A comparison between broiler chicken carcasses with and without visible faecal contamination during the slaughtering process on hazard identification of Salmonella spp

Small Contaminations on Broiler Carcasses Are More a Quality Matter than a Food Safety Issue

Depending on the interpretation of the European Union (EU) regulations, even marginally visibly contaminated poultry carcasses could be rejected for human consumption due to food safety concerns. However, it is not clear if small contaminations actually increase the already present bacterial load of carcasses to such an extent that the risk for the consumers is seriously elevated. Therefore, the additional contribution to the total microbial load on carcasses by a small but still visible contamination with feces, grains from the crop, and drops of bile and grease from the slaughter line was determined using a Monte Carlo simulation. The bacterial counts (total aerobic plate count, Enterobacteriaceae, Escherichia coli, and Campylobacter spp.) were obtained from the literature and used as input for the Monte Carlo model with 50,000 iterations for each simulation. The Monte Carlo simulation revealed that the presence of minute spots of feces, bile, crop content, and slaughter line grease do not lead to a substantial increase of the already existing biological hazards present on the carcasses and should thus be considered a matter of quality rather than food safety.

Detection and Quantification of Campylobacter in Poultry Slaughterhouses Using Conventional Microbiological Technique, Most Probable Number, and Real-Time PCR

Campylobacteriosis is one of the most common bacteria causing human gastroenteritis. Poultry is a major reservoir of Campylobacter spp. as well as the main source of transmission. Due to the increased occurrence of campylobacteriosis, poultry slaughterhouses are under pressure to deliver carcasses with low contamination. However, a few studies have been carried out to evaluate Campylobacter contamination of broiler carcasses in Brazilian slaughter lines. Therefore, in this study, we aimed at detecting and quantifying the thermotolerant Campylobacter spp. at different stages of the poultry slaughtering process. The samples were collected from 12 points in three slaughterhouses in southern Brazil, at an interval of 12 months, and were tested for Campylobacter spp. by conventional microbiological technique, the most probable number, and real-time PCR. A total of 432 samples were analyzed. The majority of strains belonged to Campylobacter jejuni (92%), and the flock positivity among the three techniques was similar in most cases. Campylobacter was detected in all slaughtering stages. Although contamination has remained similar (p > 0.05) throughout almost all the slaughter process, evisceration seemed to be an important source of contamination. Our results reinforce the idea that the final carcass quality after the slaughtering process is directly influenced by the level of contamination of the broiler flocks on arrival at the processing plant.

Systematic Review: Nontyphoidal Salmonella in Food from Latin America

In Latin America, nontyphoidal Salmonella (NTS) is one of the most important etiological agents of foodborne infections; it can survive in soil, water, and food even after processing. Here, we aimed to perform a systematic review by collecting data on the prevalence, serotypes, and antimicrobial resistance (AMR) of NTS isolated from different food products in Latin America, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Out of 1766 studies screened, 244 reports from 13 Latin American countries were eligible. Among these, 182 reported NTS prevalence, 87 reported NTS serotypes, and 83 reported serotypes with AMR patterns. The NTS prevalence ranged from 0.005% to 93.3%, regardless of country and food. Meat showed the highest NTS prevalence. Enteritidis, Typhimurium, and Derby were the most frequently observed serotypes in different food products. The serotypes Enteritidis, Typhimurium, and Infantis, isolated from animal products, showed the highest AMR rate. The presence of NTS in fruits and vegetables, which are generally consumed raw or as ready-to-eat food, indicates a high risk of salmonellosis from consuming these foods. Thus, the reduction of this pathogen in the food chain requires a One Health approach, involving good agricultural and manufacturing practices, low antimicrobial use, and proper waste management.

Characterization of Salmonella Isolates Recovered from Stages of the Processing Lines at Four Broiler Processing Plants in Trinidad and Tobago

This cross-sectional study determined the prevalence, characteristics, and risk factors for contamination of chicken with Salmonella at four operating broiler processing plants in Trinidad. Standard methods were used to isolate and characterize the Salmonella isolates. The overall prevalence of Salmonella at the four processing plants was 27.0% (107/396). The whole carcass enrichment (WCE) method yielded a statistically significantly (p = 0.0014) higher frequency of isolation (53.9%; 97/180) than the whole carcass rinse (35.0%; 63/180) and neck skin methods (42.2%; 38/90). S. enterica serotypes Enteritidis, Javiana, and Infantis were the predominant serotypes isolated accounting for 20.8%, 16.7% and 12.5%, respectively, of the serotyped isolates. Risk factors included the use of over 100 contract farmers (OR 4.4), pre-chiller (OR 2.3), addition of chlorine to chiller (OR 3.2), slaughtering sick broilers (OR 4.4), and flocks with >50% mortality. Multi-drug resistance was detected in 12.3% (14/114) of the isolates of Salmonella. Resistance was high to kanamycin (85.7%) and doxycycline (74.6%) but low to amoxicillin-clavulanic acid (2.4%) and sulphamethoxazole-trimethoprim (0.8%). The occurrence of resistant Salmonella in chickens processed at commercial broiler processing plants has implications for salmonellosis and therapeutic failure in consumers of improperly cooked contaminated chickens from these plants in the country.

High Occurrence of Multiresistant Salmonella Infantis in Retail Meat in Ecuador

Salmonella enterica is among the most important foodborne pathogens. In Ecuador, there is limited information about non-typhoidal S. enterica occurrence in raw meats, its serotype distribution, and antimicrobial resistance. In this study, we addressed this issue in 1095 retail fresh meats (chicken, pork, veal, lamb, beef, and turkey) in Quito by performing a traditional culture methodology and molecular detection. We found that S. enterica was present in 38.1% of the samples, and Salmonella Infantis was the most common serotype showing a high antibiotic resistance and a wide host range. Some host-adapted serotypes were found in uncommon sources of meat, suggesting cross-contamination and the need to implement good manufacturing practices in meat processing. High levels of multidrug resistance were found in all serotypes. There is an urgent need to identify Salmonella serotypes in food to compare with clinical data and to carry out epidemiological studies to control and prevent outbreaks and infections.

Microbiological Profile of Three Commercial Poultry Processing Plants in Colombia

Poultry meat production in Colombia has significant growth potential to fulfill national demands and to become an important global exporter. Entering export markets requires compliance with international food safety standards and the support of a rigorous national inspection system. To support the development of national standards, information about the microbiological profiles of poultry operations is needed, and no official microbiological baseline is currently available. A total of 480 chicken carcass rinses and 64 fecal samples were collected at different process sites from three commercial poultry processing establishments located in different regions of Colombia. Samples were analyzed to determine the prevalence of Salmonella and the levels of Escherichia coli in chicken rinse. Six steps were selected for sampling in the slaughter, evisceration, and chilling processes. The overall Salmonella prevalence after water immersion chilling at the three establishments was 12.5% (73 of 584 samples). E. coli levels were 1.2 to 2.2 log CFU/mL (mean, 1.65 log CFU/mL) after the chilling process. Significant differences (P < 0.05) were found for E. coli levels among the processing sites at the three establishments; however, there were no significant differences in the distribution of Salmonella-positive samples through the sites at each plant. These results can be used as reference data for microorganisms in chicken meat facilities in Colombia and will help the poultry industry and regulators in the design of new prevention programs and food safety management systems.

Evaluation of antimicrobial activities of sequential spray applications of decontamination treatments on chicken carcasses

The objective of this study was to evaluate the effects of sequential applications of ɛ-polylysine (EPL) or lauramide arginine ethyl ester (LAE) sprays followed by an acidic calcium sulfate (ACS) spray on inoculated chicken carcasses to reduce Salmonella (Salmonella enterica serovars including Salmonella typhimurium and Salmonella enteritidis) contamination during 6 days of storage (4.4°C). Secondly, reductions of the resident microflora were studied on uninoculated chicken carcasses following the sequential application of the treatments, chilling and 10 days of storage at 4.4°C. The treatment of Salmonella inoculated carcasses with 300 mg/L EPL followed by 30% ACS (EPL300-ACS30) sprays reduced Salmonella counts initially by 1.5 log cfu/mL and then by 1.2 log cfu/mL (p<0.05) following 6 days of storage at 4.4°C. Likewise, 200 mg/L LAE followed by 30% ACS (LAE200-ACS30) treatment reduced initial Salmonella counts on poultry carcasses by 1.8, 1.4 and 1.8 log cfu/mL (p<0.05), respectively, after 0, 3, and 6 days storage. Immediately after the treatments, EPL300-ACS30 and LAE200-ACS30 both reduced Escherichia coli counts significantly by 2.6 and 2.9 log cfu/mL, respectively. EPL300-ACS30 and LAE200-ASC30 were effective in lowering psychrotroph counts by 1 log cfu/mL on day 10 when compared to the control and distilled water treatments. This study demonstrated that EPL300-ACS30 and LAE200-ACS30 were effective in reducing Salmonella on inoculated chicken carcasses both after treatment and during the storage at 4.4°C for up to 6 days. In addition, reductions in psychrotroph counts indicated that these treatments might have the potential to increase the shelf-life of poultry carcasses.

Agreement of 3 carcass rinse sampling methods (split carcass, repeat rinse, and adjacent pair) on the detection of Salmonella contamination in broiler carcasses

Whole carcass rinse is the most common method used to determine Salmonella prevalence in broiler carcasses. However, there is a need to determine the carcass rinse sampling method that best measures the Salmonella status of a broiler carcass as it proceeds through processing, thus allowing the assessment of efficacy of interventions to meet Food Safety Inspection Services (FSIS) performance standards. In this study, 3 paired carcass rinse sampling methods, namely split-carcass method (rinses of 2 halves of one carcass), repeat rinse method (rinse and rerinse of same carcass), and adjacent pair method (rinses of 2 adjacent carcasses), were evaluated during actual operations in commercial poultry processing plants in the southeastern United States. The purpose of the work was to determine which method resulted in greatest agreement of Salmonella status on paired broiler carcass rinses. The adjacent pair method showed moderate agreement consistently in 3 trials of 150 pairs per trial with kappa values of 0.46, 0.55, and 0.46. The repeat rinse method showed substantial kappa agreement (0.64) in one trial and moderate kappa agreement (0.47, 0.41) in 2 other trials. In one trial, the repeat rinse method showed a significant difference in prevalence rates between repeated rinses. Even though the split carcass method showed moderate kappa agreement (0.58, 0.45) in 150 carcasses in each of 2 trials, the disadvantages of the split carcass method were that it was more labor and time intensive and the product was damaged, when compared to the other 2 methods. Overall, although prevalence estimates were fairly consistent between pairs by each method, agreement between Salmonella status of the paired samples was less than desired, mostly moderate. This lack of agreement should be considered in the design of studies assessing the efficacy of interventions for the control of Salmonella in broilers to meet FSIS performance standards.

Salmonella contamination risk points in broiler carcasses during slaughter line processing

Salmonella is one of the foodborne pathogens most commonly associated with poultry products. The aim of this work was to identify and analyze key sampling points creating risk of Salmonella contamination in a chicken processing plant in Costa Rica and perform a salmonellosis risk analysis. Accordingly, the following examinations were performed: (i) qualitative testing (presence or absence of Salmonella), (ii) quantitative testing (Salmonella CFU counts), and (iii) salmonellosis risk analysis, assuming consumption of contaminated meat from the processing plant selected. Salmonella was isolated in 26% of the carcasses selected, indicating 60% positive in the flocks sampled. The highest Salmonella counts were observed after bleeding (6.1 log CFU per carcass), followed by a gradual decrease during the subsequent control steps. An increase in the percentage of contamination (10 to 40%) was observed during evisceration and spray washing (after evisceration), with Salmonella counts increasing from 3.9 to 5.1 log CFU per carcass. According to the prevalence of Salmonella -contaminated carcasses released to trade (20%), we estimated a risk of 272 cases of salmonellosis per year as a result of the consumption of contaminated chicken. Our study suggests that the processes of evisceration and spray washing represent a risk of Salmonella cross-contamination and/ or recontamination in broilers during slaughter line processing.

Prevalence of Salmonella on retail broiler chicken meat carcasses in Colombia

A cross-sectional study was performed to estimate the prevalence of Salmonella on retail market chicken carcasses in Colombia. A total of 1,003 broiler chicken carcasses from 23 departments (one city per department) were collected via a stratified sampling method. Carcass rinses were tested for the presence of Salmonella by conventional culture methods. Salmonella strains were isolated from 27 % of the carcasses sampled. Logistic regression analysis was used to determine potential risk factors for Salmonella contamination associated with the chicken production system (conventional versus free-range), storage condition (chilled versus frozen), retail store type (supermarket, independent, and wet market), poultry company (integrated company versus nonintegrated company), and socioeconomic stratum. Chickens from a nonintegrated poultry company were associated with a significantly (P < 0.05) greater risk of Salmonella contamination (odds ratio, 2.0) than were chickens from an integrated company. Chilled chickens had a significantly (P < 0.05) higher risk of Salmonella contamination (odds ratio, 4.3) than did frozen chicken carcasses.

Indicator organisms in meat and poultry slaughter operations: their potential use in process control and the role of emerging technologies

Measuring commonly occurring, nonpathogenic organisms on poultry products may be used for designing statistical process control systems that could result in reductions of pathogen levels. The extent of pathogen level reduction that could be obtained from actions resulting from monitoring these measurements over time depends upon the degree of understanding cause-effect relationships between processing variables, selected output variables, and pathogens. For such measurements to be effective for controlling or improving processing to some capability level within the statistical process control context, sufficiently frequent measurements would be needed to help identify processing deficiencies. Ultimately the correct balance of sampling and resources is determined by those characteristics of deficient processing that are important to identify. We recommend strategies that emphasize flexibility, depending upon sampling objectives. Coupling the measurement of levels of indicator organisms with practical emerging technologies and suitable on-site platforms that decrease the time between sample collections and interpreting results would enhance monitoring process control.

Predictive models for reduction of Salmonella Hadar on chicken skin during single and double sequential spraying treatments with acetic acid

AIMS

The response surface methodology was used to evaluate the effect of acetic acid concentration, spraying time and temperature on the reduction of Salmonella Hadar on poultry skin in a laboratory spraying process, and to identify the best conditions required to develop this operation.

METHODS AND RESULTS

A comparative analysis was carried out to ascertain the effects of the application of single (SS) and double sequential decontamination (DSS) treatments on skin samples inoculated with Salm. Hadar. While on the SS treatment, the linear and quadratic acid concentration terms and the interaction of the temperature and time term of the model are statistically significant at P < or = 0.001, P < or = 0.01 and P < or = 0.05, respectively, the other terms do not significantly affect (P > 0.05) the reduction of Salm. Hadar. On the DSS model the acid concentration and time linear terms significantly affected (P < or = 0.001 and P < or = 0.01) the Salm. Hadar reduction within the experimental range assayed.

CONCLUSION

Any of the models could be used as an approach to optimize spray washing during chicken processing.

SIGNIFICANCE AND IMPACT OF THE STUDY

Neither the SS or the DSS treatment has the capability of eliminating Salm. Hadar from carcasses. However, reductions of approx. 99% initial load could be attained if DSS treatment were put into practice.

Effect of dry air or immersion chilling on recovery of bacteria from broiler carcasses

A study was conducted to investigate the effect of chilling method (air or immersion) on concentration and prevalence of Escherichia coli, coliforms, Campylobacter, and Salmonella recovered from broiler chicken carcasses. For each of four replications, 60 broilers were inoculated orally and intracloacally with 1 ml of a suspension containing Campylobacter at approximately 10(8) cells per ml. After 1 day, broilers were inoculated with 1 ml of a suspension containing Salmonella at approximately 10(8) cells per ml. Broilers were processed, and carcasses were cooled with dry air (3.5 m/s at -1.1 degrees C for 150 min) or by immersion chilling in ice water (0.6 degrees C for 50 min). Concentrations of E. coli, coliforms, Campylobacter, and Salmonella recovered from prechill carcasses averaged 3.5, 3.7, 3.4, and 1.4 log CFU/ml of rinse, respectively. Overall, both chilling methods significantly reduced bacterial concentrations on the carcasses, and no difference in concentrations of bacteria was observed between the two chilling methods (P < 0.05). Both chilling methods reduced E. coli and coliforms by 0.9 to 1.0 log CFU/ml. Air and immersion chilling reduced Campylobacter by 1.4 and 1.0 log CFU/ml and reduced Salmonella by 1.0 and 0.6 log CFU/ml, respectively. Chilling method had no effect on the prevalence of Campylobacter and Salmonella recovered from carcasses. These results demonstrate that air- and immersion-chilled carcasses without chemical intervention are microbiologically comparable, and a 90% reduction in concentrations of E. coli, coliforms, and Campylobacter can be obtained by chilling.

Effect of External or Internal Fecal Contamination on Numbers of Bacteria on Prechilled Broiler Carcasses

During processing, fecal material may contact broiler carcasses externally or internally. A study was conducted to determine the effect of external vs. internal fecal contamination on numbers of bacteria on broiler carcasses. In each of 3 trials, 12 carcasses just prior to evisceration were obtained from a commercial processing plant, placed on a shackle line, and eviscerated with commercial equipment in a pilot scale processing plant. Also, approximately 20 intestinal tracts were collected from the processing plant; then cecal contents were collected and pooled. One gram of cecal content was placed on the exterior breast skin (external), inside the carcass cavity (internal), or not applied (control). All carcasses were held 10 min, then placed on the shackle line and passed through a commercial inside-outside bird washer set at 552 kPa, 5 s dwell time, using approximately 189 L per min of tap water at ambient temperature. After a 1-min drip, whole carcass rinses were conducted on each carcass, and coliforms, Escherichia coli, and Campylobacter counts were determined and reported as log cfu/mL of rinse. External carcass contamination resulted in significantly higher (P<0.05) coliform, E. coli, and Campylobacter numbers than internal contamination (5.0 vs. 4.5, 4.9 vs. 4.2, and 3.6 vs. 2.6, respectively). Control carcass counts were significantly lower than external or internal carcass contamination counts for coliforms (3.7), E. coli (3.6), and Campylobacter (2.2). External contamination resulted in higher numbers of bacteria after carcass washing, but carcasses with internal contamination still have higher numbers of bacteria after washing than carcasses without applied contamination.

Microbiological baseline study of broiler chickens at Swedish slaughterhouses

This 1-year study was conducted to estimate the prevalence and concentrations of pathogenic and indicator bacteria on Swedish broiler chickens. A total of 636 chilled carcasses were collected from 10 slaughterhouses and sent to the National Food Administration for analyses of carcass rinses. No carcasses were positive for Salmonella. Campylobacter, predominantly Campylobacter jejuni, were detected on 15% (by enrichment) or 14% (by direct plating) of the carcasses. With one exception, all samples from late December through April were Campylobacter negative. The 10th and 90th percentiles of Campylobacter numbers per carcasses were 3.0 and 5.0 log CFU, respectively, and the maximum was 7.1 log CFU. Coagulase-positive staphylococci were detected on 68% of the carcasses, with a maximum of 3.5 log CFU/cm2. The 10th and 90th percentiles were 3.4 and 4.4 log CFU/cm2 for total aerobic microorganisms, 1.8 and 3.3 log CFU/cm2 for Enterobacteriaceae, and 2.0 and 3.6 log CFU/cm2 for Escherichia coli. No correlation was found between numbers of any indicator bacteria and numbers of pathogenic bacteria. Subsets of the samples were analyzed for Listeria monocytogenes, Clostridium perfringens, pathogenic Yersinia enterocolitica, and Enterococcus, resulting in prevalence estimates of 29, 18, 9 (as determined by a PCR assay), and 97%, respectively. L. monocytogenes was most common at slaughterhouses with a low prevalence of coagulase-positive staphylococci, and vice versa. These results will improve the ability of researchers to assess the importance of chicken as a source of foodborne pathogens and can serve as a basis for risk management actions.

Prevalence and molecular profiles of Salmonella collected at a commercial turkey processing plant

In this study, whole carcasses were sampled at eight stages on a turkey-processing line and Salmonella prevalence was determined using enrichment techniques. Recovered Salmonella was further characterized using serotyping and the molecular profiles were determined using pulsed-field gel electrophoresis (PFGE). Prevalence data showed that contamination rates varied along the line and were greatest after defeathering and after chilling. Analysis of contamination in relation to serotypes and PFGE profiles found that on some visits the same serotype was present all along the processing line while on other days, additional serotypes were recovered that were not detected earlier on the line, suggesting that the birds harbored more than one serotype of Salmonella or there was cross-contamination occurring during processing. Overall, this study found fluctuations in Salmonella prevalence along a turkey-processing line. Following washing, Salmonella prevalence was significantly reduced, suggesting that washing is critical for Salmonella control in turkey processing and has significant application for controlling Salmonella at the postdefeathering and prechill stages where prevalence increased.

Recovery of Bacteria from Broiler Carcasses Rinsed Zero and Twenty-Four Hours After Immersion Chilling

Microbiological sampling of processed broiler carcasses often relies on the technique of whole-carcass rinsing; however, the rinse sampling is sometimes done immediately after immersion chilling and sometimes as long as 24 h after immersion chilling. To test whether carcass rinses done immediately after chilling can be compared with rinses 24 h after chilling, 20 whole broiler carcasses exiting the chiller of a broiler processing plant were sampled on each of 3 d. All carcasses were bagged aseptically and rinsed for 1 min in 400 mL of sterile water. Recovered rinse liquid was poured into a sterile container, and rinsed carcasses were placed in clean plastic bags; all materials were held overnight at 4 degrees C. On the following day, all carcasses were rinsed again in 400 mL of sterile water as before, and all rinse samples were cultured by standard methods to enumerate coliforms, Escherichia coli, and Campylobacter and to determine incidence of Salmonella. Statistical analysis used paired comparisons between the same carcasses rinsed at 0 and 24 h after chilling; numbers of bacteria were expressed as log cfu/mL of rinse. In 2 of 3 replications, significantly higher numbers of coliforms and E. coli were found in the rinse samples taken immediately after chilling vs. rinse samples done at 24 h. There were no differences in numbers of Campylobacter or incidence of Salmonella between rinses taken at 0 and 24 h. More study is required to determine whether whole-carcass rinse samples performed at 0 and 24 h after chilling are microbiologically equivalent.

Predictive model for reduction of Escherichia coli during acetic acid decontamination of chicken skin

AIMS

The response surface methodology was used to evaluate the effect of operating variables (acetic acid concentration, spraying time and temperature) on the reduction of Escherichia coli populations on poultry breast skin in a laboratory showering process, as well as to identify the best conditions that are required to develop this operation.

METHODS AND RESULTS

Skin samples were inoculated with a 24-h E. coli culture and afterwards treated according to experimental design under selected acetic acid concentration, spraying time, and solution temperature. The E. coli reduction model was significantly affected by the acetic acid concentration and spraying time (P < or = 0.05 and < or =0.01), while temperature did not show a significant effect (P > 0.05).

CONCLUSION

The predictive model obtained was validated through additional confirmatory experiments and showed to be adequate, and it could be used as an approach to optimize the acetic acid spray washes during poultry carcasses processing.

SIGNIFICANCE AND IMPACT OF THE STUDY

The use of acetic acid washes in the processing of poultry does not have the capability of eliminating E. coli populations from carcasses. However, significant reductions in the initial load could be achieved.

Effect of fecal contamination and cross-contamination on numbers of coliform, Escherichia coli, Campylobacter, and Salmonella on immersion-chilled broiler carcasses

The effect of prechill fecal contamination on numbers of bacteria on immersion-chilled carcasses was tested in each of three replicate trials. For each trial, 16 eviscerated broiler carcasses were split into 32 halves and assigned to one of two groups. Cecal contents (0.1 g inoculated with Campylobacter and nalidixic acid-resistant Salmonella) were applied to each of eight halves in one group (direct contamination) that were placed into one paddle chiller (contaminated), whereas the other paired halves were placed into another chiller (control). From the second group of eight split birds, one of each paired half was placed in the contaminated chiller (to determine cross-contamination) and the other half was placed in the control chiller. Postchill carcass halves were sampled by a 1-min rinse in sterile water, which was collected and cultured. Bacterial counts were reported as log CFU per milliliter of rinsate. There were no significant statistical differences (paired t test, P < 0.05) from direct contamination for coliforms (mean 3.0 log CFU) and Escherichia coli (mean 2.7 log CFU), although Campylobacter numbers significantly increased from control values because of direct contamination (1.5 versus 2.1 log CFU), and the incidence increased from 79 to 100%. There was no significant effect of cross-contamination on coliform (mean 2.9 log CFU) or E. coli (mean 2.6 log CFU) numbers. Nevertheless, Campylobacter levels were significantly higher after exposure to cross-contamination (1.6 versus 2.0 log CFU), and the incidence of this bacterium increased from 75 to 100%. Salmonella-positive halves increased from 0 to 42% postchill because of direct contamination and from 0 to 25% as a result of cross-contamination after chilling. Water samples and surface swabs taken postchill from the contaminated chiller were higher for Campylobacter than those taken from the control chiller. Immersion chilling equilibrated bacterial numbers between contaminated and control halves subjected to either direct contamination or cross-contamination for coliforms and E. coli. Campylobacter numbers, Campylobacter incidence, and Salmonella incidence increased because of both direct contamination and cross-contamination in the chiller. Postchill E. coli numbers did not indicate which carcass halves were contaminated with feces before chilling.

Effect of prechill fecal contamination on numbers of bacteria recovered from broiler chicken carcasses before and after immersion chilling

Paired carcass halves were used to test whether fecal contamination of skin during processing of broiler chickens can be detected by increased bacterial counts in samples taken before and after immersion chilling. In each of three trials, six freshly defeathered and eviscerated carcasses were cut in half, and a rectangle (3 by 5 cm) was marked with dots of ink on the breast skin of each half. One half of each pair was chosen randomly, and 0.1 g of freshly collected feces was spread over the rectangle with a spatula. After 10 min, both halves were sprayed with tap water for 10 to 15 s until feces could no longer be seen in the marked area. Both halves were sampled with a 1-min carcass rinse and were then put in a paddle chiller with other eviscerated carcasses for 45 min to simulate industrial immersion chilling. Immediately after chilling, each carcass half was subjected to another 1-min rinse, after which the skin within the rectangle was aseptically removed from the carcass halves and stomached. Rinses of fecally contaminated halves had significantly higher Enterobacteriaceae immediately before chilling, but there were no differences in coliform and Escherichia coli counts. After chilling, there were no differences in Enterobacteriaceae, coliform, and E. coli counts in rinse or skin samples from the paired carcass halves. Correlations were generally poor between counts in rinse and skin samples but were significant between prechill and postchill rinses for both control and fecally contaminated halves. Correlations were also significant between counts in rinses of control and contaminated halves of the same carcass after chilling. Bacterial counts in postchill carcass rinses did not indicate that fecal contamination occurred before chilling.