bluuebunny/crossref_metadata_2025 huggingface dataset:
DETECTION OF FIMBRIAE (CFA/I) ON ENTEROTOXIGENIC ESCHERICHIA COLI USING ANTIBODIES
Authors: SINGLETON EMMA R. , HAMDY MOSTAFA K. , McCAY STEVEN G. , ZAPATKA FRANCIS A.
Published: April 2007

Fimbriae (CFA/I) were isolated after detachment from an enterotoxigenic Escherichia coli (ETEC) strain H10407, purified by successive isoelectric point precipitation at pH 3.5, and injected into rabbits. The antisera containing the polyclonal antibodies against the fimbrial proteins (antigens) were then used to detect the presence of CFA/I on other E. coli cultures using an indirect ELISA system. The ELISA procedures for the CFA/I assay was as sensitive as the DNA hybridization for detecting the ETEC strains. Two bands (major and minor) were present when the isolated fimbrial proteins were subjected to SDS‐PAGE. The major band had a molecular mass of 40.3 and the minor 36.4 kDa. Electron microscopy of the fimbriae appeared as thin thread rods with variable length (5–15 μm).
EFFECT OF SODIUM LACTATE, CALCIUM LACTATE AND SODIUM ALGINATE ON BACTERIAL GROWTH AND AMINOPEPTIDASE ACTIVITY
Authors: HARMAYANI ENI , SOFOS JOHN N. , SCHMIDT GLENN R.
Published: April 2007

The effects of sodium alginate (0.4 and 0.8%), calcium lactate (0.15 and 0.3%) and sodium lactate (60% solution; 1, 2, 3 and 4%) on growth and aminopeptidase activity of Pseudomonas fragi ATCC 4973 and Salmonella typhimurium in trypticase soy broth or autoclaved ground beef were studied for 5 days at 5°C. Sodium alginate and calcium lactate did not change colony counts of P. fragi or S. typhimurium; and had only slight effects on aminopeptidase activity. Sodium lactate (3 and 4%) showed inhibitory activity on growth and aminopeptidase activity of P. fragi. Sodium lactate also decreased aminopeptidase activity of S. typhimurium but had no major influence on colony counts. In general, aminopeptidase activity was inhibited more than cell multiplication by higher levels of alginate and sodium lactate.
EFFICACIES OF ACETIC, LACTIC AND TWO MIXED ACIDS IN REDUCING NUMBER OF BACTERIA ON SURFACE OF LEARN MEAT
Authors: ANDERSON MAYNARD E. , MARSHALL ROBERT T. , DICKSON JAMES S.
Published: April 2007

This study on sanitizing beef surfaces was designed to evaluate effects of mixtures of acetic, lactic, citric and ascorbic acids with individual solutions of acetic and lactic acids. Acetic acid (3%), lactic acid (3%), MA1 (2% acetic, 1% lactic, 0.25% citric and 0.1% L‐ascorbic acids) and MA2 (2% lactic, 1% acetic, 0.25% citric and 0.1% L‐ascorbic acids) solutions were applied to beef core samples of muscle inoculated with bacteria. Experimental variables were type, concentration and temperature of acid solutions and type of microorganisms. Overall, an increase in either acid concentration or treatment temperature decreased numbers of residual viable bacteria. Lactic acid solution was the most effective against S. typhimurium with a reduction of 2 log10 at 70°C. For enterobacteria, acetic, lactic and MA2 solutions at 70°C resulted in a 1.5 log10 reduction. MA2 was the most effective acid solution at both 45 and 70°C, whereas, lactic acid and the MA2 mixture did not differ in effectiveness at 20°C.
CONTAMINATION OF BEEF TISSUE SURFACES BY ARTIFICIALLY INOCULATED LOW‐MOISTURE MENSTRUA
Authors: DICKSON JAMES S.
Published: April 2007

Salmonella typhimurium was inoculated into prepared dirt (moisture content 8.8%), sand (moisture content 0.06%) and phosphate buffer, and these menstrua were used to contaminate beef tissue. Fewer bacteria adhered to the tissue surface from the low moisture menstrua when compared to contamination by buffer. Determination of SR values, an estimate of the total population associated with the surface which was physically attached, indicated that more bacteria remained in the soil menstrum than adhered to the surface, when compared to buffer and sand menstrua. Contrary to expectations, bacteria which contaminated the surface from the low moisture menstrua were not more sensitive to organic acids than those which originated from the buffer.
PHYSICOCHEMICAL AND SENSORY ANALYSES ON EGG POWDER IRRADIATED TO INACTIVATE SALMONELLA AND REDUCE MICROBIAL LOAD
Authors: NARVAIZ P. , LESCANO G. , KAIRIYAMA E.
Published: April 2007

Egg powder was treated with 0, 2, 5 and 10 kGy of gamma radiation at 20C to inactivate Salmonella and to stabilize its microbial load. Microbial, physicochemical and sensory determinations were performed during 4 months of storage to select the optimal radiation dose to attain the objective without significantly reducing egg quality. Microbial results show that 2.0 kGy inactivated Salmonella and reduced microbial load to levels below those stipulated by the Argentine regulations. Physicochemical determinations of egg powder extracts for peroxide number, spectrophotometric measurements in the visible and ultraviolet regions, functional properties on sponge cakes made with egg powder (height, comprssion‐relaxiation cycle parameters), foam stability and viscosity showed that gamma radiation at the dose of 2 kGy, did not cause significant changes in these parameters. Higher radiation doses (5 and 10 kGy) did increase rancidity, pigment loss and protein chain scission. Sensory determinations performed on egg powder, and on cakes manufactured with it, agreed with the physicochemical results. After 110 storage days, 2 kGy was the most suitable of the tested doses.
EFFECT OF REDUCED pH ON SECRETION, STABILITY AND ACTIVITY OF LISTERIA MONOCYTOGENES LISTERIOLYSIN O1
Authors: MCKELLAR ROBIN C.
Published: April 2007

The effect of environmental parameters on secretion, stability and activity of Listeria monocytogenes listeriolysin O (LLO) was examined. Increasing the initial glucose concentration in proteose peptone medium resulted in reduced LLO activity and lower final pH. Yield of LLO was substantially increased when the medium was buffered with ß‐glycerophosphate. Extended storage of active LLO in growth medium adjusted to pH 5.3 resulted in loss of only 10% LLO activity; however, up to 90% activity was lost during storage atpH < 4.5. In contrast, LLO activity was maximal at pH between 4.0 and 5.5. When the initial pH of culture medium was adjusted to give a final pH after growth of 5.3, as little as 10% of the maximum LLO activity was obtained. The results suggest that the degree of acidity may control both secretion and stability of LLO.
INHIBITION OF LISTERIA MONOCYTOGENES BY LIQUID SMOKE AND ISOEUGENOL, A PHENOLIC COMPONENT FOUND IN SMOKE
Authors: FAITH NANCY G. , YOUSEF AHMED E. , LUCHANSKY JOHN B.
Published: April 2007

The behavior of Listeria monocytogenes was monitored in wiener exudate or Tryptose Broth (TB) in the presence of liquid smoke (CharSol Supreme) or smoke ingredients (i.e., phenols and acetic acid). L. monocytogenes grew in untreated exudate held at 25C, but was inactivated in the presence of 0.2 and 0.6% liq'iid smoke (D‐values of 36 and 4.5 h, respectively). Of 11 individual phenols tested, only isoeugenol exhibited antilisterial activity in TB at 37C. Growth of the pathogen in the presence of isoeugenol (100 ppm) was inhibited to a greater extent in TB acidified with acetic acid to pH 5.8 compared to pH 7.0. These studies confirm the potent antilisterial activity of liquid smoke and establish the potential of isoeugenol for controlling the growth of L. monocytogenes in certain processed meats.
METHODS FOR THE DETECTION OF FOODBORNE LISTERIA MONOCYTOGENES IN THE U.S.
Authors: DEVER FRANCES P. , SCHAFFNER DONALD W. , SLADE PETER J.
Published: April 2007

A review of methods for the isolation and detection of Listeria monocytogenes used in the United States is presented. Methods reviewed include the cold enrichment technique, the FDA Method, the USDA Method, and two rapid techniques, the Listeria‐Tek enzyme‐linked immunosorbent assay and the Gene‐Trak Listeria Assay. Comparisons of new rapid biochemical test kits, the MICRO‐ID LISTERIA System, API Listeria, and the Rosco system vs. conventional tests of identification are also reviewed. Contemporary isolation methods detect all Listeria species so confirmation of L. monocytogenes is still necessary after isolation. The USDA method is the most practical of the cultural methods due to the rapid reporting of negative samples. Rapid methods (Listeria‐Tek and the Gene‐Trak Listeria Assay) are faster and more objective than cultural procedures but still depend on sample enrichment for detection of Listeria. These rapid techniques are best utilized when screening large numbers of food samples. All the rapid biochemical test kits reviewed provide fast reliable identification of Listeria species when compared to classical techniques. However, the API Listeria system identifies the test strains without a complementary CAMP test. Refinements are still needed in both cultural and rapid methods. Future Listeria methodology must emphasize molecular techniques not requiring enrichment which would be both rapid and specific for L. monocytogenes.
CONSUMER ATTITUDES TOWARD FOOD SAFETY ISSUES
Authors: BREWER M. SUSAN , SPROULS GUY K. , RUSSON CRAIG
Published: April 2007

The objectives of this study were to survey consumer attitudes about the safety of the food supply in general, then relate general concern levels with groups of specific items of concern, regulatory issues, and prioritization of food safety funding areas. Factor analysis of 419 consumer responses showed six factors (chemical, health, spoilage, and regulatory issues, deceptive practices, and ideal situations) underlying the 31 specific items evaluated on individual 5‐point scales (1 = no concern, 5 = very strong concern). MANOVA using general level of food safety concern (independent variable) and the six scaled variables was significant. Univariate tests showed that as general level of concern with food safety increased, so did concern with chemical issues (hormones in meat, poultry, and milk, food additives, preservatives, irradiation, pesticide residues, artificial colors, natural toxins, plastic packaging, and nitrates), health issues (fat, cholesterol, calories, sugar, and vitamin content), and spoilage issues (food preparation, refrigerated, pasteurized, and shelf‐stable foods, microbial contamination, and restaurant sanitation).
INHIBITION OF LISTERIA MONOCYTOGENES AND OTHER BACTERIA BY SODIUM DIACETATE
Authors: SHELEF LEORA A. , ADDALA LAKSHMI
Published: April 2007

Growth and survival patterns of Listeria monocytogenes strain Scott A were studied in brain heart infusion broth containing sodium diacetate. Minimum inhibitory concentrations decreased with decrease in temperature, from 35 and 32 mM at 35C and 20C, respectively, to 28 mM at 5C. Broth pH containing 35, 32, and 28 mM sodium diacetate was 5.25, 5.40 and 5.60, respectively. Sodium diacetate was more effective than acetic acid alone in inhibiting the organism over the pH range of 5.0‐6.0. Addition of 21 mM (0.3%) sodium diacetate to ground beef or beef slurry suppressed total aerobic counts during refrigerated storage. Although the meat pH decreased from 5.6 to 5.2 by the addition of the compound, a major part of the antimicrobial effect was attributed to the diacetate and not just pH. Sodium diacetate suppressed growth of three additional L. monocytogenes strains and strains of Escherichia coli, Pseudomonas fluorescens, Salmonella enteriditis and Shewanella putrefaciens. P. fragi, Yersinia enterocolitica, Enterococcus faecalis, Lactobacillus fermentis and Staphylococcus aureus were insensitive to the compound. Sodium diacetate has potential for use in controlling growth of listeriae in meat, poultry and fish products and suppressing growth of certain Gram‐negative spoilage and pathogenic microorganisms.
EFFECT OF WATER ACTIVITY ON THE GROWTH OF STAPHYLOCOCCUS AUREUS AT MEAT‐CHEESE INTERFACES
Authors: RAJKOWSKI KATHLEEN T. , SCHULTZ FRANKIE , NEGRON FLOR , DICELLO ANTHONY
Published: April 2007

There is increased marketing of ready‐to‐eat nonrefrigerated snack foods which consist of meat or sausage products with low or intermediate moisture levels combined with high moisture food products, i.e., cheese products. Packaging the intermediate moisture meat in direct contact with a high moisture food might change the water activity (aw) of the products sufficiently to support growth of Staphylococcus aureus at contaminated interfaces. To evaluate this possibility, sterile sausage slices (aw= 0.60 to 0.82) were surface inoculated with log 2‐3 CFU/g of S. aureus, interfaced with processed cheese slices (aw= 0.94), vacuum packaged, and incubated at 19, 28, 37C and at cyclic temperature of 19–37–19C. S. aureus levels and water activities were determined weekly for 0 to 9 weeks. The aw at the interface changed rapidly and reached an aw that supported S. aureus growth. Growth of S. aureus occurred under all test conditions when the samples were stored at 28 and 37C. At 19C storage S. aureus remained viable for the length of the study.
EFFECT OF HEAT SHOCK ON PRODUCTION OF LISTERIOLYSIN O BY LISTERIA MONOCYTOGENES1
Authors: KIM KEETAE , MURANO ELSA A. , OLSON DENNIS G.
Published: April 2007

A Listeria monocytogenes serotype 1 strain was examined to determine the effect of heat shock on production of listeriolysin O (LLO) and the ability of injured cells to resume production of LLO after heat treatment at 62C for 10 min. Listeria cells were heat‐shocked at 48C for 2 h, and hemolytic activity quantified by hemolysis of red blood cell (RBC). Heat shocking of Listeria cells resulted in almost total reduction in LLO activity. However, within 4 h of incubation of 37C, heat‐shocked cells resumed production of LLO, achieving an activity level 40–times higher than that immediately after heat shock. In comparison, in the same time period there was an increase of only 2–fold in the hemolytic activity of nonheat‐shocked controls. These results provide additional evidence, besides increased thermotolerance, of how heat‐shock of pathogenic organisms could affect the safety of foods.
APPLICATION OF CHLORINE TO REDUCE POPULATIONS OF ESCHERICHIA COLI ON BEEF
Authors: CUTTER CATHERINE NETTLES , SIRAGUSA GREGORY R.
Published: April 2007

The effects of chlorine against 2 strains of E. coli attached to the surface of beef carcass tissue (BCT) were examined using a model carcass washer. Lean and adipose BCT with approximately 5 log10CFU/cm2 E. coli bacteria were spray‐treated with water and sodium hypochlorite (NaOCl) to give chlorine concentrations of 50, 100, 250, 500, or 800ppm, incubated for 24 h, 4C, and E. coli populations enumerated. Spray treatments with water did significantly (P < 0.05) reduce the bacterial populations of either organism attached to lean or adipose BCT, as compared to populations of controls; however, reductions were less than 0.60 log10CFU/cm2. Treatments with 500 and 800 ppm chlorine against E. coli ATCC 25922 attached to BCT resulted in the greatest reductions of 1.22 and 1.28 log10CFU/cm2, respectively. At 800 ppm chlorine, E. coli O157:H7 ATCC 43895 attached to BCT was reduced by 1.04 log10CFU/cm2, whereas spray treatments with 50, 100, 250, and 500 ppm chlorine resulted in reductions of < 1 log10CFU/cm2. Spray treatments with chlorine from sodium hypochlorite solutions reduced populations of E. coli, however, these reductions were not sufficient to completely inactivate the bacteria attached to red meat.
ESTABLISHMENT OF BASELINE DATA ON THE MICROBIOTA OF MEATS
Authors: MCNAMARA ANN MARIE
Published: April 2007

The United States Department of Agriculture's Food Safety and Inspection Service has initiated the National Microbiological Baseline Data Collection Programs to determine the prevalence and levels of selected bacteria on meat and poultry slaughtered under federal inspection. This paper reviews the methodology and results of the first completed study on samples collected from steer and heifer carcasses. Potential applications for this type of testing are discussed.
INHIBITORY EFFECTS OF FLAVOR COMPOUNDS ON STAPHYLOCOCCUS AUREUS WRRC B1241
Authors: BOWLES B.L. , SACKITEY S.K. , WILLIAMS A.C.
Published: April 2007

Acetanisole (4′‐methoxyacetophenone) (AC), benzaldehyde (BE), cinna‐maldehyde (CI), diacetyl (DI), phenylpropionaldehyde (PH), and pyruvaldehyde (PY) were tested against growth of S. aureus WRRC B124 in brain heart infusion broth. Activity was assessed in the presence and absence of oxygen at 12, 19 and 37C, and in combination with mild (20 min at 50 or 60C) heat treatments. The carbonyl compounds limited S. aureus growth at minimal inhibitory concentrations (MIC) of 0.5–8.0 mM. After 4 h at 37C, a 2 to 3‐log10 CFU/ml population reduction was observed with cultures containing 8.0 mM PH, PY, DI or CI. Activity was O2‐tension independent, with CI (0.5 mM), DI(2.0 mM) and PY(2.0 mM) being most active. The MIC for CI was temperature independent, while PY was most effective at 19C, and PH and DI at 12C. Mild heat treatment of carbonyl‐supplemented samples reduced previously observed MICs. At 60C, for example, the MICs for AC and BE, 4.0 and 8.0 mM respectively, were both reduced to 0.5 mM. The decimal reduction times for S. aureus exposed to both UV‐light and 8 mM flavor compounds were 3.3 and 4.3 s for CI and DI, respectively. However, the other compounds were not as effective in the presence of UV since the decimal reduction times ranged from 7.7 to 9.0s. The carbonyl compounds tested were effective antistaphylococcal agents and their use in combination with thermal processing may serve as a new approach to control S. aureus growth and other gram‐positive foodborne pathogens.
LACK OF CORRELATION BETWEEN PLASMID‐ASSOCIATED PHENOTYPES OF YERSINIA ENTEROCOLITICA AND PATHOGENICITY IN THE MOUSE1
Authors: BHADURI SAUMYA
Published: April 2007

Various phenotypic characteristics have been correlated with the pathogenicity of plasmid‐bearing virulent strains of Yersinia enterocolitica. Two transposon Tn801‐insertion derivatives (JD193 and JD217) of the virulence plasmid from serotype 0:3 were used to determine the correlation between pathogenicity and plasmid‐associated properties of this organism. Both Tn801‐inserted derivatives expressed five plasmid‐associated phenotypic characteristics at 37C: (1) colony morphology, (2) calcium‐dependent growth or low‐calcium response, (3) crystal violet binding, (4) autoagglutination, and (5) hydrophobicity. However, for mouse pathogenicity only JD193 was positive whereas, JD217 was avirulent for mice. Thus, it is possible to have a lack of correlation between plasmid‐mediated traits and the actual pathogenicity of the organism in the mouse; however, these plasmid‐mediated phenotypic characteristics provide simple and efficient techniques to evaluate the virulence potential of wild‐type strains isolated from food poisoning outbreaks and clinical cases.
BIOCIDAL ACTIVITY OF A PEROXIDASE‐CATALYZED SANITIZER AGAINST SELECTED BACTERIA ON INERT CARRIERS AND EGG SHELLS
Authors: KWON Y.M. , KRIEG D.P. , KUO F.‐L. , CAREY J.B. , RICKE S.C.
Published: April 2007

Microbial contamination of table eggs has become an important public health problem. In this study, peroxidase‐catalyzed compound (PCC), which is innocuous to humans, was tested for its bactericidal activity on a variety of bacteria on inert carriers and on egg shell surfaces. When inert carriers containing Salmonella choleraesuis, Staphylococcus aureus and Pseudomonas aeruginosa were exposed to PCC, population reductions were within acceptable performance standards for standard and simulated hard water conditions. When evaluated for sporicidal activity, PCC gave no positive carriers in a total of 60 carriers tested for either Bacillus subtilis or Clostridium sporogenes. Enterococcus faecalis and Pseudomonas fluorescens viable cells on egg shell surfaces were determined after dip treatment with deionized distilled water, PCC or chlorine‐treated (200 ppm) water for 1, 3 and 5 min and compared with those of a control without dip treatment. All treatments significantly reduced the viable cells (log10 CFU/egg) compared to controls for both strains (p < 0.05). Populations of both strains surviving chlorine and PCC were significantly lower than surviving deionized‐distilled water, although PCC gave higher recoveries than chlorine (p < 0.05). Populations exposed to PCC treatment were significantly decreased after 3 and 5 min, respectively (p < 0.05). The results of this study indicate that PCC has potential as a table egg sanitizer that could replace the other egg sanitizers which may be environmentally problematic. Based on the inert carrier studies, PCC may also be an effective disinfectant for egg processing equipment and plastic egg cartons in the presence of hard water or contaminating soil.
INACTIVATION OF ESCHERICHIA COLI O157:H7 BY THE COMBINATION OF ORGANIC ACIDS AND PULSED ELECTRIC FIELD
Authors: LIU XIA , YOUSEF AHMED E. , CHISM GRADY W.
Published: April 2007

Inactivation of Escherichia coli O157:H7 by pulsed electric field, benzoic or sorbic acid, alone or in combination was investigated. When the cells of E. coli O157:H7 were suspended in 10% glycerol and treated with a single highvoltage (12.5 kv/cm) electric pulse at 25C, the count decreased by 1.1–1.6 log10 CFU/mL. Presence of benzoic and sorbic acid (1000 ppm) in the suspending medium, at pH 3.4 without electric treatment, decreased the count by 1.9–2.5 and 0.6–1.1 log, respectively. A synergistic killing effect between the high electric pulse and organic acid was observed at pH 3.4, but not at pH 6.4. When the cell suspension of E. coli O157:H7 was treated with five electric pulses in the presence of benzoic or sorbic acid at pH 3.4, the count decreased by 5.6 and 4.2 logs, respectively. Inactivation of the pathogen by combinations of electric pulse and organic acid was enhanced by an increase in temperature, field strength, and number of electric pulses, Inactivation was greater when the cells were suspended in ionic suspending media (0.1% NaCl or 5mM phosphate buffer) than in nonionic media (10% glycerol or 1% sucrose).
INHIBITION OF LISTERIA MONOCYTOGENES AND OTHER BACTERIA BY A PLANT ESSENTIAL OIL (DMC) IN SPANISH SOFT CHEESE
Authors: MENDOZA‐YEPES MARIA J. , SANCHEZ‐HIDALGO LUIS E. , MAERTENS GWENDOLYN , MARIN‐INIESTA FULGENCIO
Published: April 2007

The inhibitory effects of a mixture of plant essential oils (DMC) were tested in culture media and Spanish soft cheese. The minimum inhibitory concentration (MIC) was determined in plate count agar and tryptose broth, with pH adjusted to 6.5, against Listeria monocytogenes, Listeria innocua, Staphylococcus aureus, Lactobacillus brevis, Micrococcus luteus, Salmonella cholerasuis, Escherichia coli O157:H7, Enterobacter cloacae, Pseudomonas aeruginosa and Pseudomonas fluorescens. The mixture of essential oils inhibited all Gram‐positive bacteria tested at 40 ppm, but higher concentrations were needed to inhibit Gram‐negative bacteria, and no inhibitory effect was found against Ps. fluorescens. The effects of DMC against L. monocytogenes and E. coli O157:H7 were evaluated in Spanish soft cheese (Queso Fresco, pH=6.5) stored at 7C. DMC had a bacteriostatic effect against L. monocytogenes at concentrations of 2500 ppm but was ineffective to control the growth of E. coli O157:H7.
MICROBIAL CHANGES ON FRESHLY SLAUGHTERED PORK CARCASSES DUE TO “HOT” LACTIC ACID DECONTAMINATION
Authors: VAN NETTEN P. , MOSSEL D.A.A. , HUIS J.H.J.
Published: April 2007

We studied the microbial changes on fresh (still warm) pork carcasses immediately after electrostatic spraying of lactic acid solutions and during chilled storage. Lactic acid decontamination (LAD) included electrostatic spraying of hot (55C) solutions of 1% lactic acid for 90 s and 2%‐ and 5% lactic acid for 30 and 90 s. The treatments increased the carcass surface temperature from 22C to about 32–43C. The bactericidal activity of lactic acid killed mainly Gram‐negative bacteria. Reductions in “total” psychrotrophic Gram‐negative and Entero‐bacteriaceae counts were found reliable indicators for the efficacy of LAD. Hot 2–5% LAD treatments achieved overall reductions in Gram‐negative psychrotrophs ranging from 0.8 to more than 1.4 log10 cfu per cm2. Overall reductions in mesophilic Enterobacteriaceae counts ranged from approximately 1.2 to more than 1.8 log10 cfu per cm2. Treatments with 1% lactic acid achieved marginal 0.5–0.6 overall log10 reductions in these groups of organisms. Bactericidal effects after LAD occurred during a lag period of whose duration increased with the lactic acid concentration of the spray solution. The lag lasted less than 1 day on 1% LAD, 2 days on 2% LAD and 4 days on 5% LAD meat. During these lags the meat surface pH rose from pH 2.7 to 3.2 immediately after LAD to pH 4.8 to 5.2. During aerobic chilled storage after LAD the growth of Gram‐negative psychrotrophs was controlled only temporarily. These organisms became the dominant group of organisms. The practical utility of electrostatic spraying of fresh pork carcasses with hot 1–5% LAD to improve the keeping quality is questionable.
MICROBIOLOGICAL STUDIES ON A NIGERIAN MAIZE PRODUCT, KWOKA, SUPPLEMENTED WITH SOYBEAN
Authors: EFIUVWEVWERE B.J.O. , AKOMA O.
Published: April 2007

Microbiological studies on a popular maize product (kwoka) with or without a soybean supplement (20 or 30%) were carried out during production and storage at 26–32C. Soybean ‐supplementedproduct had greater microbial diversity and higher populations than the unsupplemented control. The diversity was most evident at the slurry stage (blended mixture before steaming) which contained ten different microbial genera including Aspergillus, Enterobacter, Bacillus, Lactobacillus, Micrococcus and Pediococcus. A dramatic decrease occurred after steaming which killed most of the molds and Gram‐negative bacteria. However, within 1 day of storage, a sharp increase was observed in the microbial population of all samples and maximum load occurred in 20% soybean supplemented “kwoka” at the end of storage. The microbiota became less diverse with storage and was dominated by Bacillus, Lactobacillus and Micrococcus. packaging of ‘kwoka’ in traditional leaves was microbiologically inferior to polyethylene packaging. Changes in the acidity of 30% supplemented ‘kwoka’ were less dramatic compared to the other products. The lactics were primarily responsible for the spoilage of the products (especially the 20% supplemented) after approximately 3 days of storage at tropical ambient temperature of26–32C.; Accepted for Publication August 8, 1997
EFFECTS OF THE HEATING MEDIUM pH ON HEAT RESISTANCE OF BACILLUS CEREUS SPORES
Authors: MAZAS M. , LÓPEZ M. , GONZÁLEZ I. , GONZÁLEZ J. , BFRNARDO A. , MARTÍN R.
Published: April 2007

The influence of the pH of the heating medium (which included several foods and buffers) on the thermal resistance (D and z‐values) of spores of three Bacillus cereus strains was studied. Acidification from pH 7.0 to 4.0 produced a 5‐fold decrease in D‐values. Plots of log D vs pH gave straight lines, which made it possible to develop an equation to approximately predict the changes in heat sensitivity of B. cereus spores which occurred with changing pH. z‐Values for two of the strains studied were not affected by acidification. On the other hand, with the strain ATCC 9818, a clear and statistically significant increase in z‐value was observed as the pH decreased.
INTERACTIONS BETWEEN pH AND MALIC ACID CONCENTRATION ON THE INACTIVATION OF LISTERIA MONOCYTOGENES1
Authors: BUCHANAN R.L. , GOLDEN M.H.
Published: April 2007

The effects and interactions of malic acid concentration and pH on the inactivation kinetics of a three strain mixture of Listeria monocytogenes was studied in brain heart infusion broth (BHI). The medium was supplemented with malic acid and monosodium malate to achieve pH levels of 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 or 7.0 in conjunction with concentrations of 0.0, 0.1, 0.5, 1.0 and 2.0 M. Duplicate 20‐mL portions of each pH/malate level were inoculated (ca. 108 cfu/mL), stored aerobically at 28C, and assayed periodically for viable counts by plating on BHI agar. Survivor curves were generated by fitting data to a linear model that includes a lag term and used to calculate D‐values and “times to 4‐D inactivation”. Inactivation rates were dependent on both the pH and malic acid concentration. At the higher pH levels, malic acid appeared to provide some degree of protection compared to control cultures where the pH was adjusted with HCl. At lower pH values and at higher malic acid concentrations, a concentration‐dependent anion effect was observed. The results indicate that malic acid is a relatively benign organic acid. Its antimicrobial characteristics are similar to those of citric acid and is substantially less bactericidal than lactic or acetic acids.
COMPARISON OF A PEROXIDASE‐CATALYZED SANITIZER WITH OTHER EGG SANITIZERS USING A LABORATORY‐SCALE SPRAYER
Authors: McKEE S.R. , KWON Y.M. , CAREY J.B. , SAMS A.R. , RICKE S.C.
Published: April 2007

Microbial and foodborne pathogen contamination of eggs continues to represent an important public health concern. The goal of this study was to compare the efficacy of spraying shell eggs with PCC (peroxidase‐catalyzed compound, Enzodine
TM, Symbollon Corporation, Sudbury, MA) with that of other sanitizers in the reduction of surface microbial contamination using a laboratory‐scale sprayer apparatus. Treatments were distilled‐deionized water, PCC, chlorine (200 ppm), and quaternary ammonium (QA). Each egg was sprayed with 150 mL of the treatment over a 1 min period while being rotated at approximately 150 revolutions per min. Enumeration of aerobic plate populations indicated that all treatments (distilled‐deionized water, chlorine, PCC, and QA) significantly reduced the viable aerobic bacterial populations and Salmonella typhimurium when compared to the nonsprayed dry egg control. Spraying eggs with PCC resulted in a 6 logarithmic reduction in viable S. typhimurium populations on egg shell surfaces. Unlike results found with aerobic bacterial populations, PCC was not as effective in reducing levels of S. typhimurium to the extent of the chlorine and QA treatments (greater than 6 logarithmic reduction) but greater than 3 logarithmic reduction was observed with PCC as compared to distilled‐deionized water. This study suggests that PCC may be a viable alternative to chlorine and QA in the reduction of bacterial populations on shell egg surfaces and can be applied as a spray on egg shell surfaces.
STRATEGIES FOR THE CONTROL OF BSE AND SCRAPIE
Authors: ROGERS MARK
Published: April 2007

Transmissible Spongiform Encephalopathies, or Prion diseases, are fatal neurodegenerative diseases that affect both humans and animals. Examples include Creutzfeldt‐Jakob disease (CJD) in humans, Bovine Spongiform Encephalopathy (BSE) in cattle and scrapie in sheep and goats. They are characterized by a long incubation period, ranging from months to years, and a variable length clinical course, both determined by the particular infection and the species involved. Some 170,000 cattle in the UK have been diagnosed with BSE and have been destroyed. In the rest of Europe there have also been cases of BSE, though the numbers involved are much lower. The recent potential link between BSE and a new variant form of CJD has highlighted the importance of controlling both BSE and scrapie in Ireland. Control of the disease in both cattle and sheep is complicated by the long incubation period, the lack of suitable tests and the general lack of detailed information in relation to the biology of the disease. Factors that must be considered in designing an effective control strategy include (1) better understanding of the epidemiology of the disease, (2) developing rapid and reliable tests for the disease, (3) introducing a suitable surveillance system for both BSE and scrapie, (4) minimizing the consequences for farmers that have BSE‐infected animals, and (5) implementing and monitoring legislation to prohibit the spread of potentially infectious material. Each of these areas is discussed and it is proposed that the introduction of best available technology in both the diagnosis and surveillance of the national herd could form the basis for an effective program against animal prion diseases.
THE DEVELOPMENT OF A RISK ASSESSMENT MODEL FOR USE IN THE POULTRY INDUSTRY
Authors: OSCAR THOMAS P.
Published: April 2007

A simulation model that assesses the risk of acquiring salmonellosis from consumption and handling of chicken was created in an Excel™spreadsheet and was simulated using Risk™. The model simulated the distribution, preparation, and consumption of 1,000 chickens and was designed to determine the relationship between the level of Salmonella contamination on chickens at the processing plant exit and the risk of salmonellosis for consumers of the chickens. A scatter plot of the probability of acquiring salmonellosis from consumption of the chickens simulated versus the Salmonella load on the chickens at the processing plant exit clearly showed that highly (i.e., > 100 Salmonella/bird) contaminated chickens at the plant exit did not necessarily pose greater risk of salmonellosis than lightly (i.e., < 10 Salmonella/bird) contaminated chickens at the plant exit. Rather, greater risk of salmonellosis was realized from lightly contaminated chickens when they were temperature‐abused, undercooked, and consumed by someone from the high risk population.
THE ANTIFUNGAL ACTIVITY OF BUTYLATED HYDROXYANIZOLE AND LYSOZYME
Authors: RAZAVI‐ROHANI S. MEHDI , GRIFFITHS MANSEL W.
Published: April 2007

The antifungal activity of butylated hydroxyanizole (BHA) and lysozyme alone and combined with ethylenediaminetetraacetic acid (EDTA), at different pH (3.5, 5.6 and 7), and different NaCl concentrations (0.5 to 20%) was screened on 12 fungi. The spiral gradient end point test was used to determine the minimum inhibitory concentration (MIC). BHA was effective against all the fungi tested in the range of < 12 to 460 μg/mL. In the presence of equal amounts of EDTA, the inhibitory effect was amplified (inhibition occurred between < 12 to 200 μg/mL). The inhibition was more pronounced at pH 5.6 and at higher NaCl concentrations especially when EDTA was present. Lysozyme alone was only effective against Fusarium graminearum PM162 and Aspergillus ochraceus MM 184, but was inhibitory for all fungi, except Candida lipolitica 1591, in the presence of EDTA. The inhibition was greatest at pH 5.6 and higher NaCl concentrations, especially when EDTA was present. These studies show that the antifungal properties of lysozyme and BHA can be greatly influenced by environmental factors.
INACTIVATION OF CLOSTRIDIUM BOTULINUM TYPE E SPORES BY HIGH PRESSURE PROCESSING
Authors: REDDY N.R. , SOLOMON H. M. , FINGERHUT G.A. , RHODEHAMEL E.J. , BALASUBRAMANIAM V.M. , PALANIAPPAN S.
Published: April 2007

The effect of high pressure treatments at various temperature combinations on the inactivation of Clostridium botulinum type E spores of strains, Alaska and Beluga in phosphate buffer (0.067 M, pH 7.0) was investigated. No reduction of spores was observed at any pressurization (Maximum = 827 MPa) for temperatures below 35C. At pressurization of 827 MPa for 5 min, log unit reduction of spores increased as temperatures increased from 35 to 55C. An increase in the processing time from 5 to 10 min at a combination of high pressure (827 MPa) and low temperature (40C) resulted in a 5‐log reduction of Alaska spores. About 5‐log reductions for strains Alaska and Beluga occurred at 50 and 55C, respectively, after processing at pressures of 827 MPa for 5 min.
EFFECT OF SOLUBLE POLYLACTIC ACID DURING REFRIGERATED STORAGE OF GROUND MEATS INOCULATED WITH ESCHERICHIA COLI O157:H71
Authors: ALLANSON ANN , CURRY RANDY , UNKLESBAY NAN , IANNOTTI EUGENE , ELLERSIECK MARK
Published: April 2007

Ground beef, ground pork, and commercial breakfast sausage were inoculated (6.5 log10 CFU/mL) with a five strain mixture of Escherichia coli 0157:H7 and treated either with sterile water, or 1% or 2% solutions of soluble polylactic acid (SPLA) in sterile water and stored at 4C for 1, 24, 72 and 168 h. After 168 h, 2% SPLA was significantly (p0.05) more effective than both 1% SPLA and sterile water in reducing E. coli 0157:H7 and resulted in overall reductions of 1.68, 1.70, and 1.32 log10 CFU/mL for beef, pork, and pork sausage, respectively, when compared to control samples. The meat samples treated with 1% and 2% SPLA maintained significantly (p 0.05) lower pH values throughout refrigerated storage of 168 h with the higher concentration sustaining pH values from 3.83 to 3.92. Although the inhibitory effect of this acid increased with storage time, E. coli 0157:H7 survived these acidic conditions, with water activity levels ranging from 0.972 to 0.991.
LACTIC ACID INACTIVATION OF SALMONELLA TYPHIMURIUM ATTACHED TO CATFISH SKIN
Authors: KIM JANGH , MARSHALL DOUGLAS L.
Published: April 2007

This study was conducted to test sanitizer efficacy of lactic acid on Salmonella typhimurium populations that were firmly attached or loosely attached on catfish skin with or without mucus. For both cell types, counts of S. typhimurium were reduced from 5.9 log10 CFU/skin to below the limit of detection of 2.0 log10 CFU/skin by a 5 min exposure to 2% lactic acid. Exposure for 1 min reduced a 104 CFU/skin inoculum to below the limit of detection. Catfish skin mucus slightly decreased the antimicrobial effect of lactic acid against firmly attached S. typhimurium.
BOTULINAL TOXIN PRODUCTION IN VACUUM AND CARBON DIOXIDE PACKAGED MEAT DURING CHILLED STORAGE AT 2 AND 4C
Authors: MOORHEAD S.M. , BELL R.G.
Published: April 2007

This study was undertaken to determine if carbon dioxide packaging of meat afforded a food safety advantage over vacuum packaging with respect to botulinal toxin production during chilled storage. A cocktail of washed spores from five toxigenic clostridial strains – four reference Clostridium botulinumstrains [types A, B (2 strains) and E] and a C. butyricum type E strain – was inoculated onto lamb chumps. Of these strains, two were psychrotolerant. The inoculated chumps were individually carbon dioxide packaged and duplicate packs were placed into storage at 10, 8, 6, 4 and 2C. All storage regimens included a weekly defrost cycle when meat surface temperatures increased by up to 6 to 7C during a 2 to 2.5 h period. After 84 days storage, packs were assessed for the presence of botulinal toxin using the mouse bioassay procedure. All packs contained botulinal toxin. To compare toxin production in vacuum and carbon dioxide packs at chill temperatures, the challenge trials were repeated for 4 and 2C storage. Packs were examined at regular intervals for toxin presence. Both pack types contained toxin after 21 and 48 days storage at 4 and 2C, respectively. In the unlikely, but not impossible, event that raw meat would be contaminated with psychrotolerant toxincapable clostridial spores, product safety, with respect to botulinal toxin presence after prolonged chilled storage, requires storage temperatures to be maintained below 2C for both vacuum and carbon dioxide packaged product.
VARIATION OF LAG TIME AND SPECIFIC GROWTH RATE AMONG 11 STRAINS OF SALMONELLA INOCULATED ONTO STERILE GROUND CHICKEN BREAST BURGERS AND INCUBATED AT 25C1
Authors: OSCAR THOMAS P.
Published: April 2007

One strain of 11 serotypes or 11 strains of Salmonella, which were isolated from the ceca of broilers, were surveyed for their growth kinetics on sterile ground chicken breast burgers incubated at 25C to determine the variation of lag time and specific growth rate. Growth curves, four per strain, were fit to a two‐phase linear model to determine lag time (h) and specific growth rate (log10/h). Repeatability of growth kinetics measurements for individual strains had a mean coefficient of variation of 11.7% for lag time (range: 5.8 to 17.3%) and a mean coefficient of variation of 6.7% for specific growth rate (range: 2.7 to 13.3%). Lag time among strains ranged from 2.2 to 3.1 h with a mean of 2.8 h for all strains, whereas specific growth rate among strains ranged from 0.3 to 0.38 log10 per h with a mean of 0.35 log10per h for all strains. One‐way analysis of variance indicated that lag time (P =0.029) and specific growth rate (P =0.025) differed slightly among strains. S. Haardt had a shorter (P < 0.05) lag time than S. Agona and S. Brandenburg, whereas the specific growth rate of S. Enteritidis was less than (P < 0.05) the specific growth rates of S. Typhimurium and S. Brandenburg. All other strains had similar lag times and specific growth rates. The coefficient of variation among strains was 9.4% for lag time and 5.7% for specific growth rate. These results indicate that there were only minor differences in the lag times and specific growth rates among the strains of Salmonella surveyed. Thus, the growth kinetic values obtained with one strain of Salmonella may be useful for predicting the growth of other strains of Salmonella for which data do not currently exist.
ATTEMPTS TO UTILIZE BACTERIOPHAGE TO COMBAT SALMONELLA ENTERICA SEROVAR ENTEMTIDIS INFECTION IN CHICKENS
Authors: SKLAR IAN B. , JOERGER ROLF D.
Published: April 2007

Bacteriophage capable of lysing a nalidixic acid‐resistant Salmonella enterica serovar Enteritidis strain (SeE Nalr) were tested for the ability to reduce cecal Salmonella counts in young chickens infected with the bacterium. Qualitative analysis of cloacal swabs suggested that phage treatment can possibly reduce shedding of SeE Nalr, but average SeE Nalr counts of between 105 and 107 cfu of SeE Nalr per g of cecum were obtained even from phage‐treated 14‐day old birds and even when more than 107 plaque forming units of phage were present per gram of cecal content. The average cecal SeE Nalr counts were generally between 0.3 and 1.3 orders of magnitude lower in phage‐treated chickens than in untreated controls birds. The difference in counts was statistically not significant in three animal trials, but significant in two trials using feed particles as delivery vehicles for the phage. Although some of the SeE Nalr in the cecae of phage‐treated chickens had developed resistance to some of the phage used, factors other than phage resistance must have contributed to the failure of the phage to substantially reduce SeE Nalr counts.
CONCURRENT DETECTION OF ESCHERICHIA COLI O157:H7 AND SALMONELLA FROM A SINGLE ENRICHMENT IN 24 H
Authors: EVRENDILEK GULSUN AKDEMIR , RICHTER EDWARD R. , CHISM GRADY W.
Published: April 2007

The objective of this study was to determine if a single assay protocol could result in the concurrent detection of Escherichia coli O157:H7 and Salmonella from a single sample grown in a single enrichment in 24 h. Twenty‐five and 375 g of ground beef nonfat dry milk, and dry pet food samples were seeded with low (10 cfu/sample) and high (100 cfu/sample) levels ofE. coli O157:H7 and Salmonella cultures and incubated at 35 and 41C for 18 h for nonselective preenrichment. Incubated samples were analyzed by immunomagnetic separation (IMS) following a 6 h incubation for selective enrichment at 37C using M‐broth and enzyme linked immumosorbent assay (ELISA). Depending on the food samples and the inoculation level, the minimum concurrent detection level of E. coli O157:H7 and Salmonella was <1 cfu/g in the samples at the competitor flora level of 105 cfu/g or less in ground beef samples, but in other cases of higher competitor loads and low target inoculations E. coli O157:H7 could not be detected in the presence of the Salmonella.
INCIDENCE OF STAPHYLOCOCCUS AUREUS IN MEALS FROM CAFETERIAS
Authors: SORIANO J.M. , BLESA J. , RICO H. , MOLTÓ J.C. , MAÑES J.
Published: April 2007

A study to determine the incidence of Staphylococccus aureus in 705 meals from several cafeterias in Valencia, Spain was undertaken. Out of the 705 studied meals, 81 samples (11.1%) had coagulase positive staphylococci with a range of S. aureus from 100 to 53000 cfu/g. The four highest values (> 10,000 S. aureus cfu/g) were obtained with Russian type salad, meatballs, chicken croquettes and salad. These products involved more handling stages. These data show that food handlers may contribute to food poisoning and that there are some handling practices that require more attention.
AN ASSESSMENT OF CHEMICAL SANITIZERS ON THE MICROBIOLOGICAL PROFILE OF AIR IN A MILK PROCESSING PLANT
Authors: SALUSTIANO VALÉRIA COSTA , JOSÉ DE ANDRADE NÉLIO , CARDOSO BRANDÃO SEBASTIÃO CÉSAR , JUNIOR WILLIAN MOREIRA , NACIFE GABRIELA PIRES
Published: April 2007

The efficiency of chemical sanitizing agents to control the microbiota of milk processing areas at a dairy plant was evaluated. Diluted solutions of chlorhexidine digluconate at 1,000 and 2,000 mg.L−1, pH = 5.2 and 5.3, respectively; peracetic acid, at 45 and 75 mg.L−1, pH = 4.2 and 3.8; and a quaternary ammonium compound, pH = 9.2 and 9.3, respectively, were pulverized, at ambient temperature (20–25C) in the milk processing areas using spray equipment which produced a consistent fogging. For each 30 m2 of processing area, 0.5 L of sanitizer solutions were applied at 9 Kgf.cm−2 in 10 min. The sanitizer's efficiency was evaluated against mesophilic aerobic bacteria and yeast and molds. The microbial counts (APC) in the processing areas were detected by impaction technique, as proposed by APHA. Analysis were done before sanitizer application (T0) and after 0.5, 12 and 24 h (T1, T2 and T3), respectively. Activity of 2000 mg.L−1 of chlorhexidine and 700 mg.L−1 of quaternary ammonium against yeast and molds was observed. The T0 number of microorganisms (1.5 and 1.3 log cfu.m−3) decreased in 0.45 and 0.5 log cycle, respectively. Solutions containing 45 mg.L−1 of peracetic acid were effective to control mesophilic aerobic microorganisms. The T0 number of microorganisms (2.1 log cfu.m−3) decreased in 0.55 log cycle. Residual effects against yeasts and molds were observed for 1000 mg.L−1 of chlorhexidine digluconate and 75 mg.L−1 of peracetic acid. Chemical sanitizer applications to control the microbiological quality of the air in milk processing areas is a barrier technology that helps in the production of foods with good microbiological, sensory and organoleptic characteristics.
DEVELOPMENT AND EVALUATION OF A RISK ASSESSMENT TOOL FOR CONTROL OF ANTIMICROBIAL DRUG RESIDUES IN MILK
Authors: SHITANDI ANAKALO , KIHUMBU GATHONI
Published: April 2007

This study evaluated a developed risk assessment tool for control of antimicrobial residues in milk within Kenya. Eleven risk characteristics predicting residue contamination were identified and assessed from farms (n = 184), of which five were associated with a higher residue risk(P <0.05). A score (0–5) was derived for each of the five factors and a ± 3 score used to define high risk. The tool was validated on farms (n = 100) in a local and remote cohort study and observed to have a 91% sensitivity and 75% specificity. The risk of violative antimicrobial drug residues in milk supplies decreased by 52%(P <0.05) when the risk tool was applied in a single blind randomized control study on farms (42 cases and 42 controls). The risk assessment tool was concluded to offer good potential of being used within a control program to minimize violative antimicrobial drug residues in farm milk.