useful for individual diagnosis of M. bovis-associated disease in dairy cows. However, it might still be useful for herd- or group-level diagnosis. Antibodies in milk were only increased in cows with M. bovis mastitis, indicating that milk antibody measurements only have diagnostic utility for cows with mastitis.     

Nonlinear analysis of reinforced concrete

This paper discusses the development of two different computer programs for nonlinear analysis of reinforced concrete structures.The first program handles plane stress problems. Flow theory of plasticity is used in the modelling of concrete and reinforcement. General four-noded quadrilateral elements with selective sampling of strain are used in the discretization.The second program is developed for analysis of plates and shells. Endochronic theory is used in the constitutive law for concrete whereas an overlay model is utilized for the reinforcement. Geometric nonlinearities are accounted for through updating of coordinates for the triangular shell elements.Several examples of applications of the two programs are given. The plane stress program is used for analysis of a beam and two different corbels, while the shell program has been applied to a square plate and a shell with geometric nonlinearities.     

Calculation of turbulent three-dimensional jet induced flow in rectangular enclosures

Numerical calculations are presented for two jet induced three-dimensional flows in rectangular enclosures. The computation method uses the three velocity components and pressure as primary variables. Turbulence is modeled by a two-equation model, which incorporates governing equations for kinetic energy of turbulence and its rate dissipation. Results are compared with available velocity data. Comparisons between measured and predicted results are in general good, although some discrepancies are found. Predicted fields of both mean and isotropic turbulence velocities are shown for both cases.     

Serum concentrations of polyfluoroalkyl compounds in Faroese whale meat consumers

To learn the extent of human exposure to polyfluoroalkyl compounds (PFCs) in a remote fishing population, we measured, in Faroese children and pregnant women, the serum concentrations of nine PFCs, including perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorononanoate (PFNA), by using online solid-phase extraction coupled to isotope dilution high-performance liquid chromatography-tandem mass spectrometry. The serum samples analyzed had been collected between 1993 and 2005 from 103 children 7 years of age, 79 of these children at 14 years of age, and from 12 pregnant women and their children 5 years later. PFOS was detected in all samples analyzed, and both PFOA and PFNA were detected in all but one of the samples. The concentrations found are comparable tothose reported elsewhere. Correlations between paired concentrations were poor. However, PFOS and PFNA concentrations correlated well with the frequency of pilotwhale dinners and with concentrations of mercury and polychlorinated biphenyls. One whale meal every two weeks increased the PFOS concentration in 14-year-olds by about 25% and PFNA by 50%. The high frequency of detection of most PFCs suggests widespread exposure in the Faroe Islands already by the early 1990s, with whale meat being an important source.     

Lactobacillus plantarum inhibits growth of Listeria monocytogenes in an in vitro continuous flow gut model, but promotes invasion of L. monocytogenes in the gut of gnotobiotic rats

The ability of the pediocin AcH producing Lactobacillus plantarum DDEN 11007 and its non-producing plasmid-cured isogenic variant, DDEN 12305 to prevent the persistence and growth of Listeria monocytogenes EP2 in two gastrointestinal (GI) tract models was examined. In vitro studies conducted in a two-stage continuous flow system showed that L. plantarum DDEN 11007 inhibited L. monocytogenes EP2 under these conditions, while less effect was seen of the non-bacteriocin producing variant. The inhibitory effect was more pronounced at pH 5 than at pH 7. No effect on persistence of L. monocytogenes in the GI tract was seen in gnotobiotic rats colonized with either the pediocin AcH producing or the non-bacteriocin producing variant of L. plantarum when compared to rats inoculated with L. monocytogenes EP2 alone. Surprisingly, inoculation of the gnotobiotic animals with either of the L. plantarum strains prior to inoculation with L. monocytogenes EP2 resulted in increased occurrence of L. monocytogenes in liver and spleen when compared to the animals inoculated with L. monocytogenes EP2 alone. Our results indicate that the presence of L. plantarum in the gut of gnotobiotes facilitates L. monocytogenes invasion by an unknown mechanism. This observation is however not necessarily specifically related to L. plantarum, and should not be interpreted as the expected effect in animals carrying a conventional intestinal microflora.     

Effects of dietary α-tocopheryl acetate supplementation on α-tocopherol deposition in porcine m. psoas major and m. longissimus dorsi and on drip loss, colour stability and oxidative stability of pork meat

The effect of feeding supra-nutritional levels of α-tocopheryl acetate on its deposition in two porcine muscles of different metabolic rates (m. longissimus dorsi and m. psoas major) and the effect on meat quality (lipid oxidation, colour stability and drip loss) was studied. Pigs were fed a standard diet supplemented with three levels: 100, 200 and 700 mg/kg of α-tocopheryl acetate from the time of weaning to slaughter at 90kg live weight. Muscle α-tocopherol levels were linearly related to the logarithm of dietary α-tocopheryl acetate supplementation and the linear relationship was estimated for the two muscles. The levels of α-tocopherol in the two muscles differed by a parallel displacement with consistently higher α-tocopherol levels in m. psoas major compared to m. longissimus dorsi. Dietary α-tocopheryl acetate supplementation significantly reduced lipid oxidation as measured by thiobarbituric acid reactive substances (TBARS) in both raw and cooked meat during storage at 4 °C for 6 days. Drip loss and colour stability of raw muscles were not affected by dietary α-tocopheryl acetate levels, 100mg α-tocopheryl acetate/ kg feed resulted in sufficient α-tocopherol levels in muscles to ensure minimum drip loss and optimum colour stability.     

The occurrence of Staphylococcus aureus on a farm with small-scale production of raw milk cheese

In recent years, the small-scale production of raw milk products has increased in Norway, and there is some concern that such foods may pose a risk of staphylococcal food poisoning to consumers. The aim of the study was to evaluate potential sources of contamination of raw milk cheese with Staphylococcus aureus on a bovine dairy farm with small-scale production. Samples for bacteriological analyses (n = 144) were collected from the animals, the environment, processing equipments, from humans, and from cheeses at various stages of production. Staphylococcus aureus was isolated from 10 of 11 cows, the farmer, equipment, the environment, and the cheese. Seventy-five Staph. aureus isolates were genotyped by pulsed-field gel electrophoresis, tested for enterotoxin (SE) production by reversed passive latex agglutination, for SE genes by multiplex polymerase chain reaction, and for penicillin resistance by the cloverleaf method. Five different pulsotypes were identified and SE gene fragments were identified in 11 isolates, but no isolates produced SE or were penicillin resistant. Staphylococcus aureus was found throughout the farm, and appeared to be spread with the milk to the environment, equipment, and to products. One pulsotype dominated and was identified from most sample sites on the farm. Raw milk products are vulnerable to contamination with Staph. aureus. Strategies to reduce the occurrence of Staph. aureus in bulk milk are of particular importance on farms where milk is used for raw milk products.