Incidence of Salmonella on beef carcasses relating to the U.S. meat and poultry inspection regulations.

This article is part of a major study designed to collect baseline contamination data by sampling beef carcasses in seven slaughtering plants (four steer-heifer and three cow-bull plants) during both a dry season (November to January) and a wet season (May to June). Samples (n = 30) were excised from each of three carcass anatomical sites (brisket, flank, and rump) at each of three points in the slaughtering chain (pre-evisceration, following final carcass washing, after 24-h carcass chilling). A total of 3,780 samples (100 cm2 each) were analyzed for presence of Salmonella; aerobic plate counts, total coliform counts, and Escherichia coli counts were also made. After 24-h chilling, average incidence (expressed as a percentage) of Salmonella in the brisket, flank, and rump samples, respectively, for steer-heifer carcasses was 0.8+/-1.7, 0, and 2.5+/-5.0 for the wet season and 0.8+/-1.7, 0, and 0 for the dry season; the corresponding percentages for cowbull carcasses were 4.4+/-2.0, 2.2+/-3.9, and 1.1+/-1.9 for the wet season and 2.2+/-3.9, 1.1+/-1.9, and 0 for the dry season. Depending on plant and season, ranges of probabilities of chilled steer-heifer carcasses passing the U.S. regulatory requirements for Salmonella contamination were 0.24 to 1.0 for the brisket, 1.0 for the flank, and 0.002 to 1.0 for the rump; the corresponding ranges for the chilled cow-bull carcasses were 0.25 to 1.0, 0.25 to 1.0, and 0.70 to 1.0. When the number of positive brisket, flank, and rump samples were combined, the probabilities of passing the regulatory requirements were 0.242 to 1.0 and 0.772 to 1.0 for the wet and dry seasons, respectively, in steer-heifer plants and 0.368 to 0.974 and 0.865 to 1.0 in cow-bull plants. Correlation coefficients of aerobic plate counts, total coliform counts, and E. coli counts with Salmonella incidence were higher (P< or =0.05) for cow-bull samples that had increased incidence of the pathogen when compared to steer-heifer samples.     

In-Plant evaluation of a lactic acid treatment for reduction of bacteria on chilled beef carcasses.

The effectiveness of a lactic acid treatment consisting of spraying a 4% L-lactic acid solution (55 degrees C at source) on chilled beef carcasses to reduce bacterial populations was tested in a commercial slaughter environment. All carcasses had been treated with a proprietary decontamination treatment composed of a hot water spray followed by a lactic acid spray prior to chilling. Bacterial groups used to indicate reductions included aerobic plate count (APC), total coliform count, and Escherichia coli count, and samples were examined from the brisket, the clod, and the neck regions of 40 untreated and 40 treated carcass sides. Depending on the carcass surface region, APCs were reduced by 3.0 to 3.3 log cycles. Log coliform and E. coli counts were consistently reduced to undetectable levels. The small reductions observed for coliforms are attributable to counts on untreated carcasses already being near the lower detection limit of the counting method. The percentage of samples with detectable numbers of coliforms (positive samples) on untreated carcasses ranged from 52.5 to 92.5%, while 0.0% of the samples collected from treated carcasses contained detectable coliforms. Percent E. coli-positive samples ranged from 7.5 to 30.0% on untreated carcasses and 0.0% after treatment of carcass sides. These results indicate that a hot lactic acid spray with increased concentration and time of application may be effectively implemented for an additional decontamination treatment of chilled beef carcasses prior to fabrication.     

Sources and extent of microbiological contamination of beef carcasses in seven United States slaughtering plants

This study determined microbiological loads of beef carcasses at different stages during the slaughtering to chilling process in seven (four steer/heifer and three cow/bull) plants. Potential sources of contamination (feces, air, lymph nodes) were also tested. Each facility was visited twice, once in November through January (wet season) and again in May through June (dry season). Carcasses were sampled by aseptic excision of surface tissue (100 cm2) from the brisket, flank, and rump (30 samples each) after hide removal (pre-evisceration), after final carcass washing, and after 24-h carcass chilling. The samples were analyzed individually by standard procedures for aerobic plate counts (APC), total coliform counts (TCC), Escherichia coli biotype I counts (ECC), and presence of Salmonella. Incidence of Salmonella was higher on dry feces of older compared to younger animals, fresh feces of younger compared to older animals, and on cow/bull carcasses compared to steer/heifer carcasses. Most factors and their interactions had significant (P < or = 0.05) effects on the bacterial counts obtained. Depending on plant and season, APC, TCC, and ECC were < or =10(4), < or =10(2), and < or =10(1) CFU/cm2 in 46.7 to 93.3, 50.0 to 100.0, and 74.7 to 100.0% of the samples, respectively. TCC exceeded 10(3) CFU/cm2 in 2.5% (wet season) and 1.5% (dry season) of the samples. ECC exceeded 10(2) CFU/cm2 in 8.7%, 0.3%, and 1.5% of the pre-evisceration, final carcass-washing, and 24-h carcass-chilling samples, respectively, during the wet season; the corresponding numbers during the dry season were 3.5%, 2.2%, and 3.0%, respectively. These data should serve as a baseline for future comparisons in measuring the microbiological status of beef carcasses, as the new inspection requirements are implemented.     

Microbial assessment of an upward and downward dehiding technique in a commercial beef processing plant

Preventing microbial contamination during dehiding is challenging, and skinning methods are of critical importance for the hygienic status of beef carcasses. Two skinning methods are usually employed: upward hide pulling (UHP) and downward hide pulling (DHP). This study has compared the microbiological contamination of carcasses using both systems in a beef processing plant in the process of changing its dehiding method from UHP to DHP. 100 cm² areas from eight carcass sites (ham, chuck, rump, bung, flank, brisket, shin and neck) were sampled on 36 skinned carcasses dehided by each technique. Total viable counts (TVCs) and Enterobacteriaceae counts for each site were determined. No significant differences were observed in total (pooled-samples) carcass contamination regardless of the method used. However, significant differences (p < 0.05) in TVCs were observed at the flank, shin, brisket and neck. These differences can be attributed to possible deficiencies in the implementation of the HACCP pre-requisite programmes, and are not necessarily associated with the skinning method per se.     

FECAL COLIFORM CONTAMINATION OF BEEF CARCASSES DURING THE SLAUGHTERING PROCESS

The purpose of this study was to determine the fecal coliform counts of beef carcasses during different stages in the slaughter process. A total of nine carcasses were selected at random in the abattoir. The samples were taken by excision from three different sites; rump, brisket and shoulder. The samples were collected from the same carcasses at four different stages of processing; after dressing, after evisceration, after washing and after chilling for 24 h in a chilling room. The processing steps did not increase the fecal coliform counts on the rump samples. There were no significant differences in the samples of rump and shoulder among different processing steps. The contamination level of the brisket after washing was significantly higher than other processing steps. Brisket and shoulder parts are critical points for microbiological sampling as these sites showed higher microbial counts after chilling steps. The data obtained have relevance for the planning of washing methods for the production of clean and safe carcasses.     

Microbial contamination on beef in relation to hygiene assessment based on criteria used in EU Decision 2001/471/EC

Thirty-six carcasses were sampled over a 12-month period at an Irish beef abattoir. Between one and five carcass sites (including the hock, brisket, cranial back, bung, inside round and outside round) were sampled after hind leg skinning, hide removal, bung tying, evisceration, splitting, washing, chilling for 24 h and boning, using a wet and dry, cotton wool swab technique. For each sample, total viable counts (TVC), Escherichia coli, total coliforms and Enterobacteriaceae were enumerated. The results are considered in relation to European Union Decision 2001/471/EC which sets performance criteria for TVCs and Enterobacteriaceae in samples taken by excision. Though not explicitly stated in the Decision, it has been proposed that microbiological performance criteria for samples taken by swabbing be set at 20% of the values set for excision samples. Therefore, log mean TVCs in carcass swab samples taken before chilling are acceptable, marginal and unacceptable when they are <2.8, 2.8-4.30 and >4.30 cm(-2), respectively. By these criteria, TVCs on carcasses in the present study were in the marginal range. The marginal result for TVCs was due in the most part to hide removal operations, particularly at the hock and brisket sites. Bacterial contamination on post-chill carcasses was similar or lower to that on pre-chill carcasses, while boning resulted in general increases in TVCs and in E. coli, total coliform and Enterobacteriaceae numbers. In Decision 2001/471/EC, the effects of chilling and boning are not included in the assessment of process control. Data from this study indicate that performance criteria based on log mean Enterobacteriaceae values are unsuitable because of the infrequent occurrence of these organisms on the carcass.     

MICROBIOLOGICAL CONDITIONS OF SHEEP CARCASSES DURING THE SLAUGHTERING PROCESS

This study was undertaken to determine the microbiological quality of sheep carcasses during different stages in the slaughtering process. A total of eleven carcasses were selected at random in an abattoir. The samples were taken by excision from four different sites; leg, brisket, shoulder and neck. The samples were collected from the same carcasses at four different stages in the slaughtering process; after dressing, after evisceration, after washing and chilling. The aerobic mesophilic bacteria, coliforms and Enterobacteriaceae recovered from each sample were enumerated. Chilling reduced the aerobic mesophilic and coliform counts of carcasses, significantly. Levels of carcass microbial load after chilling were 1.69, 0.11 and 0.11 log cfu/cm² for aerobic mesophilic counts, coliform counts and Enterobacteriaceae counts, respectively. According to data obtained in the present study, chilling of carcasses was the most important step in improving the hygienic quality of carcasses. Processing stages changed significantly both aerobic mesophilic and coliform counts of neck, therefore, among different sites of carcass, neck should be the only critical site for microbiological sampling for sheep carcasses.     

The bacteriological quality of British beef 1. Carcasses sampled prior to chilling

During a survey of 11 beef abattoirs in England 2200 swab samples were taken from carcasses just before chilling. Geometric mean aerobic plate counts at 30°C on each of four carcass sites ranged from log(10) 2·45 to 4·29cfu cm(2) with the brisket and flank samples tending to be more highly contaminated than those from the fore-rib and groin. Presumptive coliforms were isolated from 24% of the samples and the proportion of positive samples among the abattoirs varied between 1·5% and 43%. Analysis of variance confirmed that the bacteriological status of beef carcasses may be influenced by a number of interacting factors, including abattoir, visit, and sampling site. However, the results showed that working methods alone were not critical factors in the production of beef of superior bacteriological quality.     

Incidence of coagulase positive Staphylococcus on beef carcasses in three Australian abattoirs.

The contamination of beef carcasses with coagulase-positive staphylococci (CPS) was studied at three beef abattoirs (A, B and C). The incidence and the number of CPS were determined on cattle hides immediately after slaughter and on three carcass sites (brisket, flank and round) at different points during processing along the slaughter line. The incidence of CPS on cattle hides ranged from 20 to 68.6%. At abattoir A, 6.5% of the carcasses sampled before evisceration were contaminated with CPS, compared to 40% of the carcasses after evisceration. The incidence on carcasses changed little during further processing; however, after chilling for 72 h, the incidence increased to 83%. After evisceration, the brisket and flank areas were more often contaminated than the round. A similar pattern of contamination was observed at abattoir B. At abattoir C, 26.7% of the samples collected before evisceration were contaminated and this fell to 16.7% after evisceration. After chilling for 72 h, the incidence of carcass contamination with CPS increased to 46.7%. The average number of CPS on contaminated carcasses prior to and after overnight chilling was less than 50 colony-forming units (cfu)/cm2 and, after weekend chilling, increased to 64 and 112 cfu/cm2 in abattoirs A and B, respectively. Of the isolates tested, 71.4% produced staphylococcal enterotoxin and 21% could not be classified phenotypically. The hands of workers and environmental sites associated with the evisceration process were examined for CPS at abattoir A. Hands were heavily contaminated and were the likely source of CPS contamination at this abattoir.     

Improvement of the hygienic performance of the hindquarters skinning operations at a beef packing plant

The hindquarters skinning operations in a commercial beef carcasses dressing process were modified, and for short trial periods reorganized for the purpose of reducing the numbers of bacteria deposited on the carcasses. During performance of modified or reorganized operations, samples were obtained from randomly selected carcasses, by swabbing specified sites related to opening cuts, rump skinning or flank skinning operations, randomly selected sites along the lines of the opening cuts, randomly selected sites on the skinned hindquarters of carcasses, or randomly selected sites on carcass sides leaving the dressing process. For each form of the hindquarters skinning operations, a set of 25 samples of each type was collected, with a single sample being obtained from each selected carcass or side. Aerobic counts, coliforms and Escherichia coli were enumerated in each sample, and a log mean value was estimated for each set of 25 counts on the assumption of a log normal distribution of the counts. The data indicated that the log numbers of total aerobes, coliforms and E. coli that were deposited on carcasses during the modified hindquarters skinning operations were generally about 0.5, 1.0 and 1.0 log unit less, respectively, than the log numbers that had been deposited on the carcasses during the unmodified operations. Reorganization of the modified operations gave further small but consistent reductions in the numbers of bacteria. It, therefore, appears that changes to dressing procedures which are guided by appropriate microbiological data can produce consistent reductions in the microbiological contamination of carcasses.     

Microbial populations on animal hides and beef carcasses at different stages of slaughter in plants employing multiple-sequential interventions for decontamination

Multiple-sequential interventions were applied commercially to reduce beef carcass contamination in eight packing plants. The study evaluated microbial populations on animal hides and changes in carcass microbial populations at various stages in the slaughtering process. Sponge swab samples yielded mean (log CFU/100 cm2) total plate counts (TPC), total coliform counts (TCC), and Escherichia coli counts (ECC) on the exterior hide in the ranges of 8.2 to 12.5, 6.0 to 7.9, and 5.5 to 7.5, respectively, while corresponding contamination levels on carcass surfaces, after hide removal but before application of any decontamination intervention, were in the ranges of 6.1 to 9.1, 3.0 to 6.0, and 2.6 to 5.3, respectively. Following the slaughtering process and application of multiple-sequential decontamination interventions that included steam vacuuming, pre-evisceration carcass washing, pre-evisceration organic acid solution rinsing, hot water carcass washing, postevisceration final carcass washing, and postevisceration organic acid solution rinsing, mean TPC, TCC, and ECC on carcass surfaces were 3.8 to 7.1, 1.5 to 3.7, and 1.0 to 3.0, respectively, while corresponding populations following a 24 to 36 h chilling period were 2.3 to 5.3, 0.9 to 1.3, and 0.9, respectively. The results support the concept of using sequential decontamination processes in beef packing plants as a means of improving the microbiological quality of beef carcasses.     

肉牛屠宰工序微生物污染状况分析和喷淋减菌技术

以减少冷却后牛胴体表面的微生物数量为目标,在企业实际生产条件下,以菌落总数为指标分析屠宰过程中各工序胴体表面的微生物变化状况,探讨不同喷淋方式的减菌效果。结果表明,屠宰工序中初始剥皮操作对胴体造成的污染最严重,其次为去脏工序。高压清水清洗对全胴体的减菌量为0.62(log10CFU/cm2);2%的乳酸喷淋对胸口部位菌落总数的减少量为1.06(log10CFU/cm2)。采用2%的乳酸喷淋可以有效减少肉牛屠宰过程中的胴体污染。     

Microbial contamination occurring on lamb carcasses processed in the United States

Lamb carcasses (n = 5,042) were sampled from six major lamb packing facilities in the United States over 3 days during each of two visits (fall or winter, October through February; spring, March through June) in order to develop a microbiological baseline for the incidence (presence or absence) of Salmonella spp. and for populations of Escherichia coli after 24 h of chilling following slaughter. Samples also were analyzed for aerobic plate counts (APC) and total coliform counts (TCC). Additionally, incidence (presence or absence) of Campylobacter jejuni/coli on lamb carcasses (n = 2,226) was, determined during the slaughtering process and in the cooler. All samples were obtained by sponge-sampling the muscle-adipose tissue surface of the flank, breast, and leg of lamb carcasses (100 cm2 per site; 300 cm2 total). Incidence of Salmonella spp. in samples collected from chilled carcasses was 1.5% for both seasons combined, with 1.9% and 1.2% of fall or winter and spring samples being positive, respectively. Mean (log CFU/cm2) APC, TCC, and E. coli counts (ECC) on chilled lamb carcasses across both seasons were 4.42, 1.18, and 0.70, respectively. APC were lower (P < 0.05) in samples collected in the spring versus fall or winter, while TCC were higher in samples collected in the spring. There was no difference (P > 0.05) between ECC from samples collected in the spring versus winter. Only 7 out of 2,226 total samples (0.3%) tested positive for C. jejuni/coli, across all sampling sites. These results should be useful to the lamb industry and regulatory authorities as new regulatory requirements for meat inspection become effective.     

Assessment of the hygienic performances of two beef carcass cooling processes from product temperature history data or enumeration of bacteria on carcass surfaces

The carcass cooling processes at two beef slaughtering plants were examined. Temperature histories were collected from the deep leg, the aitch bone pocket surface and randomly selected surface sites of carcasses passing through each process. For each process, sets of25temperature histories were collected for each type of site, with a single history being collected from each of75randomly selected carcases. A swab sample was obtained from a randomly selected site on each of25randomly selected carcasses entering and25leaving each process. Total aerobic counts, coliforms andEscherichia coliwere enumerated in each sample. Carcasses resided in the chiller at plant A for between 15.8 and 28.0h, but for between 20.0 and 24.0h at plant B. The ranges of minimum temperature attained at all three types of site were generally lower at plant B than at plant A. However, 1/25 carcasses at both plants had high minimum temperatures indicative of ineffective cooling. AnE. coliproliferation value was calculated for each temperature history from a surface site. The sets of proliferation values for aitch bone pocket sites on carcasses passing through either process complied with three points of a four point criteria for acceptable carcass cooling, but one value in each exceeded the stipulated maximum value. Proliferation values for randomly selected sites indicated that if temperature alone controlled bacterial growth during cooling, then numbers ofE. colion cooling carcasses would on average increase by about 1 log unit at plant A but by only about 0.3 log units at plant B. However, enumeration of bacteria showed that cooling reduced the mean numbers of total counts, coliforms andE. colion carcasses at plant A by <0.5 log units, while at plant B, cooling reduced the mean numbers of total counts by about 0.5 log units, and mean numbers of coliforms andE. coliby 2 log units. The findings indicate that microbiological data are required to properly assess the hygienic effects of carcass cooling processes, but that temperature history data may be conveniently used for monitoring the maintenance of standard operating procedures in such processes.     

Assessment of carcass contamination with E. coli O157 before and after washing with water at abattoirs in Nigeria

The study was carried out to assess the level of beef carcass contamination with Escherichia coli including O157 strains before and after washing with water. Samples of water used for washing carcasses were collected and thirty beef carcasses were swabbed within a period of one month in each of three abattoirs located in North-Western states of Nigeria. E. coli were enumerated as indicator organisms. Using conventional biochemical tests, the isolation rate of E. coli in the 120 swab samples collected in each abattoir from external and internal surfaces of the carcasses was 58.3% at Kano abattoir, 70.8% at Sokoto abattoir, while 76.7% was recorded at Zango abattoir. E. coli counts from external and internal surfaces of the carcasses were enumerated as mean log and ranged between 4.3 Log(10) and 4.6 Log(10) cfu/cm(2) before washing, while the values were 4.6 Log(10) and 4.9 Log(10) cfu/cm(2) after washing. Data analysis revealed that the increase in E. coli counts after washing carcasses with water was statistically significant (P<0.05) in all the abattoirs. However, there was no statistically significant difference (P>0.05) between the 3 abattoirs in mean log of E. coli counts from external surfaces of carcass after washing. E. coli O157 was identified from both the water and surfaces of carcasses using Latex agglutination kit. A prevalence of 2.8% of E. coli O157 was detected in 360 swab samples from 90 beef carcasses examined. E. coli counts from water used in washing carcasses were between 22 and 120 cfu/100 ml. Of the 72 water samples, 3(4.2%) were positive for E. coli O157. In conclusion, there was increased contamination of carcasses during processing and water used in washing carcasses might have contributed to carcass contamination in all the abattoirs studied due to use of non-potable water.     

Evaluation of peroxyacetic acid as a post-chilling intervention for control of Escherichia coli O157:H7 and Salmonella Typhimurium on beef carcass surfaces

Four experiments were conducted to test the efficacy of peroxyacetic acid as a microbial intervention on beef carcass surfaces. In these experiments, beef carcass surfaces were inoculated with fecal material (no pathogens) or fecal material containing rifampicin-resistant Escherichia coli O157:H7 and Salmonella Typhimurium. Inoculated surfaces were subjected to a simulated carcass wash with and without 2% l-lactic acid treatment before chilling. In Experiments 1 and 2, the chilled carcass surfaces were sprayed with peroxyacetic acid (200 ppm; 43°) for 15 s. Peroxyacetic acid had no effect on microbial counts of any organism measured on these carcass surfaces. However, lactic acid reduced counts of E. coli Type I (1.9log(10) CFU/cm(2)), coliforms (3.0log(10) CFU/cm(2)), E. coli O157:H7 (2.7log(10) CFU/cm(2)), and S. Typhimurium (2.8log(10) CFU/cm(2)) entering the chilling cooler and prevented growth during the chilling period. In Experiment 3, peroxyacetic acid at different concentrations (200, 600, and 1000 ppm) and application temperatures (45 and 55 °C) were used to investigate its effectiveness in killing E. coli O157:H7 and S. Typhimurium compared to 4% l-lactic acid (55 °C). Application temperature did not affect the counts of either microorganism. Peroxyacetic acid concentrations up to 600 ppm had no effect on these microorganisms. Concentrations of 1000 ppm reduced E. coli O157:H7 and S. Typhimurium by up to 1.7 and 1.3log(10) CFU/cm(2), respectively. However, 4% lactic acid reduced these organisms by 2.7 and 3.4log(10) CFU/cm(2), respectively. In Experiment 4, peroxyacetic acid (200 ppm; 43 °C) was applied to hot carcass surfaces. This treatment caused a 0.7log(10) CFU/cm(2) reduction in both E. coli O157:H7 and S. Typhimurium. The collective results from these experiments indicate that peroxyacetic acid was not an effective intervention when applied to chilled inoculated carcass piece surfaces.     

Survival of Escherichia coli O157:H7 and non-pathogenic E. coli on irradiated and non-irradiated beef surfaces

This study examined changes in numbers of pathogenic (PEC) and non-pathogenic (NPEC) Escherichia coli during storage at 10 °C on the surfaces of irradiated (IR) and non-irradiated (NIR) meat pieces excised from the neck, brisket and rump of beef carcasses and in Brain Heart Infusion Broth (BHI) and Maximum Recovery Diluent (MRD). On irradiated meat pieces, there were significant differences between mean PEC and NPEC counts at all sites. Differences in counts were also observed between IR and NIR surfaces and among the three meat sites for both E. coli types. These differences occurred only on IR samples, suggesting that the irradiation associated reductions in normal beef surface flora influenced survival of both E. coli types. PEC and NPEC counts increased during storage in BHI, but only NPEC counts increased in MRD. The results of this study highlight the impact of meat surface type and the presence/absence of the normal beef carcass surface flora on E. coli survival and/or growth during meat storage. Such previously unreported effects, and their precise mechanisms, have direct implications in the development and application of accurate models for the prediction of the safety and shelf life of stored meat.     

The development of a 'clean sheep policy' in compliance with the new Hygiene Regulation (EC) 853/2004 (Hygiene 2)

The aim of this research was to identify the risk factors associated with the transfer of bacterial contamination from the fleece to the ovine carcass thereby providing the scientific basis for the development and validation of a clean sheep policy. Two hundred sheep in lairage were graded into five categories each consisting of 40 sheep. The categories were as follows; (A) clean and dry; (B) clean and wet; (C) dirty and dry; (D) dirty and wet and (E) visible dags (dung-clotted tufts of wool) categorized by the chief veterinary inspector at the slaughter plant based on the visual inspection of the hygienic status of the fleece. Microbiological evaluations of the carcasses were conducted using swab sampling methods. Total viable counts (TVCs), Enterobacteriaceae and coliform counts were obtained from 40 animals per category at four separate sites (brisket, shoulder, flank and rump) immediately after pelt removal. Statistical analysis of TVC data obtained from the carcass indicated that the dirt level of the fleece had a significant effect on contamination levels when the fleece was dry. Enterobacteriaceae and coliform counts suggest that dirt was a contributing risk factor regardless of wetness or dryness of the animal. The clean sheep policy should therefore differentiate between clean and dirty sheep and mandate additional hygiene measures for the latter.     

不同工艺条件对猪胴体和冷却猪肉微生物去污染效果的影响

调查了冷却猪肉生产企业现有生产工艺下微生物污染的状况 ;研究了对现有生产工序 (冲淋工序、冷却工序 )采用新的处理工艺 ,包括水冲洗、乳酸喷淋、冷分割以及联合处理等对猪胴体和冷却猪肉微生物去污染的效果。结果表明 ,在现有生产工艺下 ,冷却猪肉微生物污染随季节发生显著变化 ,且达不到HACCP体系微生物控制要求 ;水冲淋、乳酸喷淋、冷分割单独处理或联合处理 ,均有显著的微生物去污染效果。如果采用热分割 ,劈半后冲洗 1min ,乳酸喷淋 1min ,则微生物去污染效果显著 ,可基本达到HACCP对微生物控制要求。如果采用冷分割 ,劈半后冲洗 1min ,冷却 2 4h ,再次采用冷分割效果较好 ,冷却猪肉可基本达到HACCP对微生物控制要求 ;若劈半后冲洗 1min ,乳酸喷淋 1min ,冷却 2 4h则可完全达到HACCP对微生物控制要求。     

Reduction of Escherichia coli O157:H7 and Salmonella typhimurium on beef carcass surfaces using acidified sodium chlorite.

The efficacy of a phosphoric acid-activated acidified sodium chloride (PASC) spray and a citric acid-activated acidified sodium chlorite (CASC) spray applied at room temperature (22.4 to 24.7 degrees C) in combination with a water wash was compared with that of a water wash only treatment for reduction of Escherichia coli O157:H7 and Salmonella Typhimurium inoculated onto various hot-boned individual beef carcass surface regions (inside round, outside round, brisket, flank, and clod). Initial counts of 5.5 and 5.4 log CFU/cm2 were obtained after inoculation with E. coli O157:H7 and Salmonella Typhimurium, respectively. Initial numbers for both pathogens were reduced by 3.8 to 3.9 log cycles by water wash followed by PASC spray and by 4.5 to 4.6 log cycles by water wash followed by CASC spray. The sprays consisted of applying 140 ml of the appropriate sanitizing solution for 10 s at 69 kPa. Corresponding reduction values obtained by water wash alone were 2.3 log. The performance of CASC appeared to be consistently better than that of PASC. In general, no effect of the carcass surface region was observed on the log reductions for either pathogen, except for the inside round, which consistently had lower reductions. Both PASC and CASC were capable of effectively reducing pathogens spread to areas beyond the initial contaminated area of the cuts to levels close to or below the counting method detection limit (0.5 log CFU/cm2). However, 30 to 50% of the carcasses treated by these antimicrobial solutions still yielded countable colonies. Results of this study indicate that acidified sodium chlorite sprays are effective for decontaminating beef carcass surfaces.