Impact of transportation and lairage on hide contamination with Escherichia coli O157 in finished beef cattle

Transportation of cattle from the feedlot to the slaughter plant could influence hide contamination of Escherichia coli O157. A study was initiated to investigate the influence of transportation and lairage on shedding and hide contamination of E. coli O157. Fecal and hide samples were obtained from 40 pens of harvest-ready beef cattle at the feedlot prior to transport and again at the slaughter plant immediately after slaughter. Potential risk factors for hide contamination at the feedlot, during transport, and at slaughter were evaluated. A multilevel Poisson regression model was used to evaluate if transportation and lairage were associated with hide contamination by E. coli O157 in finished beef cattle. Lots of cattle held in E. coli O157-positive lairage pens had eight times greater risk of having positive slaughter hide samples compared with cattle held in culture-negative pens (relative risk, 8.0; 95% confidence interval, 1.6 to 38.8). Lots of cattle that were held in lairage pens contaminated with feces had three times greater risk for positive slaughter hide samples compared with cattle held in clean pens (relative risk, 3.1; 95% confidence interval, 1.2 to 7.9). Lots of cattle that were transported for long distances (> 160.9 km) had twice the risk of having positive hide samples at slaughter compared with cattle transported a shorter distance (relative risk, 2.4; 95% confidence interval, 1.1 to 5.1). These findings suggest that transportation and lairage should be considered in E. coli O157 control strategies.     

Studies to evaluate chemicals and conditions with low-pressure applications for reducing microbial counts on cattle hides

Studies were conducted to identify effective antimicrobials and application parameters that could be used as decontamination interventions to reduce microbial loads on cattle hides before removal from carcasses. In study I, hide swatches inoculated with Escherichia coli O157:H7 were sprayed with 10% acetic acid (at 23 and 55 degrees C), 10% lactic acid (at 23 and 55 degrees C), 3% sodium hydroxide (at 23 degrees C) or 4 and 5% sodium metasilicate (at 23 degrees C). All antimicrobials were evaluated independently after being applied alone, being applied after a water rinse, or being followed by a water rinse. Antimicrobial treatments followed by a water rinse lowered E. coli O157:H7 populations by 0.6 to 2.4 log CFU/cm2 and resulted in hides with a surface pH of 6.3 to 9.2. Treatments in which a water rinse was followed by antimicrobial application lowered E. coli O157:H7 populations by 1.5 to 5.1 log CFU/cm2 but resulted in hides with a surface pH of 3.9 to 10.5. In study II, whole hides were treated with one of four antimicrobials (acetic acid, lactic acid, sodium hydroxide, or sodium metasilicate) followed by a water rinse. Hides were evaluated for aerobic bacterial counts, total coliform counts, and E. coli counts. Generally, all antimicrobials resulted in greater reductions (P < 0.05) of E. coli counts when compared with the control; however, only acetic and lactic acids resulted in greater reductions (P < 0.05) of aerobic bacterial counts and total coliform counts compared with the controls. These antimicrobials could be used to reduce microbial contamination on hides, potentially reducing microbiological contamination transferred to carcasses or to the plant environment.     

Determination of sensory, chemical and cooking characteristics of retail beef cuts differing in intramuscular and external fat

Top loin (TLS), top sirloin (TSS), and eye of round (EYS) steaks, and loin end (LRR) and blade end (BRR) rib, and eye of round (EYR) roasts were used to determine the effect of USDA quality grade, Choice or Select, external fat trim level, and internal temperature endpoint on sensory, chemical and cooking characteristics. Cuts cooked with external fat required slightly greater cooking times and had higher fat content in the lean than cuts cooked without external fat (p < 0.05). Regardless of quality grade or external fat trim, increasing internal temperature endpoint resulted in tougher, drier cuts with longer cooking times and greater cooking loss (p < 0.05). Choice TLS, TSS and LRR were higher (p < 0.05) in palatability than Select, but quality grade did not affect palatability of BRR, EYS or EYR.     

RHEED and STM study of the two-dimensional growth of InAs on GaAs (111)A

Reflection high-energy electron diffraction and scanning tunneling microscopy have been used to study the growth of InAs on GaAs (111)A by molecular beam epitaxy. In contrast to the 3-D growth mode observed for InAs on GaAs (001), there is no evidence for 3-D island formation on the (111)A surface. The precise control of the 2-D growth of InAs layers makes it possible to probe the early stages of strain relaxation by imaging misfit dislocations by STM. The band gap and position of the surface Fermi level of ultra-thin InAs films on GaAs (111)A have also been obtained by scanning tunneling spectroscopy as a function of InAs thickness. The band gap of InAs is established after about 10 MLs of InAs and an accumulation layer is formed at the surface after the growth of 20 MLs of InAs.     

Statistical accuracy of a moving equivalent dipole method to identify sites of origin of cardiac electrical activation

While radio frequency (RF) catheter ablation (RCA) procedures for treating ventricular arrhythmias have evolved significantly over the past several years, the use of RCA has been limited to treating slow ventricular tachycardias (VTs). In this paper, we present preliminary results from computer and animal studies to evaluate the accuracy of an algorithm that uses the single equivalent moving dipole (SEMD) model in an infinite homogeneous volume conductor to guide the RF catheter to the site of origin of the arrhythmia. Our method involves measuring body surface electrocardiographic (ECG) signals generated by arrhythmic activity and by bipolar current pulses emanating from a catheter tip, and representing each of them by a SEMD model source at each instant of the cardiac cycle, thus enabling rapid repositioning of the catheter tip requiring only a few cycles of the arrhythmia. We found that the SEMD model accurately reproduced body surface ECG signals with a correlation coefficients > 0.95. We used a variety of methods to estimate the uncertainty of the SEMD parameters due to measurement noise and found that at the time when the arrhythmia is mostly localized during the cardiac cycle, the estimates of the uncertainty of the spatial SEMD parameters (from ECG signals) are between 1 and 3 mm. We used pacing data from spatially separated epicardial sites in a swine model as surrogates for focal ventricular arrhythmic sources and found that the spatial SEMD estimates of the two pacing sites agreed with both their physical separation and orientation with respect to each other. In conclusion, our algorithm to estimate the SEMD parameters from body surface ECG can potentially be a useful method for rapidly positioning the catheter tip to the arrhythmic focus during an RCA procedure.     

Effects of muscle α-tocopherol level and surface microbiological contamination on retail caselife of fresh beef from the US, Japan and Australia

This study evaluated effects of dietary supplementation of vitamin E (1000 IU vitamin E/daily for 100 days prior to harvest) to fed cattle on retail caselife performance of fresh US beef in an export market (Japan). Economic performance (monetary losses associated with color deterioration) for US beef from vitamin E supplemented cattle vs beef from non-vitamin E supplemented cattle was contrasted. An additional, controlled study was performed to compare muscle α-tocopherol concentrations, color changes and microbiological growth for fresh beef derived from vitamin E supplemented US cattle and fresh beef from cattle with an unknown history, but from other countries. Australian strip loin steaks had the highest muscle α-tocopherol concentrations (4.6 μg/g tissue), followed by US strip loin steaks derived from vitamin E supplemented cattle (3.4 μg/g tissue) and Japanese strip loin steaks (2.8 or 2.5 μg/g tissue). US strip loin steaks from non-vitamin E supplemented cattle had the lowest (p<0.05) α-tocopherol levels (1.7 μg/g tissue). Aerobic plate counts and total coliform counts were generally low at 0 days of retail display, and they changed similarly among treatments over 6 days of display, regardless of the country of origin of the beef. Vitamin E supplementation of US cattle reduced total Japanese retail store losses due to discoloration of US beef, in yen, by 5.2 percentage points (p<0.05), saving Japanese retailers US $0.24/kg. Data suggest that US beef-normally perceived, in Japan, to discolor more quickly in the retail display case than beef from Australia-would compete more favorably, in shelf-life, with beef from other countries if it was derived from cattle that had been fed supplemental vitamin E.     

Reverse logistics optimization of an industrial air conditioner manufacturing company for designing sustainable supply chain: a fuzzy hybrid multi-criteria decision-making approach

Wireless Networks - Magnified resource consumption and depletion of natural resources calls for non-flexible or strict regulations and penalties on industrial operations, increased rate of...     

Objective measurements of carcass and meat quality

Lost competitiveness and declining per capita consumption have forced US meat industry sectors to become consumer oriented and address issues related to quality shortfalls. Because industry goals for value and quality-based marketing are becoming a reality, interest in objective carcass evaluation methodology has escalated. Even so, no official instrument grading systems are in place. Research addressing use of A-mode, B-mode and real-time ultrasound technique indicated several distinct advantages: (1) it may be used in live animals; (2) it may be used on slaughter floors before hide removal; (3) with development, it may accurately predict traits related to palatability; (4) it offers no health hazards; (5) it would allow complete automation of grading and remove the element of human error; and (6) with development, it offers great compatability with integrated artificial neural networking technology. However, other systems are now available which may present alternatives. Electrical conductivity (TOBEC) effectively predicts pork carcass composition, and is now used commercially. Potential exists for similar systems in the beef industry. Other instruments (NMR, CAT, PET), with continued development, offer advantages in image resolution and accuracy, but are cost prohibitive at this time. Elastography, a new technique, offers exciting prospects for the future with its potential to predict tenderness.     

Growth dynamics of GaAs, AlAs and (Al, Ga)As on GaAs (110) and (111)A substrates during molecular beam epitaxy

The growth dynamics of GaAs, AlAs and (Al, Ga)As films grown by molecular beam epitaxy (MBE) on GaAs(110) and (111)A substrates have been studied using reflection high energy electron diffraction (RHEED) intensity oscillations and scanning tunnelling microscopy (STM). In contrast to growth on (001) oriented substrates, the period of the RHEED intensity oscillation does not in general provide a measure of the growth rate. This is explained by the very different surface chemistry involved, since the short lifetime of arsenic molecules (As₂ or As₄) on non-(001) surfaces results in cation-stable surface conditions, which generate arsenic (anion)- induced intensity oscillations, whereas on (001) surfaces they are cationinduced under all normal growth conditions. The effects of this behaviour on surface morphology are illustrated, as are the relative influences of Ga and Al. STM images obtained during the first few monolayers of growth provide a detailed indication of the growth mode and in particular explain in a simple manner the origin of bilayer period RHEED intensity oscillations obtained during growth on GaAs (110).     

Postprocessing antimicrobial treatments to control Listeria monocytogenes in commercial vacuum-packaged bologna and ham stored at 10 degrees C

The antilisterial effect of chemical dipping solutions on commercial bologna and ham slices, inoculated (3 to 4 log CFU/ cm2) after processing, was evaluated during storage in vacuum packages at 10 degrees C. Samples were inoculated with a 10-strain composite of Listeria monocytogenes and subsequently immersed (25+/-2 degrees C) for 2 min in 2.5% acetic acid (AA), 2.5% lactic acid (LA), 5% potassium benzoate (PB), or 0.5% Nisaplin (commercial form of nisin, equivalent to 5,000 IU/ml of nisin) solutions, either singly or sequentially (Nisaplin plus AA, Nisaplin plus LA, or Nisaplin plus PB), and then vacuum packaged and stored at 10 degrees C for 48 days. In addition to microbiological analysis, sensory evaluations were performed on uninoculated samples treated with AA, LA, or PB. Initial reductions (day 0) of the pathogen, compared with the controls, on bologna and ham samples treated with AA, LA, or PB ranged from 0.4 to 0.7 log CFU/cm2. Higher (P < 0.05) initial reductions (2.4 to 2.9 log CFU/cm2) were obtained for samples treated with Nisaplin alone and when followed by AA, LA, or PB. L. monocytogenes populations on control bologna and ham samples increased from 3.4 log CFU/cm2 (day 0) to 7.4 and 7.8 log CFU/ cm2, respectively, in 8 days at 10 degrees C. Listericidal effects were observed for all treatments tested, except for Nisaplin applied on its own, during storage at 10 degrees C. The sequential treatment of Nisaplin plus LA reduced L. monocytogenes to undetectable levels in both products at the end of storage. The sequential treatments were also found to inhibit growth of spoilage microorganisms. Sensory evaluations indicated that dipping (2 min) of ham samples in AA (2.5%), LA (2.5%), or PB (5%) led to lower sensory scores. However, since results of this study indicated that these treatments caused extensive listericidal effects, there is possibly a potential to reduce the levels of chemicals applied and still achieve adequate antilisterial activity without major negative effects on product quality.