Impact of RN genotype and ageing time on colour characteristics of the pork muscles longissimus dorsi and semimembranosus

The effect of RN genotype on pH decline, ultimate pH, pigment content, blooming and colour stability during 6 days of display at 5 °C was studied in two pig muscles, M. longissimus dorsi (LD) and M. semimembranosus (SM), and furthermore the effect of anaerobic storage time (2 days vs. 9 days of ageing) on the same parameters was examined. The postmortem pH decline was faster and the ultimate pH lower in LD and SM of the RN⁻ genotype compared with corresponding muscles from the rn⁺ genotype. Pork of the RN⁻ genotype was initially lighter and more red and yellow than pork of the rn⁺ genotype due to a higher degree of blooming, which might be explained by the faster pH decline and/or lower ultimate pH. The level of oxymyoglobin (MbO₂) was decisive for the redness of both muscles during display in air despite a higher presence of metmyoglobin (MetMb). Pork of the RN⁻ genotype was thus redder than that of the rn⁺ genotype throughout display in air despite higher oxidation to MetMb. Ageing for 9 days in chill improved the blooming potential in pork of both genotypes compared with 2 days of ageing, resulting in superior meat colour. However, only in pork from the RN⁻ genotype, the colour was not negatively affected by ageing time upon display in air.     

De electricitatis catholici musculari - Concerning the electrical properties of muscles, with emphasis on meat quality

This study aims to explore the potential of evoked non-invasive surface electromyography (SEMG) analysis, in predicting meat quality traits in livestock. Evoked SEMG is a system that records, transdermally, electrical signals generated in muscle fibres upon external stimulation. These signals are reported as compound muscle action potentials (CMAP). CMAP parameters of LD correlated negatively and significantly to ultimate pH (pH 24 h) at day 61, but not at day 153 after birth, and a similar albeit positive correlation was observed for muscle glycogen content. Muscle glycogen content and pH 24 h correlated negatively in LD and BF. Negative significant correlations between CMAP parameters and shear force were found in LD at day 153 after birth, which might, in the range of the recording electrodes, reflect the combined effect of large cross-sectional area fibres and reduced perimysium content per unit volume of muscle. The fact that correlations between CMAP characteristics and quality traits of both metabolic and non metabolic origin could be established, warrants a fuller investigation of this method in terms of its potential as a predictive tool for meat quality traits in live animals.     

Biodegradation, bioaccessibility, and genotoxicity of diffuse polycyclic aromatic hydrocarbon (PAH) pollution at a motorway site

Diffuse pollution of surface soil with polycyclic aromatic hydrocarbons (PAHs) is problematic in terms of the large areas and volumes of polluted soil. The levels and effects of diffuse PAH pollution at a motorway site were investigated. Surface soil was sampled with increasing distance from the asphalt pavement and tested for total amounts of PAHs, amounts of bioaccessible PAHs, total bacterial populations, PAH degrader populations, the potential for mineralization of 14C-PAHs, and mutagenicity. Elevated PAH concentrations were found in the samples taken 1-8 m from the pavement. Soil sampled at greater distances (12-24 m) contained only background levels of PAHs. The total bacterial populations (CFU and numbers of 16S rDNA genes) were similar for all soil samples, whereas the microbial degrader populations (culturable PAH degraders and numbers of PAH dioxygenase genes) were most abundant in the most polluted samples close to the pavement. Hydroxypropyl-beta-cyclodextrin extraction of soil PAHs, as a direct estimate of the bioaccessibility, indicated that only 1-5% of the PAHs were accessible to soil bacteria. This low bioaccessibility is suggested to be due to sorption to traffic soot particles. The increased PAH level close to the pavement was reflected in slightly increased mutagenic activity (1 m, 0.32 +/- 0.08 revertants g(-1) soil; background/ 24 m: 0.08 +/- 0.04), determined by the Salmonella/ microsome assay of total extractable PAHs activated by liver enzymes. The potential for lighter molecular weight PAH degradation in combination with low bioaccessibility of heavier PAHs is proposed to lead to a likely increase in concentration of heavier PAHs over time. These residues are, however, likely to be of low biological significance.     

Real-time PCR quantification of the AM-toxin gene and HPLC qualification of toxigenic metabolites from Alternaria species from apples

Some Alternaria species are able to produce plant pathogenic as well as toxic metabolites. In both agriculture and the food industry it is important know if toxigenic Alternaria are present to rapidly employ the correct corrective actions. The purpose of this work was to establish a real-time PCR method, which can detect and quantify apple pathogenic and toxigenic Alternaria. An AM-toxin I primer set, which could recognize Alternaria DNA only, was designed by using primers complementary to the AM-toxin I gene. The method could detect small amounts of DNA (4 pg) and still obtain a large dynamic range (4 decades) without interference from apple material. Eight Alternaria isolates were analyzed for the presence of AM-toxin I gene and their production of secondary metabolites. Then analyses showed that all eight isolates contained the AM toxin gene and were able to produce the plant pathogenic tentoxin in addition to AM toxin I. The analyses also showed the production of tenuazonic acid, alternariols, Altenuene, altenusin and/or altertoxin I in pure culture. Analyses of inoculated apples showed that both the AM-toxin gene and alternariol monomethyl ether could be detected. Morphological analyses suggested that the eight Alternaria strains, though they all carried the AM toxin genes, probably belong to different but closely related un-described Alternaria taxa in the A. tenuissima species-group based on morphological and chemical differences.     

Post mortem energy metabolism and meat quality of porcine M. longissimus dorsi as influenced by stunning method - A (31)P NMR spectroscopic study

Post mortem changes in phosphorus metabolites and pH were studied in M. longissimus dorsi from pigs (n=10) stunned either by CO(2) (n=3), electrical (n=2), captive bolt pistol (n=2) or by anesthesia (ketamine) (n=3). (31)P-NMR spectroscopy revealed significant effects of stunning method on changes of the various phosphorus metabolites in the muscle post mortem, with the effect being most pronounced on the degradation of phosphocreatine (PCr). Moreover, the four stunning methods gave rise to large differences in the progress of pH as determined by (31)P-NMR spectroscopy. Using anesthesia as the reference showed that the captive bolt pistol caused the highest rates of post mortem degradation of phosphorus metabolites, electrical stunning intermediate, and CO(2)-stunning causing the lowest post mortem degradation rates, even though CO(2)-stunning also was associated with higher post mortem degradation rates compared with anesthesia. Finally, it was demonstrated that the water-holding capacity (WHC) of the meat was affected by the applied stunning method, as CO(2)-stunning, electrical stunning and captive bolt pistol resulted in mean drip losses of 6.4, 8.3 and 8.6%, respectively (P=0.02). The result displays the significance of induction and progress in post mortem changes on WHC in meat.     

Isolation of adipophilin and butyrophilin from bovine milk and characterization of a cDNA encoding adipophilin

The milk fat globule membrane-associated proteins adipophilin (alias adipocyte differentiation-related protein) and butyrophilin were purified from bovine milk by reverse-phase chromatography. The nucleotide sequence of bovine adipophilin was obtained via peptide mapping and sequencing of a mammary gland cDNA clone, which comprises 1841 nucleotides and has an open reading frame of 450 amino acids. By peptide mapping, 19% of the amino acid sequence was confirmed. The obtained amino acid sequence has 87 and 80% identical residues with human and mouse adipophilin, respectively. Alignment with the proteins perilipin and TIP47 revealed two highly conserved segments, which may assemble into amphipathic alpha-helices.     

Egg Consumption Modulates HDL Lipid Composition and Increases the Cholesterol-Accepting Capacity of Serum in Metabolic Syndrome

We recently demonstrated that daily whole egg consumption during moderate carbohydrate restriction leads to greater increases in plasma HDL-cholesterol (HDL-C) and improvements in HDL profiles in metabolic syndrome (MetS) when compared to intake of a yolk-free egg substitute. We further investigated the effects of this intervention on HDL composition and function, hypothesizing that the phospholipid species present in egg yolk modulate HDL lipid composition to increase the cholesterol-accepting capacity of subject serum. Men and women classified with MetS were randomly assigned to consume either three whole eggs (EGG, n = 20) per day or the equivalent amount of egg substitute (SUB, n = 17) throughout a 12-week moderate carbohydrate-restricted (25–30 % of energy) diet. Relative to other HDL lipids, HDL-cholesteryl ester content increased in all subjects, with greater increases in the SUB group. Further, HDL-triacylglycerol content was reduced in EGG group subjects with normal baseline plasma HDL-C, resulting in increases in HDL-CE/TAG ratios in both groups. Phospholipid analysis by mass spectrometry revealed that HDL became enriched in phosphatidylethanolamine in the EGG group, and that EGG group HDL better reflected sphingomyelin species present in the whole egg product at week 12 compared to baseline. Further, macrophage cholesterol efflux to EGG subject serum increased from baseline to week 12, whereas no changes were observed in the SUB group. Together, these findings suggest that daily egg consumption promotes favorable shifts in HDL lipid composition and function beyond increasing plasma HDL-C in MetS.     

Zur Bestimmung des Milchfettes

Ohne Zusammenfassung     

The effect of superplasticizers and air-entraining agents on the Zeta potential of cement particles

The effect of superplasticizers and air-entraining agents on the Zeta Potential (ZP) of a Portland cement was studied by microelectrophoresis. The purpose of the experiments was to investigate the adsorption mechanism of electronegative polymers and surface-active agents, and the interaction between these when added in combination. As a preliminary experiment the microelectrophoresis technique was investigated in order to obtain the most precise and reproducible method of measuring Zeta Potentials. The results show that the superplasticizer type with the longer polymer chain and thereby the largest amount of electronegative charges per chain gives the highest negative Zeta Potential. This is interpreted as indicating that this type of superplasticizer has a higher dispersing capability. Data from dosage of air-entraining agents show that a part of the air-entraining effect is due to the fact that the molecules are adsorbed on the cement surface, thereby making it hydrophobic. The results of combined use of superplasticizers and air-entraining agents show that only a slightly smaller ZP is obtained than when a superplasticizer is dosed alone, which however still indicates an interaction. Finally the ZP has been determined of cement alone.