The effect of high-level chlorine carcass drench on the recovery of Salmonella and enumeration of bacteria from broiler carcasses.

A study was conducted to determine the bacteriological effect of exposing processed broiler carcasses to a high (10-fold increase) concentration chlorinated drench. During each of 6 replicate trials, eviscerated prechill carcasses were obtained from a commercial processing plant and chlorine-treated carcasses were subjected to a 1-min drench in 500 mL of a 500 mg/kg chlorine solution (sodium hypochlorite). Water-drenched carcasses were treated the same way except water was used in place of chlorinated water drench. Control carcasses were not drenched. All carcasses were then subjected to a whole carcass rinse (WCR) in 450 mL of buffered peptone water, from which 50 mL of the rinsate was removed for enumeration of total aerobic bacteria (APC), Escherichia coli, and total coliforms (TC). The entire carcass was then incubated 24 h at 37°C (whole carcass enrichment, WCE) for recovery of Salmonella. Levels of bacteria recovered from WCR were lower by 0.6 log10 cfu/mL for APC, 0.8 for E. coli, and 0.9 for TC when carcasses were drenched with water compared with undrenched control levels. Similarly, the levels of bacteria recovered from WCR were further lower by 1.0 log10 cfu/mL for APC, 0.5 for E. coli, and 0.5 for TC, when carcasses were drenched with 500 mg/kg of chlorine compared with water. However, there was no significant difference (P > 0.05) in prevalence of Salmonella among the treatments (29% positive for control, 26% positive for water, 38% positive for chlorinated). These results indicate that drenching eviscerated carcasses with water or chlorinated water at 500 mg/kg significantly, but minimally, reduces the numbers of APC, E. coli, and TC bacteria recovered compared with undrenched carcasses. However, neither drenching carcasses with water or high chlorine had an effect on the prevalence of Salmonella that remain with the carcass as determined by WCE. The results of this study confirms the importance of maintaining and replenishing free chlorine for optimal antimicrobial activity, because chlorine at 500 mg/kg was rapidly used within 1 min of exposure to the carcass to <10 mg/kg.

Effects of vibratory microscreening on proximate composition and recovery of poultry processing wastewater particulate matter.

Experiments were conducted to compare the effects of tertiary microscreen gap size on the proximate composition and rate of recovery of particulate matter from poultry processing wastewater (PPW). A high-speed vibratory screen was installed within the wastewater treatment area of a southeast US broiler slaughter plant after the existing primary and secondary mechanical rotary screens. Microscreen panels with nominal gap size openings of 212, 106 and 45mum were investigated. The particulate matter samples recovered were subjected to proximate analysis to determine percent moisture, fat, protein, crude fiber and ash. The average percent wet weight moisture (%WW) content for all samples was 79.1. The average percent dry matter (%DM) fat, protein, crude fiber and ash were 63.5, 17.5, 4.8 and 1.5, respectively. The mean concentration of total solids (TS) recovered from all microscreen runs was 668mg/L, which represents a potential additional daily offal recovery rate of 12.1metric tons (MT) per 3.78 million L (1.0 million gallons US) of PPW. There was no significant difference in the performance of the three microscreen gap sizes with regard to proximate composition or mass of particulate matter recovered.

Proximate composition of poultry processing wastewater particulate matter from broiler slaughter plants.

An experiment was conducted to compare the proximate composition of particulate matter recovered from poultry processing wastewater (PPW) generated by broiler slaughter plants. Poultry processing wastewater is the cumulative wastewater stream generated during the processing of poultry following primary and secondary physical screening (typically to 500 mum) that removes gross offal. Composite samples of PPW from 3 broiler slaughter plants (southeast United States) were collected over 8 consecutive weeks. All 3 broiler slaughter plants process young chickens with an average live weight of 2.0 kg. At each plant, a single 72-L composite sample was collected using an automatic sampler programmed to collect 1 L of wastewater every 20 min for 24 h during one normal processing day each week. Each composite sample was thoroughly mixed, and 60 L was passed through a series of sieves (2.0 mm, 1.0 mm, 500 mum, and 53 mum). The amount of particulate solids collected on the 2.0 mm, 1.0 mm, and 500 mum sieves was insignificant. The solids recovered from the 53-mum sieve were subjected to proximate analysis to determine percent moisture, fat, protein, ash, and fiber. The average percentages of fat, protein, ash, and fiber for all samples on a dry-weight basis were 55.3, 27.1, 6.1, and 4.1, respectively. Fat made up over half of the dry-weight matter recovered, representing PPW particulate matter between 500 and 53 mum. Despite the variation in number of birds processed daily, further processing operations, and number and type of wastewater screens utilized, there were no significance differences in percentage of fat and fiber between the slaughter plants. There were significant differences in percent protein and ash between the slaughter plants.

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.

Microbial recovery from genetically featherless broiler carcasses after forced cloacal fecal expulsion.

A study was conducted to determine external microbiology of genetically featherless broiler carcasses after forced cloacal fecal expulsion. Full-fed featherless broilers were placed into coops, transported, unloaded, shackled, stunned, suffocated, weighed, and divided into 3 treatments groups. Carcasses were transferred to a separate shackle line and passed through a machine designed to induce defecation (squeeze) and then remove external feces (wash). Treatments were obtained by turning the squeezing and washing components on or off. Treatments were as follows: S carcasses were squeezed but not washed; W carcasses were not squeezed but were washed; and SW carcasses were squeezed and washed. Concentrations of total aerobic microorganisms (AB), Escherichia coli (EC), coliforms (CF), and Campylobacter (CPY) recovered from whole carcass rinses did not vary with treatment (P > 0.05). However, counts of Salmonella (SAL) in rinses of S carcasses were 1.4 log(10) cfu/mL greater than counts of SAL found in rinses of SW carcasses (P < 0.05). The SAL prevalence was similar for S (86% positive), W (90% positive), and SW (83% positive) carcasses (P > 0.05). Populations of AB and CF recovered from wash water (water applied in the machine after fecal expulsion) for SW carcasses were significantly higher by 3.1 and 1.5 log(10) cfu/mL, respectively, than the populations of the same bacteria recovered from wash water for W carcasses (P < 0.05). Levels of EC and CPY recovered from wash water did not vary with treatment. There was no difference in CPY and SAL prevalence in water collected after washing W carcasses or SW carcasses (P > 0.05). Data from the present study show that controlled cloacal fecal expulsion followed by carcass washing immediately after slaughter can be used to minimize the numbers of carcass Salmonella and can reduce the likelihood of visible carcass fecal contamination or cross-contamination to other carcasses and processing equipment.

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.

Germicidal ultraviolet light to lower numbers of Listeria monocytogenes on broiler breast fillets.

Raw broiler breast fillets were subjected to germicidal ultraviolet (UV) light (dose of 1,000 microW/cm(2) for 5 min at a wavelength of 254 nm) to evaluate its potential to reduce Listeria monocytogenes numbers on raw product before shipment to a poultry further-processing plant. Boneless, skinless breast fillets were inoculated with 4 different strains of L. monocytogenes 5 min before treatment. After the UV treatment, breast fillets were stored at 4 degrees C for 24 h. Enumeration of remaining L. monocytogenes was performed using the spread plate method on modified Oxford agar. An approximate 2-log reduction in viable L. monocytogenes was observed with all 4 strains on UV-treated breast fillets as compared with the nontreated breast fillets. The UV treatment caused only slight changes in meat color (lightness, redness, and yellowness) on day of treatment or after 7 d of storage. This study suggests that UV treatment of raw breast fillets at a slaughter plant can significantly reduce L. monocytogenes without negatively affecting meat color. This process could be used to reduce the negative effect of raw poultry as a transmission vector of L. monocytogenes into a poultry further-processing plant.

Evaluation of carcass scraping to enumerate bacteria on prechill broiler carcasses.

Experiments were conducted to evaluate a scraping method for enumerating bacteria on broiler carcasses. In experiment 1, coliforms and Escherichia coli were determined by the whole-carcass rinse (WCR) method and by scraping the skin surface and rinsing the blade (BR). In each of 2 replicate trials, 4 prechill broiler carcasses were collected from 2 different commercial processing plants. The WCR method was conducted on each carcass, then a blunt edge blade was used to scrape an area measuring approximately 80 cm(2) of the breast (front) skin and on the back of the carcass. After scraping, each blade and adhering residue was rinsed in 30 mL of 0.1% peptone. One milliliter of rinsate each from the WCR and BR was plated to determine total coliforms and E. coli. In experiment 2, 6 carcasses were collected from a processing plant in each of 2 replicate trials. Carcasses were split, with one half scraped on all skin surfaces, and the other half remaining unscraped as a control; all halves were then subjected to half-carcass rinses using 200 mL of 0.1% peptone. Coliforms and E. coli were enumerated. Results from both experiments are reported as log cfu/mL. In experiment 1, mean coliform WCR counts (5.1) were significantly higher (P < 0.05) than back BR (2.8), which were higher than front BR (2.2). Mean E. coli WCR counts (4.5) were higher than back BR (2.4), which were higher than front BR (1.6). The counts for BR adjusted for the greater surface area sampled by WCR were still lower than the WCR counts. Experiment 2 results showed no difference between control and scraped carcass halves for coliforms (4.7) or E. coli (4.6). Overall, results showed that scraping either prior to or after rinsing did not increase enumeration of coliforms or E. coli. Scraping could be a viable method to compare the numbers of bacteria on different areas of the same carcass.

A method for estimating the relative degree of saponification of xanthophyll sources and feedstuffs.

Saponification of xanthophyll esters in various feed sources has been shown to improve pigmentation efficiency in broiler skin and egg yolks. Three trials were conducted to evaluate a rapid liquid chromatography procedure for estimating the relative degree of xanthophyll saponification using samples of yellow corn, corn gluten meal, alfalfa, and 6 commercially available marigold meal concentrates. In each trial, samples were extracted using a modification of the 1984 Association of Official Analytical Chemists hot saponification procedure with and without the addition of KOH. A comparison of the chromatography results was used to estimate percent saponification of the original sample by dividing the nonsaponified extraction values by the saponified extraction values. A comparison of the percent saponified xanthophylls for each product (mg/kg) was: yellow corn, 101; corn gluten meal, 78; alfalfa, 97.9; and marigold concentrates A through F, 99.8, 4.6, 99.0, 95.6, 96.8, and 6.6, respectively. These results indicate that a modification of the 1984 Association of Official Analytical Chemists procedure and liquid column chromatography can be used to quickly verify saponification and can be used to estimate the relative degree of saponification of an unknown xanthophyll source.

Broiler carcass bacterial counts after immersion chilling using either a low or high volume of water.

A study was conducted to investigate the bacteriological impact of using different volumes of water during immersion chilling of broiler carcasses. Market-aged broilers were processed, and carcasses were cut into left and right halves along the keel bone immediately after the final bird wash. One half of each carcass pair was individually chilled at 4 degrees C in a separate bag containing either 2.1 L/kg (low) or 16.8 L/kg (high) of distilled water. Carcass halves were submersed in a secondary chill tank containing approximately 150 L of an ice-water mix (0.6 degrees C). After chilling for 45 min, carcass halves were rinsed with 100 mL of sterile water for 1 min. Rinses and chill water were analyzed for total aerobic bacteria (APC), Escherichia coli, Enterobacteriaceae, and Campylobacter. After chilling with a low volume of water, counts were 3.7, 2.5, 2.6, and 2.1 log(10) cfu/mL of rinse for APC, E. coli, Enterobacteriaceae, and Campylobacter, respectively. When a high volume of chill water was used, counts were 3.2, 1.7, 1.6, and 1.8 log(10) cfu/mL of rinse for APC, E. coli, Enterobacteriaceae, and Campylobacter, respectively. There was no difference in bacterial counts per milliliter of chill water among treatments. These results show that using additional water during immersion chilling of inoculated broilers will remove more bacteria from the carcass surfaces, but numbers of bacteria per milliliter in the chiller water will remain constant. The bacteriological impact of using more water during commercial immersion chilling may not be enough to offset economic costs.

The influence of extraction and precipitation pH on the dry matter yield of broiler dark meat.

In recent years, demand for white meat products has resulted in excess supplies and depressed prices of leg meat in the United States. One approach to increasing the utilization of dark meat is to extract the pigments and fat to make the resulting product more acceptable for the production of further-processed meat products. To date, such technologies have been inefficient (low yields) or have resulted in products of limited use. Three replicate trials were conducted to determine the effects of extraction pH and precipitation pH on the wet and dry extract yields of boneless, skinless broiler leg meat. Broiler leg meat was chopped with added water and extracted by adjusting the pH to 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, and 12.0 while mixing. After determination of extraction yields, each extraction was adjusted to pH 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, and 5.2 to determine the effect of precipitate pH on total wet and dry yields. Dry yield increased with extraction pH and precipitation pH. However, the greatest yields, over 70%, were at extraction pH values above 10.5, which have been associated with the production of potentially harmful by-products. Combinations of extraction pH values between 9 and 10.5 and precipitation pH values above 4.4 resulted in dry yields of approximately 65%. These results indicate that pH extraction and precipitation may result in economically viable yields. Further research is needed to determine the optimal conditions of yield, composition, and functionality.

Physical and functional properties of intact and ground pale broiler breast meat.

The functional and physical properties of intact and ground meat were determined during 4 replicate trials on a total of 180 pale [lightness (L*) > 53] and normal (46 < L* < 53) boneless, skinless breast fillets collected from 2 commercial processing plants. At 24 h postmortem, L*, redness (a*), yellowness (b*), and pH were determined on each fillet. The left fillet from each breast was ground and used to determine cook loss (CL) and Allo-Kramer (AK) shear on meat patties as well as moisture uptake (MU) and CL on meat slurries before and after adjustment to the normal meat pH of 5.9. The right fillet from each breast was kept intact and used to determine expressible moisture (EM), CL, and AK shear on the intact meat. Compared with normal fillets, pale fillets exhibited significantly higher L* values, lower ultimate pH (5.67 vs. 5.94), higher AK (3.5 vs. 2.9 kg/g), higher EM, lower MU, and higher CL measured on the intact fillets, ground meat patties, and meat slurries. Adjustment of the pH of the pale meat slurries to normal meat pH (5.9) resulted in a higher MU (11.05 vs. 3.69%), indicating a partial restoration of protein functionality. These results indicate that wide differences in raw broiler breast meat color, mainly due to differences in the muscle pH, are related to important variations in the water-holding and binding capacities of the meat. The effect of low meat pH can be partially ameliorated in ground meat by pH adjustment.

Recovery of salmonellae following pH adjusted pre-enrichment of broiler carcasses treated with trisodium phosphate.

Trisodium phosphate (TSP) has been reported to decrease the recovery of salmonellae from processed poultry carcasses. It has been suggested that the high pH and detergent-like properties of TSP solutions are responsible for the reduction in salmonellae recovery. This project was conducted to determine if controlling pH during salmonellae pre-enrichment alters the effect of TSP on salmonellae recovery. Carcasses were obtained from a commercial processing plant immediately after the final inside-outside carcass washer, prior to any other antimicrobial treatments, and before chilling. Carcasses were assigned to 1 of 4 treatment groups: (1) TSP and alkaline pre-enrichment, (2) TSP and neutral pre-enrichment, (3) non-TSP and alkaline pre-enrichment, 4) non-TSP and neutral pre-enrichment. Carcasses were placed into plastic bags with 500 mL of buffered peptone water (with or without pH adjustment) and shaken for 1 min. Preincubation pH of the rinsate was measured. Carcasses were incubated in the rinse at 37 degrees C for 24 h, and incidence of salmonellae was determined. The pH of the preincubation rinsate was 8.4 for the TSP alkaline pre-enrichment, 7.2 for the TSP neutral pre-enrichment, 8.6 for the non-TSP alkaline pre-enrichment, and 7.1 for the non-TSP neutral pre-enrichment. Salmonellae were detected from 40% of the TSP alkaline pre-enrichment carcasses, 44% of the TSP neutral pre-enrichment carcasses, 54% of the non-TSP alkaline pre-enrichment carcasses, and 38% of the non-TSP neutral pre-enrichment carcasses. Neither TSP treatment nor pre-enrichment pH adjustment significantly influenced carcass salmonellae detection.

N-ethylmaleimide (NEM) can significantly improve in situ hybridization results using 35S-labeled oligodeoxynucleotide or complementary RNA probes.

We predicted that a significant source of background labeling after in situ hybridization (ISH) using 35S-labeled probes is attributable to a chemical reaction between the phosphorothioate moiety of the probe [O3P = S] and disulfides in tissue. These covalent bonds would immobilize probe in the tissue, thereby increasing background labeling. On the basis of this view, we have explored the use of N-ethylmaleimide (NEM) to irreversibly alkylate the phosphorothioate moiety of the probe and/or to alkylate free sulfhydryls in tissue to block the formation of disulfides as a method of reducing background labeling. We report that NEM can significantly decrease background labeling of 35S-labeled oligodeoxynucleotide or cRNA probes but does not affect specific labeling. We conclude that the use of NEM in ISH protocols, as outlined here, may be an additional element researchers may consider to improve the signal-to-noise ratio.

A single administration of ethanol simultaneously increases c-fos mRNA and reduces c-jun mRNA in the hypothalamus and hippocampus.

We have previously demonstrated that a single administration of ethanol induces the expression of c-fos mRNA in the hypothalamic paraventricular nucleus (PVN). However, Fos protein must interact with a member of the Jun family to form functional heterodimers. To determine whether ethanol may have differential effects on c-fos and c-jun expression, we injected male rats acclimated to a 25 degrees C environment with ethanol (3 g/kg b.wt.) or saline. Using in situ hybridization histochemistry with oligonucleotide probes, we found that ethanol increased c-fos mRNA in the PVN, but decreased c-jun mRNA both in the PVN and in hippocampus. Considering that ethanol produces hypothermia and that the PVN contains neurons activated during hypothermia, we evaluated the effect of cold on c-fos and c-jun mRNA. Both cold and ethanol increased c-fos mRNA, and the effects were additive. However, c-jun mRNA levels in both PVN and hippocampus were unaffected by temperature. Finally, c-jun mRNA levels in the hippocampus were significantly reduced by chronic ethanol exposure, and this trend was also observed in the PVN. These findings demonstrate that a single injection of ethanol has opposite effects on the expression of nuclear transcription factors which interact to regulate gene expression in the nervous system.

In situ hybridization of mRNA expression for IP3 receptor and IP3-3-kinase in rat brain after transient focal cerebral ischemia.

Loss of intracellular calcium homeostasis has been regarded an important factor underlying neuron cell death after cerebral ischemic insult. In the brain, a major mechanism for regulation of intracellular calcium is through the signal transduction pathway involving hydrolysis of poly-phosphoinositides and release of the second messenger, inositol 1,4,5-trisphosphate (IP3). IP3 mobilizes calcium by interacting with an intracellular receptor. Upon its release after agonist stimulation, this second messenger is catabolized by a 3-kinase and a 5-phosphatase. In this study, in situ hybridization was carried out to examine the mRNA expression of IP3, receptor (IP3R) and IP3 3-kinase (IP3K) in rat brain cortex after transient focal cerebral ischemia induced by temporary occlusion of the middle cerebral artery (MCA) and the common carotid arteries (CCAs). Results indicate a large decrease (52%) in IP3R mRNA levels in the ischemic cortex as compared to that in the contralateral side at 4 h after a 45 min ischemic insult. By 16 h, practically no IP3R mRNA could be detected in the ischemic cortex. On the other hand, IP3K mRNA levels remained unaltered until 16 h after reperfusion, during which time, expression in the infarct core decreased but that surrounding the core area increased instead. Hybridization of adjacent brain sections with probes for neuron specific enolase (NSE) and beta-actin indicated also a time-dependent decrease in mRNA levels after ischemia, but these changes were less dramatic as compared to IP3R. At 16 and 24 h after reperfusion, there was an increase in beta-actin mRNA in cortical areas outside the MCA cortex, suggesting of reactive gliosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Recovery of Salmonella from retail broilers by a whole-carcass enrichment procedure.

Fresh whole broiler carcasses were purchased from grocery stores over a 20-week period. Carcasses were selected on the basis of their having intact packages and unique U.S. Department of Agriculture (USDA) plant numbers and sell-by dates, such that each bird represented a single processing plant-processing day combination. Carcasses were tested for Salmonella with a rinse aliquot obtained after whole-bird incubation in the rinse media for 24 h. On the basis of the number of unique processing plants (USDA plant numbers) and expiration dates involved, the number of birds available each week ranged from 6 to 17. Over the 20-week period, 251 independent carcasses from 14 processing plants were tested. The percentages of carcasses testing positive for Salmonella ranged from 0 (for 1 week) to >60% (for 3 weeks). For only 4 of the 20 weeks was an incidence of Salmonella-positive carcasses of <20% found. For the entire 20-week study, 85 (33.9%) of the 251 carcasses tested were found to be Salmonella positive. For those processing plants from which >10 carcasses were obtained, the percentages of carcasses testing positive for Salmonella ranged from <20 (two plants) to >40% (four plants). These results indicate that a whole-carcass enrichment may be more sensitive for the detection of Salmonella-positive carcasses than the traditional whole-carcass rinse followed by immediate testing of a subsample aliquot when small numbers of Salmonella are expected.

Comparison of sampling methods for the detection of Salmonella on whole broiler carcasses purchased from retail outlets.

An experiment was conducted to compare the effectiveness levels of two methods in recovering Salmonella from the same carcass. One hundred fresh whole broiler chickens were purchased from retail outlets over a 5-week period (20 carcasses per week). After carcasses had been aseptically removed from the packages and giblets had been removed, the carcasses were placed in sterile bags containing 400 ml of 1% buffered peptone water, the bags were shaken for 60 s, and a 30-ml aliquot was removed and incubated for 24 h at 37 degrees C (aliquot sample). Then, an additional 130 ml of 1% buffered peptone water was immediately added to the bag with the carcass (bringing the volume to 500 ml), the bag was reshaken, and the carcass and rinse were incubated for 24 h at 37 degrees C (whole-carcass enrichment sample). Following incubation, 0.5-ml samples for the two methods were placed into 10 ml of Rappaport-Vassiliadis broth and into 10 ml of tetrathionate (Hajna) broth and incubated at 42 degrees C for 24 h. Each broth was then streaked onto BG Sulfa agar and modified lysine iron agar and incubated for 24 h at 35 degrees C. Suspected Salmonella colonies were inoculated onto triple sugar iron and lysine iron agar slants and incubated at 35 degrees C for 24 h. Presumptive positive results were confirmed by Poly O and Poly H agglutination tests. Over the 5-week period, 13% of the aliquot samples tested positive for Salmonella, compared with 38% of the whole-carcass enrichment samples from the same carcasses. Recovery rates ranged from 0 of 20 samples to 4 of 20 samples for aliquot method and from 4 of 20 samples to 10 of 20 samples for the whole-carcass enrichment method over the 5-week period. These results indicate that when small numbers of Salmonella are expected, the sampling method has a major influence on the identification of Salmonella-positive carcasses.

Effect of chemical cleaning agents and commercial sanitizers on ATP bioluminescence measurements.

Nine chemical cleaning agents at three concentrations were studied to determine the effect on ATP bioluminescence measurements from pure ATP (PATP) and ATP from chicken exudate (CJATP). The nine commercial cleaning and sanitizing chemicals were concentrated foaming acid (FA), acid sanitizer (AS), iodine cleaner-disinfectant (ZI), alkaline cleaner-degreaser (PC), chlorinated alkaline cleaner (CA), chlorinated sanitizer (CS), quaternary ammonium (QA), antibiofilm agent (AB), and acidic peroxygen sanitizer (HP). Effect was reported as a percent change from the log10 relative light unit (LRLU) measurements of the control groups. All cleaners and sanitizers were tested at one-tenth of the manufacturer's recommended level (MRL), MRL, and two times MRL. FA, PC, and CA at all three concentrations significantly decreased PATP and CJATP LRLU. AS decreased PATP and CJATP LRLU at 200 and 400 ppm quaternary ammonium. ZI decreased PATP LRLU at MRL or greater, while CJATP LRLU were decreased by all concentrations of ZI tested. CS decreased PATP LRLU in a dose-dependent manner; however, for CJATP, LRLU decreased slightly at the two lower concentrations but were not affected by 1,200 ppm CS. QA at MRL or above for PATP or at all concentrations for CJATP significantly increased LRLU. AB decreased LRLU at all concentrations tested for PATP or at MRL or greater for CJATP. HPA at MRL or greater for PATP or at all concentrations for CJATP significantly reduced LRLU. These results demonstrate that commercial sanitizers and cleansers may squelch or increase LRLU measurements when the chemical comes into direct contact with the ATP bioluminescence reagents. Hence, when using ATP bioluminescence as a means of determining sanitary quality of food-processing equipment, it is essential to consider the type and concentration of chemical cleaner or sanitizer being used on the equipment prior to testing.

Effect of chemical sanitizing agents on ATP bioluminescence measurements.

Experiments were conducted to determine the effects of sodium hypochlorite (SH), quaternary ammonium (QA), trisodium phosphate (TSP), lactic acid (LA), hydrogen peroxide (HP), and trichlosan (TR) on ATP bioluminescence measurements. Each sanitizer was tested at three different levels and compared to a control group containing no sanitizer. ATP from three sources was analyzed, Escherichia coli, chicken blood, and a pure ATP standard. The effect of each sanitizer was reported as a percent decrease in log10 relative light units (LRLU) for the treatment groups when compared to LRLU from the control groups. SH concentrations of 30, 50, and 70 ppm and quaternary ammonium at concentrations of 10, 20, and 30 ppm had no effect on LRLU measurements, regardless of the ATP source. LA concentrations of 0.5% and higher reduced LRLU by 75%. LRLU measurements were significantly (P < or = 0.05) reduced by approximately 60% when levels of TSP exceeded 1%. HP had no effect on LRLU measurements from any of the ATP sources at 0.1%; however, at 1% HP significantly (P < or = 0.05) decreased LRLU measurements by approximately 60% for all ATP sources. TR at 0.25% had no significant effect on LRLU measurements from any of the ATP sources. TR at 0.5 and 1% reduced LRLU measurements by 30 and 50%, respectively. These results indicate that commercial sanitizers containing LA, TSP, HP, or TR may negatively affect LRLU measurements if the sanitizer is allowed to come into direct contact with the ATP bioluminescence reagents.