C-27-1 

Report #2 Short-term temperature abuse of raw meats 

Modified version of article accepted for publication by the Journal of Food Safety 

Growth of Escherichia coli O157:H7 and Salmonella Serovars on Raw Beef, 

Pork, Chicken, Bratwurst, and Cured Corned Beef: 

Implications for HACCP Plan Critical limits 

Steven C. Ingham1*, Jill A. Losinski1

, Katie L. Becker1, and Dennis R. Buege2 

University of Wisconsin-Madison 

1

Department of Food Science 

2 Department of Animal Sciences 

* Corresponding author: 

1605 Linden Drive, Madison, WI 53706-1565 

Phone 608-265-4801, fax 608-262-6872, e-mail scingham@wisc.edu 
ABSTRACT Small amounts (0.35 – 0.88 oz / 10 – 25 g; 0.98 – 3.22 in2

 / 6.3 – 

20.8 cm2

 inoculated area) of raw ground beef; intact beef, pork, and chicken 

(dark and white meat); bratwurst, and cured corned beef were inoculated with 

Salmonella serovars and E. coli O157:H7, refrigerated 24 h at 41°F (5°C), and 

then held either at 48 - 52°F / 9 - 11°C for up to 8 h or at room temperature (68 - 

76°F / 20 – 24°C) for up to 2h. Except for a 0.2 log CFU increase in Salmonella 

spp. in ground beef during 2 h at room temperature, pathogens did not grow. 

Results of trials with commercial amounts of beef, pork, chicken, ground beef, 

and bratwurst exposed to 50°F (10° C) for 8 h or 72°F (22°C) for 2 h also showed 

no pathogen growth. Potential critical limits for processing of previously 

refrigerated raw meat products are exposure temperatures between 41 and 50°F 

(5 and 10 °C) for not more than 8 hours or between 41 and 72°F (5°C and 22°C) 

for not more than 2 hours. 
INTRODUCTION Under the United States Department of Agriculture (USDA) 

regulations mandating the Hazard Analysis Critical Control Point (HACCP) 

system for ensuring safe meat and poultry products (USDA, 1996), a Critical 

Control Point (CCP) is defined as “a point, step, or procedure in a food process 

at which control can be applied and, as a result, a food safety hazard can be 

prevented, eliminated, or reduced to acceptable levels”. The major CCP in 

HACCP plans for raw meat and poultry products is often the step in the process 

at which the product is warmest. For example, the stuffing step may be the CCP 

in a process for making uncooked bratwurst. At such a step, certain critical limits 

must be met to ensure control of significant hazards previously identified by the 

processor when doing a hazard analysis. Two significant microbiological 

hazards associated with raw meat and poultry products are Salmonella serovars 

and Escherichia coli O157:H7. Processors of raw products may have limited 

control over whether these pathogens are present in the raw meat they receive 

for processing. Therefore, processors must select a CCP and associated critical 

limits that will minimize the risk associated with contaminated raw ingredients. 

Regulatory officials expect processors of raw products to use CCP critical limits 

(time and temperature) that have been scientifically validated to not allow growth 

of Salmonella serovars and E. coli O157:H7. For processors of raw poultry 

products, the existing regulatory limit of 55°F (13°C) for maximum product 

temperature during processing (United States Department of Agriculture, 2003) 

can be used as a critical limit, or a more restrictive critical limit may be chosen. 

Although validation of critical limits ideally should involve in-plant microbiological 
testing (Brashears, et al., 2002), wide-scale microbiological testing is not feasible 

for most very small processors. The objective of this study was to provide initial, 

laboratory-based evidence supporting simple critical limits that could be validated 

for use in raw meat and poultry HACCP plans. 

MATERIALS AND METHODS 

Preparation of Inoculum Although contamination of raw meat or poultry 

by a single pathogen strain is possible in a plant setting, the present study used 

multi-strain “cocktails” of Escherichia coli O157:H7 and Salmonella serovars to 

account for potential variation. The following Escherichia coli O157:H7 strains 

were used: ATCC 43894, 51657, 51658, and 43895 (obtained from American 

Type Culture Collection, Manassas, VA; the first three strains were originally from 

infected patients and the fourth was from ground beef implicated in an outbreak), 

and USDA-FSIS-380-94 (obtained from Dr. John Luchansky, Food Research 

Institute, University of Wisconsin-Madison; originally from salami implicated in an 

outbreak). Salmonella serovars used were S. Hadar S21, S. Typhimurium S9, S. 

Infantis S20, S. Enteritidis E40, S. Anatum S14, and S. Heidelberg S13. All of 

the salmonellae were obtained from Dr. Eric Johnson, Food Research Institute, 

University of Wisconsin-Madison and had been used in previous challenge 

studies. The original source was unknown for strains S21 and S20, while strains 

S9, S13, and S14 were originally isolated from samples submitted to the 

Wisconsin State Laboratory of Hygiene. Strain E40 was a chicken ovary isolate. 

Frozen stock cultures were maintained in Brain Heart Infusion broth (BHIB; Difco, 
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Becton Dickinson, Sparks, MD) with 10% (v/v) added glycerol (Fisher Scientific, 

Itasca, IL). Working cultures were prepared by growing each strain for two 

passages in BHIB and then streaking on Brain Heart Infusion Agar (BHIA; Difco). 

Following growth on BHIA for 24 h at 95°F (35°C), the working cultures were 

stored at 41°F (5°C). For each trial, a colony of each culture was transferred 

separately to 0.3 oz (9 ml) of BHIB and incubated for 24 h at 95°F (35°C), and 

then centrifuged at 8,000 x g for 10 minutes. Each culture was then resuspended in 0.3 oz (9 ml) of Butterfield’s Phosphate Diluent (BPD, NelsonJameson, Marshfield, WI) and all of the cultures for each genus were combined. 

For bratwurst and corned beef experiments, and trials with commercial amounts 

of products, the cultures for each genus were combined in a sterile 1.7 oz (50-ml) 

plastic tube, centrifuged, decanted, re-suspended to the original volume in BPD 

and then the resulting cocktails for the two genera were combined, with an 

overall population for each genus of 9.6 – 10.3 log CFU/oz (8.1 – 8.8 log 

CFU/ml). 

Meat and poultry products For trials with small amounts (0.35 – 0.88 oz 

/ 10 – 25 g; 0.98 – 3.22 in2

 / 6.3 – 20.8 cm2 inoculated area) of meat, ground beef 

(20% fat), boneless beef round steak, boneless center cut pork chops, chicken 

leg quarters (connected drumstick and thigh, up to 6% retained water), and 

boneless skinless chicken breasts were purchased at a local grocery store 

(separate purchases for each trial), transported to the laboratory within 15 

minutes, and refrigerated < 24 h until used. Uncooked bratwurst, from three 
different manufacturers, was purchased frozen from the same local grocery 

store, transported to the laboratory and thawed under refrigeration. None of 

these products contained ingredients added for the purpose of inhibiting 

microbial growth. Uncooked, cured, corned beef briskets with garnish spices 

added (proprietary mix) were shipped overnight from a local processor in cooler 

boxes with ice packs. The corned beef represented three production lots, with 

each lot being studied in an independent trial. The corned beef was vacuumpackaged and had been cured with up to 30% of a mixture of water, salt, sodium 

phosphate, sugar, hydrolyzed corn protein, monosodium glutamate, sodium 

nitrite, sodium erythorbate, sodium nitrate, flavoring, and dextrose. Although 

some of these ingredients could potentially inhibit Salmonella and E. coli 

O157:H7, their addition was done primarily to obtain desired color and flavor, and 

to inhibit endospore germination and outgrowth. The corned beef was 

refrigerated 4 d before use. To prepare samples, products were divided or cut 

into smaller portions (0.35 – 0.88 oz / 10 – 25 g; 0.98 – 3.22 in2

 / 6.3 – 20.8 cm2 

inoculation area) and stored at 41°F (5°C) until inoculation. The ground beef was 

subdivided and shaped into small “mini-patties” (0.9 oz / 25 g), and the beef and 

pork were cut into small pieces (1 in x 1 in / 2.5 cm x 2.5 cm surface area, 0.5 in / 

1.2 cm thick). For chicken, the skin was removed from the chicken parts and 

small pieces (1 in x 1 in / 2.5 cm x 2.5 cm surface area, 0.5 in / 1.2 cm thick) 

were cut from the surface muscle. Bratwursts (4-5 links per lot) were cut into 16 

equal-sized pieces. The pieces were left intact for external (casing surface) 

inoculation. For internal inoculation, each link was cut in half longitudinally, and 
then the resulting half-links were subdivided into 16 equal-sized pieces. The 

outer layer of each corned beef brisket was aseptically removed and cut into 3 in 

x 3 in x 0.5 in thick (6.3 cm x 6.3 cm x 0.6 cm thick) pieces. 

For trials with commercial amounts of meat products, two beef rounds 

(average weight 58.3 lb / 26.4 kg), two beef briskets (average weight 8. 8 lb / 4.0 

kg), two boneless pork loins (average weight 9.3 lb / 4.2 kg), twelve boneless 

skinless chicken breasts (average weight 1.3 lb / 615 g), six 3.1 lb / 1.4 kg chubs 

of ground beef round, and 18 fresh pork bratwursts with natural casing (average 

weight 0.2 lb / 100 g) were purchased from local grocery stores and transported 

within 15 minutes to a controlled environment chamber at the University of 

Wisconsin-Madison where the products were stored at 41°F (5°C). 

Inoculation of Meat Pieces Each mini-patty or piece of meat was 

inoculated with 0.003 oz (0.1 ml) of a 1:1,000 dilution (BPD) of the E. coli 

O157:H7 cocktail and 0.003 oz (0.1 ml) of a 1:1,000 dilution of the Salmonella 

spp. cocktail. For bratwurst and corned beef pieces, the inoculation was done 

with a 1:10 dilution of the combined two-genus cocktail, 0.003 oz (0.1 ml) for 

bratwurst and 0.01 oz (0.3 ml) for corned beef. Each inoculated piece was 

aseptically transferred to a sterile sample bag and refrigerated for 24 h at 41°F 

(5°C) to ensure that inoculum cells were not actively reproducing, thus simulating 

the situation on meat shipped and stored under refrigeration. After this 24 h 

refrigeration period, enumeration of inoculum organisms was done for three 
patties/pieces per storage treatment for each trial of each product type, as 

described below. 

In trials with commercial amounts of products, the package of product was 

aseptically opened, and the packaging material either folded back (beef, pork, 

ground beef) or removed (chicken, bratwurst). Products were inoculated with a 

1:10 dilution of the combined two-species cocktail as follows: each of two beef 

rounds was inoculated at four sites with 0.017 oz (0.5 ml) spread over each 4 in 

x 4 in (10 x 10 cm) site, each of two beef briskets was inoculated at four sites 

with 0.017 oz (0.5 ml) spread over each 3 in x 3 in (7.5 x 7.5 cm) site, each of 

two boneless pork loins was inoculated at four sites with 0.017 oz (0.5 ml) spread 

over each 2.5 in x 3 in (6.3 x 7.5 cm) site, each of twelve boneless skinless 

chicken breasts was inoculated with 0.017 oz (0.5 ml) spread over one half of the 

exposed surface, each of two chubs of ground beef round was inoculated over 

the entire upper surface with 0.03 oz (1.0 ml), the exterior of each of four fresh 

pork bratwursts was inoculated with 0.008 oz (0.25 ml) spread over the entire 

upper surface and four bratwursts were sliced open and for each bratwurst 0.008 

oz (0.25 ml) was spread evenly inside the cut. After a 30-minute wait to allow 

bacterial attachment, the packaging material was placed back over the 

inoculated surface of beef, pork, and ground beef. Inoculated chicken breasts 

and bratwursts were individually placed into commercial zip-lock food storage 

bags. Inoculated meat products then remained in the 41°F (5°C) environmental 

chamber for 24 h until exposure to potential growth conditions. 
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Exposure of Inoculated Meat Products to Potential Growth 

Conditions After refrigeration, the inoculated mini-patties and small meat pieces 

were analyzed for initial inoculum levels or exposed to either room temperature 

(68 – 76°F / 20 - 24°C) for 1 h or 2 h, or 48 – 52°F (9-11°C, in a refrigerated 

incubator) for 2 , 4, 6, or 8 h. Because of the small amounts of meat/poultry 

studied, environment temperature was monitored, instead of product 

temperature, using a thermocouple probe (K-type) with an attached data-logger 

(Model SP-150, Dickson Instruments, Addison, IL). Inoculated commercial 

amounts of meat products were exposed to a temperature of either 50°F (10°C) 

for 8 hours or 72°F (22°C) for 2 hours. In trials with commercial amounts of 

products, the environmental chamber temperature was then returned to 41°F 

(5°C). Thermocouple probes (K-type) were inserted just under the surface of a 

beef round and bratwurst during the 50°F (10°C) and 72°F (22°C) trials. An 

attached data-logger recorded the time and temperature at 5-minute intervals. 

Enumeration of Inoculum Organisms After the mini-patties or small 

meat pieces had been exposed to refrigeration and/or the various 

temperature/time combinations, surviving pathogens were enumerated. 

Enumeration was done for three samples following each storage treatment in 

each trial. Initially, 3.3 oz (99 ml) of BPD was added to a sample bag and the 

contents were stomached for 2 minutes using a Stomacher 400 lab blender 

(Fisher Scientific, Itasca, IL). Subsequent dilutions were made in BPD and 

spread-plates were prepared (one plate per dilution) on Sorbitol MacConkey agar 
(SMAC; Oxoid, Inc., Ogdensburg, NY) and XLD agar (Oxoid) for enumeration of 

E. coli O157:H7 and Salmonella serovars, respectively. Plates were incubated at 

95°F (35°C) for 24 h, typical colonies (white/colorless on SMAC, black on XLD) 

were counted and log CFU was calculated for each mini-patty or piece. To 

confirm that the colonies counted were the inoculum organisms, each of five 

typical colonies per plating medium (trials with ground beef, intact beef, pork, 

chicken) or one colony per trial (trials with bratwurst and corned beef) was 

transferred to BHIA and incubated for 24 h at 95°F (35°C). A presumptive E. coli 

O157:H7 colony from each BHIA plate was then tested for Gram reaction, cell 

morphology, oxidase reaction, presence of O157 antigen (DrySpot latex 

agglutination kit; Oxoid), and, for trials with ground beef, intact beef, pork, and 

chicken, appearance of growth on Levine’s EMB agar (Difco). A presumptive 

Salmonella colony from each BHIA plate was tested for Gram reaction, cell 

morphology, oxidase reaction, and biochemical characteristics (API 20E kit; 

bioMerieux, Inc., Hazelwood, MO). Throughout the study, all presumptive 

colonies were confirmed as the appropriate inoculum species. 

For trials with commercial amounts of product, samples were analyzed 

after 24 at 41°F (5°C) and then after 4 and 8 h exposure to 50°F (10°C) or after 1 

and 2 h exposure to 72°F (22°C); samples were also analyzed 24 h after the 

50°F (10°C) trials. Each sample was obtained by excising the inoculated area 

with a sanitized (70% ethanol) knife. The sample was transferred to a stomacher 

filter bag and analyzed as described above. Confirmation tests confirmed 

presumptive colonies as described above. 
Statistical analysis For trials with small amounts (0.35 – 0.88 oz / 10 – 

25 g; 0.98 – 3.22 in2

 / 6.3 – 20.8 cm2 inoculated area) of meat, the log CFU/piece 

values for each sample after a given storage treatment in a trial were averaged. 

Then, the three resulting values (three trials) for a given storage treatment were 

averaged. The resulting value was compared to the value obtained after 24 h at 

41°F (5°C) using the two-sample t-test (Minitab, release 12.22, Minitab, Inc., 

State College, PA) with a significance level of 0.05. No statistical analysis was 

done for trials with commercial amounts of meat. 

RESULTS AND DISCUSSION 

Initially, small amounts of ground beef, intact beef, pork, chicken dark meat, and 

chicken white meat; cured corned beef, and bratwurst were inoculated with multistrain cocktails of Salmonella spp. and E. coli O157:H7. Small amounts of 

product were used because they would warm up much faster than the large 

amounts of meat used in meat processing plants, thus increasing the likelihood 

of pathogen growth. Samples were inoculated with approximately 5 log CFU of 

E. coli O157:H7 and Salmonella spp., refrigerated at 41°F (5°C) for 24 h (to be 

sure that the inoculum organisms were not reproducing, simulating their condition 

in previously refrigerated meat) and then exposed to either 48-52°F (9-11°C) for 

up to 8 h, or room temperature (68-76°F / 20-24°C) for up to 2 h. In these initial 

trials, changes in log CFU/piece were small after all storage treatments tested, 

ranging from an increase of 0.2 to a decrease of 0.2 (Table 1). No value 
obtained after any storage treatment was significantly different (P < 0.05) from 

the initial value, with the exception of that for Salmonella on the ground beef 

mini-patties after 2 h at room temperature (panel A); however, the latter 0.2 

increase in log CFU/piece is probably not of practical significance. It was clear 

from these results that short-term increases in raw meat temperature would have 

little effect on numbers of E. coli O157:H7 and Salmonella serovars present on 

meat and poultry products. Interestingly, the results suggested that short-term 

exposure of poultry pieces to temperatures above the 55°F (13°C) regulatory limit 

would not result in dangerous pathogen growth. The lack of growth observed in 

laboratory experiments was consistent with that predicted for E. coli O157:H7 

and Salmonella by the United States Department of Agriculture, Agricultural 

Research Service PMP 6.1 computer-generated predictive model (USDA-ARS, 

Eastern Regional Research Center, Wyndmoor, PA). For a pH 6.5 broth system 

with 0.5% water-phase salt and no added sodium nitrite (least restrictive 

conditions in the model), the model predicted that E. coli O157:H7 would remain 

in lag phase for 54.0, 6.6, and 3.6 h at 50, 68, and 76°F (10, 20, and 24°C), 

respectively. Generation times for E. coli O157:H7 at these temperatures were 

predicted to be 5.3, 1.1 and 0.7 h, respectively. For Salmonella under the same 

broth culture conditions, the model predicted lag times of 63.4, 6.9, and 4.5 h and 

generation times of 9.4, 1.0 and 0.6 h, respectively. 

The surface temperature for small pieces of meat would rapidly increase 

to at or near the storage temperature, with the interior temperature also 

increasing rapidly. In intact-whole muscle product (beef, pork, and chicken 
pieces), pathogenic bacteria are only expected to be on the surface, since the 

interior of muscle tissue is virtually free of microbes. The surface is the first part 

of the samples to warm or cool when exposed to changing temperatures. Within 

practical limits, temperature changes within intact muscle have little effect on 

surface microbial growth. Ground meat (mini-patties and bratwurst) represents a 

different case since microbes are distributed throughout, and the slowest-cooling 

part of the ground meat mass is the key area when evaluating microbial growth. 

Compared to the samples used in our study, larger masses of meat would take 

considerably longer to increase in temperature, and thus there would be a 

smaller likelihood of pathogen growth. In addition, though, large masses of 

ground meat would take a longer time to cool once they did increase in 

temperature. Ideally, meat and poultry processors should determine actual 

processing plant and product temperatures at various times during the 

processing day, over an extended time, to fully understand their product 

temperature history. Additionally, processors should obtain microbiological 

testing data for indigenous microorganisms, e.g. coliform count, Aerobic Plate 

Count, for use in validating critical limits. If no increase in numbers of these 

indigenous microbes occurs when the proposed critical limits are followed, then 

the critical limits could be considered fully validated. Such an approach was 

taken by Brashears et al. (2002) to validate a beef fabrication critical limit of 

processing room temperature at 57°F (14°C) or lower for no more than 4 hours. 

Results of subsequent trials with commercial amounts of meat (Table 2) 

confirmed the findings of trials with small meat pieces. There was no evidence of 
growth on any of the products during exposure to either 50°F (10°C) for 8 hours 

or 72°F (22°C) for 2 hours. In 50°F (10°C) trials the temperatures just below the 

surface of the beef round (largest piece of meat) and the bratwurst (smallest 

piece) did not exceed 47°F (8.3°C) during 8 hours and were back to 41°F (5°C) 

within 5.5 and 0.5 hours, respectively, after the room was re-cooled. In 72°F 

(22°C) trials, the beef round temperature did not exceed 55°F (13°C) during the 2 

h exposure time, and had cooled to 41°F (5°C) in 1.5 h after the room was recooled. The bratwurst surface temperature rose to 66°F (19°C) during 2 h at 

72°F (22°C), but had cooled to 41°F (5°C) within 1.25 h after the room was recooled. Samples analyzed 24 h after the end of the 50°F (10°C) exposure 

showed no evidence of pathogen growth. These findings suggest that pathogen 

growth is unlikely in re-cooling raw meat and poultry products after short-term 

exposure to 50 – 72°F (10 - 22°C) temperatures. 

Given that 41°F (5°C) is widely regarded as a safe temperature for 

preventing growth of non-psychrotrophic pathogenic bacteria in potentially 

hazardous foods (United States Food & Drug Administration, 2001), critical limits 

for a specific HACCP plan could address the time that the relevant temperature 

(product or processing room) is above this temperature. With temperature and 

microbiological data in hand, processors could establish scientifically valid critical 

limits involving processing plant or product temperatures and times, and design 

their monitoring programs accordingly. Our results suggest that the following 

times and temperatures should be considered potential critical limits for 

preventing the growth of Salmonella spp. and E. coli O157:H7 on raw meat and 
poultry: products can be exposed to temperatures between 41 and 50°F (5 and 

10 °C) for not more than 8 hours or to temperatures between 41 and 72°F (5°C 

and 22°C) for not more than 2 hours. The existing regulatory limit for raw poultry 

temperature during processing is supported by our results. Furthermore, our 

poultry results could be useful in evaluating poultry processing deviations 

involving short-term temperature elevation. 

ACKNOWLEDGEMENTS This work was partially funded by the United States 

Department of Agriculture, Food Safety & Inspection Service, contract USDAFIS-27-2003. 

REFERENCES 

1. BRASHEARS, M.M., E.S. DORMEDY, J.E. MANN, and D.E. BURSON. 

2002. Validation and optimization of chilling and holding temperature 

parameters as Critical Control Points in raw meat and poultry processing 

establishments. Dairy, Food and Environmental Sanitation 22, 246-251. 

2. UNITED STATES DEPARTMENT OF AGRICULTURE. 1996. Pathogen 

reduction; hazard analysis and critical control point (HACCP) systems. 

Final Rule. Federal Register 61 (144): 38805-38855. 

3. UNITED STATES DEPARTMENT OF AGRICULTURE. 2003. Poultry 

products inspection regulations – temperatures and chilling and freezing 

procedures. 9 CFR part 381.66. 
4. UNITED STATES FOOD & DRUG ADMINISTRATION. 2001. Food Code 

2001, Recommendations of the United States Public Health Service, Food 

& Drug Administration. Section 3-501.16 and corresponding annex (pp. 

68, 309-310). National Technical Information Service, report number PB 

2002100819, Springfield, VA. 
TABLE 1. 

LOG CFU/G OF SALMONELLA SEROVARS AND E. COLI O157:H7 ON SMALL 

AMOUNTS (0.35 – 0.88 oz / 10 – 25 g; 0.98 – 3.22 in2 / 6.3 – 20.8 cm2 INOCULATED 

AREA) OF MEAT AND POULTRY PRODUCTS STORED AT 41°F (5°C) FOR 24 H 

AND THEN AT EITHER 50°F (10°C) OR ROOM TEMPERATURE (RT; 68-76°F / 20-

24°C). PRODUCTS ARE GROUND BEEF MINI-PATTY (PANEL A), INTACT BEEF 

(B), INTACT PORK (C), CHICKEN WHITE MEAT (D), CHICKEN DARK MEAT 

(E), BRATWURST EXTERIOR (F), BRATWURST INTERIOR (G), AND CURED 

CORNED BEEF (H). 

A = ground beef mini-patty 

Storage Treatment Log CFU per piece A 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 4.7 (0.1) 4.5 (0.1) 

1 h at RT 4.7 (0.1) 4.5 (0) 

2 h at RT 4.8 (0.1) 4.7 (0.1)B 

2 h at 50°F 4.7 (0) 4.5 (0) 

4 h at 50°F 4.7 (0.1) 4.5 (0) 

A

 VALUES ARE MEANS (N = 3) WITH STANDARD DEVIATIONS IN 

PARENTHESES. ABSENCE OF A SUPERSCRIPT INDICATES NO 

SIGNIFICANT DIFFERENCE (P > 0.05) FROM INITIAL VALUE). 

B VALUE IS SIGNIFICANTLY DIFFERENT (P < 0.05) FROM INITIAL VALUE. 
B = beef piece 

Initial (24 h, 41°F) 4.6 (0.1) 4.6 (0.1) 

1 h at RT 4.7 (0.1) 4.6 (0.1) 

2 h at RT 4.8 (0.1) 4.6 (0.1) 

2 h at 50°F 4.7 (0) 4.5 (0.1) 

4 h at 50°F 4.8 (0.1) 4.6 (0) 

C = pork piece 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 4.6 (0) 4.5 (0.1) 

1 h at RT 4.5 (0) 4.5 (0.1) 

2 h at RT 4.5 (0.1) 4.5 (0.1) 

2 h at 50°F 4.6 (0.1) 4.5 (0.1) 

4 h at 50°F 4.5 (0.1) 4.5 (0.1) 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 
D = chicken white meat piece 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 4.7 (0.2) 4.3 (0.2) 

1 h at RT 4.6 (0.1) 4.2 (0.2) 

2 h at RT 4.7 (0.2) 4.3 (0.1) 

2 h at 50°F 4.8 (0.1) 4.3 (0.1) 

4 h at 50°F 4.7 (0.1) 4.2 (0.1) 

E = chicken dark meat piece 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 4.7 (0) 4.3 (0.1) 

1 h at RT 4.7 (0.2) 4.4 (0.1) 

2 h at RT 4.8 (0.1) 4.3 (0.1) 

2 h at 50°F 4.6 (0.1) 4.3 (0.1) 

4 h at 50°F 4.7 (0.1) 4.4 (0.1) 
F = exterior of bratwurst 

Initial (24 h, 41°F) 5.3 (0.1) 5.2 (0.1) 

4 h at 50°F 5.1 (0.2) 5.0 (0.2) 

6 h at 50°F 5.2 (0.1) 5.1 (0.1) 

8 h at 50°F 5.2 (0.1) 5.1 (0.2) 

G = interior of bratwurst 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 5.5 (0.1) 5.4 (0.1) 

4 h at 50°F 5.5 (0) 5.4 (0.1) 

6 h at 50°F 5.5 (0.1) 5.3 (0.2) 

8 h at 50°F 5.5 (0.1) 5.3 (0) 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 
H = corned beef piece 

Initial (24 h, 41°F) 5.9 (0.1) 5.8 (0.1) 

4 h at 50°F 5.9 (0.1) 5.8 (0) 

6 h at 50°F 5.9 (0.2) 5.8 (0.1) 

8 h at 50°F 5.8 (0.2) 5.7 (0.2)) 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 
TABLE 2. 

LOG CFU/G OF SALMONELLA SEROVARS AND E. COLI O157:H7 ON 

COMMERCIAL AMOUNTS OF MEAT AND POULTRY PRODUCTS STORED 

AT 41°F (5°C) FOR 24 H AND THEN AT EITHER 50°F (10°C) OR ROOM 

TEMPERATURE (68-76°F / 22°C). PRODUCTS ARE BEEF ROUND (PANEL 

A), BEEF BRISKET (B), PORK LOIN (C), CHICKEN BREAST (D), GROUND 

BEEF (E), BRATWURST EXTERIOR (F), AND BRATWURST INTERIOR (G). 

A = beef round 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars. 

Initial (24 h, 41°F) 4.8 4.7 

1 h at 72°F 5.3 5.3 

2 h at 72°F 4.7 4.5 

Initial (24 h, 41°F) 5.3 5.1 

4 h at 50°F 5.5 5.4 

8 h at 50°F 5.3 5.1 
B = beef brisket 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 5.1 5.1 

1 h at 72°F 4.7 4.5 

2 h at 72°F 4.6 4.4 

Initial (24 h, 41°F) 5.3 4.8 

4 h at 50°F 5.5 5.1 

8 h at 50°F 4.6 4.4 

C= Pork Loin 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 4.8 4.7 

1 h at 72°F 4.5 4.1 

2 h at 72°F 4.2 3.9 

Initial (24 h, 41°F) 4.7 4.7 

4 h at 50°F 4.8 4.6 

8 h at 50°F 4.5 4.4 
D = Chicken breast 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 4.9 4.8 

1 h at 72°F 4.8 4.7 

2 h at 72°F 4.8 4.6 

Initial (24 h, 41°F) 4.6 4.1 

4 h at 50°F 4.6 4.3 

8 h at 50°F 4.9 4.7 

E = Ground beef 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 4.9 4.8 

1 h at 72°F 4.6 4.5 

2 h at 72°F 4.7 4.6 

Initial (24 h, 41°F) 4.6 5.3 

4 h at 50°F 5.2 4.9 

8 h at 50°F 5.0 4.8 
F = Bratwurst exterior 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 4.6 4.3 

1 h at 72°F 4.8 4.4 

2 h at 72°F 4.7 4.4 

Initial (24 h, 41°F) 4.7 4.3 

4 h at 50°F 4.7 4.5 

8 h at 50°F 4.7 4.4 

G = Bratwurst Interior 

Storage Treatment Log CFU per piece 

Conditions E. coli O157:H7 Salmonella serovars 

Initial (24 h, 41°F) 5.4 5.1 

1 h at 72°F 4.9 4.8 

2 h at 72°F 5.3 5.0 

Initial (24 h, 41°F) 5.5 5.2 

4 h at 50°F 5.1 5.1 

8 h at 50°F 5.0 5.2