Extent of dark-cutting in beef carcasses graded Canada B4.

Recovering value from dark cutting carcasses (Canada B4) was investigated by examining twelve muscles in the loin, fore- and hindquarters of atypical (AT, pH < 5.8), borderline (BD, 5.8 < pH < 6.0) and classic (CL, pH > 6.0) dark cutting carcasses. Subjective and objective colour, purge loss, and colour stability were measured over 4 days of retail display. Forequarter muscles from all dark cutting carcasses were not different from those of normal Canada AA carcasses, suggesting that forequarter muscles may be preferentially harvested for sale through normal retail outlets. None of the adductor, biceps femoris, gluteus medius, and semitendinosus muscles in the AT carcasses were dark and all had retail display colour stability comparable to that of normal steaks, indicating that these muscles in these carcasses are undervalued. Sorting of dark cutting carcasses by longissimus thoracis pH or a* and b* values will allow for value to be recovered from atypical dark cutting carcasses.

Man-made radionuclides confirm rapid burial of kepone in james river sediments.

Profiles of man-made radionuclides in sediment cores from the James River estuary confirm the rapid burial of the pesticide Kepone. The greatest deposition of Kepone has occurred in zones characterized by very high sedimentation rates, 10 to 20 centimeters per year. Since sediment is the major Kepone reservoir, rapid burial probably reduces the exposure of organisms to further contamination. Disturbance caused by hurricanes or dredging, however, could return highly contaminated sediment to the surface although this sediment would be diluted with less contaminated particles.

Understanding the quality of typical and atypical dark cutting beef from heifers and steers.

Dark cutting beef with pH <6.0 may have glucidic potential approaching that of normal beef but has increased toughness that may also be influenced by cattle sex and carcass characteristics. Beef longissimus thoracis (LT) from normal (Canada AA; n=24), and typical (TB4; pH>5.9, n=20) and atypical (AB4; pH<5.9, n=20) dark cutting carcasses were analyzed to investigate relationships between beef quality, pH, glucidic potential and carcass characteristics. Results indicated that reduced lactate and glucidic potential were accompanied by increased pH and reduced L*, a* and b* values. Mean glucidic potential was lowest (P<0.0001) for TB4 whereas glucidic potentials for heifers and steers AB4 LT were sufficient to attain normal pH, substantiating the existence of atypical dark cutting. Warner-Bratzler shear force of AB4 remained higher (P<0.05) than that of Canada AA LT confirming AB4 as the toughest beef irrespective of sex and carcass characteristics.

Control Points To Reduce Movement of Central Nervous System Tissue during Beef Slaughter.

Consumption of central nervous system tissue (CNST) from cattle with bovine spongiform encephalopathy (BSE) is thought to cause the human neurological disease, variant Creutzfeldt-Jacob disease. To identify points of cross-contamination of beef carcasses with CNST, 55 young beef cattle were slaughtered and processed through a federally inspected multispecies abattoir. The objectives of this study were to evaluate CNST spread following the placement of a plug in the penetration site of the skull after captive bolt stunning, to evaluate cross-contamination of carcasses before and after splitting, to compare the effects of hot water pasteurization (84°C for 10 s) versus cold water wash (10°C for 30 s) for reducing CNST on the carcass, and to examine other possible sources of cross-contamination in the abattoir. Results indicated that the use of a plastic plug reduced CNST contamination near the bolt penetration site. This study also confirmed that carcass splitting resulted in an increase in CNST contamination at various areas of the carcass. Hot water pasteurization appeared to be an effective means of removing CNST contamination from carcasses in most of the areas sampled.

Unexpectedly high radioactivity burdens in ice-rafted sediments from the Canadian Arctic Archipelago.

Unexpectedly high specific activities of (137)Cs (1800-2000 Bq kg(-1) dry weight) have been detected in fine-grained sediments entrained in multi-year sea ice floes grounded in Resolute Bay near the center of the Northwest Passage through the Canadian Arctic Archipelago. These results are remarkable because: (1) the specific activities are about two orders of magnitude higher than average specific activities detected in previous studies of sea ice rafted sediments from the Arctic Ocean, (2) two independent observations of these unexpectedly high specific activities were made several years apart, (3) the sampling site is on the opposite side of the Arctic basin from potential radioactive sources such as disposal and weapons testing sites of the former Soviet Union and nuclear fuel reprocessing sites in western Europe, and (4) the closest compositional match to known geologic source regions is Banks Island, on the western edge of the Arctic Archipelago, although a smaller number of grains from one of the two samples were mineralogically matched to sediments in the Laptev Sea. Consequently, the sediments are probably not from a single distinct source and were likely mixed during sea ice transport. Coupled with previous observations of higher radionuclide specific activities in some sea ice rafted sediments relative to bottom sediments, these new observations indicate that comparatively high as well as variable radioactive contaminant burdens in ice rafted sediments must be common and geographically independent of proximity to known contaminant sources. The mechanisms that would facilitate these unexpected high radionuclide burdens in sea ice are not known and require additional study, as well as investigations of the implications for the transport and fate of contaminants in Arctic sea ice.

Rapid discrimination of enhanced quality pork by visible and near infrared spectroscopy.

This study tested the ability of visible and near infrared spectroscopy (Vis-NIRS) to discriminate enhanced quality pork. Vis-NIR spectra were collected on intact chops from 148 pork carcasses using a portable LabSpec®4 spectrometer (350-2500 nm). Partial least squares discriminant analyses based on Vis-NIR spectra correctly classified 94, 95 and 100% of the 2d, and 95, 98 and 100% of the 14 d aged pork samples within Lacombe, Duroc and Iberian pig breeds, respectively. Moreover, Vis-NIRS correctly classified 97 and 99% of the moisture enhanced (ME) and Non-ME pork samples aged for 2d, and 94 and 95% of those aged for 14 d, as well as 94 and 97% of the 2 and 14 d aged pork samples, respectively. Conversely, Vis-NIRS technology could not differentiate pork samples based on pre-slaughter diet or post-slaughter carcass chilling process. Vis-NIRS can segregate enhanced quality pork according to production factors and post-mortem strategies such as pig breed, moisture enhancing and ageing period.

Effects of diets supplemented with sunflower or flax seeds on quality and fatty acid profile of hamburgers made with perirenal or subcutaneous fat.

Steers were fed grass hay or red clover silage based diets containing flaxseed or sunflower seed as sources of 18:3n-3 and 18:2n-6 respectively. Hamburgers were made from triceps brachii and perirenal or subcutaneous fat. Perirenal-hamburgers contained more polyunsaturated fatty acids (PUFA), several PUFA biohydrogenation intermediates (BHI), and 18:0 (P<0.05). Oxidative stability was similar across hamburgers (P>0.05). Sensory differences were found due to hamburger fat source, but were < one panel unit. Within perirenal-hamburgers, feeding flaxseed increased 18:3n-3 and its BHI (P<0.05), and feeding sunflower seed increased 18:2n-6 and its BHI (P<0.05). Feeding flaxseed increased off-flavour intensity and oxidation in perirenal-hamburgers (P<0.05). Feeding oilseeds in forage based diets while using perirenal fat to make hamburgers provides opportunities to increase PUFA and BHI with potential to impact human health, but control measures need to be explored to limit oxidation and off-flavours when feeding flaxseed.

Influence of hydrological and geochemical processes on the transport of chelated metals and chromate in fractured shale bedrock.

Field-scale processes governing the transport of chelated radionuclides in groundwater remain conceptually unclear for highly structured, heterogeneous environments. The objectives of this research were to provide an improved understanding and predictive capability of the hydrological and geochemical mechanisms that control the transport behavior of chelated radionuclides and metals in anoxic subsurface environments that are complicated by fracture flow and matrix diffusion. Our approach involved a long-term, steady-state natural gradient field experiment where nonreactive Br- and reactive 57Co(II)EDTA2- 109CdEDTA2-, and 51Cr(VI) were injected into a fracture zone of a contaminated fractured shale bedrock. The spatial and temporal distribution of the tracer and solutes was monitored for 500 days using an array of groundwater sampling wells instrumented within the fast-flowing fracture regime and a slower flowing matrix regime. The tracers were preferentially transported along strike-parallel fractures coupled with the slow diffusion of significant tracer mass into the bedrock matrix. The chelated radionuclides and metals were significantly retarded by the solid phase with the mechanisms of retardation largely due to redox reactions and sorption coupled with mineral-induced chelate-radionuclide dissociation. The formation of significant Fe(III)EDTA byproduct that accompanied the dissociation of the radionuclide-chelate complexes was believed to be the result of surface interactions with biotite which was the only Fe(III)-bearing mineral phase present in these Fe-reducing environments. These results counter current conceptual models that suggest chelated contaminants move conservatively through Fe-reducing environments since they are devoid of Fe-oxyhydroxides that are known to aggressively compete for chelates in oxic regimes. Modeling results further demonstrated that chelate-radionuclide dissociation reactions were most prevalent along fractures where accelerated weathering processes are expected to expose more primary minerals than the surrounding rock matrix. The findings of this study suggest that physical retardation mechanisms (i.e. diffusion) are dominant within the matrix regime, whereas geochemical retardation mechanisms are dominant within the fracture regime.

Calibration of a portable intrinsic Ge gamma-ray detector using point sources and testing for field applications.

A simple procedure using point sources is described for the calibration of portable high-resolution gamma-ray detectors used in field surveys. The point source data are fitted by empirical equations that are used to calculate efficiency for field applications. Two models for the distribution of radionuclides are treated: a thin surface-film model and a vertically homogeneous model. The success of the procedure has been demonstrated by field applications in plots where the levels of contamination are known.

Discovery of a 137Cs hot particle in municipal wastewater treatment sludge.

Analysis of primary treatment sludge from a municipal wastewater treatment plant revealed elevated 137Cs concentrations in one sample. This elevated activity was associated with a radioactive particle that, when isolated and quantified, was found to contain 1.82 kBq of 137Cs. Additional analysis indicated an absence of alpha activity, and energetic beta radiation, if present, was less than the 137Cs activity. The particle was approximately 50 microns in diameter, appeared not to be an aggregate, and was nonmetallic.

Pestivirus infections in Norway. Serological investigations in cattle, sheep and pigs.

Serum samples from 1,133 dairy cows (187 herds), 3,712 ewes (103 flocks) and 1,317 adult pigs (877 herds), were tested for neutralizing antibodies against the NADL strain of bovine virus diarrhoea virus. The prevalence rate of seropositive animals was 18.5% in cattle, 4.5% in sheep and 2.2% in pigs, such seroreactors being found in 28% of the cattle herds and 18% of the sheep flocks. In all three species the rate showed considerable herd and geographical variation. In cattle the seroreactor rate was similar in herds with normal reproduction and in 62 herds with problems of repeat breeding. Of 31 pig sera containing antibodies against the NADL strain, 27 were also positive in a neutralization test for antibodies against swine fever virus (Baker strain). However, all sera showed a higher titre of antibodies against the bovine strain than against the swine fever virus. It was concluded that the immune response of the pigs had been induced by ruminant pestivirus, and not by swine fever virus.

The impact of ultimate pH on muscle characteristics and sensory attributes of the longissimus thoracis within the dark cutting (Canada B4) beef carcass grade.

Canada B4 beef carcasses are penalized because the longissimus thoracis (LT) at the grade site (12-13th ribs) is darker than the color threshold for normal bright cherry-red beef. Previous studies have shown that not all B4 carcasses have pH>6.0; therefore, the relationship between LT pH and meat quality was investigated by collecting thirty half-carcasses comprised of the following: ten Canada AA (AA, control), ten B4 with LT pH>6.0 (CL, classic), and ten B4 with LT pH<6.0 (AT, atypical). LT from CL carcasses had the lowest mean lactate level, lowest glucidic potential and highest mean pH value. LT muscle from CL and AT carcasses was dark and had decreased purge, drip loss and cooking loss. Warner-Bratzler shear force values and sensory panel results showed that AT beef was toughest (P<0.0001), substantiating economic penalty. Causal mechanisms for AT carcasses may be inconsistent with traditional DFD theory because of close to normal final muscle pH.

Contribution of myofibrillar and connective tissue components to the Warner-Bratzler shear force of cooked beef.

Myofibrillar (MF-SF) and connective tissue (CT-SF) peak shear forces were interpolated from Warner-Bratzler shear force (SF) deformation curves of cooked bovine M. gluteus medius (GM) and M. semitendinosus (ST) from 112 crossbred steers in a 2×2×2 factorial experiment examining the interactions between slaughter age, growth promotants and breed cross (British versus Continental). Mixed model analyses, Pearson correlations and stepwise multiple regression identified relationships between shear forces, meat quality measurements and production treatments. Connective tissue contribution to SF increased with slaughter age and implantation in the ST and with slaughter age only in the GM. Myofibrillar contribution to SF increased with slaughter age for the ST and with Continental genetics for the GM. Variation in ST SF and MF-SF was best described by muscle weight, which increased with animal age, while GM SF and MF-SF variation was best described by cooking loss, indicating that ST and GM SF were most affected by connective and myofibrillar proteins, respectively.

Quantifying the relative contribution of ante- and post-mortem factors to the variability in beef texture.

This study aims to investigate the relative contribution of ante- and post-mortem factors to the final quality of beef. In all, 112 steers (four breed-crosses) were arranged in a 2 × 2 × 2 factorial experimental including production system, growth implant and ß-adrenergic agonist strategies. Carcasses were suspended by the Achilles tendon or the aitch bone and meat was aged for 2/6/13/21/27 days (longissimus muscle) or 2/27 days (semimembranosus muscle). Meat quality traits related to beef texture were measured. Statistical analyses were developed including ante- and post-mortem factors and their relative contribution to the variability observed for each measured trait was calculated. The main factor responsible for the variability in sarcomere length was the suspension method (91.1%), which also influenced drip-loss (44.3%). Increasing the percentage of British breeds increased (P < 0.05) the intramuscular fat content in longissimus muscle, but only when implants were not used. Thus, the breed-cross, implant strategy and their interaction were responsible for >58% of the variability in this trait. The variability in instrumental and sensory tenderness was mainly affected by post-mortem factors (carcass suspension, ageing time and their interaction), explaining generally ∼70% of the variability in these traits. Breed-cross was the second most important effect (∼15%) when carcass suspension was not considered in the model, but still ageing time was responsible for a much larger proportion of the variability in tenderness (>45%). In conclusion, post-mortem handling of the carcasses may be much more effective in controlling beef tenderness than pre-mortem strategies.