Effect of Degree of Sanitation From Slaughter Through Fabrication on the Microbiological and Sensory Characteristics of Beef

Evaluation of hot-water and sanitizer dip treatments of knives contaminated with bacteria and meat residue

Hot water (HW; 82.2 degrees C, 180 degreesF) is used for sanitation of meat cutting implements in most slaughter facilities, but validation of actual practices against meat-borne bacterial pathogens and spoilage flora is lacking. Observed implement immersions in HW in two large pork processing plants were found to typically be < or = 1 s. Impact of these practices on bacteria on metal surfaces was assessed in the laboratory, and alternative treatments were investigated. Knives were inoculated with raw pork residues and Escherichia coli O157:H7, Salmonella Typhimurium DT104, Clostridium perfringens, and Lactobacillus spp. and were sampled before and after 1- or 15-s dips of blades in HW, warm water (48.9 degrees C), or warm sanitizers (neutral or acid quaternary ammonium compounds [QAC] at 400 ppm, or peroxyacetic acid at 700 ppm H2O2 and 165 ppm peroxyacetic acid). Simultaneous scrubbing and 15-s dipping in HW or acid QAC was also evaluated. Reductions on knives dipped for 1 s were usually < 1 log and were not significantly different (P > 0.05) between treatments. Reductions of E. coli O157:H7 after 15 s in HW, neutral QAC, acid QAC, or peroxyacetic acid were 3.02, 2.38, 3.04, and 1.52 log, respectively. Reductions of other bacteria due to HW were not significantly different from sanitizers and were significantly greater than warm water for all bacteria except C. perfringens. Combined scrubbing and 15-s dipping in HW resulted in a 2.91- and 2.25-log reduction of E. coli O157:H7 and Salmonella Typhimurium DT104, respectively, whereas reduction caused by acid QAC was significantly less at about 1.7 log each. Brief dip treatments of contaminated knives have limited efficacy, but longer immersions cause greater reductions that were not enhanced by scrubbing. QAC is a suitable alternative to HW in this application.

Effect of various chemical decontamination treatments on natural microflora and sensory characteristics of poultry

Regulation (EC) No. 853/2004 of the European Parliament and of the Council provides a legal basis permitting the use of antimicrobial treatments to remove surface contamination from poultry. This paper reports the results of research into the effects on natural microflora, pH, and sensorial characteristics achieved by dipping chicken legs (15 min, 18+/-1 degrees C) into solutions (wt/vol) of 12% trisodium phosphate (TSP), 1200 ppm acidified sodium chlorite (ASC), 2% citric acid (CA), 220 ppm peroxyacids (Inspexx 100; PA), and water. Samples were collected immediately after evisceration, subjected to the treatments listed or left untreated (control) and tested after 0, 1, 3 and 5 days of storage (3 degrees C+/-1 degrees C). For most microbial groups similar counts were observed on water-dipped and on untreated legs. All the chemical compounds were effective in reducing microbial populations throughout storage, with TSP, ASC and CA showing the strongest antimicrobial activity. The average reductions (mean+/-standard deviation) relative to untreated samples caused by chemical treatments when considering simultaneously all storage days ranged (log(10) cfu/g skin) from 0.53+/-0.83 (PA) to 1.98+/-0.62 (TSP) for mesophilic aerobic counts, from 0.11+/-0.89 (PA) to 1.27+/-1.02 (CA) (psychrotrophs), from 1.34+/-1.40 (PA) to 2.15+/-1.20 (CA) (Enterobacteriaceae), from 1.18+/-1.24 (PA) to 1.98+/-1.16 (CA) (coliforms), from 0.66+/-0.99 (PA) to 1.86+/-1.80 (TSP) (Micrococcaceae), from 0.54+/-0.74 (TSP) to 2.17+/-1.37 (CA) (enterococci), from 0.72+/-0.66 (TSP) to 2.08+/-1.60 (CA) (Brochothrix thermosphacta), from 0.78+/-1.02 (PA) to 1.99+/-0.96 (TSP) (pseudomonads), from 0.21+/-0.61 (PA) to 1.23+/-0.60 (TSP) (lactic acid bacteria), and from 1.14+/-0.89 (PA) to 1.45+/-0.61 (ASC) (moulds and yeasts). The microbial reductions throughout storage increased, decreased, or did not vary, in accordance with microbial group and chemical involved. Similar pH values were observed for untreated samples and for those dipped in PA and water on all sampling days. ASC-treated samples showed a lower pH than controls to day 1. TSP-treated legs exhibited the highest pH values and CA-treated ones the lowest, throughout storage. Hedonic evaluation (nine-point structured scale, untrained panellists) showed similar colour, smell and overall acceptability scores for dipped and untreated samples on day 0 and day 1. From day 3 sensorial attributes scored lower for untreated, PA- and water-dipped legs, as compared to legs treated with TSP, ASC and CA. Only for these three groups of samples were average scores higher than 6 (shelf-life limit value) observed by the end of storage. Results from the present study suggest that the treatments tested improve the microbial quality of chicken without adverse sensorial effects.

Microbial contamination of carcasses, meat, and equipment from an Iberian pork cutting plant

An assessment and follow-up of the microbial contamination of an Iberian pork cutting room is presented. Samples were taken from carcasses (n = 76), meat pieces (three types, n = 71), meat for dry-cured sausages (3 types, n = 66), and surfaces of equipment (n = 158). Aerobic plate counts (APC) at 37 degrees C on meat pieces (primal cuts) were lower than on carcasses (3.62 log CFU/10 cm2 against 4.63 log CFU/10 cm2), probably owing to the removal of the skin. However, more than 80% of the meat pieces showed presence of Escherichia coli. For the three types of meat intended for dry-cured sausages, higher counts (P < 0.001) were found for meat type 3--an important cut obtained from the vertebral column--at 2.62 log CFU/g for E. coli; the particular surface used in the handling of meat type 3 also showed high counts (P < 0.001) for E. coli. Consequently, attention should be paid to the hazard analysis critical control point plan at this stage. Salmonella was isolated from 3.94% of the carcass surfaces (perianal zone), 4.46% of meat pieces, and 13.58% of meat for dry-cured sausages. Moreover, the percentages for isolation of Salmonella from carcasses of Iberian pigs (extensive rearing) in our study were lower than those generally reported in the literature for "white pigs" (intensive rearing). Coagulase-positive Staphylococcus aureus was isolated in 31.82% of meat samples for dry-cured sausages, in 16.90% of meat pieces, and in 15.50% of the equipment after 4 h of work. Of the coagulase-positive strains isolated, 47.61% were producers of enterotoxin.

A simulation model for studying the role of pre-slaughter factors on the exposure of beef carcasses to human microbial hazards

A Monte Carlo simulation model was constructed for assessing the quantity of microbial hazards deposited on cattle carcasses under different pre-slaughter management regimens. The model permits comparison of industry-wide and abattoir-based mitigation strategies and is suitable for studying pathogens such as Escherichia coli O157:H7 and Salmonella spp. Simulations are based on a hierarchical model structure that mimics important aspects of the cattle population prior to slaughter. Stochastic inputs were included so that uncertainty about important input assumptions (such as prevalence of a human pathogen in the live cattle-population) would be reflected in model output. Control options were built into the model to assess the benefit of having prior knowledge of animal or herd-of-origin pathogen status (obtained from the use of a diagnostic test). Similarly, a facility was included for assessing the benefit of re-ordering the slaughter sequence based on the extent of external faecal contamination. Model outputs were designed to evaluate the performance of an abattoir in a 1-day period and included outcomes such as the proportion of carcasses contaminated with a pathogen, the daily mean and selected percentiles of pathogen counts per carcass, and the position of the first infected animal in the slaughter run. A measure of the time rate of introduction of pathogen into the abattoir was provided by assessing the median, 5th percentile, and 95th percentile cumulative pathogen counts at 10 equidistant points within the slaughter run. Outputs can be graphically displayed as frequency distributions, probability densities, cumulative distributions or x-y plots. The model shows promise as an inexpensive method for evaluating pathogen control strategies such as those forming part of a Hazard Analysis and Critical Control Point (HACCP) system.

Integrating microbial decontamination with organic acids in HACCP programmes for muscle foods: prospects and controversies

A considerable literature reports the antibacterial efficacy of dilute solutions of organic acids (lactic, acetic). With carcasses an overall reduction in surface contaminants of 1.5 log cycles can be expected. Carcass decontamination may not improve the safety of the resultant meat, but laboratory trials confirm that acid decontamination of subprimal and retail cuts is more efficacious. An advantage over many other intervention strategies is that residual antimicrobial activity is demonstrable over extended periods of storage. These studies have also shown that some meatborne pathogens are particularly sensitive to organic acids (i.e., Yersinia enterocolitica) while others are resistant (i.e., E. coli O157:H7). Dilute solutions of organic acids (1 to 3%) are generally without effect on the desirable sensory properties of meat when used as a carcass decontaminant. However, dependent on treatment conditions, lactic and acetic acid can produce adverse sensory changes when applied directly to meat cuts, with irreversible changes in appearance being a frequent occurrence. It is speculated that organic acid decontamination will be implemented in American abattoirs in an effort to meet specified performance standards for pathogen reduction as part of an overall HACCP program. In contrast, the EU advocates that strictly controlled processing hygiene is sufficient to ensure the safety of the product. Additional research is necessary to establish a set of treatment conditions that may permit a practicable reduction in bacterial contamination throughout the processing chain with a measurable effect on safety and storage life, without imposing any change in sensory properties. It will also be necessary to develop standard, objective measures to assess HACCP and the efficacy of decontamination procedures. Without such commercial studies controversy on the practicality of acid decontamination will persist.

Microbiological contamination of carcasses related to hygiene practice and facilities on slaughtering lines

The purpose of the study was to investigate the association between the hygienic practice of slaughterhouse workers and the microbiological contamination level of carcasses. In 5 Finnish slaughterhouses the workers' hygienic practice was observed and the carcasses were sampled by the swabbing method. The overall means (log10 cfu cm-2) of the aerobic plate count in pork and beef carcasses were 3.23 and 2.65, respectively. Hygienic practice was found to be associated with the carcass contamination level, especially the disinfection frequency. In those slaughterhouses, where the disinfection frequency was low, the contamination level of carcasses was high. Designing slaughtering lines so as to make hygienic working possible is evidently very important. However, the enforcement of hygienic practice, such as the regular disinfection of working tools, is also important in reducing the microbiological contamination of carcasses.

Effect of pre-slaughter washing of lambs on the microbiological and visible contamination of the carcases

Studies in four slaughterhouses with contrasting dressing systems showed that microbiological contamination with total aerobic bacteria and Escherichia coli was greater on carcases which had been washed before slaughter, irrespective of wool length, and was generally higher on carcases derived from woolly lambs than on those derived from shorn lambs. The effects of pre-slaughter washing on the forequarters compared with the hindquarters were not consistent, and this was attributed to differences between the dressing systems applied in the slaughterhouses. Over all trials the mean total aerobic count ranged from 3.45 to 5.36 log10/cm2, and the mean counts of E coli ranged from 0.39 to 2.11 log10/cm2. There was less visible contamination on the carcases of washed lambs than on those of unwashed lambs. The differences in contamination with wool were largely dependent on the level of contamination of individual carcases, whereas the differences in contamination with faecal material and dirt or sand were largely dependent on the prevalence of affected carcases. The use of pre-slaughter washing to compensate in visual terms for poor pre-slaughter presentation results in a detrimental effect on microbiological loads on ovine carcases.