D. P. Smith

Microbiology of Broiler Carcasses and Chemistry of Chiller Water as Affected by Water Reuse

A study was conducted to determine the effects of treating and reusing poultry chiller water in a commercial poultry processing facility. Broiler carcasses and chiller water were obtained from a commercial processing facility which had recently installed a TOMCO Pathogen Management System to recycle water in sections 2 and 3 of two 3-compartment chillers. In this system, reused water is blended with fresh water to maintain the chiller volume. Carcasses were sampled prechill and postchill (final exit), and chiller water was sampled from the beginning and end of each of the 3 sections. Carcasses were subjected to a whole carcass rinse (WCR) in 0.1% peptone. Numbers of Escherichia coli (EC), coliforms (CF), and Campylobacter (CPY) were determined from the WCR and chiller water samples. Prevalence of Salmonella (SAL) was also determined on the WCR and chiller water samples. On average, prechill levels of bacteria recovered from rinses were 2.6, 2.9, and 2.6 log10 cfu/mL for EC, CF, and CPY, respectively. Ten out of 40 (25%) prechill carcasses were positive for SAL. After chilling, numbers of EC, CF, and CPY recovered from carcass rinses decreased by 1.5, 1.5, and 2.0 log10 cfu/mL, respectively. However, 9 out of 40 (22%) postchill carcasses were positive for SAL. When the chiller water samples were tested, counts of EC, CF, and CPY were found only in water collected from the first section of the chiller (inlet and outlet). Two of 4 water samples collected from the inlet of the first section tested positive for SAL. This study shows that fresh and reused water can be used to cool poultry in chiller systems to achieve a reduction in numbers of bacteria (EC, CF, and CPY) or equivalent prevalence (SAL) of bacteria recovered from broiler carcasses.

The Effect of Chilling in Cold Air or Ice Water on the Microbiological Quality of Broiler Carcasses and the Population of Campylobacter

Cold air or ice water can be used to chill poultry carcasses after slaughter. The objective of this study was to compare the effect of 2 chill methods on broiler carcass bacteria. Broiler carcasses were cut in half along the dorsal-ventral midline; one half was subjected to an ice-water immersion chill in an agitated bath for 50 min, whereas the reciprocal half was subjected to an air chill in a 1 degrees C cold room for 150 min. Total aerobic bacteria, coliforms, Escherichia coli, and Campylobacter were enumerated from half-carcass rinses. Species of Campylobacter isolates was determined by a commercial PCR method, which was followed by molecular subtyping with pulsed-field gel electrophoresis and determination of antimicrobial susceptibility to 9 drugs. Although significantly fewer of each bacterial type were detected per milliliter from immersion-chilled carcasses than from air-chilled carcasses, in each case the difference was less than 1 log(10) cfu/mL. Chilling method did not affect species; both Campylobacter jejuni and Campylobacter coli were recovered. Results of pulsed-field gel electrophoresis subtyping did not suggest that either chilling method selected for any specific subtypes; most subtypes were found on carcass halves used for both the air chill and water immersion chill. Resistance to 2 antimicrobial drugs was noted in 9 C. coli isolates, 6 from air-chilled carcass halves and 3 from immersion-chilled carcass halves. These data showed that immersion-chilled carcasses had lower numbers of bacteria; however, the difference was not large and may have been due to simple dilution. Both methods were effective for lowering carcass temperature, and neither chilling method seemed to select for specific species, subtypes, or antimicrobial-resistant Campylobacter.

Effect of dry-air chilling on sensory descriptive profiles of cooked broiler breast meat deboned four hours after the initiation of chilling

The objective of this study was to evaluate the effect of a dry air-chilling (AC) method on sensory texture and flavor descriptive profiles of broiler pectoralis major (fillet) and pectoralis minor (tender). The profiles of the muscles immersion-chilled and deboned at the same postmortem time and the profiles of the muscles hot-boned (or no chill) were used for the comparison. A total of 108 eviscerated carcasses (6-wk-old broilers) were obtained from a commercial processing line before the chillers. Carcasses were transported to a laboratory facility where they were either i) chilled by a dry AC method (0.7 degrees C, 150 min in a cold room), ii) chilled by immersion chilling (IC; 0.3 degrees C, 50 min in a chiller), or iii) not chilled (9 birds per treatment per replication). Both IC and AC fillets and tenders were removed from the bone at 4 h after the initiation of chilling (approximately 4.75 h postmortem) in a processing area (18 degrees C). The no-chill muscles were removed immediately upon arrival. The sensory properties (21 attributes) of cooked broiler breast meat were evaluated by trained panelists using 0- to 15-point universal intensity scales. The average intensity scores of the 9 flavor attributes analyzed ranged from 0.9 to 4.0. Regardless of breast muscle type, there were no significant differences in sensory flavor descriptive profiles between the 3 treatments. The average intensity scores of the 12 texture attributes ranged from 1.5 to 7.5 and there were no significant differences between the AC and IC samples. The average intensity scores of the texture attributes, cohesiveness, hardness, cohesiveness of mass, rate of breakdown, and chewiness of the no chill fillets and tenders were significantly higher than those of either of the chilled samples. These results demonstrate that chicken breast meat from AC retains sensory flavor profile characteristics but AC results in sensory texture profile differences when compared with no-chill meat. Sensory flavor and texture profiles of AC broiler breast meat do not differ from those of IC samples when the muscles are deboned at the same time after the initiation of chilling.

Recovery of Bacteria from Broiler Carcasses After Immersion Chilling in Different Volumes of Water, Part 2

Experiments were conducted to determine the relationship between poultry chilling water volume and carcass microbiology. In the first study, the volume of water used during immersion chilling was found to have a significant effect on the counts of bacteria recovered from broiler carcass halves; however, these volumes (2.1 and 16.8 L/kg) were extreme and did not reflect commercial levels. A second study using commercial chilling volumes was conducted with 3.3 L/kg (low) or 6.7 L/kg (high) distilled water in the chiller. Prechill broiler carcasses were removed from a commercial processing line, cut into left and right halves, and one-half of each pair was individually chilled in a bag containing low or high volume of water. Bags containing halves were submersed in a secondary chill tank containing approximately 150 L of an ice-water mix (0.6 degrees C). After 45 min, halves were removed, allowed to drip for 5 min, and rinsed with 100 mL of sterile water for 1 min. Rinses were analyzed for total aerobic bacteria, Escherichia coli, Enterobacteriaceae, and Campylobacter. When the numbers of bacteria in the half-carcass rinses (HCR) were compared, counts recovered from halves chilled in a low volume of water were the same as those recovered from the halves chilled with a high volume of water (P > 0.05). Levels found in the HCR ranged from 4.0 to 4.2 log(10) cfu/mL for aerobic bacteria, 3.3 to 3.5 log(10) cfu/mL for E. coli, 3.6 to 3.8 log(10) cfu/mL for Enterobacteriaceae, and 2.4 to 2.6 log(10) cfu/mL for Campylobacter. Data were also analyzed using a paired comparison t-test, and this analysis showed that there was no difference (P > 0.05) in the numbers of aerobic bacteria, E. coli, Enterobacteriaceae, or Campylobacter recovered from paired-halves chilled in different volumes of water. The present study shows that under the conditions outlined in this experiment, doubling the amount of water during immersion chilling (3.3 vs. 6.7 L/kg) did not improve the removal of bacteria from the surfaces of chilled carcasses.

Effect of stomaching on numbers of bacteria recovered from chicken skin

Stomaching of skin samples releases only slightly more bacteria than a single rinse. Successive rinses, however, continue to remove almost as many bacteria as the first rinse. One hypothesis to explain this observation is that relatively violent treatment of skin generates smaller pieces of skin, thus increasing the net surface area and effectively sequestering bacteria in a water film on the skin pieces so that numbers of bacteria suspended in the rinsate do not increase. An experiment was conducted to determine whether inoculated marker bacteria are removed from the rinse liquid as skin pieces are stomached and naturally occurring bacteria are released. In each of 4 replications, 5 prechill broiler carcasses were collected from a commercial processing plant. Two 5-g pieces (n = 40) of breast skin were removed from each carcass and placed in a stomacher bag. An inoculum of 30 mL of 0.85% saline solution containing approximately 10(4) of nalidixic acid-resistant Salmonella enterica serovar Typhimurium per milliliter was added to each sample. Skin samples were hand-massaged for 30 s to mix the inoculum, after which a 1-mL aliquot was removed for enumeration of bacteria. A similar sample was taken after 4 min of vigorous stomaching of the skin sample. Bacterial counts recovered from the 30-s hand-massage were 4.3, 2.7, 2.6, and 3.7 log(10) cfu/mL of rinsate for aerobic bacteria, coliforms, Escherichia coli, and Salmonella, respectively. After stomaching, counts were 4.3, 2.9, 2.8, and 3.8, respectively. There was no difference in aerobic plate counts, but mean coliform and E. coli counts were significantly higher (P < 0.05) after stomaching. Numbers of inoculated Salmonella did not decrease. Breaking up the skin into smaller pieces by stomaching did not reduce the number of inoculated bacteria suspended in the rinsate.

Sampling method and location affect recovery of coliforms and Escherichia coli from broiler carcasses

Two experiments were conducted, the first to determine whether numbers of recovered bacteria differed due to sampling method used or due to location on carcass sampled (breast or leg quarters) and the second to determine if numbers of bacteria differed between the front (ventral) and back (dorsal) side of the carcass. In both experiments, eviscerated broiler carcasses were obtained from a commercial processing plant just before the final inside-outside bird washer. In experiment 1, carcasses (3 in each of 4 replicate trials) were separated into leg quarters and breast quarters (n = 48) and either rinsed or ground and stomached for microbiological sampling. In experiment 2, for 3 replicate trials of 4 carcasses each, necks, wings, and legs were manually removed; the remaining trunks were cut through the sides to produce front (ventral) and back (dorsal) halves (n = 24); and then rinsed. For both experiments, coliforms and Escherichia coli were enumerated. In experiment 1, significantly higher numbers (P < 0.05) of coliforms and E. coli were recovered by rinsing than by grinding from both breast and leg quarters. Leg quarters were found to have higher bacterial numbers than breasts from grind samples, but no quarter differences were found for rinse samples. In experiment 2, higher (P < 0.05) numbers of coliforms and E. coli were recovered from the dorsal carcass half compared with the ventral half. Bacterial counts of broiler carcasses are affected by both the sampling method used and by carcass location sampled.

Effect of Blood Spots in Table Egg Albumen on Salmonella Growth

Presence of blood spots in eggs has been correlated with a greater rate of Salmonella Enteritidis contamination. Therefore, this study was conducted to determine whether Salmonella inoculated into egg albumen with naturally occurring blood spots would survive or grow. In each of 3 trials, white shell table eggs with blood spots were collected from a commercial egg-processing plant after candling. In each trial, eggs were broken out, and approximately 4 mL of clear albumen (CLEAR) and 4 mL of bloody albumen (BLOOD) from each of 10 eggs were placed in sterile test tubes and inoculated with a nalidixic acid-resistant Salmonella Typhimurium. For inoculation, 0.1 mL of the Salmonella Typhimurium suspension (containing 7.1, 7.7, or 7.0 log cfu/mL in trials 1 to 3, respectively) was added to each tube. Tube contents were mixed and incubated at 25 degrees C for 24 h. Immediately after inoculation (0 h) and again after 24 h, 0.1 mL from each tube was plated onto Brilliant Green-Sulfa agar with 200 ppm nalidixic acid and incubated at 37 degrees C for 24 h. Results are reported as log colony-forming units per milliliter of albumen. No significant differences (P < 0.05) in mean Salmonella Typhimurium counts were found between CLEAR or BLOOD samples at 0 h (5.6 vs. 5.8, respectively), indicating that initial inoculation levels were consistent between treatments. After 24 h, CLEAR samples were slightly but significantly lower than BLOOD samples for Salmonella Typhimurium (6.5 vs. 6.8, respectively). Salmonella Typhimurium numbers increase somewhat in albumen with or without blood, but slightly greater numbers are produced in albumen with blood spots. In this experiment, blood in the albumen of table eggs contributed to the survival and growth of Salmonella Typhimurium inoculated into egg albumen.