A baseline survey of the microbiological quality of chicken portions and carcasses at retail in two Australian states (2005 to 2006).

Raw poultry products were purchased from the retail market place in two Australian states, New South Wales (n = 549) and South Australia (n = 310). The products sampled on a proportional volume basis were chicken portions with the skin off or skin on, in bulk or tray packs, and whole carcasses. They were collected from butcher shops, supermarkets, and specialty stores from urban areas during the winter (2005) and summer (2006) months. The samples were analyzed to determine the prevalence and concentration of Escherichia coli, Salmonella, and Campylobacter spp. in addition to total viable counts. Salmonella was found in 47.7 and 35.5% of retail chicken samples (35.3 and 21.9% were the less virulent Salmonella Sofia), at mean counts of -1.42 and -1.6 log MPN/cm2 in New South Wales and South Australia, respectively. Campylobacter was found in 87.8 and 93.2% of samples at mean counts of 0.87 and 0.78 log CFU/cm2, respectively. In both states in both seasons, the mean total viable count was 5 log CFU/cm2. On whole birds, E. coli was detected in all winter samples and on 92.9 and 85.7% of summer samples in New South Wales and South Australia, respectively; the log of the geometric mean per square centimeter was 0.5 in winter and slightly lower in summer. On chicken portions, E. coli was detected in around 90% of winter samples in both states, and in summer on 75.1 and 59.6% of samples in New South Wales and South Australia, respectively. The log of the geometric mean CFU per square centimeter for E. coli was 0.75 and 0.91 in winter, and 0.66 and 0.5 in summer in New South Wales and South Australia, respectively.

Autoradiography in mice of tritiated 2-(2-furyl)benzimidazole and melanin-binding in vitro.

The distribution of tritiated 2-(2-furyl)benzimidazole ([3H]FB) in male and pregnant albino mice and male pigmented mice was studied by whole-body autoradiography. The most notable finding was the accumulation of radioactivity in the melanin-containing tissues of the eye, the inner ear and the hair follicles. An additional study in vitro on isolated bovine-eye melanin showed a substantial binding of [3H]FB to the melanin. The general distribution was characterized by a rapid excretion pattern, except for uptake in the thyroid and nasal mucosa. Transfer to fetuses was significant and the fetal distribution was dominated by excretion.

Low voltage electrical stimulation and post-mortem energy metabolism in beef.

In the present study, the influence of low voltage electrical stimulation on glycolysis, concentrations of creatine phosphate and adenine nucleotides, as well as the relationship between metabolic activity and tenderness, was examined in bovine M. longissimus dorsi. During stimulation, about 50% of the creatine phosphate was consumed and the immediate pH drop was, on average, 0·21 units. The increased energy consumption resulted in a decrease in the halftime of ATP from 10 h in non-stimulated muscles to 5 h in electrically stimulated muscles. The total high energy phosphate turnover was found to be 2400 µmol/h/g during stimulation and 18 µmol/h/g immediately following stimulation compared with 9 µmol/h/g for the non-stimulated counterpart. No obvious abnormalities were found in the course of changes during energy metabolism following stimulation, besides the increased metabolic rate. Significant relationships were found between the degradation of several of the energy metabolites during stimulation and improvements in tenderness. It is concluded that, within the variation found in this study, the better the effect of electrical stimulation in increasing the metabolic rate, the better the resulting meat tenderness. Results also showed that the higher the shear force in the non-stimulated part, the better was the effect of electrical stimulation in improving the meat tenderness.

Ultrastructural and biochemical changes in electrically stimulated dark cutting beef.

In dark cutting beef, with a high ultimate pH, ultrastructural and biochemical changes were followed during the very early post-mortem period in non-stimulated and electrically stimulated muscles. The consumption of ATP was extremely rapid in the electrically stimulated dark cutting muscle. In these samples pronounced changes in the ultrastructure were seen in the form of heavy contractions and complete disorganization of the tissue. The changes could have been caused by a combined effect of super-contractions and proteolytic activity. The changes seen in electrically stimulated samples were not reflected in improvements of the instrumentally evaluated tenderness.

Post-mortem metabolism in fresh porcine, ovine and frozen bovine muscle.

Post-mortem metabolism was followed by phosphorus-31-NMR in muscle samples obtained from freshly slaughtered pigs and lambs. Resonances for creatine phosphate (CP), ATP, inorganic phosphate (Pi) and sugar phosphates (SP) could be discerned and the intracellular pH could be determined from the spectra. The rates of post-mortem metabolism varied in the following fashion: porcine muscle > ovine muscle > bovine muscle. However, the course of post-mortem metabolism was, in all cases, the same. CP disappeared first and then ATP. Simultaneously, Pi increased, while SP remained relatively constant. The intracellular pH decreased to pH 5·5 in all tissues. In a separate set of experiments the post-mortem metabolism during thawing was studied in bovine muscles that had been frozen immediately after slaughter. Again, the same course of post-mortem metabolism was observed, but the thaw shortening was accompanied by an extremely rapid post-mortem metabolism, which was more than ten times as fast as that measured for fresh bovine muscles. The intracellular pH decreased from 7·2 to 5·5 in 45 min. This rapid metabolism started only after the sample ha reached 0°C. Resonances for metabolites were broadened in frozen muscles due to the limited motions that are allowed within the ice lattice.

The incidence of dark cutting beef in Sweden.

The incidence of DFD (Dark, Firm, Dry) in Swedish cattle was studied at four abattoirs and the influence of some parameters of special interest for the development of DFD were evaluated. The pH was measured in a total of 2686 carcasses of different categories. Carcasses with a pH(24) ≥ 6·2 were classified as being DFD. Only for electrically stimulated carcasses could the pH(24) be considered to be the ultimate pH value. DFD incidences of 3·4% and 13·2% were recorded as overall means for electrically stimulated and non-stimulated carcasses, respectively. The highest incidence was found in young bull carcasses having almost twice as high an incidence of DFD compared with the other categories. Considering seasonal variations, the highest incidence of DFD was found in the period May to August but significant differences in pH were found only for short lairage times. Overnight lairaging increased the incidence of DFD. However, the influence of the lairage time is closely related to the lairage conditions and needs further study.

Post-mortem energy metabolism in bovine muscles studied by non-invasive phosphorus-31 nuclear magnetic resonance.

Phosphorus-31 Nuclear Magnetic Resonance ((31)P-NMR) has been utilized to follow non-invasively the post-mortem metabolism of the major phosphorylated metabolites in muscles from beef slaughter carcasses. In addition to adenosine-5'-triphosphate (ATP), creatine phosphate (CP) and inorganic phosphate (P(i)) considerable amounts of glucose- and fructose-6-phosphate (G6P and F6P, respectively) as well as glycerol-3-phosphate (Glyc3P) were detected. ATP was mainly present as a Mg(2+)-ATP complex. Adenosine-5'-diphosphate (ADP) appeared to be mainly bound to muscle proteins. A good quantitative agreement was found for the levels of ATP, CP and sugar phosphates (SP) when estimated by NMR or enzymatic assays. Since the chemical shifts of the P(i) and sugar phosphate resonances are a function of the pH, the intracellular pH could be directly deduced from the NMR spectra. Values obtained in this manner were, within the errors of both methods, the same as those determined in iodoacetate/KCl homogenates. The pH gradients within the tissue never exceeded 0.3 pH units. In a final set of experiments we used (31)P-NMR 10 study the effects of electrical stimulation on the intracellular pH and post-mortem metabolism. It was concluded that (31)P-NMR, due to its non-invasive nature plus the fact that some of the NMR parameters are sensitive to the intracellular environment, provides a useful complement to existing methods for the study of post-mortem metabolism.

Harmonisation of food categorisation systems for dietary exposure assessments among European children.

Within the European project called EXPOCHI (Individual Food Consumption Data and Exposure Assessment Studies for Children), 14 different European individual food consumption databases of children were used to conduct harmonised dietary exposure assessments for lead, chromium, selenium and food colours. For this, two food categorisation systems were developed to classify the food consumption data in such a way that these could be linked to occurrence data of the considered compounds. One system served for the exposure calculations of lead, chromium and selenium. The second system was developed for the exposure assessment of food colours. The food categories defined for the lead, chromium and selenium exposure calculations were used as a basis for the food colour categorisation, with adaptations to optimise the linkage with the food colour occurrence data. With this work, an initial impetus was given to make user-friendly food categorisation systems for contaminants and food colours applicable on a pan-European level. However, a set of difficulties were encountered in creating a common food categorisation system for 14 individual food consumption databases that differ in the type and number of foods coded and in level of detail provided about the consumed foods. The work done and the problems encountered in this project can be of interest for future projects in which food consumption data will be collected on a pan-European level and used for common exposure assessments.