Browsing by Subject "E. coli O157:H7"
Now showing 1 - 13 of 13
Results Per Page
Sort Options
Item AI-2-like acttivity mediated E. coli O157:H7 survival and virulence gene expression in the presence of ground beef extracts(Texas A&M University, 2006-08-16) Soni, Kamleshkumar ArvindkumarCell-to-cell communication, termed quorum sensing, mediated by AI-2 like activity, has been reported to regulate the expression of a variety of genes in E. coli O157:H7. A previous study in our laboratory has shown that foods can contain compounds that can interfere with AI-2 signaling. The underlying hypothesis of our studies is that the autoinducer molecules such as AI-2 are involved in the virulence and survival of enteric bacterial pathogens on food and food ingredients. The influence of AI-2 like activity on the survival and expression of virulence genes (hha and yadK) in E.coli O157:H7 was studied when the organism was stored in different types of ground beef extracts such as: cooked, uncooked, and autoclaved. The survival was observed at refrigeration temperature, while change in gene expression was studied using real-time PCR. Higher survival was observed in the cell exposed to cell free supernatant (CFS) containing AI-2 like molecules, compared to the one which was exposed to heat degraded AI-2 like molecules. The survival of cells was higher when exposed to cooked ground beef extracts compared to uncooked and autoclaved ground beef extracts. Similarly, higher gene expressions of both hha and yadK genes were observed in cells that were exposed to cooked beef extract samples as compared to samples that wereuncooked or autoclaved. About a 2 fold higher gene expression for both hha and yadK gene was observed when cells were subjected to cooked ground beef extracts in the presence of AI-2 like molecules compared to the ones exposed to uncooked ground beef extracts in the presence of AI-2 like molecules. Likewise, 3-fold higher gene expression was observed for cells exposed to cooked ground beef extracts compare to autoclaved ground beef extracts in the presence of AI-2 like molecules. The results suggest that the survival and virulence of enteric bacterial pathogens such as E.coli O157:H7 can be influenced by the interaction of food components and autoinducers such as AI-2, that are involved in bacterial cell communications.Item Application of antimicrobial treatments in a commercial simulation to reduce E. coli O157:H7 and Salmonella spp. in beef trim and in ground beef(2006-12) Harris, Deidrea D.; Miller, Markus F.; Brashears, Mindy M.; Brooks, Chance J.Pathogens are of great concern for processors for food safety issues and for economic reasons. While beef trimmings and ground beef are to be cooked by the consumer, the processor must recall the raw product if testing indicates the presence of Escherichia coli O157:H7. Processors have very few interventions for beef trimmings and ground beef. A limited amount of research has been completed to determine antimicrobial effects under commercially simulated conditions on beef trim to reduce pathogens. 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 pathogen levels in beef trim prior to and after grinding in a simulated processing environment utilizing a belt turning and spray application. The effectiveness of these interventions on Escherichia coli O157:H7 and Salmonella Typhimurium were determined prior to treatment and at the following processing points: 1) just after treatment (20 minutes); 2) just after grind (6 hours); and 3) 24 hours after anaerobic storage at 4°C. Trim was inoculated with Escherichia coli O157:H7 and Salmonella Typhimurium, with an inoculation level of 1x105 cfu/g. Sensory preparation was similar to the experimental design above except none of the trim was inoculated with pathogens. The organoleptic properties were evaluated during short term refrigerated storage at 6 and 24 hours after preparation. Raw patties were packaged on a Styrofoam tray and displayed in a retail display case. Visual panelists were trained to determine beef color, color uniformity, percentage of discoloration and browning evaluations of the raw patties based on appearance and composition. Muscle luminance, redness and yellowness of the raw product were objectively measured using the Minolta Spectrophotometer. Triangle test were used for comparison of the control and treated samples at 6 and 24 hours after production. Panelists (n = 24) were given three coded samples, including two of the same sample and one odd sample. Panelists were asked to determine the odd or different sample. Results from this study indicate that all antimicrobial interventions, including sterile water, reduced pathogen loads (P < 0.05) for both Escherichia coli O157:H7 and Salmonella Typhimurium in ground beef by almost 1 log cycle. The antimicrobial treatments of: sterile water, 5% lactic acid, 2% acetic acid, 5% acetic acid, and acidified sodium chlorite (1000 ppm) significantly reduced Escherichia coli O157:H7 (P < 0.05) in ground beef. The antimicrobial treatments of: acetic and lactic acids (2% and 5%), acidified sodium chlorite (1000 ppm), and sterile water significantly reduced pathogen loads of Salmonella Typhimurium (P < 0.0001) in ground beef 6 and 24 hours after processing. Utilizing a triangle test there was no significant difference P < 0.05 in the mean of correct responses between controls, 2% lactic acid, 5% lactic acid, 2% acetic acid, 5% acetic acid and acidified sodium chlorite (1000 ppm) within treatment, 6 or 24 hours samples from a non-trained sensory panel.Item Chemical inhibition of the thyroid gland and its effects on E. coli O157:H7 fecal shedding patterns in sheep(Texas A&M University, 2005-11-01) Schroeder, Sasha BrookeDue to the seasonal nature of E. coli O157:H7 shedding and of hormone production by the thyroid gland, two studies were initiated to determine whether chemical inhibition of the thyroid gland influences fecal shedding of Escherichia coli O157:H7. Twenty-four crossbred sheep (68.6 kg BW) were randomly assigned to pen and either 0.0 mg/kg BW PTU or 20 mg/kg BW PTU for 5, 11, or 14 days. Sheep were experimentally infected (d 0) with E. coli O157:H7 11 days prior to PTU treatment. Fecal and serum samples were collected for bacterial enumeration and for analysis of T3 and T4, respectively. Sheep were humanely euthanized and tissue and content samples were collected from the rumen, ileum, colon and rectum. Detection of E. coli O157:H7 increased toward the terminal end of the GI tract. In the treatment group, serum T3 levels decreased to an overall lower level than the control group. A correlation was seen between T3 levels and daily O157:H7 bacterial shedding (P=0.003; r=0.37). In experiment 2, 12 growing lambs (41.04 kg BW) were exposed to either 0.0 mg/kg BW PTU or 40 mg/kg BW PTU for 21 days. Fecal samples were collected for analysis of generic E. coli and body weights were recorded on days 0, 7, 14, and 21. Feed intake was recorded throughout the experiment. Animals were experimentally infected with E. coli O157:H7 on day 15. Sheep were humanely euthanized on day 21 and GI tract tissue and content was collected from the rumen, ilium, colon and rectum. A date by treatment interaction was observed for T4 (P=0.0016) and hormone levels decreased in treated animals. Thyroxine and E. coli O157:H7 display a multivariate treatment (P=0.0005) and date effect (P=0.0174) but no significant interaction. Triiodothyronine and E. coli O157:H7 shedding have a slight date trend (P=0.065) but no significant treatment or treatment by date interaction. Generally, the treatment group shed genreric E. coli at higher levels throughout the study period with slightly more than a log count difference between groups at the last collection point (control = 3.8 CFU/gram of feces (log10); treatment = 4.9 CFU/gram of feces (log10)). Results from these experiments suggest that correlations exist between both E. coli O157:H7 and generic E. coli shedding in sheep.Item Citrus Bioactive Compounds: Isolation, Characterization and Modulation of Bacterial Intercellular Communication and Pathogenicity(2012-07-16) Vikram, AmitThe secondary metabolites of citrus such as limonoids and flavonoids constitute an important part of human diet. The present work was undertaken to elucidate the effect of citrus limonoids and flavonoids on the bacterial cell-cell signaling in Vibrio harveyi, Escherichia coli O157:H7 and Salmonella Typhimurium LT2. The first experiment was focused on purification of limonoids from grapefruit and sour orange seeds. The limonoids were extracted using organic solvents and purified by chromatographic techniques. A total of ten limonoids (7 aglycones and 3 glucosides) were purified. Currently, simultaneous measurement of aglycones and glucosides of limonoids is not available. To address this limitation, an analytical method using high performance liquid chromatography was developed with the capability of measuring both aglycones and glucosides in a single run. Furthermore, its applicability in the fruit and juice samples was demonstrated. The third study investigated the V. harveyi cell-cell signaling inhibitory potential of purified limonoids. Isolimonic acid, ichangin, obacunone and nomilin were showed potent inhibitory activity. Furthermore, isolimonic acid and ichangin inhibit the signal transduction pathway by up-regulating the response regulator luxO. Isolimonic acid was also found to be a potent inhibitor of Escherichia coli O157:H7 cell-cell signaling in the fourth study. The results demonstrated that isolimonic acid inhibits the autoinducer/epinephrine mediated cell-cell signaling, biofilm and virulence in QseBC and QseA dependent fashion. Further investigations using limonin analogues, in the fifth study, demonstrated that the analogue limonin-7-methoxime inhibited the E. coli biofilm in type 1 pili and antigen 43 dependent-fashion, by preventing the binding of the adhesins to plastic surfaces. Another limonoid, obacunone was demonstrated to attenuate the Salmonella virulence by repressing Salmonella Pathogenicity Island 1 (SPI-1) in EnvZ/OmpR dependent mecahnism. The seventh study showed that naringenin, among the flavonoids, was the most potent inhibitor of V. harveyi and E. coli O157:H7 cell-cell signaling. Furthermore, naringenin was found to repress the (SPI-1) in PstS-HilD dependent fashion in the eighth study. In conclusion, the current project identified several limonoids and flavonoids with cell-cell signaling inhibitory property in three bacterial species.Item Escherichia coli O157:H7 and Salmonella Typhimurium Risk Assessment during the Production of Marinated Beef Inside Skirts and Tri-tip Roasts(2010-10-12) Muras, Tiffany MarieThis study was conducted to determine the survival of Escherichia coli O157:H7 and Salmonella Typhimurium in marinade that was used to vacuum tumble beef inside skirts and beef tri-tip roasts. The depth of penetration of each microorganism into the individual meat products, and the survival of these microorganisms in the products as well as marinade stored over time were evaluated. Two commercial marinades were used, Reo TAMU Fajita Marinade and Legg's Cajun Style Marinade. Eighteen beef inside skirts and 18 tri-tips were used during this study. Both inside skirts and tri-tips were vacuum tumbled for a total of 1 h. Samples of products were tested immediately following tumbling (day 0), or were vacuum packaged and stored in the cooler (approximately 2 degrees C) to be tested 7 and 14 days following tumbling. Samples of the spent marinade were taken and tested initially following tumbling (day 0), and were also stored in a cooler and tested 3 and 7 days after the marinade was used. The results of the study showed that with both marinades S. Typhimurium and E. coli O157:H7 penetrated throughout the skirt meat. After having been stored for 7 days following tumbling, the log value of both S. Typhimurium and E. coli O157:H7 decreased in the meat. After 14 days of storage following tumbling, the log value of both S. Typhimurium and E. coli O157:H7 continued to decrease; however, both pathogens were still detectable. The penetration of the pathogens in the tri-tip roast varied depending on the thickness of the roast. The thicker roasts had undetectable levels of both pathogens in the geometric center; however, the thinner tri-tip roasts had detectable levels at the geometric center. The spent marinade tested on day 0, 3, and 7 showed that the microorganisms were able to survive in the marinade at refrigerated temperatures. The results of this study demonstrated that pathogens may penetrate into the interior of beef skirts and tri-tips during vacuum tumbling with contaminated marinade, and that pathogens survive during refrigerated storage of spent marinade. Industry should consider these data when evaluating potential food safety risks associated with the production of vacuum tumbling beef products.Item Evaluation of Escherichia coli O157:H7 Translocation and Decontamination for Beef Vacuum-packaged Subprimals Destined for Non-intact Use(2012-07-16) Lemmons, Jacob LynnThe 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 non-intact use. Cap-on and cap-off beef top sirloin butts were inoculated with two levels of E. coli O157:H7! a high-inoculum at approximately 10^4 CFU/cm^2 and a low-inoculum at approximately 10^2 CFU/cm^2. Following inoculation, the subprimals were vacuum packaged and stored for either 0, 14, or 28 days. Upon opening, 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 and partial-surface trimming were 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 non-detectable levels.Item Evaluation of Hot Water Wash Parameters to Achieve Maximum Effectiveness in Reducing Levels of Salmonella Typhimurium, Escherichia coli O157:H7 and coliforms/Escherichia coli on Beef Carcass Surfaces(2010-07-14) Davidson, Melissa A.This study measured and compared different temperatures and dwell times of hot water treatment on the reduction of Escherichia coli O157:H7 and Salmonella Typhimurium on beef carcass surfaces. Two different types of beef surfaces, lean and fat, were inoculated with a fecal slurry containing E. coli O157:H7 and S. Typhimurium at ca. 7-log CFU/g, washed to remove gross fecal matter, and rinsed with hot water between 66 and 82 degrees C (150 to 180 degrees F water) for either 5, 10, or 15 s. There were no differences (P > 0.05) in the log reductions of S. Typhimurium and E. coli O157:H7 on the lean surfaces for all three temperature treatments (66, 74, and 82 degrees C). Although the 15 s treatment resulted in a numerically higher log reduction than the other treatments, each of the times resulted in at least a 1 log reduction of both S. Typhimurium and E. coli O157:H7 for lean surfaces. For the fat surfaces, all time treatments for the 82 degrees C and the 10 and 15 s treatments for the 74 degrees C resulted in the highest log reduction for S. Typhimurium. The 5 and 10 s dwell times for treatments at 66 degrees C and the 5 s dwell time at 74 degrees C resulted in the lowest log reduction of S. Typhimurium and E. coli O157:H7. For E. coli O157:H7 all temperature and time treatments resulted in at least a 1 log reduction for the fat surfaces of the outside round. Therefore, hot water treatment is a proven method for reducing both coliforms and pathogenic bacteria.Item Evaluation of the Relationship Between Stress Response and the Fecal Shedding of Escherichia Coli O157:H7(Texas A&M University, 2006-10-30) Schuehle, Celeste ElaineThis study was conducted to determine if a relationship exists between temperament, stress response, and the shedding of Escerhichia coli O157:H7. Cattle (n = 150) were evaluated for disposition and stress response before shipping to the feeding operation, upon arrival at the feedlot, at approximately 70d on feed, and prior to transport to the harvesting facility. Chute and pen scores, as well as serum cortisol concentrations, were measured in order to assess individual temperament and stress response. A temperament index was created to classify cattle as Excitable, Intermediate, or Calm. The presence of E. coli O157:H7 was determined by rectal swabs on the live cattle and swabs of colons collected postmortem at the processing facility. As expected, variables for pre-shipment temperament index, exit velocity, pen score, arrival and midpoint exit velocity, and mid-point cortisol concentrations differed (P < 0.05) greatly between temperament groups. However, pre-shipment chute scores and cortisol concentration, as well as arrival and final cortisol concentrations differed (P < 0.05) only for Excitable cattle compared to both Calm and Intermediate groups. The percentage of cattle shedding the pathogen at arrival was approximately equal between temperament groups. When sampled before shipment to the processing facility, a higher proportion (P = 0.03) of cattle displaying Calm temperaments shed E. coli O157:H7 than the other groups. Results from postmortem colon samples exhibited a similar trend. When the results from all four sampling periods were pooled, the Calm cattle had a greater numerical percentage test positive for E. coli O157:H7. However, the pooled frequency distribution is largely dictated by the results of the final sampling time. Based on these results, it appears that Excitable cattle are not more likely to shed E. coli O157:H7. In fact, it seems that Calm cattle may be equally or more susceptible to shed at later points in the feeding period. However, it is important to note that a relatively small number of the samples tested positive for E. coli O157:H7, thus, potentially causing dramatic changes in the distributions.Item Quantification of the Antimicrobial Substances Produced by Lactic Acid Bacteria used as an Intervention to Inhibit Escherichia coli O157:H7 and Salmonella in vitro and on Fresh Spinach (Spinacia oleracea)(2012-02-14) Calix Lara, ThelmaThe metabolic activity of bacterial microorganisms may influence the growth and metabolic activities of other microbes that are present in any specific niche. Lactic acid bacteria (LAB) are antagonistic to some microbial pathogens by the metabolic production of compounds with antimicrobial activity. Consequently, investigators have measured the effects of those antimicrobials to inhibit specific pathogens. However, the mode(s) of action of LAB against foodborne pathogens on products and/or in broth is not completely understood. Therefore, the objectives of this research were to (i) determine the LAB dose required for inhibition of Escherichia coli O157:H7 and Salmonella enterica in vitro and on spinach, and (ii) identify and quantify the major antimicrobial substances synthesized by LAB as a function of postinoculation storage conditions. Assays were performed at 7 degrees C under aerobic conditions. The foodborne pathogens dose responses were assessed in a liquid microbiological medium (in vitro) and on spinach leaf surfaces. Different levels of foodborne pathogens and LAB cultures were used. The addition of LAB cultures did not reduce E. coli O157:H7 or Salmonella enterica populations when performed in vitro. However, when LAB cultures were sprayed on the surfaces of spinach leaves at 8.0 log10 CFU/g, there were significant reductions on E. coli O157:H7 of 1.62 and 0.73 log10 CFU/g (after 3 days) and on Salmonella enterica of 1.85 and 0.71 log10 CFU/g (after 6 days) for treatments inoculated with an initial level of 2.0 and 4.0 log10 CFU/g, respectively. After quantification of the antimicrobial compounds synthesized by LAB cultures, they were correlated against the population growth of targeted pathogens. The highest Llactic acid (3.71 plus/minus 0.14 micromoles/ml, day 12) and hydrogen peroxide (3.72 plus/minus 3.34 microM, day 6) production were obtained from the in vitro sample inoculated with 8.0 log10 CFU/ml of LAB and 0.0 log10 CFU/ml of pathogens. The highest bacteriocin production (0.1 plus/minus 0.01 mg/ml) was obtained from the in vitro sample with 8.0 log10 CFU/ml of LAB and 2.0 log10 CFU/ml of pathogens. In conclusion, the LAB cultures were able to produce detectable amounts of antimicrobials that may be used as intervention and/or sciencebased practice against foodborne pathogens by producers and the industry.Item Survivability of E. coli O157:H7 in needle tenderized beef steaks during lactic acid application and cooking(2010-12) Chancey, Cassandra L.; Brooks, Chance J.; Brashears, Mindy M.; Jackson, Samuel P.; Thompson, Leslie D.Illness has been associated with the consumption of non-intact beef products. Because blade tenderization is commonly used in the beef industry to improve meat tenderness, measures must be taken to reduce the threat the pathogen translocation from the surface of beef cuts during mechanical tenderization. The objective of this research was to characterize the effects of 5% lactic acid on needle-tenderized beef strip loins inoculated with Escherichia coli O157:H7 and managed under simulated industry conditions prior to cooking to various endpoint temperatures. Subprimals were inoculated with either a low or high level of E. coli O157:H7 (103CFU/cm2 and 105CFU/cm2, respectively) using a dip method at the BSL-II pathogen processing facility, at Texas Tech University (Lubbock, TX). Subprimals were then stored for 7 days at 2-4oC. At 7 days, subprimals were mechanically tenderized (Model H, Jaccard, Orchard Park, NY) and cut into 2.54 cm2 thick steaks, then stored at 2-40C for 21 days. At 28 days, the steaks were transported to the Experimental Sciences Building (ESB), at Texas Tech University (Lubbock, TX) to be cooked to internal temperatures of 55, 60, 65, 70, or 75oC. At low inoculation levels (103cfu/cm2), after processing, and cooking, E. coli O157:H7 was not detected on internal meat samples. However, E. coli was detected when high inoculums steaks (105cfu/cm2) that were cooked to 55, 60, or 70⁰C. Regardless, at low inoculation levels (typical of industry contamination) 5% lactic acid treatment, vacuum packaging, refrigerated storage and cooking reduced E. coli O157:H7 to non-detectable levels in needle tenderized beef steaks cooked to 55°C or higher internal temperatures.Item The survivability, growth and heat susceptibility of E. coli O157:H7 in enhanced beef brine solutions containing potassium lactate and lactic acid producing bacteria(2009-05) Rosenberg, Ashley; Brooks, Chance J.; Brashears, Mindy M.; Loneragan, Guy H.; Miller, Markus F.Meat enhancement is used to increase consumer satisfaction through improved palatability and uniformity. Brine solutions that are re-covered or reused during the processing of enhanced meat cuts have a high risk of cross contamination. The objectives of the present study were to determine the effect of potassium lactate and lactic acid bacteria on the survivability and heat susceptibility of E. coli O157:H7 in brine solutions used to enhance beef products and to determine the effect of these interventions on consumer sensory scores and shelf life characteristics. To characterize safety, beef strip loins were enhanced with brine solutions (0.3% sodium chloride and 0.35% phosphate at 10% pump level) inoculated with high or low levels of E. coli O157:H7 and one of the following interventions: 0, 1.5, 2.5% potassium lactate or lactic acid bacteria (LAB 107 CFU/ml). Treated subprimals were fabricated into steaks and randomly allotted to one of the following internal endpoint temperatures: 0 (not cooked), 50, 55, 60, 65, 70 and 75°C. Once endpoint temperature was reached, the interior of each steak was sampled and E. coli O157:H7 was enumerated (high level) or detected (low level). To characterize palatability and shelf life, beef strip loin subprimals were enhanced with brine solutions containing previously mentioned interventions plus a non-enhanced control. Consumer panelists evaluated palatability at 14 d postmortem and lean color on days 1, 3, and 7 of display (after a 14 d postmortem dark storage period). Display steaks were packaged in high-oxygen (80% O2 / 20%CO2) or low-oxygen (0.4%CO/30%CO2/69.6%N2) modified atmosphere packages. Data analysis showed no significant interactions between intervention treatment and steak temperature endpoints, indicating E. coli O157:H7 from treated brine solutions were not more susceptible to heat during cooking. Results also indicate the transference of pathogens into meat products was low for all interventions, regardless of inoculation level. Internal steak temperature (especially 70 and 75 °C) remains the most effective way to reduce pathogen levels in steaks enhanced with inoculated brine solutions. Steaks packaged in high-oxygen MAP and enhanced with a brine solution containing 1.5 or 2.5% potassium lactate maintained more desirable lean color scores throughout display and were more likely to be purchased by consumers than steaks enhanced with other treatments. Finally, the presence of potassium lactate (1.5 and 2.5%) and lactic acid producing bacteria had no detrimental impact on consumer palatability, while enhanced steaks were more desirable than non-enhanced controls.Item The use of xylitol to minimize contamination of beef carcass surfaces with salmonella typhimurium and escherichia coli o157:h7(Texas A&M University, 2006-08-16) Greiner, Steven ThomasEffects of a 10% xylitol solution (X) on adhesion of Escherichia coli O157:H7 and Salmonella serotype Typhimurium to meat surfaces were examined utilizing three approaches. In Experiment 1, rifampicin-resistant strains of E. coli O157:H7 and S. Typhimurium were dispersed in xylitol or a peptone solution (containing approximately 8.9 mean log per ml of each pathogen) and used to inoculate beef outside round meat surfaces. Samples were then rinsed with water or not rinsed in a 2X2 factorial arrangement. No interaction existed between inoculum type and post-inoculation treatments (P > 0.84). Incubation of pathogens in peptone or xylitol had minimal impact on pathogen adhesion (P > 0.76). Rinsing reduced counts by approximately 0.5 log CFU/cm2 (P < 0.01). Experiment 2 meat samples received a pretreatment of a water rinse, xylitol, or no rinse, followed by inoculation with pathogens dispersed in peptone solution (containing approximately 8.6 log mean log per ml of each pathogen). Samples received a post-inoculation treatment of a water rinse, xylitol rinse or no rinse in a 3X3 factorial arrangement. No interactions between pre- and post-inoculation factors were observed for surface pathogen load (P > 0.50). Post-inoculation rinsing reduced counts by approximately 0.5 log CFU/cm2 (P < 0.01) with no difference between water and xylitol (P > 0.64). Experiment 3 carcass surfaces were inoculated with pathogens at an initial level of 5.5 log CFU/cm2 and received a hot (35??C) water wash, 2.5% L-lactic acid spray, 10% xylitol spray, lactic acid + xylitol or hot water + xylitol. Pathogen counts were taken at 0 and 24 h post treatment. Lactic acid treatments reduced Salmonella by 3.3 log CFU/cm2 at 0 h (P < 0.01) and by 2.6 log CFU/cm2 after 24 h (P < 0.02). Hot water treatments reduced Salmonella by 1.5 log CFU/cm2 at 0 h (P < 0.07). Xylitol did not minimize pathogens (P > 0.62) nor did it increase effectiveness of other treatments. These data indicate that xylitol is ineffective at preventing E. coli O157:H7 and S. Typhimurium adhesion to meat surfaces.Item Validation of Texas beef jerky processing(2009-06-02) Espitia, Felicia DanielleThis study evaluated the thermal drying process commonly used by small and very small beef jerky operations in Texas. It was intended to determine the impact of relative humidity on the production of beef jerky and to provide documentation to beef jerky producers to support their Hazard Analysis and Critical Control Point programs. This project was divided into two phases: Phase I provided a low level of relative humidity (15-25%), whereas Phase II provided a high level (100%) for 25% of the cooking cycle. Both phases consisted of three trials, each representing one of the treatments (n=18) applied to the samples. The first treatment served as the control group and included samples that were non-inoculated, while the other two treatments included inoculations of samples with a bovine fecal slurry and rifampicin-resistant Salmonella Typhimurium. Each of the three treatments for both phases was analyzed for reduction of microbial levels in addition to temperature and product composition. Once the two phases had been completed and all data were analyzed, it was concluded that there was not a statistical difference between the level of reduction for Aerobic Plate Counts, coliforms, Escherichia coli and Salmonella provided by Phase I with low humidity and Phase II with high humidity. Both levels of humidity provided similar levels of reduction within each trial, suggesting that the level of humidity does not have a great impact on the level of microbial reduction achieved. However, this study did not provide the adequate level of initial inoculation levels to support the required 6.5 log reduction stated in 9 CFR 318.7. Inoculation levels were lower than 6.5 logs for all three treatments in both phases, resulting in lower levels of overall reduction. Therefore, based upon the information provided by this study, it cannot be concluded that a low level of humidity will achieve a 6.5 log reduction as mandated in 9 CFR 318.17.