Concentration-dependent inhibition of Escherichia coli O157:H7 and heterocyclic amines in heated ground beef patties by apple and olive extracts,onion powder and clove bud oil

The effects of plant compounds on Escherichia coli O157:H7 and two major heat-induced heterocyclic amines (HCAs) MeIQx and PhIP in grilled ground beef patties were determined. Ground beef with added apple and olive extracts, onion powder, and clove bud oil was inoculated with E. coli O157:H7 (10⁷ CFU/g) and cooked to reach 45 °C at the geometric center, flipped and then cooked for another 5 min. Cooled samples were taken for microbiological and HCA analyses. Olive extract at 3% reduced E. coli O157:H7 to below detection. Reductions of up to 1 log were achieved with apple extract. Olive and apple extracts reduced MeIQx by up to 49.1 and 50.9% and PhIP by up to 50.6 and 65.2%, respectively. Onion powder reduced MeIQx and PhIP by 47 and 80.7%, respectively. Inactivation of E. coli O157:H7 and suppression of HCAs in grilled meat were achieved by optimized amounts of selected plant compounds.     

Attachment and biofilm formation by Escherichia coli O157:H7 at different temperatures, on various food-contact surfaces encountered in beef processing

Escherichia coli O157:H7 attached to beef-contact surfaces found in beef fabrication facilities may serve as a source of cross-contamination. This study evaluated E. coli O157:H7 attachment, survival and growth on food-contact surfaces under simulated beef processing conditions. Stainless steel and high-density polyethylene surfaces (2 × 5 cm) were individually suspended into each of three substrates inoculated (6 log CFU/ml or g) with E. coli O157:H7 (rifampicin-resistant, six-strain composite) and then incubated (168 h) statically at 4 or 15 °C. The three tested soiling substrates included sterile tryptic soy broth (TSB), unsterilized beef fat-lean tissue (1:1 [wt/wt]) homogenate (10% [wt/wt] with sterile distilled water) and unsterilized ground beef. Initial adherence/attachment of E. coli O157:H7 (0.9 to 2.9 log CFU/cm²) on stainless steel and high-density polyethylene was not affected by the type of food-contact surface but was greater (p < 0.05) through ground beef. Adherent and suspended E. coli O157:H7 counts increased during storage at 15 °C (168 h) by 2.2 to 5.4 log CFU/cm² and 1.0 to 2.8 log CFU/ml or g, respectively. At 4 °C (168 h), although pathogen levels decreased slightly in the substrates, numbers of adherent cells remained constant on coupons in ground beef (2.4 to 2.5 log CFU/cm²) and increased on coupons in TSB and fat-lean tissue homogenate by 0.9 to 1.0 and 1.7 to 2.0 log CFU/cm², respectively, suggesting further cell attachment. The results of this study indicate that E. coli O157:H7 attachment to beef-contact surfaces was influenced by the type of soiling substrate and temperature. Notably, attachment occurred not only at a temperature representative of beef fabrication areas during non-production hours (15 °C), but also during cold storage (4 °C) temperatures, thus, rendering the design of more effective sanitation programs necessary.     

Enhancing the thermal destruction of Escherichia coli O157:H7 in ground beef patties by trans-cinnamaldehyde

The effect of trans-cinnamaldehyde (TC) on the inactivation of Escherichia coli O157:H7 in undercooked ground beef patties was investigated. A five-strain mixture of E. coli O157:H7 was inoculated into ground beef (7.0 log CFU/g), followed by addition of TC (0, 0.15, and 0.3%). The meat was formed into patties and stored at 4 °C for 5 days or at −18 °C for 7 days. The patties were cooked to an internal temperature of 60 or 65 °C, and E. coli O157:H7 was enumerated. The numbers of E. coli O157:H7 did not decline during storage of patties. However, cooking of patties containing TC significantly reduced (P < 0.05) E. coli O157:H7 counts, by >5.0 log CFU/g, relative to the reduction in controls cooked to the same temperatures. The D-values at 60 and 65 °C of E. coli O157:H7 in TC-treated patties (1.85 and 0.08 min, respectively) were significantly lower (P < 0.05) than the corresponding D-values for the organism in control patties (2.70 and 0.29 min, respectively). TC-treated patties were more color stable and showed significantly lower lipid oxidation (P < 0.05) than control samples. TC enhanced the heat sensitivity of E. coli O157:H7 and could potentially be used as an antimicrobial for ensuring pathogen inactivation in undercooked patties. However detailed sensory studies will be necessary to determine the acceptability to consumers of TC in ground beef patties.     

A simplified method for numerical simulation of gas grilling of non-intact beef steaks to eliminate Escherichia coli O157:H7

The objective of this work was to develop a numerical simulation method to study the heat transfer process and inactivation of Escherichia coli O157:H7 during gas grilling of non-intact beef steaks (NIBS). A finite difference and optimization algorithm was developed to determine the effective heat transfer parameters during grilling. After validation, these parameters were used in a finite element method to simulate the temperature profiles at various locations of NIBS (2.54 cm in thickness). The computer simulation results showed that E. coli O157:H7 may survive the heating processes if normal grilling conditions for intact beef steaks were used. Computer simulation results also suggested that E. coli O157:H7 might be effectively inactivated if NIBS (2.54 cm) were evenly flipped (every 4 min) and cooked for 16 min during cooking. The result of this study may help the food service industry to develop more adequate grilling methods and conditions to cook NIBS.     

Antibacterial effects of natural tenderizing enzymes on different strains of Escherichia coli O157:H7 and Listeria monocytogenes on beef

This study determined the efficacy of actinidin and papain on reducing Listeria monocytogenes and three mixed strains of Escherichia coli O157:H7 populations on beef. The average reduction of E. coli O157:H7 was greater than that of L. monocytogenes and higher concentrations of either protease yielded greater reduction in bacterial populations. For instance, actinidin at 700 mg/ml significantly (p ≤ 0.05) reduced the population of L. monocytogenes by 1.49 log cfu/ml meat rinse after 3 h at 25 & 35 °C, and by 1.45 log cfu/ml rinse after 24 h at 5 °C, while the same actinidin concentration significantly reduced the populations of three mixed strains of E. coli O157:H7 by 1.81 log cfu/ml rinse after 3 h at 25 & 35 °C, and 1.94 log cfu/ml rinse after 24 h at 5 °C. These findings suggest that, in addition to improving the sensory attributes of beef, proteolytic enzymes can enhance meat safety when stored at suitable temperatures.     

Effect of cooking procedures of kiymali pide,a traditional Turkish fast-food,on destruction of Escherichia coli O157:H7

The objective of the present study was to obtain data about cooking time and temperature of kiymali pide in the restaurants and to investigate thermal inactivation of E. coli O157:H7 during experimental kiymali pide making. A field study was conducted in randomly selected 23 of 87 pide restaurants. Processing parameters including oven temperature, cooking period and post-cooking temperature were determined. Kiymali pide samples were prepared using ground beef filling experimentally inoculated with E. coli O157:H7 (7.6 log₁₀ CFU/g). Pide samples were cooked at a conventional oven at 180 °C for 180, 240, 270, 300 and 330 s. Results of the current study suggest that cooking kiymali pide at 180 °C for at least 330 s (5.5 min) may provide sufficient food safety assurance (≥ 6 log₁₀ CFU/g) for E. coli O157:H7.     

Inactivation of Escherichia coli O157:H7 on stainless steel upon exposure to Paenibacillus polymyxa biofilms

We investigated the potential use of biofilm formed by a competitive-exclusion (CE) microorganism to inactivate Escherichia coli O157:H7 on a stainless steel surface. Five microorganisms showing inhibitory activities against E. coli O157:H7 were isolated from vegetable seeds and sprouts. The microorganism with the greatest antimicrobial activity was identified as Paenibacillus polymyxa (strain T5). In tryptic soy broth (TSB), strain T5 reached a higher population at 25 °C than at 12 or 37 °C without losing inhibitory activity against E. coli O157:H7. When P. polymyxa (6 log CFU/mL) was co-cultured with E. coli O157:H7 (2, 3, 4, or 5 log CFU/mL) in TSB at 25 °C, the number of E. coli O157:H7 decreased significantly within 24 h. P. polymyxa formed a biofilm on stainless steel coupons (SSCs) in TSB at 25 °C within 24 h, and cells in biofilms, compared to attached cells without biofilm formation, showed significantly increased resistance to a dry environment (43% relative humidity [RH]). With the exception of an inoculum of 4 log CFU/coupon at 100% RH, upon exposure to biofilm formed by P. polymyxa on SSCs, populations of E. coli O157:H7 (2, 4, or 6 log CFU/coupon) were significantly reduced within 48 h. Most notably, when E. coli O157:H7 at 2 log CFU/coupon was applied to SSCs on which P. polymyxa biofilm had formed, it was inactivated within 1 h, regardless of RH. These results will be useful when developing strategies using biofilms produced by competitive exclusion microorganisms to inactivate foodborne pathogens in food processing environments.     

Adaptation of Escherichia coli O157:H7 to acid in traditional and commercial goat milk amasi

Acid resistance of Escherichia coli O157:H7 strains UT 10 and UT 15 were determined in traditional Amasi fermented for 3 days at ambient temperature (ca 30 °C) and commercial Amasi fermented at 30 °C for 24 h and stored at 7 °C for 2 days. Escherichia coli O157:H7 counts in commercial Amasi were detected at 2.7 log₁₀ cfu/ml after 3 days while those in traditional Amasi could not be detected after the same period. There was no significant difference (p ? 0.05) in the survival of acid adapted (AA) and non-adapted (NA) E. coli O157:H7 in traditional Amasi, while in commercial Amasi, the NA strain survived significantly (p ? 0.05) better than its AA counterpart. Regardless of prior adaptation to acid, E. coli O157:H7 can survive during fermentation and storage of fermented goat milk Amasi. Also, the fermentation time, pH and storage temperature affects the survival of E. coli O157:H7 in the fermented milk.     

Microbiological and organoleptic characteristics of beef trim and ground beef treated with acetic acid, lactic acid, acidified sodium chlorite, or sterile water in a simulated commercial processing environment to reduce Escherichia coli O157:H7 and Salmonella

The objective of this study was to validate the effectiveness of acetic and lactic acids (2% and 5%), acidified sodium chlorite (1000 ppm), and sterile water in reducing Escherichia coli O157:H7 and Salmonella Typhimurium in inoculated beef trim in a simulated processing environment. Samples were collected to assess microbial characteristics at three processing points. Results from this study indicate that all treatments, including sterile water, reduced pathogen concentrations (P < 0.05) of both E. coli O157:H7 and Salmonella Typhimurium in ground beef up to 0.5 and 0.6 log by 24 h, respectively. In some cases, there were no significant differences between the antimicrobial treatments and the sterile water using this application method. Triangle sensory test results of non-inoculated beef indicated there were no differences (P < 0.05) in the means of correct responses between controls or antimicrobial treatments at 6 or 24 h. While interventions are important for beef trim, use of the interventions must be validated under industry conditions to ensure proper effectiveness.     

Escherichia coli O157:H7 survival,biofilm formation and acid tolerance under simulated slaughter plant moist and dry conditions

Microorganisms persisting in slaughter plant environments may develop acid resistance and be translocated to other environmental surfaces or products. The objective of this study was to evaluate the potential of Escherichia coli O157:H7 to form biofilms and maintain acid resistance, under different culture habituation scenarios, on stainless steel coupons (2 × 5 × 0.08 cm), in the presence of beef carcass decontamination runoff fluids (washings). Coupons were stored in test tubes with unsterilized water washings (WW; pH 6.94) or lactic acid washings (LAW; pH 4.98), which were inoculated with E. coli O157:H7 (10³–10⁴ CFU/ml) and incubated at 15 (24 or 48 h) or 35 °C (7 or 24 h), simulating different habituation scenarios on sites of a slaughter plant, including sanitation and overnight drying, during consecutive operational shifts. Acid resistance (AR) of planktonic and detached E. coli O157:H7 cells was assessed in tryptic soy broth adjusted to pH 3.5 with lactic acid. The highest pre-drying attachment and AR of E. coli O157:H7 were observed after 24 h at 35 °C and 48 h at 15 °C. Drying reduced (P < 0.05) recovery of attached E. coli O157:H7 cells; however, exposure of dried coupons to uninoculated washings allowed recovery of attached E. coli O157:H7, which restored AR, especially under conditions that favored post-drying growth. Exposure of attached cells to 50 ppm PAA for 45 s before drying, as well as habituation in LAW, reduced the recovery and AR of E. coli O157:H7. Therefore, incomplete removal of biofilms may result in cells of increased AR, especially in sites within a slaughter plant, in which liquid meat wastes may remain for long periods of time.     

Inactivation of Escherichia coli O157:H7 in liquid whole egg using combined pulsed electric field and thermal treatments

Inactivation of Escherichia coli O157:H7 in liquid whole egg using thermal and pulsed electric field (PEF) batch treatments, alone and in combination with each other, was investigated. Electric field intensities in the range from 9 to 15 kV/cm were used in the study. The threshold temperature for thermal inactivation alone was 50 °C. PEF enhanced the inactivation of E. coli O157:H7 when the sample temperature was higher than the thermal threshold temperature. The maximum inactivation of E. coli O157:H7 obtained using thermal treatment alone was ∼2 logs at 60 °C. However, combined heat and PEF treatments resulted in up to 4 log reduction of the pathogen. The kinetic rate constants k_TE for combined treatments at 55 °C varied from 0.025 to 0.119 pulse⁻¹ whereas the rate constants at 60 °C ranged from 0.034 to 0.228 pulse⁻¹. These results indicated a synergy between temperature and electric field on the inactivation of E. coli O157:H7 within a given temperature range.     

Detection of E. coli O157:H7 in raw ground beef by Pathatrix™ immunomagnetic-separation, real-time PCR and cultural methods

Detection of Escherichia coli O157:H7 by conventional cultural methods can be difficult in food matrices with a high background flora such as raw ground beef. Raw ground beef samples, artificially contaminated separately with five strains of E. coli O157:H7 at low (~ 0.2 cfu/g) and high (~ 2 cfu/g) levels, were enriched by two enrichment protocols; buffered peptone water (BPW) at 37 °C for 5 h and 24 h and modified buffered peptone water with pyruvate (mBPWp) for 5 h at 37 °C followed by adding selective agents and incubating at 42 °C to 24 h. Detection of added E. coli O157:H7 by real-time PCR (RTiPCR) and recovery on isolation agars was performed before and after PATHATRIX™ immunomagnetic separation (IMS). RTiPCR detection and cultural recovery of inoculated E. coli O157:H7 after 5 h enrichment were poor at 0.21-0.24 cfu/g. The addition of IMS after 5 h enrichment did not improve RTiPCR detection but markedly improved recovery by culturing. By extending enrichment to 24 h, RTiPCR detection improved to 76% for either enrichment protocol without IMS. When 24 h enrichment was followed by IMS, RTiPCR detection was also further improved. Cultural recovery after 24 h enrichment was 56% and 84% without IMS and 100% and 92% after IMS for BPW and mBPWp respectively. Extended enrichment to 24 h followed by IMS was found to be sensitive and reliable for detection and cultural recovery from raw ground beef using either enrichment method.     

The growth,survival and thermal inactivation of Escherichia coli O157:H7 in a traditional South African sausage

This study investigated the growth and survival of Escherichia coli O157:H7 inoculated into boerewors models with (B + P) and without (B − P) sulphur dioxide preservative at a low (L) and high (H) inoculum followed by storage at 0, 4 and 10 °C for 10 days. The pathogen’s thermal inactivation at 50, 60, 65 and 70 °C was also evaluated in B + P. The B − P at both low and high inocula had significantly higher recoveries at all temperatures compared to B + P. The BL + P and BH + P had significant reductions in recoveries at 0 °C, declining to below detectable limits at days 8 and 10, respectively. At 4 °C, the BL + P and BH + P recoveries declined significantly at day 10. At 10 °C, significant increases were observed from days 0 to day 10 in both models and at low and high inocula. At 0 °C, the BL − P and BH − P treatments had significant declines in recoveries. The combination of sulphur dioxide preservative and low temperature demonstrated the best efficacy against E. coli O157:H7 survival. Thermal inactivation of E. coli O157:H7 was 60 min at 60 °C, 80 s at 65 °C and 60 s at 70 °C. This study demonstrated that E. coli O157:H7 can survive in boerewors with and without preservative and is more sensitive to heat treatment at 70 °C.     

Use of low dose e-beam irradiation to reduce E. coli O157:H7, non-O157 (VTEC) E. coli and Salmonella viability on meat surfaces

This study determined the extent that irradiation of fresh beef surfaces with an absorbed dose of 1 kGy electron (e-) beam irradiation might reduce the viability of mixtures of O157 and non-O157 verotoxigenic Escherichia coli (VTEC) and Salmonella. These were grouped together based on similar resistances to irradiation and inoculated on beef surfaces (outside flat and inside round, top and bottom muscle cuts), and then e-beam irradiated. Salmonella serovars were most resistant to 1 kGy treatment, showing a reduction of ≤ 1.9 log CFU/g. This treatment reduced the viability of two groups of non-O157 E. coli mixtures by ≤ 4.5 and ≤ 3.9 log CFU/g. Log reductions of ≤ 4.0 log CFU/g were observed for E. coli O157:H7 cocktails. Since under normal processing conditions the levels of these pathogens on beef carcasses would be lower than the lethality caused by the treatment used, irradiation at 1 kGy would be expected to eliminate the hazard represented by VTEC E. coli.     

Assessment of Escherichia coli O157:H7-specific bacteriophages e11/2 and e4/1c in model broth and hide environments

The efficacy of bacteriophages e11/2 and e4/1c as potential biocontrol agents for Escherichia coli O157:H7 in food applications was assessed under conditions relevant to the food chain environment. The stability of each phage was determined following exposure to varying environmental conditions (pH, temperature, water activity, and sodium chloride) and the ability of each phage to infect and reduce E. coli O157:H7 numbers under selected conditions was also examined. Both e11/2 and e4/1c significantly (p < 0.05) reduced numbers of E. coli O157:H7 when exposed to pH values ranging from pH > 4 to pH 9, temperatures from 4 °C to 37 °C, water activity values of 0.87 or 0.91 to 1.00 and NaCl concentrations of 1% to 2.5%. Subsequently, a cocktail of both phages was used (e11/2 and e4/1c) to assess reduction of E. coli O157:H7 on cattle hide pieces. This involved inoculating pieces of hide (20 × 20 cm) with E. coli O157:H7 (approximately 10⁶ cfu/cm²) which were subsequently treated with either a suspension of a phage cocktail, consisting of e11/2 and e4/1c (multiplicity of infection of 1000 and 10,000, respectively) or water or not treated. Two different investigations were carried out; immediately or 1 h after treatment application was performed in different experiments. Swab samples taken immediately after phage treatment showed no significant (p > 0.05) reduction of E. coli O157:H7 numbers compared to the water treated or untreated samples. However, an extended exposure time of 1 h following phage application revealed a significant reduction (p < 0.05) (1.5 log₁₀ cfu/cm² reduction) in E. coli O157:H7 numbers compared to the numbers recovered on samples treated with water only. These findings demonstrate the potential use of e11/2 and e4/1c phages as a biocontrol agent for E. coli O157:H7 within various stages of the food chain, including on cattle hide.     

Application of caffeine, 1,3,7-trimethylxanthine,to control Escherichia coli O157:H7

The objective of this research was to determine the effectiveness of caffeine on inactivation of Escherichia coli O157:H7 in brain heart infusion (BHI) broth. Overnight samples of five E. coli O157:H7 strains of (E0019, F4546, H1730, 944 and Cider) were used in this study. These strains were individually inoculated at an initial inoculum level of 2 log CFU/ml into BHI broth containing caffeine at different concentrations (0.00%, 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1.50%, 1.75%, and 2.00%). Samples were then incubated at 37 °C for 24 h. Bacterial growth was monitored at different time intervals by measuring turbidity at 610 nm using a spectrophotometer. Results revealed that the addition of caffeine inhibited the growth of E. coli O157:H7. Significant growth inhibition was observed with concentration levels of 0.50% and higher. These results indicate that caffeine has potential as an antimicrobial agent for the treatment of E. coli O157:H7 infection and should be investigated further as a food additive to increase biosafety of consumable food products.     

Efficacy of washing with hydrogen peroxide followed by aerosolized antimicrobials as a novel sanitizing process to inactivate Escherichia coli O157:H7 on baby spinach

Aerosolization was investigated as a potential way to apply allyl isothiocyanate (AIT), hydrogen peroxide (H₂O₂), acetic acid (AA) and lactic acid (LA) on fresh baby spinach to control Escherichia coli O157:H7 during refrigeration storage. In this study, baby spinach leaves were dip-inoculated with E. coli O157:H7 to a level of 6 log CFU/g and stored at 4 °C for 24 h before treatment. Antimicrobials were atomized into fog-like micro-particles by an ultrasonic nebulizer and routed into a jar and a scale-up model system where samples were treated. Samples were stored at 4 °C for up to 10 days before the survival of the cells was determined. A 2-min treatment with 5% AIT resulted in a > 5-log reduction of E. coli O157:H7 on spinach after 2 days refrigeration regardless if the samples were pre-washed or not; however, this treatment impaired the sensory quality of leaves. Addition of LA to AIT improved the antimicrobial efficacy of AIT. In the jar system, washing with 3% H₂O₂ followed by a 2-min treatment of 2.5% LA + 1% AIT or 2.5% LA + 2% AIT reduced E. coli O157:H7 population by 4.7 and > 5 log CFU/g, respectively, after 10 days refrigeration. In the scale-up system, up to 4-log reduction of bacterial population was achieved for the same treatments without causing noticeable adverse effect on the appearance of leaves. Thus, this study demonstrates the potential of aerosolized AIT + LA as a new post-washing intervention strategy to control E. coli O157:H7 on baby spinach during refrigeration storage.     

Comparative efficacy of Zataria multiflora Boiss., Origanum compactum and Eugenia caryophyllus essential oils against E. coli O157:H7, feline calicivirus and endogenous microbiota in commercial baby-leaf salads

Ready-to-eat salads using baby-leaf and multi-leaf mixes are one of the most promising developments in the fresh-cut food industry. There is great interest in developing novel decontamination treatments, which are both safe for consumers and more efficient against foodborne pathogens. In this study, emulsions of essential oils (EOs) from Origanum compactum (oregano), Eugenia caryophyllus (clove), and Zataria multiflora Boiss (zataria) were applied by spray (0.8 ml) after the sanitizing washing step. The aim was to investigate their ability to control the growth of potentially cross-contaminating pathogens and endogenous microbiota in commercial baby leaves, processed in a fresh-cut produce company. Zataria EO emulsions of 3%, 5% and 10% reduced Escherichia coli O157:H7 by 1.7, 2.2 and 3.5 log cfu/g in baby-leaf salads after 5 days of storage at 7 °C. By contrast, reductions in E. coli O157:H7 counts remained the same when clove was applied at concentrations of 5% and 10% (2.5 log cfu/g reduction). Oregano (10%) reduced inoculated E. coli O157:H7 counts in baby-leaf salads by a maximum of 0.5 log cfu/g after 5 days of storage. Zataria showed strong antimicrobial efficacy against E. coli O157:H7 and also against the endogenous microbiota of baby-leaf salads stored for 9 days. Feline calicivirus (FCV), a norovirus surrogate, survived on inoculated baby-leaf salads during refrigerated storage (9 days at 7 °C) regardless of treatment. Refrigeration temperatures completely annulled the effectiveness of the EOs against FCV inoculated in baby-leaf salads as occurred in FCV cultures. This study shows that EOs, and zataria in particular, have great potential use as an additional barrier to reduce contamination-related risks in baby-leaf salads. However, further research should be done into foodborne viruses in order to improve food safety.     

Modelling of Escherichia coli O157:H7 growth at various storage temperatures on beef treated with electrolyzed oxidizing water

The influence of storage temperature (4, 10, 15, 20, 25, and 30 °C) on the growth of Escherichia coli O157:H7 in beef untreated (control) and treated by acidic electrolyzed oxidizing water (AcEOW) or slightly acidic electrolyzed oxidizing water (SAcEOW) was examined. A Baranyi model was employed to describe growth parameters such as specific growth rate (SGR) and lag time (LT) as a function of storage temperature. SGR increased and LT declined with rising temperatures in all samples. There were no significant differences between the SGR and LT values obtained from beef treated with AcEOW or SAcEOW. Secondary models were established for SGR and LT to evaluate the effects of storage temperature on the growth kinetics of E. coli O157:H7 in treated and untreated beef. Mathematical evaluation was carried out to validate the performance of the developed models.     

Fate of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella on fresh-cut celery

Illnesses from Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella have been associated with the consumption of numerous produce items. Little is known about the effect of consumer handling practices on the fate of these pathogens on celery. The objective of this study was to determine pathogen behavior at different temperatures under different storage conditions. Commercial fresh-cut celery was inoculated at ca. 3 log CFU/g onto either freshly cut or outer uncut surfaces and stored in either sealed polyethylene bags or closed containers. Samples were enumerated following storage for 0, 1, 3, 5, and 7 days when held at 4 °C or 12 °C, and after 0, 8, and 17 h, and 1, and 2 days when held at 22 °C. At 4 °C, all populations declined by 0.5–1.0 log CFU/g over 7 days. At 12 °C, E. coli O157:H7 and Salmonella populations did not change, while L. monocytogenes populations increased by ca. 0.5 log CFU/g over 7 days. At 22 °C, E. coli O157:H7, Salmonella, and L. monocytogenes populations increased by ca. 1, 2, or 0.3 log CFU/g, respectively, with the majority of growth occurring during the first 17 h. On occasion, populations on cut surfaces were significantly higher than those on uncut surfaces. Results indicate that populations are reduced under refrigeration, but survive and may grow at elevated temperatures.