Use of hot water for beef carcass decontamination

Effect of ozone application on bovine carcasses in abattoir cold chambers

Different technologies have been evaluated to promote food safety and improve the microbiological quality and shelf life of food. The aim of this work was to determine the effect of gaseous ozone on beef carcass weight loss and indicator microorganism counts in an exporting abattoir. Two gaseous ozone concentrations (3 and 10 ppm) were applied on carcasses from Experiment 1 (Exp. 1, n = 100 test, n = 100 control) and Experiment 2 (Exp. 2, n = 100 test, n = 100 control), respectively. Cold chamber without ozone was used as control in both experiments. For mesophilic aerobic organism (MAO), coliform and Escherichia coli counts, 100 cm2 of each carcass was swabbed before and 10, 20 and 30 h after ozone application. In Exp. 1, the carcass entire surface was swabbed for Shiga-toxin (stx) gene detection. The counts of MAO were influenced by treatment and sampling time in both experiments. In Exp. 1, control carcasses had higher counts than ozonated carcasses at all sampling times, whereas the opposite occurred in Exp. 2. Coliform count was affected by sampling time in Exp. 2, whereas E. coli count was not affected in any experiment. All samples analyzed were stx-negative. Differences in carcass weight loss were not significant. In conclusion, gaseous ozone was not effective to reduce bacterial load or carcass weight loss. To our knowledge, this is the first study evaluating ozone effect on beef carcasses conducted in a commercial abattoir, not at laboratory scale. Future research would help demonstrate whether the use of ozone impacts on the quality and sensory characteristics of beef.

Advances in emerging technologies for the decontamination of the food contact surfaces

Foodborne pathogens could be transferred to food from food contact surfaces contaminated by poor hygiene or biofilm formation. The food processing industry has various conditions favouring microbes' adherence, such as moisture, nutrients, and the microbial inoculums obtained from the raw material. The function of the ideal antimicrobial surface is preventing initial attachment of the microbes, killing the microbes or/and removing the dead bacteria. This review article provides detail about the challenges food industries are facing with respect to food contact materials. It also summarises the merits and demerits of several sanitizing methods developed for industrial use. Furthermore, it reviews the new and emerging techniques that enhance the efficiency of reducing microbial contamination. Techniques such as surface functionalisation, high-intensity ultrasound, cold plasma technologies etc. which have high potential to be used for the decontamination of food contact surfaces are discussed. The emerging designs of antibacterial surfaces provide the opportunity to reduce or eradicate the adhesion of microorganisms. The most important purpose of these surfaces is to prevent the attachment of bacteria and to kill the bacteria that come in contact. These emerging technologies have a high potential for developing safe and inert food contact materials for the food industry.

Encapsulated Plant-Derived Antimicrobial Reduces Enteric Bacterial Pathogens on Melon Surfaces during Differing Contamination and Sanitization Treatment Scenarios

This study aimed to quantify survival in Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium isolates on melon rind surface samples achieved by sanitizer treatment under three differing melon contamination and sanitization scenarios. Sanitizing treatments consisted of the plant-derived antimicrobial (PDA) essential oil component (EOC) geraniol (0.5 wt.%) entrapped in the polymeric surfactant Pluronic F-127 (GNP), 0.5 wt.% unencapsulated geraniol (UG), 200 mg/L hypochlorous acid at pH 7.0 (HOCl), and a sterile distilled water wash (CON). The experimental contamination and sanitization scenarios tested were: (1) pathogen inoculation preceded by treatment; (2) the pathogen was inoculated onto samples twice with sanitizing treatment applied in between inoculation events; or (3) pathogen inoculation followed by sanitizing treatment. Reductions in the numbers of surviving pathogens were dependent on the sanitizing treatment, the storage period, or the interaction of these effects. GNP treatment provided the greatest reductions in surviving pathogen counts on melon rinds, but these did not regularly statistically differ from those achieved by HOCl or UG treatment. GNP treatment provided the best pathogen control under differing conditions of pre- and/or post-harvest cross-contamination and can be applied to reduce the risk of pathogen transmission on melon rinds.

Biomapping of Microbial Indicators on Beef Subprimals Subjected to Spray or Dry Chilling over Prolonged Refrigerated Storage

As the global meat market moves to never frozen alternatives, meat processors seek opportunities for increasing the shelf life of fresh meats by combinations of proper cold chain management, barrier technologies, and antimicrobial interventions. The objective of this study was to determine the impact of spray and dry chilling combined with hot water carcass treatments on the levels of microbial indicator organisms during the long-term refrigerated storage of beef cuts. Samples were taken using EZ-Reach™ sponge samplers with 25 mL buffered peptone water over a 100 cm² area of the striploin. Sample collection was conducted before the hot carcass wash, after wash, and after the 24 h carcass chilling. Chilled striploins were cut into four sections, individually vacuum packaged, and stored to be sampled at 0, 45, 70, and 135 days (n = 200) of refrigerated storage and distribution. Aerobic plate counts, enterobacteria, Escherichia coli, coliforms, and psychrotroph counts were evaluated for each sample. Not enough evidence (p > 0.05) was found indicating the hot water wash intervention reduced bacterial concentration on the carcass surface. E. coli was below detection limits (<0.25 CFU/cm²) in most of the samples taken. No significant difference (p > 0.05) was found between coliform counts throughout the sampling dates. Feed type did not seem to influence the (p > 0.25) microbial load of the treatments. Even though no immediate effect was seen when comparing spray or dry chilling of the samples at day 0, as the product aged, a significantly lower (p < 0.05) concentration of aerobic and psychrotrophic organisms in dry-chilled samples could be observed when compared to their spray-chilled counterparts. Data collected can be used to select alternative chilling systems to maximize shelf life in vacuum packaged beef kept over prolonged storage periods.

Antimicrobial-Loaded Polymeric Micelles Inhibit Enteric Bacterial Pathogens on Spinach Leaf Surfaces During Multiple Simulated Pathogen Contamination Events

Protecting fresh-packed produce microbiological safety against pre- and post-harvest microbial pathogen contamination requires innovative antimicrobial strategies. Although largely ignored in the scientific literature, there exists the potential for gross failure in food safety protection of fresh fruits and vegetables leading to opportunity for multiple produce contamination events to occur during production and post-harvest handling of food crops. The primary objective of this research was to determine the efficacy of plant-derived antimicrobial-loaded nanoparticles to reduce Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium on spinach leaf surfaces whilst simulating multiple pathogen contamination events (pre-harvest and post-harvest). Spinach samples were inoculated with a blend of E. coli O157:H7 and S. Typhimurium, each diluted to ~8.0 log10 CFU/mL. The inoculated samples were then submerged in solutions containing nanoparticles loaded with geraniol (GPN; 0.5 wt.% geraniol), unencapsulated geraniol (UG; 0.5 wt.%), or 200 ppm chlorine (HOCl; pH 7.0), with untreated samples serving for controls. Following antimicrobial treatment application, samples were collected for surviving pathogen enumeration or were placed under refrigeration (5°C) for up to 10 days, with periodic enumeration of pathogen loads. After 3 days of refrigerated storage, all samples were removed, aseptically opened and subjected to a second inoculation with both pathogens. Treatment of spinach surfaces with encapsulated geraniol reduced both pathogens to non-detectable numbers within 7 days of refrigerated storage, even with a second contamination event occurring 3 days after experiment initiation. Similar results were observed with the UG treatment, except that upon recontamination at day 3, a higher pathogen load was detected on UG-treated spinach vs. GPN-treated spinach. These data fill a research gap by providing a novel tool to reduce enteric bacterial pathogens on spinach surfaces despite multiple contamination events, a potential food safety risk for minimally processed edible produce.

Intraobserver and interobserver reliability of mud scoring systems for use in cattle at slaughter

At slaughter plants, live cattle are often scored for mud coverage as mud on hides can impact food safety and drives decisions regarding interventions during processing. Currently, there is no standardized method utilized to assess mud coverage. The aim of this study was to determine the intraobserver and interobserver reliability of 3, 4, and 5 point mud scoring systems. Beef cattle (n = 110) were videotaped during movement to holding pens upon arrival at a commercial slaughter facility. Five scorers were assigned to a 3, 4, or 5 point scoring system (n = 15), reviewed the video and assigned the cattle a mud score. A multi-rater weighted kappa analysis was used to determine intraobserver and interobserver reliability for each system. Although all scorers in the 3 point analysis and one scorer each for the 4 and 5 point analysis demonstrated moderate intraobserver reliability, all interobserver reliability kappas were poor (kappa ≤0.12). Further exploration to develop a suitable system that is repeatable is recommended.

Efficacy of antimicrobial interventions in reducing Salmonella enterica, Shiga toxin-producing Escherichia coli, Campylobacter, and Escherichia coli biotype I surrogates on non-chilled and chilled, skin-on and skinless pork

Effect of various antimicrobial interventions on pork carcass cuts - skin-on and skinless, non-chilled and chilled - was studied. Carcass pieces were inoculated with Salmonella enterica, Shiga toxin-producing Escherichia coli (STEC), Escherichia coli pathogen surrogates or Campylobacter spp. Inoculated pieces were assigned to one of the following antimicrobial treatments: 2.5% and 5.0% room temperature lactic acid, 2.5% and 5.0% warm (55 °C) lactic acid, 400 ppm (0.4 mg/mL) room temperature peroxyacetic acid (PAA) or warm (55 °C) water. Treated pieces were sampled before antimicrobial treatment of non-chilled pork tissue, then at 30 m and 24 h post-treatment. For chilled pork, samples were collected after 24 h chilling and 30 m post-treatment. Lactic acid and PAA treatments reduced (P < 0.05) pathogenic and surrogate bacteria; warm water did not produce similar results. Objective and sensory color evaluations on treated pork indicated minimal negative impacts on pork color. Various antimicrobial interventions were effective in reducing surrogates on pork without diminishing quality.

Inactivation of Salmonella and Shiga toxin-producing Escherichia coli (STEC) from the surface of alfalfa seeds and sprouts by combined antimicrobial treatments using ozone and electrolyzed water

Individual chemical and non-chemical treatments have failed to disinfect alfalfa seeds and sprouts from pathogens thoroughly. This study investigated the disinfection of alfalfa seeds and sprouts using a procedure combining ozone with acidic (pH 3.0) electrolyzed water (AEW). Inoculated alfalfa seeds with a cocktail of 3 strains Salmonella and 3 strains of STEC were treated sequentially with aqueous ozone followed by AEW. Treatment started by immersing the samples into ozonated water (5 mg/L ozone) for 15 or 20 min with persistent oxygen feeding pressurized with 10 psi. The samples then were immersed in 1 L of AEW for 15 min. Salmonella and STEC were significantly (P < 0.05) reduced by 3.6 and 2.9 log CFU/g on seeds respectively, and by 3.1 and 3.0 log CFU/g reduction on sprouts. Significant differences (P < 0.05) were found in the magnitude of the log reduction between Salmonella and STEC on seeds and between seeds and sprouts. Using combined treatments showed no significant changes in the quality, including shelf life, weight, and color in sprouts as compared to controls. The findings suggest that the combination of ozone and AEW is effective in inactivation of Salmonella and STEC on alfalfa seeds and sprouts with no adverse effects on sprouts quality.

Inhibition of Escherichia coli O157:H7 and Salmonella enterica Isolates on Spinach Leaf Surfaces Using Eugenol-Loaded Surfactant Micelles

Spinach and other leafy green vegetables have been linked to foodborne disease outbreaks of Escherichia coli O157:H7 and Salmonellaenterica around the globe. In this study, the antimicrobial activities of surfactant micelles formed from the anionic surfactant sodium dodecyl sulfate (SDS), SDS micelle-loaded eugenol (1.0% eugenol), 1.0% free eugenol, 200 ppm free chlorine, and sterile water were tested against the human pathogens E. coli O157:H7 and Salmonella Saintpaul, and naturally occurring microorganisms, on spinach leaf surfaces during storage at 5 °C over 10 days. Spinach samples were immersed in antimicrobial treatment solution for 2.0 min at 25 °C, after which treatment solutions were drained off and samples were either subjected to analysis or prepared for refrigerated storage. Whereas empty SDS micelles produced moderate reductions in counts of both pathogens (2.1–3.2 log₁₀ CFU/cm²), free and micelle-entrapped eugenol treatments reduced pathogens by >5.0 log₁₀ CFU/cm² to below the limit of detection (<0.5 log₁₀ CFU/cm²). Micelle-loaded eugenol produced the greatest numerical reductions in naturally contaminating aerobic bacteria, Enterobacteriaceae, and fungi, though these reductions did not differ statistically from reductions achieved by un-encapsulated eugenol and 200 ppm chlorine. Micelles-loaded eugenol could be used as a novel antimicrobial technology to decontaminate fresh spinach from microbial pathogens.

Quantification of Bacteria Indicative of Fecal and Environmental Contamination from Hides to Carcasses

Fecal bacteria, which reside in the gastrointestinal tract of cattle, can contaminate beef carcasses during processing. In beef cattle slaughter plants, the presence and concentrations of generic Escherichia coli, coliforms, Enterobacteriaceae (EB), and total aerobic bacteria are monitored as indicator organisms of fecal and environmental contamination. The objectives of this study were as follows: (1) to determine the concentrations of generic E. coli, coliforms, EB, and aerobic bacteria on beef carcasses at different processing points in Midwestern commercial beef slaughter plants during the summer, spring, and fall seasons; and (2) to estimate bacterial transfer on carcasses during the hide removal and evisceration processes. Hide and carcass surface sample swabs were collected from slaughtered cattle at four large commercial processing plants. At each plant visit (3 visits to each of the 4 plants) and during 3 seasons, 20 samples were collected at 5 points: hide-on (hide of animal near exsanguination pit), hide-off carcass, pre-evisceration carcass, postevisceration carcass, and postintervention carcass, for a total of 3600 samples. Bacterial concentrations were determined using 3M^™ Petrifilm^™ plates. Associations between season and processing plant with concentrations of E. coli, coliforms, EB, and total aerobic bacteria, overall, between hide-on and hide-off, and between pre- and post-evisceration, were evaluated using multilevel mixed-effects linear regression models. Bacterial concentrations on beef carcasses significantly decreased throughout processing. Moreover, hide removal was an important source of carcass contamination, given bacterial concentrations detected on hide-off carcass samples were the highest, and bearing in mind that carcass muscle surfaces should be sterile. Results from this study indicate that the interventions applied by the processing plants were effective, as they probably contributed to the significant reduction of bacterial concentrations of carcasses.

Validation of Antimicrobial Interventions for Reducing Shiga Toxin-Producing Escherichia coli Surrogate Populations during Goat Slaughter and Carcass Chilling

Demand and consumption of goat meat is increasing in the United States due to an increase in ethnic populations that prefer goat meat. As ruminant animals, goats are known reservoirs for Shiga toxin-producing Escherichia coli (STEC) and proper handling, especially during slaughter, is imperative to reduce the likelihood of carcass and meat contamination. However, the majority of antimicrobial intervention studies during the slaughter of ruminant species have focused on beef, highlighting the need for validation studies targeting small ruminants, such as goats, during slaughter and chilling procedures. The objective of this research was to evaluate 4.5% lactic acid (LA; pH 2.1), peroxyacetic acid (PAA; 400 ppm; pH 4.7), a hydrochloric and citric acid blend (Citrilow [CL]; pH 1.2), 5% levulinic acid plus 0.5% sodium dodecyl sulfate (LVA+SDS; pH 2.60), and a nontreated control (CON) for their efficacy in reducing STEC surrogates and their effect on carcass color from slaughter through 24-h chill. Fifteen goat carcasses across three replications were inoculated with a five-strain cocktail (ca. 5 log CFU/cm² attachment), containing rifampin-resistant surrogate E. coli (BAA-1427, BAA-1428, BAA-1429, BAA-1430, and BAA-1431) and were randomly assigned to an antimicrobial treatment. Antimicrobials were applied prechill and 24 h postchill. Mean log reductions achieved after prechill treatment with LA, PAA, CL, and LVA+SDS were 2.00, 1.86, 2.26, and 1.90 log CFU/cm², respectively. Antimicrobial treatment after the 24-h chilling, resulted in additional reductions of surrogate E. coli by 0.99, 1.03, 1.94, and 0.47 log CFU/cm² for LA, PAA, CL, and LVA+SDS, respectively. Antimicrobial treatments did not impact goat carcass objective color (L* and a*), except for b*. The antimicrobials tested in this study were able to effectively reduce surrogate STEC populations during slaughter and subsequent chilling without compromising carcass color.

Evaluation of Commercial Prototype Bacteriophage Intervention Designed for Reducing O157 and Non-O157 Shiga-Toxigenic Escherichia coli (STEC) on Beef Cattle Hide

Microbiological safety of beef products can be protected by application of antimicrobial interventions throughout the beef chain. This study evaluated a commercial prototype antimicrobial intervention comprised of lytic bacteriophages formulated to reduce O157 and non-O157 Shiga-toxigenic Escherichia coli (STEC) on beef cattle hide pieces, simulating commercial pre-harvest hide decontamination. STEC reduction in vitro by individual and cocktailed phages was determined by efficiency of plating (EOP). Following STEC inoculation onto hide pieces, the phage intervention was applied and hide pieces were analyzed to quantify reductions in STEC counts. Phage intervention treatment resulted in 0.4 to 0.7 log10 CFU/cm² (p < 0.01) E. coli O157, O121, and O103 reduction. Conversely, E. coli O111 and O45 did not show any significant reduction after application of bacteriophage intervention (p > 0.05). Multiplicity of infection (MOI) evaluation indicated E. coli O157 and O121 isolates required the fewest numbers of phages per host cell to produce host lysis. STEC-attacking phages may be applied to assist in preventing STEC transmission to beef products.

National Beef Quality Audit-2016: Transportation, mobility, and harvest-floor assessments of targeted characteristics that affect quality and value of cattle, carcasses, and by-products

The National Beef Quality Audit-2016 (NBQA-2016) was conducted to assess current transportation, mobility, and quality characteristics of U.S. fed steers and heifers. Data were collected at 17 beef processing facilities between March and November 2016. About 8,000 live cattle were evaluated for transportation and mobility, and about 25,000 carcasses were evaluated on the slaughter floor. Cattle were in transit to the slaughter facility for a mean duration of 2.7 h from a mean distance of 218.5 km using trailers with dimensions ranging from 17.84 m² to 59.09 m². Area allotted per animal averaged 1.13 m² and ranged from 0.85 m² to 2.28 m². A total of 96.8% of cattle received a mobility score of 1 (walks easily, no apparent lameness). Identification types (35.1% had multiple) were lot visual tags (61.5%), individual tags (55.0%), electronic tags (16.9%), metal-clip tags (9.2%), bar-coded tags (0.05%), wattles (0.01%), and other (2.6%). Cattle were black-hided (57.8%), Holstein (20.4%), red-hided (10.5%), yellow-hided (4.8%), gray-hided (2.9%), brown-hided (1.3%), and white-hided (1.1%). Unbranded hides were observed on 74.3% of cattle; 18.6% had brands located on the butt, 6.3% on the side, and 1.3% on the shoulder (values exceed 100% due to multiple brands). For hide-on carcasses, 37.7% displayed no mud or manure; specific locations for mud or manure were legs (40.8%), belly (33.0%), tail region (15.5%), side (6.8%), and top-line (3.9%). Cattle without horns represented 83.3% of the sample, and cattle that did have horns measured: < 2.54 cm (5.5%), 2.54 to 12.7 cm (8.3%), and > 12.7 cm (2.9%). Carcasses without bruises represented 61.1% of those sampled, whereas 28.2% had 1, 8.2% had 2, 2.1% had 3, and 0.3% had 4 bruises. Of those carcasses with a bruise, the bruise was located on the loin (29.7%), round (27.8%), chuck (16.4%), rib (14.4%), and brisket/plate/flank (11.6%). Frequencies of offal condemnations were livers (30.8%), lungs (18.2%), viscera (16.3%), hearts (11.1%), heads (2.7%), and tongues (2.0%). Compared to NBQA-2011, fewer cattle were identified for traceability, fewer were black-hided, a greater number were Holstein cattle, more with no brand and no horns, fewer without bruises, more liver, lung, and viscera condemnations, and fewer heads and tongues were condemned. The NBQA remains an influential survey for the U.S. beef industry to provide benchmarks and strategic plans for continued improvement of beef quality and consistency.

Meta-analysis on the effect of interventions used in cattle processing plants to reduce Escherichia coli contamination

Cattle coming from feedlots to slaughter often harbor pathogenic E. coli that can contaminate final meat products. As a result, reducing pathogenic contamination during processing is a main priority. Unfortunately, food safety specialists face challenges when trying to determine optimal intervention strategies from published literature. Plant intervention literature results and methods vary significantly, making it difficult to implement interventions with any degree of certainty in their effectiveness. To create a more robust understanding of plant intervention effectiveness, a formal systematic literature review and meta-analysis was conducted on popular intervention methods. Effect size or intervention effectiveness was measured as raw log reduction, and modeled using study characteristics, such as intervention type, temperature of application, initial microbial concentration, etc. Least-squares means were calculated for intervention effectiveness separately on hide and on carcass surfaces. Heterogeneity between studies (I²) was assessed and factors influencing intervention effectiveness were identified. Least-squares mean reductions (log CFU/cm²) on carcass surfaces (n=249) were 1.44 [95% CI: 0.73-2.15] for acetic acid, 2.07 [1.48-2.65] for lactic acid, 3.09 [2.46-3.73] for steam vacuum, and 1.90 [1.33-2.47] for water wash. On hide surfaces (n=47), least-squares mean reductions were 2.21 [1.36-3.05] for acetic acid, 3.02 [2.16-3.88] for lactic acid, 3.66 [2.60-4.72] for sodium hydroxide, and 0.08 [-0.94-1.11] for water wash. Meta-regressions showed that initial microbial concentrations and timing of extra water washes were the most important predictors of intervention effectiveness. Unexplained variation remained high in carcass, hide, and lactic acid meta-regressions, suggesting that other significant moderators are yet to be identified. The results will allow plant managers and risk assessors to evaluate plant interventions, variation, and factors more effectively.

Predictive modeling for hot water inactivation of planktonic and biofilm-associated Sphingomonas parapaucimobilis to support hot water sanitization programs

Hot water sanitization is a common means to maintain microbial control in process equipment for industries where microorganisms can degrade product or cause safety issues. This study compared the hot water inactivation kinetics of planktonic and biofilm-associated Sphingomonas parapaucimobilis at temperatures relevant to sanitization processes used in the pharmaceutical industry, viz. 65, 70, 75, and 80°C. Biofilms exhibited greater resistance to hot water than the planktonic cells. Both linear and nonlinear statistical models were developed to predict the log reduction as a function of temperature and time. Nonlinear Michaelis-Menten modeling provided the best fit for the inactivation data. Using the model, predictions were calculated to determine the times at which specific log reductions are achieved. While ≥80°C is the most commonly cited temperature for hot water sanitization, the predictive modeling suggests that temperatures ≥75°C are also effective at inactivating planktonic and biofilm bacteria in timeframes appropriate for the pharmaceutical industry.

Evaluating the Efficacy of Three U.S. Department of Agriculture-Approved Antimicrobial Sprays for Reducing Shiga Toxin-Producing Escherichia coli Surrogate Populations on Bob Veal Carcasses

Effective antimicrobial intervention strategies to reduce Shiga toxin-producing Escherichia coli (STEC) risks associated with veal are needed. This study evaluated the efficacy of lactic acid (4.5%, pH 2.0), Citrilow (pH 1.2), and Beefxide (2.25%, pH 2.3) for reducing STEC surrogates on prerigor and chilled bob veal carcasses and monitored the effects of these interventions on chilled carcass color. Dehided bob veal carcasses were inoculated with a five-strain cocktail of rifampin-resistant, surrogate E. coli bacteria.E. coli surrogates were enumerated after inoculation, after water wash, after prechill carcass antimicrobial spray application, after chilling for 24 h, and after postchill carcass antimicrobial spray application; carcass color was measured throughout the process. A standard carcass water wash (∼50°C) reduced the STEC surrogate population by 0.9 log CFU/cm(2) (P ≤ 0.05). All three antimicrobial sprays applied to prerigor carcasses delivered an additional ∼0.5-log reduction (P ≤ 0.05) of the surrogates. Chilling of carcasses for 24 h reduced (P ≤ 0.05) the surrogate population by an additional ∼0.4 log cycles. The postchill application of the antimicrobial sprays provided no further reductions. Carcass L*, a*, and b* color values were not different (P > 0.05) among carcass treatments. Generally, the types and concentrations of the antimicrobial sprays evaluated herein did not negatively impact visual or instrumental color of chilled veal carcasses. This study demonstrates that warm water washing, followed by a prechill spray treatment with a low-pH chemical intervention, can effectively reduce STEC risks associated with veal carcasses; this provides processors a validated control point in slaughter operations.

Inhibition of Bacterial Pathogens in Medium and on Spinach Leaf Surfaces using Plant-Derived Antimicrobials Loaded in Surfactant Micelles

Encapsulation of hydrophobic plant essential oil components (EOC) into surfactant micelles can assist the decontamination of fresh produce surfaces from bacterial pathogens during postharvest washing. Loading of eugenol and carvacrol into surfactant micelles of polysorbate 20 (Tween 20), Surfynol® 485W, sodium dodecyl sulfate (SDS), and CytoGuard® LA 20 (CG20) was determined by identification of the EOC/surfactant-specific maximum additive concentration (MAC). Rheological behavior of dilute EOC-containing micelles was then tested to determine micelle tolerance to shearing. Antimicrobial efficacy of EOC micelles against Escherichia coli O157:H7 and Salmonella enterica serotype Saintpaul was first evaluated by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Pathogen-inoculated spinach was treated with eugenol-containing micelles applied via spraying or immersion methods. SDS micelles produced the highest MACs for EOCs, while Tween 20 loaded the lowest amount of EOCs. Micelles demonstrated Newtonian behavior in response to shearing. SDS and CG20-derived micelles containing EOCs produced the lowest MICs and MBCs for pathogens. E. coli O157:H7 and S. Saintpaul were reduced on spinach surfaces by application of eugenol micelles, though no differences in numbers of surviving pathogens were observed when methods of antimicrobial micelle application (spraying, immersion) was compared (P ≥ 0.05). Data suggest eugenol in SDS and CG20 micelles may be useful for produce surface decontamination from bacterial pathogens during postharvest washing.

PRACTICAL APPLICATION

Antimicrobial essential oil component (EOC)-containing micelles assist the delivery of natural food antimicrobials to food surfaces, including fresh produce, for decontamination of microbial foodborne pathogens. Antimicrobial EOC-loaded micelles were able to inhibit the enteric pathogens Escherichia coli O157:H7 and Salmonella Saintpaul in liquid medium and on spinach surfaces. However, pathogen reduction generally was not impacted by the method of micelle application (spraying, immersion washing) on spinach surfaces.

Investigation into Formation of Lipid Hydroperoxides from Membrane Lipids in Escherichia coli O157:H7 following Exposure to Hot Water

Although studies have shown antimicrobial treatments consisting of hot water sprays alone or paired with lactic acid rinses are effective for reducing Escherichia coli O157:H7 loads on beef carcass surfaces, the mechanisms by which these interventions inactivate bacterial pathogens are still poorly understood. It was hypothesized that E. coli O157:H7 exposure to hot water in vitro at rising temperatures for longer time periods would result in increasing deterioration of bacterial outer membrane lipids, sensitizing the pathogen to subsequent lactic acid application. Cocktails of E. coli O157:H7 strains were subjected to hot water at 25 (control) 65, 75, or 85 °C incrementally up to 60 s, after which surviving cells were enumerated by plating. Formation of lipid hydroperoxides from bacterial membranes and cytoplasmic accumulation of L-lactic acid was quantified spectrophotometrically. Inactivation of E. coli O157:H7 proceeded in a hot water exposure duration- and temperature-dependent manner, with populations being reduced to nondetectable numbers following heating of cells in 85 °C water for 30 and 60 s (P < 0.05). Lipid hydroperoxide formation was not observed to be dependent upon increasing water temperature or exposure period. The data suggest that hot water application prior to organic acid application may function to increase the sensitivity of E. coli O157:H7 cells by degrading membrane lipids.

Peri- and Postharvest Factors in the Control of Shiga Toxin-Producing Escherichia coli in Beef

Certain Shiga toxin-producing Escherichia coli (STEC) strains are important causes of food-borne disease, with hemorrhagic colitis and, in some cases, hemolytic-uremic syndrome as the clinical manifestations of illness. Six serogroups and one serotype of STEC (O26, O45, O103, O111, O121, O145, and O157:H7) are responsible for the vast majority of cases in the United States. Based on recent data for all food commodities combined, 55.3% and 50.0% of the outbreaks of STEC O157 and non-O157 in the United States, respectively, are attributable to beef as a food source. Consequently, the U.S. Department of Agriculture, Food Safety and Inspection Service declared these organisms as adulterants in raw, nonintact beef. In North America, cattle are a major reservoir of STEC strains, with organisms shed in the feces and contaminated hides of the animals being the main vehicle for spread to carcasses at slaughter. A number of peri- and postharvest interventions targeting STEC have been developed, and significant progress has been made in improving the microbiological quality of beef in the past 20 years as a result. However, continued improvements are needed, and accurate assessment of these interventions, especially for non-O157 STEC, would greatly benefit from improvements in detection methods for these organisms.

Effect of the use of a neutralizing step after antimicrobial application on microbial counts during challenge studies for orange disinfection

The effects of using a neutralizer after applying antimicrobial treatments and the effect of time lapse between treatment application and subsequent recovery and enumeration of Escherichia coli O157:H7 and Salmonella were investigated in Valencia oranges. Inoculated oranges surfaces were washed with distilled water for 15 s and then sprayed with a solution containing 200 mg/liter sodium hypochlorite (pH 6.5) for 15 s; they were then dipped in L-lactic acid (2.0% at 55°C) for 1 min or in distilled water at 80°C for 1 min. Posttreatment, oranges were divided into two groups. In the first group, oranges were dipped in neutralization treatment: 270 ml of buffered peptone water for 2 min for lactic acid-treated oranges, 270 ml of Dey-Engley broth for 2 min for chlorine-treated oranges, or 3.7 liters of tap water (25°C) for 10 s for hot water-treated oranges. The second group of treated oranges was not subjected to any neutralizer. All oranges then were kept at room temperature (average 26.2°C) and sampled at 0, 7.5, and 15 min for enumeration of surviving Salmonella and E. coli O157:H7. The orange surface (30 cm(2)) was excised for pathogen enumeration. The presence of free chlorine and changes in pH and temperature on the orange surface were determined in uninoculated, treated oranges. Free chlorine was detected on oranges after treatment; the change in temperature of orange surfaces was greater during treatment with hot water than with lactic acid. Nevertheless, pathogen enumeration did not show any impact of neutralizer use on the residual activity of antimicrobials or any impact of the time elapsed between antimicrobial treatment and recovery of bacterial pathogens from inoculated oranges (P ≥ 0.05). The results of this study indicate that the lack of a neutralizing step before enumeration of pathogens is not likely to affect the accuracy of results during challenge studies to test pathogen reduction strategies on oranges.

Evaluation of peroxyacetic acid as a post-chilling intervention for control of Escherichia coli O157:H7 and Salmonella Typhimurium on beef carcass surfaces

Four experiments were conducted to test the efficacy of peroxyacetic acid as a microbial intervention on beef carcass surfaces. In these experiments, beef carcass surfaces were inoculated with fecal material (no pathogens) or fecal material containing rifampicin-resistant Escherichia coli O157:H7 and Salmonella Typhimurium. Inoculated surfaces were subjected to a simulated carcass wash with and without 2% l-lactic acid treatment before chilling. In Experiments 1 and 2, the chilled carcass surfaces were sprayed with peroxyacetic acid (200 ppm; 43°) for 15 s. Peroxyacetic acid had no effect on microbial counts of any organism measured on these carcass surfaces. However, lactic acid reduced counts of E. coli Type I (1.9log(10) CFU/cm(2)), coliforms (3.0log(10) CFU/cm(2)), E. coli O157:H7 (2.7log(10) CFU/cm(2)), and S. Typhimurium (2.8log(10) CFU/cm(2)) entering the chilling cooler and prevented growth during the chilling period. In Experiment 3, peroxyacetic acid at different concentrations (200, 600, and 1000 ppm) and application temperatures (45 and 55 °C) were used to investigate its effectiveness in killing E. coli O157:H7 and S. Typhimurium compared to 4% l-lactic acid (55 °C). Application temperature did not affect the counts of either microorganism. Peroxyacetic acid concentrations up to 600 ppm had no effect on these microorganisms. Concentrations of 1000 ppm reduced E. coli O157:H7 and S. Typhimurium by up to 1.7 and 1.3log(10) CFU/cm(2), respectively. However, 4% lactic acid reduced these organisms by 2.7 and 3.4log(10) CFU/cm(2), respectively. In Experiment 4, peroxyacetic acid (200 ppm; 43 °C) was applied to hot carcass surfaces. This treatment caused a 0.7log(10) CFU/cm(2) reduction in both E. coli O157:H7 and S. Typhimurium. The collective results from these experiments indicate that peroxyacetic acid was not an effective intervention when applied to chilled inoculated carcass piece surfaces.

Efficacy of antimicrobials for the disinfection of pathogen contaminated green bell pepper and of consumer cleaning methods for the decontamination of knives

While there is strong focus on eliminating pathogens from produce at a commercial level, consumers can employ simple methods to achieve additional pathogen reductions in the domestic kitchen. To determine the ability of antimicrobials to decontaminate peppers, samples of green bell pepper were inoculated with Salmonella enterica and Escherichia coli O157:H7 and then immersed in 3% (v/v) hydrogen peroxide (H₂O₂), 2.5% (v/v) acetic acid (AA), 70% (v/v) ethyl alcohol (EtOH), or sterile distilled water (SDW). The potential for transfer of pathogens from contaminated peppers to other non-contaminated produce items, and the effect of knife disinfection in preventing this cross contamination, were also tested. Knife disinfection procedures were evaluated by chopping inoculated peppers into 1 cm² pieces with kitchen knives. Experimental knives were then treated by either no treatment (control), wiping with a dry sterile cotton towel, rinsing under running warm water for 5 or 10s, or applying a 1% (v/v) lauryl sulfate-based detergent solution followed by rinsing with warm running water for 10s. Following disinfection treatment, knives were used to slice cucumbers. Exposure to H₂O₂ for 5 min and EtOH for 1 min resulted in reductions of 1.3±0.3 log₁₀ CFU/cm² for both pathogens. A 5 min exposure to AA resulted in a reduction of S. enterica of 1.0±0.7 log₁₀ CFU/cm² and E. coli of 0.7±0.8 log₁₀ CFU/cm². No differences (p ≥ 0.05) were found between numbers of pathogens on knives and numbers of pathogens transferred to cucumber slices, suggesting that organisms remaining on knife surfaces were transferred to cucumbers during slicing. Findings suggest that EtOH and H₂O₂ may be effective antimicrobials for in-home decontamination of peppers, and that use of detergent and warm water is effective for decontamination of implements used during meal preparation.

Addition of a surfactant to tryptic soy broth allows growth of a lactic acid bacteria food antimicrobial, Escherichia coli O157:H7, and Salmonella enterica

AIMS

  This study aimed to determine the survival and growth of Escherichia coli O157:H7 and Salmonella enterica subsp. enterica in a medium supporting the growth of a Lactic Acid Bacteria (LAB) food antimicrobial culture.

METHODS AND RESULTS

  Foodborne pathogens and LAB were cultured individually in tryptic soy broth (TSB), tryptic soy broth supplemented with one g l(-1) Tween 80(®) (TSB-T80), and de Man, Rogosa and Sharpe (MRS) broth. Growth of E. coli O157:H7 and Salmonella was similar in TSB and TSB-T80 but was significantly less in MRS. Conversely, LAB growth was similar in MRS and TSB-T80 but was significantly less in TSB.

CONCLUSIONS

  Supplementation of TSB with Tween 80(®) allows growth of LAB to levels similar to that observed with MRS but does not inhibit the growth of E. coli O157:H7 and Salmonella. We present the formulation of a medium useful in studies useful for evaluating competitive inhibition of foodborne pathogens by LAB in vitro.

SIGNIFICANCE AND IMPACT OF THE STUDY

  This study reports the utility of TSB-T80 for the completion of in vitro competitive inhibition assays incorporating a Lactic Acid Bacteria food safety culture.

Dispersion and survival of Escherichia coli O157:H7 and Salmonella Typhimurium during the production of marinated beef inside skirt steaks and tri-tip roasts

To determine the depth of pathogen dispersion and the ability of pathogens to survive in enhanced beef products and spent marinade, beef inside skirt steaks and tri-tip roasts were vacuum tumbled with two commercial marinades. The marinades were inoculated with Escherichia coli O157:H7 and Salmonella Typhimurium, resulting in an approximate count of 5.2 log CFU/ml. Both inside skirt steaks and tri-tip roasts were vacuum tumbled for 1 h and sampled immediately after tumbling (day 0), or were vacuum packaged, stored (ca. 4°C), and sampled on days 7 and 14. Samples of the spent marinade were taken after tumbling (day 0) and on days 3 and 7. For both marinades, Salmonella Typhimurium and E. coli O157:H7 were dispersed throughout the inside skirt steaks during vacuum tumbling. Although Salmonella Typhimurium and E. coli O157:H7 for the skirt steaks were still detectable after 14 days of storage, the log values were lower than those on days 0 and 7. For the tri-tip roasts, the pathogen distribution varied, depending on the thickness of the roasts, and pathogens were detectable on days 0, 7, and 14. The spent marinade sampled on days 0, 3, and 7 showed that the pathogens survived at refrigerated temperatures. Because pathogens can transfer to the interior of beef inside skirt steaks and tri-tip roasts when vacuum tumbled with contaminated marinade and survived during refrigerated storage, establishments should consider the potential food safety risks associated with reuse of marinade during the production of vacuum-tumbled beef products.

Comparison of different washing treatments for reducing pathogens on orange surfaces and for preventing the transfer of bacterial pathogens to fresh-squeezed orange juice

The objectives of this study were to compare the effectiveness of various washing treatments for reducing Escherichia coli O157:H7, Salmonella sp., and Listeria monocytogenes populations on orange surfaces and to measure the effect of some of these treatments in preventing the transfer of pathogens during juice extraction. Orange surfaces inoculated with L. monocytogenes or a mixture of E. coli O157:H7 and Salmonella Typhimurium were washed by water spray and then sprayed with or dipped in water at 80°C for 1 min, 70% ethanol for 15, 30, or 45 s or 1, 2, or 4 min, 2 or 4% lactic acid solution at 55°C for 15, 30, or 45 s or 1, 2, or 4 min, or 200 mg/liter hypochlorite at pH 6.5 or 10 for 15 s. The surviving populations of these pathogens on the oranges were enumerated after each treatment. In a further stage, the ability of these pathogens to be transferred to the juice during extraction was tested. Juice was obtained from inoculated oranges that were subjected to selected treatments using chlorine, lactic acid, ethanol, and hot water as described above, and then bacterial counts in orange juice were determined. The application of these treatments reduced the populations of pathogens on orange surfaces by 1.9 to >4.9 log, 1.9 to >4.6 log, and 1.4 to 3.1 log cycles for E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes, respectively. The treatments using hot water or lactic acid showed greater reductions than other treatments. The time, antimicrobial concentration, and form of application affected the bacterial reduction. All treatments resulted in undetectable counts in the juice. Nevertheless, pathogens were recovered by the enrichment-plating method. Treatment of oranges before juice extraction may reduce the risk associated with consuming orange juice.

Reduction of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes with electrolyzed oxidizing water on inoculated hass avocados (Persea americana var. Hass)

This study was intended to evaluate the bactericidal effect of electrolyzed oxidizing water (EOW) and chlorinated water on populations of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes inoculated on avocados (Persea americana var. Hass). In the first experiment, inoculated avocados were treated with a water wash applied by spraying tap water containing 1 mg/liter free chlorine for 15 s (WW); WW treatment and then spraying sodium hypochlorite in water containing 75 mg/liter free chlorine for 15 s (Cl75); WW treatment and then spraying alkaline EOW for 30 s (AkEW) and then spraying acid EOW (AcEW) for 15 s; and spraying AkEW and then AcEW. In another experiment, the inoculated avocados were treated by spraying AkEW and then AcEW for 15, 30, 60, or 90 s. All three pathogen populations were lowered between 3.6 and 3.8 log cycles after WW treatment. The application of Cl75 did not produce any further reduction in counts, whereas AkEW and then AcEW treatment resulted in significantly lower bacterial counts for L. monocytogenes and E. coli O157:H7 but not for Salmonella. Treatments with AkEW and then AcEW produced a significant decrease in L. monocytogenes, Salmonella, and E. coli O157:H7 populations, with estimated log reductions of 3.9 to 5.2, 5.1 to 5.9, and 4.2 to 4.9 log CFU/cm², respectively. Spraying AcEW for more than 15 s did not produce any further decrease in counts of Salmonella or E. coli O157:H7, whereas L. monocytogenes counts were significantly lower after spraying AcEW for 60 s. Applying AkEW and then AcEW for 15 or 30 s seems to be an effective alternative to reduce bacterial pathogens on avocado surfaces.

Evaluation of Escherichia coli O157:H7 translocation and decontamination for beef vacuum-packaged subprimals destined for nonintact use

The translocation of Escherichia coli O157:H7 as well as the impact of water washing and partial or complete surface trimming as possible pathogen reduction strategies were evaluated for vacuum-packaged beef subprimals destined for nonintact use. Cap-on and cap-off beef top sirloin butts were inoculated with two levels of E. coli O157:H7: a high-inoculum level of approximately 10(4) CFU/cm(2) and a low-inoculum level of approximately 10(2) CFU/cm(2). Following inoculation, the subprimals were vacuum packaged and stored for 0, 14, or 28 days. Upon removal from storage, the following sites were evaluated: exterior of the bag, purge, the inoculation site on the subprimal, the area adjacent to the inoculation site, and the surface opposite from the inoculation site. The following treatments then were applied: water wash, water wash followed by full-surface trimming, water wash followed by partial-surface trimming, full-surface trimming, full-surface trimming followed by water wash, partial-surface trimming, and partial-surface trimming followed by water wash. For both high- and low-inoculated top sirloin butts, contamination of adjacent and opposite surfaces was found after vacuum packaging. Of the treatments applied, water washing alone was the least effective for both high- and low-inoculated subprimals. Full trimming, with or without a water wash, proved to be the most effective treatment used to reduce E. coli O157:H7 to nondetectable levels.

Validation of lactic acid bacteria, lactic acid, and acidified sodium chlorite as decontaminating interventions to control Escherichia coli O157:H7 and Salmonella Typhimurium DT 104 in mechanically tenderized and brine-enhanced (nonintact) beef at the purveyor

After three different outbreaks were linked to the consumption of nonintact meat products contaminated with Escherichia coli O157:H7, the U.S. Food Safety and Inspection Service published notice requiring establishments producing mechanically tenderized and moisture-enhanced beef products to reassess their respective hazard analysis and critical control point systems, due to potential risk to the consumers. The objective of this study was to validate the use of lactic acid bacteria (LAB), acidified sodium chlorite (ASC), and lactic acid (LA) sprays when applied under a simulated purveyor setting as effective interventions to control and reduce E. coli O157:H7 and Salmonella Typhimurium DT 104 in inoculated U.S. Department of Agriculture (USDA) Choice strip loins (longissimus lumborum muscles) pieces intended for either mechanical blade tenderization or injection enhancement with a brine solution after an aging period of 14 or 21 days at 4.4°C under vacuum. After the mechanical process, translocation of E. coli O157:H7 and Salmonella Typhimurium DT 104 from the surface into the internal muscles occurred at levels between 1.00 and 5.72 log CFU/g, compared with controls. LAB and LA reduced internal E. coli O157:H7 loads up to 3.0 log, while ASC reduced the pathogen 1.4 to 2.3 log more than the control (P < 0.05), respectively. Salmonella Typhimurium DT 104 was also reduced internally 1.3 to 2.8, 1.0 to 2.3, and 1.4 to 1.8 log after application of LAB, LA, and ASC, respectively. The application of antimicrobials by purveyors prior to mechanical tenderization or enhancement of steaks should increase the safety of these types of products.

Investigation of water washes suitable for very small meat plants to reduce pathogens on beef surfaces

Water washing with a handheld hose was performed on beef surfaces to ascertain the most effective combination of methods needed to remove potentially harmful microorganisms. For these experiments, beef brisket surfaces were experimentally inoculated with a fecal slurry containing Escherichia coli O157:H7, Salmonella Typhimurium, Campylobacter coli, and Campylobacter jejuni. In a pilot study, surfaces were washed with cold water (15 degrees C) at various water pressures, spray distances, application times, and drip times, and remaining bacterial populations were determined following the enumeration and isolation of pathogens and naturally occurring hygiene indicators (mesophilic aerobic bacteria, coliforms, and E. coli). The most efficacious combinations of these washing conditions were applied subsequently to artificially contaminated beef brisket surfaces in conjunction with hot (77 degrees C), warm (54 degrees C), and additional cold (15 degrees C) water washes. In the cold water washing pilot study, combinations of physical washing conditions significantly reduced all bacterial populations (P < 0.05). Further studies clearly indicated the superior bactericidal effectiveness of hot water washing; E. coli O157:H7 and Salmonella Typhimurium were reduced by 3.8 and 4.1 log CFU/cm(2), respectively. Overall, higher water temperature, longer application times, and shorter spray distances more effectively removed pathogens from inoculated beef surfaces. These findings will be used to formulate water washing recommendations for very small meat processing establishments.

Validation of intervention strategies to control Escherichia coli O157:H7 and Salmonella typhimurium DT 104 in mechanically tenderized and brine-enhanced beef

After three different outbreaks were linked to the consumption of nonintact meat products contaminated with Escherichia coli O157:H7, the U.S. Department of Agriculture, Food Safety and Inspection Service published notice requiring establishments producing mechanically tenderized and moisture-enhanced beef products to reassess their respective hazard analysis and critical control point system, due to potential risk to the consumers. The purpose of this study was to determine the effectiveness of different intervention strategies (lactic acid, lactic acid bacteria, and acidified sodium chlorite) to control E. coli O157:H7 and Salmonella enterica serotype Typhimurium definitive phage type 104 in mechanically tenderized and brine-enhanced beef strip loins when applied to the steaks prior to packaging and shipment for processing. After the mechanical process, translocation of E. coli O157:H7 and Salmonella Typhimurium DT 104 from the surface into the internal muscles occurred at levels between 2.0 and 4.0 log CFU/g (from an initial inoculation level of 5.0 log) after mechanical tenderization, and at levels of 1.0 to 3.0 log CFU/g after injection, with all the interventions consistently presenting lower microbial counts (P < 0.05) than did the controls. Lactic acid bacteria reduced internal E. coli O157:H7 loads 1.2 to > 2.2 log cycles, while the acidified sodium chlorite and lactic acid reduced them between 0.8 and 3.0 log, respectively. Salmonella Typhimurium DT 104 was also reduced internally after application of all interventions between 0.9 and 2.2 log. The application of antimicrobials to the steaks prior to packaging and shipment on day 0 was effective in reducing internalization of both pathogens in nonintact beef products stored for both 14 and 21 days.

Fluorescent protein-marked Escherichia coli biotype I strains as surrogates for enteric pathogens in validation of beef carcass interventions

The efficacy of antimicrobial interventions implemented in slaughter establishments to reduce enteric pathogens on beef carcasses should optimally be validated under commercial operation conditions. This study was conducted to identify surrogate organisms for enteric pathogens that could be used to validate beef carcass interventions. The growth, resistance, and attachment properties of nonpathogenic fluorescent protein-marked Escherichia coli strains were compared with those of E. coli O157:H7 and Salmonella strains. Growth curves were obtained based on growth in tryptic soy broth at 37 degrees C. In general, growth parameters were not different among potential surrogates and target pathogens (P > 0.05). Thermal resistance was compared in phosphate-buffered saline (pH 7.4) at 55, 60, and 65 degrees C, and D-values of potential surrogates were not different (P > 0.05) or were higher (P < 0.05) than those of the target pathogens. Acid resistance was tested in phosphate-buffered saline acidified with L-lactic acid at pH 2.5, 3.0, and 3.5, and log reductions (CFU per milliliter) were not different (P > 0.05) among potential surrogates and E. coli O157:H7 strains; however, some Salmonella serotypes were less acid resistant than were surrogates (P < 0.05). The cell surface hydrophobicity was different (P < 0.05) among surrogates and some E. coli O157:H7 strains, but the strength of attachment to beef carcasses was not different (P > 0.05) among all microorganisms. Log reductions (CFU per square centimeter) after application of hot water washes and 2% L-lactic acid sprays on beef carcasses were not different (P > 0.05) among surrogates and pathogens. The nonpathogenic E. coli strains evaluated in this study could be used as surrogates for E. coli O157:H7 and Salmonella to validate hot water and lactic acid interventions on beef carcasses.

Effects of potassium lactate, sodium metasilicate, peroxyacetic acid, and acidified sodium chlorite on physical, chemical, and sensory properties of ground beef patties

Beef trimmings were treated with 3% potassium lactate (KL), 4% sodium metasilicate (NMS), 0.02% peroxyacetic acid (PAA) or 0.1% acidified sodium chlorite (ASC) or left untreated (CON). Beef trimmings were ground, pattied, and sampled for 7 days. Under simulated retail display, instrumental color, sensory characteristics, TBARS, pH, and Lee-Kramer shear force were measured to evaluate the impact of the treatments on the quality attributes. The NMS and PAA patties were redder (a(∗), P<0.05) than CON on days 0-3. Panelists found KL, NMS, PAA, and ASC patties to have less (P<0.05) or similar (P>0.05) off odor to CON on days 0-3. The NMS and PAA treated patties had lower (P<0.05) lipid oxidation than the CON at days 0, 3, and 7. Therefore, KL, NMS, PAA, and ASC treatments on beef trimmings can potentially improve or maintain quality attributes of beef patties.

Reduction of Escherichia coli O157:H7 and Salmonella on baby spinach, using electron beam radiation

The effect of low-dose electron beam (e-beam) radiation on the reduction of Escherichia coli O157:H7 and Salmonella in spinach was studied. Fresh baby spinach (Spinacia oleracea) was inoculated with a bacterial cocktail containing multiple strains of rifampin-resistant E. coli O157:H7 and rifampin-resistant Salmonella. Inoculated samples were exposed to e-beam radiation from a linear accelerator and tested for counts of both E. coli O157:H7 and Salmonella. Irradiated spinach was also stored for 8 days at 4 degrees C, and counts were made at 2-day intervals to determine if there was any effect of radiation on the survival trend of both pathogens. When no pathogens were detected on plates, additional enrichment plating was conducted to verify total destruction. Respiration rates were measured on spinach samples exposed to e-beam radiation. Each dose of e-beam radiation significantly reduced the numbers of E. coli O157:H7 and Salmonella from initial levels of 7 log CFU/g. Treatment by e-beam radiation at a dose of 0.40 kGy resulted in a reduction in populations of E. coli O157:H7 and Salmonella of 3.7 and 3.4 log cycles, respectively. At 0.70 kGy, both pathogens were reduced by 4 log. All doses above 1.07 kGy showed reductions greater than 6 log and decreased to undetectable levels when stored for 8 days. The respiration rate of spinach showed no changes after irradiation up to 2.1 kGy. These results suggest that low-dose e-beam radiation may be a viable tool for reducing microbial populations or eliminating E. coli O157:H7 and Salmonella from spinach without product damage.