Suitability of different bacterial groups for determining faecal contamination during post scalding stages in the processing of broiler chickens

Use of a scald additive to reduce levels of Salmonella typhimurium during poultry processing

This study was conducted to evaluate the efficacy of a scald additive, RP scald, to reduce Salmonella Typhimurium (ST) levels on inoculated poultry carcasses. The RP scald (contains sodium hydroxide) in a 1% solution has a pH of 11.0, which may reduce bacteria levels on carcasses. In this study, 600 broilers (Ross 708 straight run, 6 wk of age) with 300 broilers in each of 2 experimental trials were divided into 4 scald treatments (inoculated with ST) and 2 noninoculated groups. The treatment groups included 4 scald treatments (n = 50 per experimental group per trial): soft scald (SS; 50 degrees C for 90 s), soft scald with 1.0% added RP scald (SSRP), hard scald (56.6 degrees C for 45 s; HS), and hard scald with 1.0% added RP scald. The noninoculated groups (n = 50 per group per trial) are represented by SS0 and HS0. After defeathering, carcass rinses were collected for ST detection. Results indicated that inoculated broilers from hard scald with 1.0% added RP scald had the lowest Salmonella recovery, whereas carcasses from the SS treatment with no RP additive had the highest ST recovery. In trial 1, the SSRP was more effective in reducing ST than HS alone; however, this trend was not consistent. In trial 2, HS alone was more effective in ST reduction than SSRP. Within each scald temperature, the addition of RP scald increased ST reduction; therefore, RP scald may be effective in reducing ST on broiler carcasses in poultry scalder applications, particularly when hard scald temperatures are used.

Partitioning of external and internal bacteria carried by broiler chickens before processing

Broiler chickens from the loading dock of a commercial processing plant were sampled to determine the incidence and counts of coliforms, Escherichia coli, and pathogenic bacteria. Feathers were removed by hand from ten 6-week-old chickens from each of seven different flocks and rinsed in 400 ml of 0.1% peptone water. Heads and feet were removed and rinsed, and the picked carcass was also rinsed, each in 200 ml. The ceca, colon, and crop were aseptically removed and stomached separately in 100 ml of peptone water. Campylobacter was present in six of the seven flocks. Salmonella was isolated from 50 of the 70 carcasses, with at least 2 positive carcasses in each flock, and five-tube most-probable-number (MPN) assays were performed on positive samples. Significantly (P < 0.05) more coliforms and E. coli were found in the ceca than in the feathers, which in turn carried more than the other samples, but total external and internal counts were roughly equivalent. Counts of Campylobacter were higher in the ceca and colon than in the other samples. Salmonella was isolated in external samples from 46 of the 50 positive carcasses compared with 26 positive internal samples or 17 positives in the ceca alone. The total MPN of Salmonella was approximately equivalent in all samples, indicating that contamination was distributed through all external and internal sampling locations. Salmonella-positive samples did not carry higher counts of coliforms or E. coli, and there were no significant correlations between the indicators and pathogens in any sample. Campylobacter numbers in the ceca were correlated with Campylobacter numbers in the feathers and colon, but Salmonella numbers in those samples were not correlated. The pattern of bacterial contamination before processing is complex and highly variable.

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.

Microbiological quality of broiler carcasses during processing in two slaughterhouses in Turkey

The effect of processing procedures on the microbial quality and safety of broiler carcasses was investigated in 2 processing plants. Neck skin samples were taken from broilers at the main stages of processing and changes in total viable count (TVC) and in the counts of Coliforms, Enterobacteriaceae, and Staphylococci/Micrococci were monitored. Processing reduced TVC more than 2 log cycles for the 2 processing plants investigated. The counts of Coliform bacteria decreased from 5.35 to 3.99 log cfu/g, Enterobacteriaceae from 5.36 to 3.81 log cfu/g, and Staphylococci/Micrococci from 6.90 to 4.11 log cfu/g for the first processing plant. The counts of Coliforms, Enterobacteriaceae, and Staphylococci/Micrococci were reduced from 5.67 to 3.92 log cfu/g, from 5.75 to 3.91 log cfu/g, and from 6.85 to 3.94 log cfu/g, respectively, by processing in the second plant. Cross-contamination with Salmonella spp. during processing was observed and the incidences of Salmonella spp. on the carcasses increased from 40 to 60% and from 33.3 to 40% during processing at plants 1 and 2, respectively. The incidences of Salmonella spp. in all broilers (n = 90 carcasses for each plant) were 36.6 and 31.1% at plants 1 and 2, respectively. Although a high proportion of microorganisms were removed from carcasses during processing, dissemination of Salmonella spp. was found to be unavoidable.

Variation in numbers of bacteria on paired chicken carcass halves

Bacterial counts from paired broiler carcass halves were examined for relationships between numbers and kinds of bacteria that might indicate fecal contamination. Broiler carcasses removed from a commercial processing plant just before chilling were split aseptically along the midline, and each side was rinsed in 400 mL of phosphate buffered saline for 1 min with either mechanical or hand shaking. Both halves of six carcasses were rinsed on four different days for a total of 24 carcasses sampled with each shaking method. Aerobic bacteria, coliforms, Escherichia coli, and Campylobacter jejuni were enumerated and summed to obtain whole carcass counts. There were no significant (P < 0.05) differences in numbers of bacteria recovered by the two rinse methods. In left-right comparisons, only E. coli was significantly different (P = 0.04), with the right side having higher counts (least-square means of 1.09 vs. 0.97). For aerobic plate count (APC), coliforms, E. coli, and Campylobacter, correlations between paired left and right side counts were between 0.78 and 0.86. The correlation between whole carcass counts and absolute left-right differences was significant for APC (0.43), but was not significant for coliforms, E. coli, and Campylobacter, so higher whole carcass counts were not associated with higher counts on one side of the carcass. Correlations between different bacteria on whole carcasses were significant for E. coli-APC (0.39), E. coli-coliforms (0.67), and APC-coliforms (0.71), but other combinations had non-significant correlations. The correlation was not significant between E. coli and Campylobacter, a relatively fragile organism whose presence can be interpreted to indicate fairly recent fecal contamination. There were no indications that high E. coli counts on inspection-passed, prechill carcasses indicated recent fecal contamination.

Bacterial counts associated with poultry processing at different sampling times

Aerobic plate counts, Enterobacteriaceae counts and Pseudomonas counts were performed on neck skin samples from six processing steps in a poultry abattoir at three different sampling times. Sampling time 1 was shortly after start-up of processing operations, time 2 after a tea break which was preceded by a cold water rinse-down of equipment surfaces, and time 3 before shut-down. No significant differences (P > 0.05) in microbial numbers of neck skin samples were observed between the three sampling times at the six sampling sites. At this particular processing plant, therefore, sampling at any time of the processing shift would thus not lead to significantly different bacterial counts of neck skins. The lowest aerobic plate counts, over all three sampling times, were obtained for neck skins sampled after spray washing, and the highest for neck skins sampled after packaging. This indicated the efficacy of the washing step in reducing microbial contamination but subsequent re-contamination of carcasses. Despite the Pseudomonas counts of neck skins being lower than the Enterobacteriaceae counts at the beginning of processing, packaging of carcasses resulted in Pseudomonas counts that were higher than the Enterobacteriaceae counts.

Relationship between aerobic bacteria, salmonellae and Campylobacter on broiler carcasses

Broiler carcasses were removed from commercial processing lines immediately after defeathering, before chilling, and after chilling to determine whether any relationship exists between aerobic bacteria and the human enteropathogens salmonellae and Campylobacter. In two experiments, a whole carcass rinse procedure was used to sample 30 carcasses after defeathering, 90 carcasses before chilling, and 90 carcasses after chilling, for a total of 210 different carcasses. Aerobic bacteria and Campylobacter spp. were enumerated and the incidence of salmonellae was determined. Salmonellae and Campylobacter incidences were 20 and 94%, respectively, for all carcasses sampled. After picking, neither salmonellae-positive nor Campylobacter-positive carcasses had mean aerobic most probable number (MPN) values that were different from carcasses negative for those organisms. Immediately before chilling, aerobic and Campylobacter counts were 7.12 and 5.33 log10 cfu per carcass, respectively. Immersion chilling reduced aerobic counts by approximately 1.8 log and Campylobacter by 1.5 log, with no change in salmonellae-positive carcasses. There was no difference in aerobic or Campylobacter counts between carcasses that were positive or negative for salmonellae at any of the sampling locations, nor was any correlation found between levels of aerobic organisms and Campylobacter. Carcasses with aerobic counts above the mean or more than one standard deviation above the mean also failed to show any correlation. Discriminant analysis indicated error rates as high as 50% when numbers of aerobic bacteria were used to predict incidence of salmonellae or Campylobacter on individual carcasses. Aerobic bacteria are not suitable as index organisms for salmonellae or Campylobacter on broiler carcasses.

Effect of cloacal plugging on microbial recovery from partially processed broilers

Experiments were performed to test the contribution of bacteria contained in the intestinal tract of broilers at the beginning of processing to counts on the exterior of modified New York-dressed carcasses. Thirty-two birds were processed for each of seven replications. Within each replication, batches of four birds were electrocuted, scalded, and picked, with batches alternating between treatment and control groups. Treated birds were cloacally plugged with rayon fiber tampons prior to electrocution to prevent escape of intestinal contents during scalding and picking. Control birds were processed in the same manner, except that cloacal plugs were inserted immediately after defeathering to reduce escape of intestinal contents during sampling. Gram-negative enteric bacteria and Campylobacter spp. were enumerated on carcasses by whole carcass rinse procedure and in cecal contents. Counts were converted to log10 and subjected to analysis of variance. Cecal levels of Gram-negative enterics were significantly higher for plugged birds, but there was not a significant difference between levels of cecal Campylobacter spp. between treatment groups. Plugging before electrocution resulted in significantly lower levels (2.5 vs 3.0 log10 cfu/mL) of Campylobacter spp. and Gram-negative enteric bacteria (3.0 vs 3.4 log10 cfu/mL) in carcass rinses of treatment birds than in those of controls. All carcasses were positive for Gram-negative enterics. Cloacal plugging resulted in significantly lower incidence of Campylobacter spp. carcass contamination as determined by chi-square. Intestinal carriage of both campylobacters and Gram-negative enteric bacteria appears to influence the microbial quality of the carcass during processing.

The role of defeathering in the contamination of turkey skin by Salmonella species and Listeria monocytogenes

This study was undertaken to determine whether the incidence of either Salmonella spp. or Listeria monocytogenes on turkeys at three commercial processors could be related to the type of defeathering system: 1) conventional, 58 C common bath scald; 2) kosher, 7 C common bath scald; or 3) steam-spray, 62 C nonimmersion scald. Flocks were sampled before defeathering, after defeathering, and after chill at each facility. The incidence of Salmonella-positive turkeys significantly increased subsequent to conventional defeathering (10 positive out of 14) as compared with before defeathering (3/14). The number of Salmonella-positive carcasses following kosher (0/14) and steam-spray (2/14) defeathering were similar to the number of Salmonella-positive carcasses found prior to defeathering (1/14 and 3/14, respectively). The incidence of Salmonella-positive carcasses following chill was slightly lower, but not significantly different than the number of Salmonella-positive carcasses found immediately following defeathering at all processors (8/14, 0/14, 1/14 for conventional, kosher, and steam-spray processors, respectively). Although L. monocytogenes was detected on turkeys sampled before chilling (2/10, kosher) and after chilling (8/14, kosher; 1/14, conventional), no L. monocytogenes was detected on turkeys at any of the processors prior to the evisceration process. Flocks with high aerobic plate counts prior to processing were more likely to contain Salmonella-positive birds throughout processing. Aerobic plate counts of all flocks were similar after chill whether or not Salmonella spp. and L. monocytogenes were detected.

Microbiological survey of a South African poultry processing plant

Bacterial populations associated with poultry processing were determined on neck skin samples, equipment surfaces and environmental samples by replicate surveys. Aerobic plate counts, Enterobacteriaceae counts, Enterobacteriaceae counts and Pseudomonas counts were performed by standard procedures and the prevalence of Listeria, presumptive Salmonella and Staphylococcus aureus determined. Statistically significant (P < 0.05) increases in counts of all types of bacteria were obtained on product samples as a result of processing. Although bacterial counts on neck skin samples decreased by 0.3 to 0.4 log CFU g-1 after spray washing of carcasses, subsequent spinchilling and packaging of whole carcasses resulted in 0.7 to 1.2 log CFU g-1 increases. Bacterial numbers on equipment surfaces, however, decreased significantly from the "dirty" to the "clean" areas of the abattoir. Transport cages, "rubber fingers", defeathering curtains, shackles and conveyor belts repeatedly showed aerobic plate counts in excess of 5.0 log CFU 25 cm-2. Aerobic plate counts of scald tank and spinchiller water were 2 log CFU ml-1 higher than those of potable water samples. Bacterial numbers of the air in the "dirty" area were higher than those of the "clean" area. Listeria, presumptive Salmonella and Staphylococcus aureus were isolated from 27.6, 51.7 and 24.1% of all product samples, respectively, and Listeria and Staphylococcus aureus were also isolated from selected equipment surfaces.

Microbiological and shelf life assessment of chilled eviscerated whole chicken broilers in Saudi Arabia

1. The microbiological quality and shelf life of chicken carcasses marketed in Riyadh, Saudi Arabia were assessed. 2. The mean initial microbial counts (log10 count/cm2) were 4.67, 4.14, 2.21, 2.78 and 2.96 for total aerobes, psychrotrophs, coliforms, Staphylococcus aureus and yeasts and moulds, respectively; these counts suggest a moderate level of contamination during processing. 3. Yeasts and moulds were present in relatively large numbers and constituted a considerable portion of the spoilage flora. 4. The mean shelf life of chicken broilers was 9.6, 6 and 4.4 d at 4, 7 and 10 degrees C, respectively. Storage at 4 degrees C resulted in better keeping than storage at 7 degrees C or 10 degrees C, while there was no significant difference between 7 degrees and 10 degrees C. 5. The initial total of aerobes, psychrotrophs and yeasts and moulds were found to negatively correlate with shelf life.

Contamination of broiler carcass skin during commercial processing procedures: an electron microscopic study

Scanning and transmission electron microscopy were used in conjunction with normal microbiological cultural techniques to examine some aspects of contamination of broiler carcass skin by bacteria during processing. The autochthonous skin microflora of poultry, before processing, was mainly Micrococcus spp. which were located in accumulations of sebum-like substances on the surface of the stratum corneum. During scalding and plucking, the skin epidermis was removed, and exposed dermal tissue was contaminated by microorganisms from the mechanical plucker and subsequent stages of processing. Major sources of psychrotrophic contamination were the immersion washer and chiller water. Microbial contaminants were found within a fluid film on the skin surface and inside deep skin channels. Skin microtopography and the presence of the liquid film were implicated as major factors controlling contamination during processing.

Removing faecal contamination of broilers by spray-cleaning during evisceration

1. The faecal contamination of broiler carcasses during evisceration results in an increase in contamination with Enterobacteriaceae, including any salmonellas present. 2. This increase can be prevented completely by spray-cleaning carcasses during the various stages of evisceration. 3. If the carcasses are cleaned only at the end of the evisceration process, the numbers of Enterobacteriaceae are not reduced to initial levels and Salmonella contamination is less efficiently removed.