Petrifilm Aerobic Count Plates Research Articles

Research Note: Reducing food loss in the manufacturing process of chickens by reconditioning dropped raw poultry carcasses with peroxyacetic acid and sodium hypochlorite (chlorine) solution

Food waste and food loss has been a growing concern in the manufacturing industry with a gap between identifying the problem and implementing a solution. The manufacturing process of chicken is largely automated by conveyor belts and machines in which initial application of either peroxyacetic acid (PAA) or sodium hypochlorite (chlorine) solution is utilized to reduce the microbial load and prevent food borne illnesses on the chicken products as they are processed and packaged for distribution. However, during this automated process whole chickens can drop from the manufacturing line and become contaminated leading to the disposal and waste of the product. A solution to reduce food waste was to analyze a reconditioning procedure within the manufacturing process. The study evaluated the aerobic microbial growth on salvaged marinated deli raw whole chickens without giblets (WOGs) from conveyor belt loss reconditioned in either PAA or sodium hypochlorite (chlorine) solution to undropped chicken WOGs. Chicken rinsate and segmented samples were collected from each parameter and tested for microbial growth using Petrifilm aerobic plate count (APC) plates and converting results into log colony forming units (CFU). A difference (P < 0.05) was observed with the reconditioning of the WOGs in PAA (0.71 log10 CFU/mL) compared to the control (1.45 ± 0.26 log10 CFU/mL), for rinses. Of the segmented samples, the trussing strings displayed a significant decrease in APC counts for both chlorine (2.30 ± 0.49 log10 CFU/g) and PAA (2.3 ± 0.49 log10 CFU/g) reconditioning compared to the control (2.72 ± 0.39 log10 CFU/g). Reconditioning of salvaged deli chicken WOGs in chlorine or PAA is comparable to or better than the conventional process for the reduction of APC, it is an effective strategy to reintroduce dropped marinated deli chicken WOGs to the manufacturing line and can reduce food waste at a manufacturing level.

In vitro comparison of methods for sampling copper-based antimicrobial surfaces.

Self-sanitizing surfaces such as copper (Cu) are increasingly used on high-touch surfaces to prevent the spread of harmful viruses and bacteria. Being able to monitor the antimicrobial properties of Cu is fundamental in measuring its antimicrobial efficacy. Thorough investigations into reliable methods to enumerate bacteria from self-sanitizing surfaces are lacking in the literature. This study demonstrates that direct use of Petrifilm on Cu surfaces most likely revives stressed and dying bacteria, which induces increased bacterial counts. This phenomenon was not observed with indirect collection methods. Studies assessing time-kill kinetics or long-term efficacy of Cu should consider the impact of the collection method chosen.

Camel Milk Composition and Microbial Reduction with Different Pasteurization Methods

The objective of this study was to investigate the efficacy of different thermal pasteurization methods on (1) the survival of the total aerobic bacteria, E. coli O157: H7, in camel milk, and (2) the camel milk components such as the fatty acid profile, lipid peroxidation, protein fractions, and the composition of volatile compounds. Samples of camel milk (N=9) were pasteurized at 65°C/30 min (PAST-1), 72°C/5 min (PAST-2), and 80°C/15 min (PAST-3). The survival of E. coli O157: H7 was evaluated using the traditional plate count agar (PCA) method while the total aerobic bacteria were enumerated using the petrifilm aerobic count plates (ACP). Complete elimination (P10 CFU/ml reduction). All pasteurization methods had a significant (PE. coli O157: H7 resulting in a 6 log10 CFU/ml reduction. There were no significant (P>0.05) differences in the fatty acid profile including the cis-9, trans-11 conjugated linoleic acid (CLA), and trans-10, cis-12 CLA, and the lipid peroxidation products between raw and pasteurized milk samples. The milk protein profile was marginally altered by PAST-2 and PAST-3 treatments but not PAST-1. Thirty-four volatile compounds (VCs) were detected in the raw milk samples compared to 29 VCs in the pasteurized milk samples. Pasteurization treatments altered the concentrations of some milk VCs, increasing the Heptanal, Tridecanal, and Undecanal while decreasing the 2-Decanal and 2-Undecanal. This study shows that PAST-1 and PAST-3 treatments are more effective than PAST-2 at inactivating total aerobic bacteria. Additionally, the absence of significant changes in milk compositions indicates that PAST-1 and PAST-3 could be applied without affecting the nutritional value of camel milk.

Investigating the Etiology of Increased Incidence of Sour Knuckles in Commercial Beef Processing Facilities

ObjectivesCattle weights have increased during the last couple of decades and have not always been accompanied by improvements in facility capabilities and management. Alongside quality issues of color, tenderness, and water holding capacity, issues such as sour muscles and bone taints are now appearing with great frequency in the meat industry. Development of off-flavor/sourness in deep muscles such as knuckles (vastus femoris, vastus lateralis, vastus medialis, and rectus femoris) has been a long-standing issue in the beef industry, however, has not been well characterized. Therefore, the objective of this study was to investigate the cause, and characterize sour odor associated with beef knuckles using microbial, odor panel, and gas chromatography-mass spectrometric (GC–MS) analyses.Materials and MethodsKnuckles (n = 10) identified as having no sour odor (control), slight odor, or severe odor were collected from the fabrication line of a commercial beef processing plant. Sponge samples of synovial fluid and femur surface of the round were also obtained at the time of collection, for determination of anaerobic sporeformer counts. The collected knuckles were transported on ice to the laboratory where they were aseptically separated into two halves, with one half destined for microbial, odor, and GC–MS analyses on the day of collection (Day 0) and the other half for the same analyses after 35 d of vacuum packaged storage at 2°C (Day 35). For microbial analysis, 15 g of tissue was excised from the muscle surface and was analyzed for aerobic plate counts (Petrifilm Aerobic Count plates) and lactic acid bacteria counts (Lactobacilli MRS agar). Samples (5 g) for GC–MS were held at –80°C until analysis. The remainder of the sample was diced and used for trained odor panels. Data were analyzed using the ANOVA function in R (v. 3.5.1.), with a significance level of α = 0.05. Upon finding significant differences (P &lt; 0.05) the means function was used to determine differences between groups.ResultsIrrespective of sourness classification of the knuckles, similar (P &gt; 0.05) anaerobic sporeformer counts were obtained for the synovial fluid and femur surface. Additionally, muscle tissue samples from control, slightly sour and severely sour knuckles had similar (P &gt; 0.05) aerobic plate counts and lactic acid bacteria counts. Odor panelists identified differences (P &lt; 0.05) for all attributes between control and sour knuckles (slight and severe) on Day 0. Similarly, on Day 35, differences (P &lt; 0.05) were observed between control, slightly sour, and severely sour knuckles for all attributes, with severe receiving the highest score for all categories. GC–MS results showed no differences (P &gt; 0.05) between control and sour knuckles for propionic, butyric, isobutyric, and acetonic acid.ConclusionMicrobiological analysis found no differences in culturable organisms between control, slight, and severely sour knuckles on Day 0 or Day 35. However, odor panelists were able to identify differences between control and sour knuckles even after 35 d in vacuum packaging. GC–MS analysis did not indicate a statistical difference in the abundance of volatiles between the treatments, probably due to high variations within treatment groups.

Equine Skin Antisepsis Using an Alcohol-Based Rub

Alcohol-based antisepsis has been extensively studied in human health care, but only little information is available regarding efficacy and tolerance in other species. The purpose of this study was to determine if an alcohol-based antiseptic is effective at reducing bacterial counts on equine skin and the appropriate contact time to do so, without causing any adverse skin reactions. Samples were collected before and after preparation from clipped sites over both jugular veins of horses and were plated on 3M Petrifilm Aerobic Count Plates in duplicate. Trial 1 tested an alcohol-based product (ET—80% ethanol) against a control of sterile saline at a contact time of 180-second. Trial 2 tested two different contact times of ET—90 and 180 seconds. All samples were assessed for colony-forming unit counts using an automated 3M Petrifilm reader. Data were analyzed by Kruskal-Wallis test, and the significance was set at P < .05. The results determined that ET had a mean 2.95 log10 reduction from prepreparation to postpreparation colony-forming unit counts. A significant difference in log reduction between ET and control (P = .0033) was observed. There was no difference in log10 reduction between the two contact times (P = .75). Mild urticaria was the only skin reaction observed and was often present in both ET and control groups. These findings demonstrate that ET is effective at reducing bacterial counts on equine skin at a contact time of 90 seconds without producing significant adverse skin reaction.

Research and application on the characteristics of compound cold water soluble gel in petrifilm aerobic count plates

The performance of compound cold water soluble gel in petrifilm aerobic count plates was evaluated in terms of particle size, pH, transmittance, gel strength, water absorption, and water retention. Results demonstrated that when the ratio of sodium polyacrylate and guar gum is 2:8 in cold water soluble gel, the compound gel has 1.0% concentration, neutral pH, 446 g/cm2 gel strength, 79.6% transmittance, 103.6 g/g water adsorption, and 14.4% water retention, which have no significant difference with 1.0% agar. After surfactants, somatomedin, glucose, and bean dregs were added, the sample solution was absorbed completely and colony diameter on petrifilm plates reached 0.95 mm, which is appropriate for counting. The petrifilm plate method based on prepared cold water soluble gel can achieve the same limit of detection (10° cfu/mL) and sensitivity (100%) in counting of five strains compared with the National Standards of Aerobe Plate Count Method. The petrifilm plate method also showed high accuracy and linearly dependent coefficient (R2 = 0.9933). The accordance rate between the petrifilm plate method and the national standard agar plate count method reached as high as 90% in food detection. The compound cold water soluble gel can be used as a good petrifilm plate for aerobic bacterial count.

Effectiveness of 1,3-Dibromo-5,5-Dimethylhydantoin Applied in a Pre-Evisceration Wash Cabinet for Reducing Microbial Contamination on Beef Carcasses

ObjectivesThe objective of this study was to evaluate the effect of a bromine-based antimicrobial (1,3-dibromo-5,5-dimethylhydantoin; DBDMH), for use in a pre-evisceration carcass wash cabinet, against naturally occurring beef carcass associated microflora.Materials and MethodsThe study was conducted in a commercial beef harvest facility. Carcasses were randomly selected prior to the pre-evisceration wash cabinet for treatment application, which included 2 concentrations of DBDMH: low (280 to 350 ppm) and high (550 to 630 ppm). Prior to treatment application, carcasses were swabbed (10 × 10 cm2) on the ventral midline region with a sampling sponge hydrated with 10 mL Dey/Engley neutralizing broth, to serve as the initial counts (untreated control). After DBDMH was applied to the carcasses, a second sample was taken, to provide remaining bacterial populations after treatment. The 2 DBDMH treatments were replicated over 2 production days per treatment (N = 80; n = 40). All sponge samples were analyzed for aerobic plate counts (APC) and Enterobacteriaceae counts (EB) using Petrifilm Aerobic Count Plates and Petrifilm Enterobacteriaceae Count Plates, respectively. Bacterial populations for all samples were converted and expressed as log CFU/cm2. The study was designed as a paired comparison conducted on 2 different test days per treatment (4 total production days), for 2 DBDMH concentration levels. Day was treated as a fixed effect due to the unpredictable variation of the microbial conditions of carcasses on each production day. Data were analyzed using the Mixed Procedure of SAS (SAS Inst. Inc., Cary, NC) and expressed as least squares means for log CFU/cm2. Differences were reported with a significance level of a = 0.05.ResultsThere were significant main effects of treatment and day for APC populations recovered from carcasses treated with DBDMH at 280 to 350 ppm (treatment: P < 0.0001; day P = 0.0181). Due to these main effects, APC results were separated by each production test day to evaluate efficacy of the treatment. The APC populations recovered from beef carcasses before treatment with the low concentration of DBDMH (280 to 350 ppm) were 3.4 and 2.8 log CFU/cm2, from d 1 and 2, respectively (Table 1). Following DBDMH application, APC were 1.4 and 1.0 log CFU/cm2 for d 1 and 2, respectively (Table 1). The EB populations obtained before and after treatment with the low DBDMH concentration were < 0.1 and < –0.6 log CFU/cm2; respectively (Table 1). For carcasses treated with DBDMH at 550 to 630 ppm, a significant interaction between treatment and day (P = 0.0028) was observed for the APC data; therefore, APC results were separated by each production test day. Prior to DBDMH application at 550 to 630 ppm, the APC were 2.7 and 2.8 log CFU/cm2 for d 1 and 2, respectively (Table 1). The APC declined (P < 0.05) after DBDMH was applied, and APC of 1.1 and 2.2 log CFU/cm2 for d 1 and 2, respectively, were obtained (Table 1). Corresponding EB populations before and after the high concentration treatment were < –0.1 and < –0.6 log CFU/cm2, respectively (Table 1).ConclusionIn conclusion 1,3-dibromo-5,5-dimethylhydantoin was effective against naturally occurring microflora present on beef carcasses when applied in a pre-evisceration wash cabinet.

Effectiveness of 1,3-Dibromo-5,5-Dimethylhydantoin Applied in a Pre-Evisceration Wash Cabinet for Reducing Microbial Contamination on Beef Carcasses

ObjectivesThe objective of this study was to evaluate the effect of a bromine-based antimicrobial (1,3-dibromo-5,5-dimethylhydantoin; DBDMH), for use in a pre-evisceration carcass wash cabinet, against naturally occurring beef carcass associated microflora.Materials and MethodsThe study was conducted in a commercial beef harvest facility. Carcasses were randomly selected prior to the pre-evisceration wash cabinet for treatment application, which included 2 concentrations of DBDMH: low (280 to 350 ppm) and high (550 to 630 ppm). Prior to treatment application, carcasses were swabbed (10 × 10 cm2) on the ventral midline region with a sampling sponge hydrated with 10 mL Dey/Engley neutralizing broth, to serve as the initial counts (untreated control). After DBDMH was applied to the carcasses, a second sample was taken, to provide remaining bacterial populations after treatment. The 2 DBDMH treatments were replicated over 2 production days per treatment (N = 80; n = 40). All sponge samples were analyzed for aerobic plate counts (APC) and Enterobacteriaceae counts (EB) using Petrifilm Aerobic Count Plates and Petrifilm Enterobacteriaceae Count Plates, respectively. Bacterial populations for all samples were converted and expressed as log CFU/cm2. The study was designed as a paired comparison conducted on 2 different test days per treatment (4 total production days), for 2 DBDMH concentration levels. Day was treated as a fixed effect due to the unpredictable variation of the microbial conditions of carcasses on each production day. Data were analyzed using the Mixed Procedure of SAS (SAS Inst. Inc., Cary, NC) and expressed as least squares means for log CFU/cm2. Differences were reported with a significance level of a = 0.05.ResultsThere were significant main effects of treatment and day for APC populations recovered from carcasses treated with DBDMH at 280 to 350 ppm (treatment: P < 0.0001; day P = 0.0181). Due to these main effects, APC results were separated by each production test day to evaluate efficacy of the treatment. The APC populations recovered from beef carcasses before treatment with the low concentration of DBDMH (280 to 350 ppm) were 3.4 and 2.8 log CFU/cm2, from d 1 and 2, respectively (Table 1). Following DBDMH application, APC were 1.4 and 1.0 log CFU/cm2 for d 1 and 2, respectively (Table 1). The EB populations obtained before and after treatment with the low DBDMH concentration were < 0.1 and < –0.6 log CFU/cm2; respectively (Table 1). For carcasses treated with DBDMH at 550 to 630 ppm, a significant interaction between treatment and day (P = 0.0028) was observed for the APC data; therefore, APC results were separated by each production test day. Prior to DBDMH application at 550 to 630 ppm, the APC were 2.7 and 2.8 log CFU/cm2 for d 1 and 2, respectively (Table 1). The APC declined (P < 0.05) after DBDMH was applied, and APC of 1.1 and 2.2 log CFU/cm2 for d 1 and 2, respectively, were obtained (Table 1). Corresponding EB populations before and after the high concentration treatment were < –0.1 and < –0.6 log CFU/cm2, respectively (Table 1).ConclusionIn conclusion 1,3-dibromo-5,5-dimethylhydantoin was effective against naturally occurring microflora present on beef carcasses when applied in a pre-evisceration wash cabinet.

Comparison of 3M™ Petrifilm™ Aerobic Count Plates to Standard Plating Methodology for Use with AOAC Antimicrobial Efficacy Methods 955.14, 955.15, 964.02, and 966.04 as an Alternative Enumeration Procedure: Collaborative Study

A multilaboratory study was conducted to determine the equivalence of the 3M Petrifilm Aerobic Count Plate and standard plating methodology for measuring viable bacteria and spores recovered from hard-surface carriers (stainless steel and porcelain), also known as "control carrier counts," used in AOAC antimicrobial efficacy test methods. Six laboratories participated in the study in which carriers inoculated with Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica, and spores of Bacillus subtilis were evaluated using 3M Petrifilm Aerobic Count (AC) plates and standard plating side-by-side. The data were analyzed using a matched-pair t-test to determine the between-method effect with confidence intervals. For all test organisms pooled across all laboratories, the mean difference in log10 concentration between the standard plate count method and 3M Petrifilm AC Plates was -0.012, with a 95% confidence interval of (-0.090, +0.066), which was well within the -0.5, +0.5 interval established as the acceptance criterion. The between-carrier SD averaged 0.139; the between-replicate SD was 0.050. The carrier reproducibility, given that a single replicate per carrier is done, was estimated to be 0.148. Although differences were seen in the final concentrations of the test organisms among laboratories, there were no statistical differences between the enumeration methods. Based on the results from this study, 3M Petrifilm AC Plates are equivalent to standard plating methodology and can be used as an alternative procedure for the enumeration of test organisms used in AOAC Methods 955.14, 955.15, 964.02, and 966.04.

Technical note: Enumeration of mesophilic aerobes in milk: Evaluation of standard official protocols and Petrifilm aerobic count plates

Enumeration of mesophilic aerobes (MA) is the main quality and hygiene parameter for raw and pasteurized milk. High levels of these microorganisms indicate poor conditions in production, storage, and processing of milk, and also the presence of pathogens. Fifteen raw and 15 pasteurized milk samples were submitted for MA enumeration by a conventional plating method (using plate count agar) and Petrifilm Aerobic Count plates (3M, St. Paul, MN), followed by incubation according to 3 official protocols: IDF/ISO (incubation at 30°C for 72h), American Public Health Association (32°C for 48h), and Brazilian Ministry of Agriculture (36°C for 48h). The results were compared by linear regression and ANOVA. Considering the results from conventional methodology, good correlation indices and absence of significant differences between mean counts were observed, independent of type of milk sample (raw or pasteurized) and incubation conditions (IDF/ISO, American Public Health Association, or Ministry of Agriculture). Considering the results from Petrifilm Aerobic Count plates, good correlation indices and absence of significant differences were only observed for raw milk samples. The microbiota of pasteurized milk interfered negatively with the performance of Petrifilm Aerobic Count plates, probably because of the presence of microorganisms that poorly reduce the dye indicator of this system.

PERFORMANCE OF PETRIFILM AEROBIC COUNT PLATES ON ENUMERATION OF LACTIC ACID BACTERIA IN FERMENTED MILKS

ABSTRACT This study aimed to compare Petrifilm Aerobic Count (AC) plates and the conventional pour plate methodology using the de Man–Rogosa–Sharpe (MRS) agar for the enumeration of lactic acid bacteria (LAB) in fermented milks (FMs), with different starter cultures added. FM samples (n = 66) were collected and plated on both methodologies, with incubation under anaerobic conditions at 35C for 48 h. The count results were compared by analysis of variance (P ≤ 0.05) and regression analysis. No differences between the mean counts obtained by both methodologies were observed, even when distinct FMs were compared. Considering all samples, a high correlation level was obtained between Petrifilm AC and MRS agar (r = 0.92), but these indexes were lower in FMs with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (r = 0.90) and Lactobacillus fortis (r = 0.81). Despite some slight interferences, Petrifilm AC has proven to be a convenient methodology on enumerating LAB in FM.PRACTICAL APPLICATIONSThis study focused on the evaluation of an important tool for monitoring the microbiologic quality in the food industry. Petrifilm plates are widely used in the food industry, and their application for several microorganisms groups and foods must be properly evaluated for convenient application. Petrifilm Aerobic Count (AC) plates, associated to the de Man–Rogosa–Sharpe broth, were already described as adequate for the lactic acid bacteria (LAB) enumeration in foods. However, A previous study was conducted only with experimental inoculation of LAB in sterile milk and naturally occurring LAB in raw milk (Nero et al. 2006). This article is a complement of the first one, and we show the convenience of Petrifilm AC plates on LAB enumeration in fermented milks, considering different types of LAB starter cultures on the performance of this methodology.

COMPARISON OF PETRIFILM AEROBIC COUNT PLATES AND DE MAN–ROGOSA–SHARPE AGAR FOR ENUMERATION OF LACTIC ACID BACTERIA

ABSTRACT This study aimed to compare Petrifilm aerobic count (AC) plates (3M Microbiology, St. Paul, MN) and de Man–Rogosa–Sharpe (MRS) agar for enumeration of lactic acid bacteria (LAB). The study was conducted with suspensions of 10 species of LAB prepared in reconstituted powdered milk. Raw milk samples, without any added bacteria, were also tested. For selective enumeration in Petrifilm AC plates, the suspensions of LAB and the raw milk samples were submitted to decimal dilutions in MRS broth prior to plating. Petrifilm AC and MRS agar plates were incubated in jars at 30C for 72 h, in microaerophilic conditions (Campygen, Oxoid, Basingstoke, U.K.). Differences in counts in the two culture media were not significant (P ≤ 0.05), regardless of the species of the LAB. Results presented high correlation indexes for both LAB suspensions (r = 0.9922, r2 = 0.9845, P = 0.00) and raw milk samples (r = 0.9841, r2 = 0.9685, P = 0.00). These results indicate that the advantages of using Petrifilm AC plates for a rapid enumeration in aerobic microorganisms can be extended for enumeration of LAB in foods. Their convenience is particularly interesting for testing fermented milk products.

Incidences of Problematic Organisms on Petrifilm Aerobic Count Plates Used To Enumerate Selected Meat and Dairy Products

Petrifilm aerobic count plates are similar to or better than conventional pour plates. Petrifilm has its problems, however; some microorganisms can liquefy the Petrifilm gel and others do not produce the necessary color change with the indicator dye used. Petrifilm aerobic count plates were compared with the pour plates for determining the incidence and identification of problematic organisms in 329 meat and dairy products. Petrifilm plates produced higher mean counts with better repeatability than did pour plates. There was also close correlation between methods with coefficients of 0.97 to 1.0. Bacillus subtilis, Bacillus licheniformis, and a group D Streptococcus liquefied Petrifilm gels in 17.4% of the samples tested: dairy products accounted for 16.0%, and meats accounted for the remaining 1.4%. Liquefaction hindered enumeration in 3.2% of the Petrifilm plates used. Streptococcus viridans was not detectable on Petrifilm plates after the recommend incubation period, and this organism occurred in 0.3% of the Petrifilm plates used. These results indicate that Petrifilm plates would be unsuitable for samples with large numbers of these organisms. Knowledge of the contaminating flora may be an asset when utilizing Petrifilm aerobic count plates for the enumeration of microbes in food.

Evaluation of Dry Sheet Medium Culture Plate (Compactdry TC) Method for Determining Numbers of Bacteria in Food Samples

The Compactdry, a ready-to-use and self-diffusible dry medium sheet culture system, has been developed by the Nissui Pharmaceutical Co. Ltd. for enumerating bacteria in food. The Compactdry consists of special spread sheet with culture medium that is the same as standard method nutrients, a cold water-soluble gelling agent, and a unique plastic dish. The procedure for bacterial examination in a sample solution (1 ml) is to just inoculate a test solution into the center of the self-diffusible medium and incubate at 35°C for 48 h. The Compactdry TC (CTC) for the enumeration of total aerobic bacteria from 97 food samples was compared with the standard plate count (SPC) method and 3M Petrifilm aerobic count plates (PAC). The correlation coefficients between the CTC and SPC method, the CTC and PAC, and the PAC and SPC method were 0.97, 0.99, and 0.97, respectively. The Compactdry system is useful for the enumeration of total aerobic bacteria in food and may be a possible suitable alternative to the conventional pour-plate or the Petrifilm plate methods.

Trisodium Phosphate and Cetylpyridinium Chloride Spraying on Chicken Skin to Reduce Attached Salmonella typhimurium

Spraying treatments with trisodium phosphate (TSP) and cetylpyridinium chloride (CPC) were evaluated for their effectiveness in reducing Salmonella typhimurium attached to chicken skins. Chicken skins with an area of 38.5 cm2 were cut from the breast areas of pre-chill chicken carcasses, mounted in a plastic holder, and inoculated with S. typhimurium . The inoculated skins were sprayed with tap water, 10% (wt/vol) TSP, or 0.1 % CPC solutions at 10, 35, or 60°C and 206.8, 413.7, 620.5, 827.4, or 1034.2 kPa for 30 s. After spraying, each skin was rinsed with tap water, transferred to a plastic bag containing 50 ml buffered peptone water, and stomached for 1 min. The stomaching water was collected, diluted serially, plated on xylose lysine tergitol 4 (XLT4) agar and Petrifilm aerobic count plates, and incubated for 18 to 24 h at 37°C. The results showed that tap water spraying reduced S. typhimurium by 0.7 to 1.6 log, while the reduction ranges for TSP and CPC spraying treatments were 1.6 to 2.3 and 1.5 to 2.5 log, respectively. Greater reductions in the numbers of S. typhimurium were obtained in TSP spraying treatments in the high pressure range (620.5 to 1034.2 kPa) and in CPC spraying treatments at 10°C.