bluuebunny/crossref_metadata_2025 huggingface dataset:
INHIBITION OF LISTERIA MONOCYTOGENES, SALMONELLA TYPHIMURIUM AND ESCHERICHIA COLI 0157:H7 ON BEEF MUSCLE TISSUE BY LACTIC OR ACETIC ACID CONTAINED IN CALCIUM ALGINATE GELS1
Authors: SIRAGUSA GREGORY R. , DICKSON JAMES S.
Published: April 2007

A method of applying organic acids contained in a calcium alginate gel was tested for inhibiting bacteria contaminating sterile lean beef tissue surfaces. Treated samples were incubated at 5C under controlled moisture conditions for up to 7 days and viable populations of the pathogens determined. For counts of L. monocytogenes, recovered on tryptic soy agar, alginate/lactic acid treatment reduced the log10 counts 1.8 units vs 0.96 for acid treatment without alginate. With acetic acid, log10 reductions were 1.51 vs 2.33 for the alginate/acetic acid vs acetic acid treatment alone. S. typhimurium was reduced 2.11 log10 units vs 1.11 for alginate/lactic acid and acid treatments alone, respectively. The same trend held for E. coli 0157:H7, although the reduction was considerably less, 0.74 log10 reduction vs 0.5 for alginate/lactic acid application vs acid alone. Both Gramnegative organisms were less inhibited by acetic acid treatments.
IMPROVEMENT IN MICROBIOLOGICAL QUALITY AND SHELF‐LIFE OF BUFFALO MEAT AT AMBIENT TEMPERATURE BY GAMMA IRRADIATION
Authors: NAIK G.N. , PAUL PUSHPA , CHAWLA S.P. , SHERIKAR A.T. , NAIR P.M.
Published: April 2007

The effect of low dose gamma‐irradiation (2.5 kGy) on the shelf‐life of prepacked fresh buffalo meat at ambient temperature (28–30C) in terms of microbiological, chemical and sensory qualities was studied. Unirradiated samples initially showed the presence of Enterobacteriaceae and Staphylococcus spp. These gradually increased during storage. After 12 h of holding, Clostridium spp. were observed in these samples. On the basis of microbiological, chemical and sensory analyses, the shelf‐life was limited to 18 h. In contrast, Clostridium spp. and Enterobacteriaceae were not detected in irradiated samples throughout the storage period and Staphylococcus spp. were detected only after 12 h of holding. Irradiated samples had a shelf‐life of 42 h.
RECOVERY LIMITS OF HEAT‐INJURED LISTERIA MONOCYTOGENES FROM ENRICHMENT BROTH AND ENRICHED CULTURES OF INOCULATED FOODS
Authors: TRAN TONY T. , HITCHINS ANTHONY D.
Published: April 2007

Recovery of heat‐injured Listeria monocytogenes strain LM82 was evaluated quantitatively in Listeria enrichment broth (LEB) and in enriched cultures of cooked shrimp and Brie cheese. LM82 cells [108 colony forming units (CFU)/ml] were heated for 60 min at 52C in phosphate‐buffered saline. After 24 and 48 h enrichment, injured LM82 (6 replicates at each of 5 inoculation levels) were isolated on 3 selective media: lithium chloride‐phenylethanol‐moxalactam agar (LPMA), modified McBride agar (MMA) and Oxford agar (OXA). The recovery limit was expressed as a 50% end point value (RL50), which is the calculated inoculation value necessary to recover LM82 on half of the replicates of each type of isolation agar plate after streaking from the enrichment of measured inoculum. The RL50 values for injured cells were comparable to those of uninjured cells after 48 h enrichment in LEB without food. The type of isolation agar did not affect the RL50 value, although with food, MMA gave consistently but not significantly higher values, i.e., recovery inferior to that of LPMA and OXA. RL50 values were higher in Brie and cooked shrimp, presumably because of the competitive microflora in those foods. Addition of lactose or pyruvate to LEB improved recovery but had little or no effect when foods were present.
LISTERIA MONOCYTOGENES SURVIVAL ON SHELL EGGS AND RESISTANCE TO SODIUM HYPOCHLORITE1
Authors: BARTLETT F.M.
Published: April 2007

The survival of a mixture of five strains of Listeria monocytogenes inoculated onto the surface of chicken eggs and stored at 10C for up to 14 days was studied. The numbers of survivors which were loosely bound to the shell decreased steadily from day 1 to 7, with no detectable Listeria after 11 days. The Listeria cells which were judged to be tightly bound to the shell did not decrease significantly after 11 days, with less than a 2‐log reduction at 14 days. Application of sodium hypochlorite solutions (50 ppm and 100 ppm available chlorine) to inoculated eggs completely eliminated the loosely bound cells after the shortest exposure time used (30 s), while little or no decrease was observed for the cells which were more strongly attached, even after 5 min. No Listeria were recovered from the egg contents (meat) of any of the inoculated eggs used in this study.
INHIBITION OF SALMONELLA TYPHIMURIUM ON POULTRY BY THE LACTOPEROXIDASE SYSTEM1
Authors: WOLFSON LISA M. , SUMNER SUSAN S. , FRONING GLENN W.
Published: April 2007

The antibacterial activity of the lactoperoxidase (LP) system on the growth and survival of a naladixic acid resistant strain of Salmonella typhimurium on poultry was determined. The LP system treatment, which consisted of lactoperoxidase (1 μg/ml), potassium thiocyanate (5.9 mM), and hydrogen peroxide (2.5 mM) (final concentrations) in water, reduced the level of Salmonella on inoculated chicken legs. The magnitude of reduction was dependent on temperature and time. For a water temperature of 25C and a time of 30 min, a 13.2% reduction was seen, as compared to a water temperature of 60C and a time of 15 min which showed a 80.6% reduction. In a 48 h shelf‐life study, the LP system controlled growth of psychrotrophic bacteria on chicken legs. Hunterlab color values (L, a, b) for chicken thigh skin and oxidative deterioration as measured by TBA values for chicken thigh meat did not significantly differ (p < 0.01 and p < 0.05, respectively) between control and treated thighs.
BACTERIAL ADHERENCE AND VIABILITY ON CUTTING BOARD SURFACES
Authors: ABRISHAMI SIMIN H. , TALL BEN D. , BRUURSEMA THOMAS J. , EPSTEIN PAUL S. , SHAH DHIREN B.
Published: April 2007

The adherence and viability of Escherichia coli inoculated onto the surfaces of plastic cutting boards and new and used wood cutting boards were evaluated. Most of the inoculum was recovered from all surfaces after resident drying times of 5 min and from plastic surfaces at 24 h. When the exposure time was extended to 2 h, > 90% of the cells placed on new and used dry wood surfaces were not recovered after vigorous rinsing. Scanning electron microscopy showed that the bacteria resided within the structural xylem fibers and vegetative elements of the wood. After resident drying times of up to 2 h, almost 75% of the adherent bacteria on the wood surfaces were viable, as defined by a nalidixic acid direct viable count procedure. Microcosm studies showed no intrinsic growth‐supporting or toxic properties of the cutting board materials. Bacteria that adhered to plastic surfaces were more easily removed by low‐temperature washing than were cells that adhered to wood surfaces. These studies demonstrated that bacteria adhering to wood surfaces resided within the structural and vegetative elements of the wood's xylem tissues and were viable; wood was more retentive than plastic; penetration of the inoculum liquid promoted cell adherence to the wood matrix; and conditioning of wood with water before inoculation interfered with bacterial adherence.
OPTIMIZATION OF LISTERIOLYSIN O PRODUCTION BY LISTERIA MONOCYTOGENES1
Authors: KIM KEETAE , MURANO ELSA A. , OLSON DENNIS G.
Published: April 2007

Listeria monocytogenes serotype 1 and Scott A strains were examined to determine the effect of culture conditions onproduction of listeriolysin O (LLO). The hemolytic activity was assayed by hemolysis of sheep red blood cells. The optimum pH range for LLO production in serotype 1 and Scott A were pH 6.2–6.0 and pH 5.8–6.0, respectively. Production of LLO by serotype 1 was 20–fold higher than by Scott A. Addition of more than 1.0% glucose significantly reduced production of LLO by the cells, while favoring growth. By adding 0.5% glucose after stationary phase and adjusting pH to 5.5–7.0, maximum LLO was produced after 2 h incubation at 37C by both strains.
PSYCHROTROPHIC AND MESOPHILIC FUNGI ISOLATED FROM IMPORTED FROZEN LEAN MEAT IN EGYPT
Authors: NASSAR AHMED M. , ISMAIL MADY A.
Published: April 2007

From 475 samples of imported frozen lean beef in Egypt, 859 psychrotrophic fungal strains (770 strains by the dilution plating and 89 strains by direct plating) were isolated. There were also 1291 mesophilic fungal strains isolated (1133 and 158 strains by the two different methods, respectively). The predominant psychrotrophs identified were species of Cladosporium and Penicillium while most mesophiles were in the genera of Aspergillus, Cladosporium and Penicillium.
SURVIVAL OF SALMONELLA TYPHIMURIUM, ESCHERICHIA COLI O157:H7 AND LISTERIA MONOCYTOGENES DURING STORAGE ON BEEF SANITIZED WITH ORGANIC ACIDS
Authors: DICKSON J.S. , SIRAGUSA G.R.
Published: April 2007

Sterile beef tissue was inoculated with either Salmonella typhimurium, Escherichia coli O157:H7 or Listeria monocytogenes Scott A and washed with 23C distilled water, 1% lactic acid or 1% acetic acid. The washed tissue was subjected to simulated dry chilling or spray chilling followed by storage at 5C. The washed tissue was stored at 5C for up to 21 days at 26% relative humidity, and total bacterial populations were determined by plating on nonselective and selective agars. There was no significant difference in the surviving populations of S. typhimurium, Escherichia coli O157:H7, or L. monocytogenes after storage, irrespective of chilling method. The surviving populations of bacteria were significantly lower on acid washed adipose tissue, when compared to the comparable water washed tissue. These results indicate that although injury and recovery of pathogenic bacteria may occur as a result of organic acid carcass sanitizing treatments, there was no practical significance of this phenomenon after 3 days of storage.
THE EFFECTIVENESS OF CARCASS DECONTAMINATION SYSTEMS FOR CONTROLLING THE PRESENCE OF PATHOGENS ON THE SURFACES OF MEAT ANIMAL CARCASSES1
Authors: SIRAGUSA GREGORY R.
Published: April 2007

The effectiveness of decontamination systems for controlling the presence of pathogens and spoilage organisms on carcasses is discussed. Research using organic acids and water (hot or cold) demonstrates the general effectiveness of such treatments in lowering the aerobic plate counts (APC) on carcasses by 1–3 log10 cfu per unit area. Chlorine has been found to be relatively ineffective for use in animal carcass spray washers. An example of direct application of the bacteriocin nisin to inoculated tissue in a spray washer is discussed. Reductions attributable to nisin were 2–2.5 log10 cfu per unit area higher than those reported for various organic acids or water. Areas for further research are highlighted along with the potential use of newer technologies to elucidate attachment and detachment mechanisms of bacteria to meat animal carcasses.
EXPANDED MODEL FOR THE AEROBIC GROWTH OF AEROMONAS HYDROPHILA
Authors: PALUMBO SAMUEL A. , WILLIAMS AARON C. , BUCHANAN ROBERT L. , CALL JEFFREY C. , PHILLIPS JOHN G.
Published: April 2007

The previously published (Palumbo et al. 1991) response surface model for describing the influence of temperature, pH, NaCl, and sodium nitrite on the aerobic growth of Aeromonas hydrophila K144 in BHI broth has been expanded to incorporate additional data. The effects of the variables on A. hydrophila aerobic growth kinetics were modeled by response surface analysis using quadratic and cubic polynomial models of (1) natural logarithm transformation of both the Gompertz B and M parameters and the lag phase duration (LPD) and generation time (GT), and (2) the square root transformation of B and 1/M calculated from 268 cultures (212 of which supported growth) from 81 variable combinations. In addition, the six models generated also were subjected to backward elimination regression analysis to remove nonsignificant variables. Based on examination of the adjusted R2 values of the resulting 12 models, three were selected for further evaluation by comparing their observed and predicted T1000‐values (time for a 1000‐fold increase in number; this concept incorporates the influence of the variables on both lag and generation times), LPDs and GTs. Using this method of comparison and evaluation, models based on cubic polynomial, natural logarithm transformation of GT and LPD gave the best “first estimates” of the aerobic growth characteristics of A. hydrophila.
INHIBITION OF SPOILAGE AND PATHOGENIC BACTERIA ASSOCIATED WITH FOODS BY COMBINATIONS OF ANTIMICROBIAL AGENTS
Authors: RAZAVI‐ROHANI S. MEHDI , GRIFFITHS MANSEL W.
Published: April 2007

The antibacterial activity of combinations of lysozyme, monolaurin (ML), triglycerol 1,2 laurate (TGL) and butylated hydroxyanizole (BHA) against 7 Gram‐positive and 8 Gram‐negative bacteria was studied at different pH, NaCl and EDTA concentrations by the spiral gradient end point test. The inhibitory effect of lysozyme in combination with ML was slightly greater for Gram‐positive than for Gram‐negative bacteria, but their combined effect was not markedly more inhibitory than ML alone. Lysozyme and TGL together were only inhibitory at low pH and high NaCl concentrations in the presence of EDTA. There was an increase in inhibition when lysozyme and BHA were combined. For Gram‐positive bacteria, inhibition by ML and BHA together was more marked than when either was present singly. However, ML decreased the antibacterial activity of BHA against Gram‐negative bacteria. Similarly, TGL was antagonistic to BHA action against both Gram‐positive and Gram‐negative bacteria. In general, the inhibition produced by all combinations was greater as the pH decreased and the NaCl concentration increased, especially in the presence of EDTA.
ISOLATION OF BDELLOVIBRIOS THAT PREY ON ESCHERICHIA COLI O157:H7 AND SALMONELLA SPECIES AND APPLICATION FOR REMOVAL OF PREY FROM STAINLESS STEEL SURFACES1
Authors: FRATAMICO PINA M. , COOKE PETER H.
Published: April 2007

Predatory bacteria of the genus Bdellovibrio that prey upon Escherichia coli O157:H7 and Salmonella species were isolated from soil and sewage samples. Bdellovibrio isolates 45k (from soil) and 88e (from sewage) attacked and lysed the E. coli and Salmonella strains tested, with log10 reductions ranging from 2.5 to 7.9 CFU/mL after 7h incubation, using a two‐membered culture system. The predators showed activity against the bacteria within the temperature range of 19 to 37C. Bdellovibrio isolate 45k reduced a population of E. coli dried on stainless steel surfaces by 3.6 log10 CFU/cm2 following 24 h contact time and at a 10:1 predator to prey ratio and was also effective in reducing the level of biofilm cells. Bdellovibrios can potentially be utilized for removal of bacteria from surfaces of food processing equipment and possibly for controlling the growth of pathogenic and spoilage bacteria in foods.
PURIFICATION OF THE ANTI‐LISTERIAL BACTERIOCINLIKE INHIBITORY SUBSTANCE PRODUCED BY ENTEROCOCCUS FAECIUM 108
Authors: DALLAS HUGH L. , SATHYAMOORTHY VENUGOPAL , HITCHINS ANTHONY D.
Published: April 2007

Extracellular antimicrobial substances produced by certain enterococci inhibit Listeria monocytogenes. Enterococcus faecium 108, a competitive food isolate, produced a heat‐stable and protease‐sensitive anti‐L. monocytogenes bacteriocin‐like substance (Ef108) in Listeria selective enrichment broth and other media. Ef108 activity was purified to homogeneity by a four‐step procedure including (NH4)2SO4 fractionation, chromatography on anion exchange QSepharose column, and two Superose 12 gel filtration columns. In activities represented by two peaks (Ef108A and Ef108B), 90% of the crude activity was due to peak B. Ef108A is believed to be a variable aggregate of the active moiety in Ef108B. All Listeria spp. and five L. monocytogenes serotypes were inhibited by Ef108B in several media including Listeria enrichment medium. The Ef108 activity may be due to a bacteriocin‐like inhibitory substance produced by E. faecium 108 that may suppress the growth and predominance of Listeria monocytogenes during selective enrichment.
EFFECT OF SANITIZERS ON LISTERIA MONOCYTOGENES ATTACHED TO LATEX GLOVES
Authors: McCARTHY SUSAN A.
Published: April 2007

Contamination of ready‐to‐eat seafoods with Listeria monocytogenes is a major concern of the seafood industry. One means of control is the use of hand sanitizers. Five sanitizers (chlorine bleach, Zep‐i‐dineTM, Zepamine ATM, ZepTM Instant Hand Sanitizer, and Ultra‐KleenTM) were evaluated for effectiveness against L. monocytogenes attached to latex gloves in the presence of phosphate buffered saline or crab cooking water. Cooking water had been used to boil the crabs and was heavily laden with organic nutrients. Chlorine, Zepamine ATM, and Ultra‐KleenTM reduced numbers of attached L. monocytogenes to nondetectable levels in the presence of phosphate buffered saline; Zep‐i‐dineTM and ZepTM Instant Hand Sanitizer were less effective. In the presence of crab cooking water, only Ultra‐KleenTM reduced cell numbers to nondetectable levels; the effectiveness of the remaining sanitizers was reduced. Extreme care must be taken when choosing hand sanitizers as their efficacy may be affected by organic residues on the gloves of food handlers.
SURVIVAL OF SALMONELLAE IN ORANGE JUICE1
Authors: PARISH M.E. , NARCISO J.A. , FRIEDRICH L.M.
Published: April 2007

Salmonella serovars gaminara, hartford, rubislaw and typhimurium were inoculated into pasteurized orange juice adjusted to pH 3.5, 3.8, 4.1 and 4.4 and incubated at 0 and 4C. Inoculated salmonellae (106 colony‐forming units/mL) survived in detectable numbers up to 27 days at pH 3.5, 46 days at pH 3.8, 60 days at pH 4.1, and 73 days at pH 4.4. Lag times before initial cell populations began to decline were directly correlated with pH and ranged from < 1 day at pH 3.5 up to 27 days at pH 4.4. Death rates were inversely correlated with pH. Results suggest that salmonellae which might contaminate orange juice could survive sufficient time to cause illness.
INHIBITION OF FOODBORNE BACTERIAL PATHOGENS BY NATURALLY OCCURRING FOOD ADDITIVES
Authors: BOWLES B.L. , JUNEJA V.K.
Published: April 2007

In this study, diacetyl (DI), benzaldehyde (BE), pyruvic aldehyde (PY) and piperonal (PI) were tested for activity against Yersinia enterocolitica, Listeria monocytogenes, Salmonella typhimurium, Bacillus cereus, Shigella flexneri, Aeromonas hydrophila, Escherichia coli O157:H7, Staphylococcus aureus, and proteolytic Clostridium botulinum spores. The minimal inhibitory concentrations (MICs) required to inhibit pathogens ranged from 0.05 to 7.81 mM. The only exception was C. botulinum which was least sensitive, with DI or PY MIC of 25 mM; the MIC of BE or PI was 125 mM. A 30 min 56.8C heat treatment, of the organism/inhibitor mixture, reduced the MICs of BE and PI by 50–87%, and 77% less PY was required to inhibit E. coli O157:H7. BE or PI reduced C. botulinum spore 80C thermal‐ and radio‐resistance. To determine whether antibacterial plant components exist naturally at inhibitory concentrations, EtOH‐extracts of asparagus (As), carrots (Ca), radishes (Ra), shallots (Sh), and turnips (Tu) were tested for antibotulinal activity. As or Ca extracts were antigerminative at 0.07%. When combined equal quantities of As and Ca were tested, ± 0.03% delayed germination, however. Although no activity was observed when Ra and Sh were test singly, 0.13% AsCaRa, AsCaRaSh or AsCaRaShTu combinations were inhibitory. These data indicate that the naturally occurring food additives may be employed to control the foodborne pathogens assessed in this study.
BIOGENIC AMINES IN FINNISH DRY SAUSAGES
Authors: EEROLA H.S. , SAGUÉS A.X. ROIG , HIRVI T.K.
Published: April 2007

A study was conducted to determine the biogenic amine levels of Finnish dry sausages and to compare the results with those of other surveys of different types of fermented sausages. Sausages with high amine concentration were analyzed microbiologically in order to identify amine‐producing microorganisms. Tyramine was the most common amine: the mean of 68 samples was 82 mg/kg and the mode 110 mg/kg. Other vasoactive amines found were histamine (<1–200 mg/kg), phenylethylamine (<1–48 mg/kg) and tryptamine (<10–91 mg/kg). Increased amounts of the spoilage indicator amines putrescine and cadaverine were found from most of the samples containing vasoactive amines. The formation of amines can be linked with problem(s) in hygienic conditions of raw materials and manufacturing practices and it is thus proposed that the sum of tyramine, histamine, putrescine and cadaverine could serve as an indicator of quality in fermented meat products.
INHIBITION OF LISTERIA MONOCYTOGENES BY CINNAMIC ACID: POSSIBLE INTERACTION OF THE ACID WITH CYSTEINYL RESIDUES
Authors: KOUASSI YAO , SHELEF LEORA A.
Published: April 2007

The effects of cinnamic acid (C6H5CH=CHCOOH) on L. monocytogenes strain Scott A and listeriolysin O (LLO) activity were studied. In addition, a possible mode of action of the acid was investigated. L. monocytogenes was more susceptible to cinnamic acid than to benzoic acid, and lowering the broth pH increased the inhibition. LLO activity was inhibited in the presence of 0.1% cinnamic or benzoic acid, and western blot analysis showed reduced intensity of listeriolysin bands in the presence of 0.2% of the acids. Addition of cysteine (5 mM) to cinnamic acid in PBS, pH 7.0, caused gradual reduction in UV absorption of the acid during incubation for 12 h. Cinnamic acid (>0.5%, pH 7.0) inhibited glucose uptake and ATP production in resting cells of L. monocytogenes. Results suggest a role of the cinnamate anion in the antilisterial and anti‐LLO activity and potential applications in the food industry.
USE OF OZONE TO INACTIVATE MICROORGANISMS ON LETTUCE
Authors: KIM JIN‐GAB , YOUSEF AHMED E. , CHISM GRADY W.
Published: April 2007

When ozone (1.3 mM) was bubbled for 3 min in a mixture of shredded lettuce and water, counts ofmesophilic andpsychrotrophic bacteria decreased 1.4 and 1.8 log10 cfu/g, respectively. Counts of these microorganisms on lettuce, from a different batch, decreased 3.9 and 4.6 log, respectively, during 5 min of ozone treatment. Shredded lettuce was treated with gaseous ozone, or mixed with aqueous solution of ozone (1:20 w/w) with or without bubbles. For effective delivery of ozone, stirring (low and high speed), sonication or stomaching was applied during the ozonation. Washing the lettuce with water only decreased total count on shredded lettuce by 0.74–1.0 log cfu/g. When lettuce in a treatment chamber was flushed with gaseous ozone, the total count decreased 0.85 log cfu/g, but when vacuum was applied before the ozone flush, the total count decreased 0.96 log cfu/g. Bubbling ozone in water‐lettuce mixture while sonicating, high‐speed stirring, or before stomaching inactivated 1.4, 1.9 and 1.9 log cfu/g, respectively. In conclusion, bubbling gaseous ozone in water is the most effective ozonation method. Efficient ozone delivery to microorganisms on lettuce requires a combination of ozone bubbling and high‐speed stir.
SPORULATION TEMPERATURE AND HEAT RESISTANCE OF BACILLUS SPORES: A REVIEW
Authors: PALOP ALFREDO , MAÑAS PILAR , CONDÓN SANTIAGO
Published: April 2007

Sporulation temperature is one of the most important factors that determine the heat resistance of spores. Bacterial spores are usually more heat resistant when they are formed at higher temperatures. Sporulation temperature also influences the effect of pH of heating menstruum and the effect of different acids on spore heat resistance. Heat resistance is maximum at neutral pH and decreases with acidification, but when spores are sporulated at high temperatures the effect of acidic pH on heat resistance is lower at high heat treatment temperatures. Lactic and acetic acid decrease spore heat resistance more than other acidulants, but only when spores had been sporulated at high temperatures. These effects should be considered by canning factories of acid/acidified foods, especially in hot climate areas, where these high temperatures can be easily reached. The level of mineralization of spores obtained at different Sporulation temperatures seems to be the most important mechanism responsible for their heat resistance.
CONSUMER FOOD SAFETY KNOWLEDGE AND PRACTICES
Authors: BRUHN CHRISTINE M. , SCHUTZ HOWARD G.
Published: April 2007

Consumer knowledge of safe handling guidelines and their reported practices assessed by a mail survey indicated consumers considered themselves informed about food safety, and most reported taking action to minimize risk from potential hazards. However, most responses were related to nutritional changes, and 20% indicated they did not know how to reduce risks from microbiological hazards. Consumers were knowledgeable about appropriate safeguards in selection and cooking specific foods, however mistakes were reported in temperature control and handling leftovers. Consumer Reports, university scientists, health professionals and science magazines were considered ihe most reliable source of food safety information. Industry advertisement appears to raise consumer concern in some areas. Educational intervention should emphasize the importance of temperature control and sanitation rather than taste to determine safety. Consumers should receive information about protective technologies like heat and irradiation pasteurization.
COMPARISON OF CHLORINE WITH AN IODINE‐BASED COMPOUND ON EGGSHELL SURFACE MICROBIAL POPULATIONS IN A COMMERCIAL EGG WASHER
Authors: KNAPE K.D. , CAREY J.B. , BURGESS R.P. , KWON Y.M. , RICKE S.C.
Published: April 2007

Microbial contamination of egg shells is of great importance in the commercial production of table eggs. The objective of this project was to determine the effectiveness of an iodine‐based disinfectant (IBD) on the microbial population of eggshell surfaces under simulated industry egg processing conditions with a commercial egg washer used as the delivery system for sanitizers. Recirculated egg washer water containing 3.69–5.81 log colony‐forming units (CFU)/mL aerobic organisms and 2.02–2.47 g/L total dissolved solids (TDS) was obtained from a commercial egg processing facility and used to simulate conditions found in the commercial egg industry. Sanitizing treatments consisted of distilled deionized water (DDW), IBD, and chlorine (CL; 200 ppm). Enumeration of aerobic plate populations indicated that IBD and CL treatment significantly (p < 0.05) decreased microbial populations on the shell compared to DDW treatment when egg wash water TDS were lower (2.02 – 2.03 g/L) and wash water aerobic plate counts (APC) were higher (5.05 – 5.85 log CFU/mL). When egg wash water TDS was higher (2.47 g/L) and wash water APC were lower (3.69 log CFU/mL) sanitizers were not effective in reducing egg shell microbial populations. No difference in egg shell APC counts was detected between the IBD and CL. In a second trial, cycloheximide or tetracycline amendments were added to media to test the effectiveness of the treatments on either mold and fungi or bacteria alone. When wash water TDS were higher (2.44–2.46 g/L) the sanitizers were again less effective against bacteria compared to samples from lower TDS while fungal populations did not show any significant differences among the treatments. It was concluded from this study that the IBD is an effective sanitizer when used in conjunction with a commercial egg washer but potential efficacy is dependent on the level of TDS in the egg wash water.
LATE LOGARITHMIC SALMONELLA TYPHIMURIUM HEp‐2 CELL ASSOCIATION AND INVASION RESPONSE TO SHORT‐CHAIN FATTY ACID ADDITION
Authors: DURANT J.A. , LOWRY V.K. , NISBET D.J. , STANKER L.H. , CORRIER D.E. , RICKE S.C.
Published: April 2007

The entry of Salmonella into the intestinal epithelial cells is essential for its pathogenesis. In the present stuay, late logarithmic growth (12 h) in Luria Bertani broth supplemented (25, 50, or 100 mM) with acetate, propionate, butyrate, or a mixture of the three short‐chain fatty acids (SCFA), influenced the ability ofS. typhimurium to associate and invade cultured HEp‐2 cells. The response to SCFA addition was dependent on the concentration and the pH of the medium. Cell‐association was decreased 4 to 100‐fold at pH 6 and 2 to 20‐fold at pH 7. At pH 7, invasion was increased 2‐fold when bacteria were cultured in the presence of all concentrations of acetate and 25 mM propionate or butyrate; however, a 1.5 to 163‐fold decrease in invasion occurred at pH 6 for all SCFA. The SCFA concentration also affected cell‐association and invasion of S. typhimurium, especially at pH 6. In general, for each of the SCFA at pH 6 a lower percentage of cell‐association and invasion was observed as the SCFA concentration was increased while at pH 7 decreases did not consistently occur as SCFA concentration was increased. These differences among the SCFA along with the pH effects suggest that the concentration of SCFA and the pH of the intestinal lumen may influence the expression of the invasion phenotype of S. typhimurium.
MICROBIOLOGICAL AND CHEMICAL PROPERTIES OF IRRADIATED MANGO
Authors: EL‐SAMAHY S.K. , YOUSSEF BOTHAINA M. , ASKAR A.A. , SWAILAM H.M.M.
Published: April 2007

Fourteen fungal species belonging to five genera, Aspergillus, Cladosporium, Penicillium, Fusarium and Scoplariopsis were isolated from the surface of mango fruits, (Mangifera indica L.) variety “Zebda”. Mycotoxin production by isolated molds was tested in Czapek‐Dox broth as well as mango pulp. The irradiation decimal reduction doses (D10 values) of the molds were determined in either physiological saline solution or mango pulp. The effects of ionizing radiation in combination with hot water‐dipping (55C/5 min) on shelf‐life extension and the microbiological, chemical, rheological and organoleptic properties of mango fruit (at mature green stage) stored at 12°C and 80–85% relative humidity were determined. Results showed that Zebda mango irradiated with doses of 1.0 kGy can be stored 50 days at 12°C without any undesirable changes to measured nutrient and sensory quality when compared to unirradiated mangoes refrigerated for 25 days.
INFLUENCE OF STARVATION, TEMPERATURE, AND pH ON CULTURABILITY OF ESCHERICHIA COLI O157:H7
Authors: ZHAO LIQIANG , MATTHEWS KARL R.
Published: April 2007

In farm and food processing environments Escherichia coli O157:H7 can survive for days to months. In this study, we investigated the influence of starvation, pH (pH 4 or 7), temperature (4, 10 and 22C), and exposure to chlorine (50, 100, 150, 200 ppm) on culturability of E. coli O157:H7. The culturable cell population in PBS decreased to an undetectable level at 4C and 10C, but not at 22C during the experimental period. Cells suspended in PBS adjusted to pH 4 lost culturability more rapidly than at pH 7. Culturable cells were not detectable after exposure to chlorine, however, viable cell populations in the range of 1 – 2 log remained stable for 5 days. During loss of culturability two distinct morphological cell populations emerged; typical rod shaped and coccoid shaped cells. In this study, independent of exposure to chlorine, conditions of low temperature and low pH had the greatest influence on entry of E. coli O157:H7 into a VNC state.
EFFECT OF FILMS OF DIFFERENT OXYGEN TRANSMISSION RATE ON TOXIN PRODUCTION BY CLOSTRIDIUM BOTULINUM TYPE E IN VACUUM PACKAGED COLD AND HOT SMOKED TROUT FILLETS
Authors: DUFRESNE ISABELLE , SMITH JAMES P. , LIU JIUN NI , TARTE ILSEMARIE , BLANCHFIELD BURKE , AUSTIN JOHN W.
Published: April 2007

Studies were done to determine the effect of film oxygen transmission rate (OTR) on the time to toxicity in vacuum packaged cold and hot smoked rainbow trout fillets challenged with C. botulinum type E (102 spores/g) and stored at refrigerated conditions (4C), and under mild (8C) and moderate (12C) temperature abuse conditions. While no samples were toxic at 4C, toxin was detected within 28 days at 8C for cold smoked trout fillets vacuum packaged in films with high OTR. Toxin was also detected for most vacuum packaged hot smoked trout fillets within 14–28 days at 8C, with the exception of trout fillets packaged in films with an OTR > 10,000 cc/m2/day. In most cases at 8C, spoilage, based on odor/color scores, preceded or occurred simultaneously with toxigenesis. At 12C all cold and hot smoked trout were toxic after 14–21 days and samples packaged in films with an OTR <5000 cc/m2/day became toxic before, or at the same time as, samples became spoiled. This study has shown that vacuum packaging of trout fillets in low gas barrier films, ranging in OTR from approximately 3,000 to approximately 10,000 cc/m2/day at 24C and 0% relative humidity (RH), did not prevent the growth and toxin production by C. botulinum in vacuum packaged cold and hot smoked trout fillets at 12C. Additional barriers, other than the OTR of the packaging film, need to be considered to ensure the safety of vacuum packaged trout fillets, particularly at mild to moderate temperature abuse storage conditions.
INHIBITION OF LISTERIA INNOCUA AND L. MONOCYTOGENES IN A LABORATORY MEDIUM AND COLD‐SMOKED SALMON CONTAINING LIQUID SMOKE
Authors: VITT SUSAN M. , HIMELBLOOM BPIAN H. , CRAPO CHARLES A.
Published: April 2007

Five commercial liquid smokes were tested in vitro and the most inhibitory to Listeria monocytogenes ATCC 19115 and L. innocua ATCC 33090 was Charsol Supreme. Chum salmon samples (100‐g each) were brined, dipped for 15 s at varying concentrations of liquid smoke, inoculated with L. innocua, cold‐processed and analyzed. Liquid smoke concentrations of 60–100% reduced L. innocua by 3‐log10/g in the final product. Dwell times of 15 s to 5 min using 60% liquid smoke gradually decreased Listeria survival with an optimum 5‐min dip. Isoeugenol was antilisterial in vitro but lacked synergism with liquid smoke in cold‐smoked salmon. An immunoassay kit detected low inoculum levels (< 100 CFU/g) of L. innocua in one of three samples that were treated with liquid smoke for two and four minutes. Charsol Supreme was antilisterial but could not be relied on to totally eliminate Listeria in cold‐smoked salmon. Panelists found the 0 to 2‐min dipped sockeye salmon slightly desirable with no significant (p < 0.05) differences. The 5‐min treatment was significantly (p < 0.05) darker, scored lower in desirability and flavor and contained 93 ppm of phenolic compounds.
POSTIMPLEMENTATION COSTS OF HACCP AND SSOP'S IN GREAT PLAINS MEAT PLANTS1
Authors: BOLAND MICHAEL , HOFFMAN DANA PETERSON , FOX J.A. (SEAN)
Published: April 2007

The objective of this analysis was to determine the costs of the development and implementation of HACCP, SSOP's, Salmonella Performance Standards, and Generic E. coli Process Control Testing for small meat and poultry plants. USDA estimated these costs to be $0.0024 per pound with the release of the Pathogen Reduction Ruling. Weighted averages from two other studies estimating implementation costs were $0.0005 and $0.0139 per pound. To collect data and measure actual implementation costs, phone surveys and personal interviews were conducted with small meat (defined as having 10 or more employees but less than 500) slaughter and processing plants in North Dakota, South Dakota, Nebraska, Kansas, Missouri, and Oklahoma. The analysis suggests that the plants incurred an average of $0.009 per pound in development and implementation costs for these regulations.
SUPERCRITICAL CARBON DIOXIDE TREATMENT TO INACTIVATE AEROBIC MICROORGANISMS ON ALFALFA SEEDS
Authors: MAZZONI ANGELA M. , SHARMA RATNA R. , DEMIRCI ALI , ZIEGLER GREGORY R.
Published: April 2007

The supercritical carbon dioxide (SC‐CO2) process involves pressurizing CO2 in a chamber which generates liquid phase of carbon dioxide. Pressurized liquid CO2 has a strong extraction capability of organic and inorganic compounds. The recent studies have also demonstrated that antimicrobial effect of SC‐CO2 due extraction some cellular components of microorganisms. The efficacy of a supercritical carbon dioxide treatment on alfalfa seeds contaminated with Escherichia coli K12 was tested at 2000, 3000, and 4000 psi at 50C. Samples were treated for 15, 30, and 60 min at each pressure. After pummeling the seed samples in 0.1% peptone water, the initial and final Escherichia coli and total aerobic bacteria on the seeds were determined by plating on 3M Petri Films. After 48 h of incubation at 37 C, the colonies were enumerated. Treated seeds were evaluated in terms of germination characteristics. For aerobic plate count, the effect of pressure in the range of 2000–4000 psi was not statistically significant (p > 0.05) even though 85.6% inactivation was achieved at 4000 psi for 60 min. For E. coli, the reductions for 2000, 3000, and 4000 psi treatments for 15 min were 26.6, 68.1, and 81.3%, respectively. As the time was increased from 15 to 60 min at 4000 psi, the percent E. coli reduction increased from 81.3% to 92.8%. The percent germination for all treatments was over 90%. There was no significant difference (p > 0.05) in the germination rate of treated and untreated seeds. Supercritical carbon dioxide treatments demonstrated a reduction of E. coli K12 and total aerobic counts without affecting the germination characteristics of alfalfa seeds (p < 0.05). This study was a step in the direction of improving safety of alfalfa seeds used to produce fresh sprouts, which have been the cause of several outbreaks.
CYTOTOXICITY ASSESSMENT OF BACILLUS STRAINS ISOLATED FROM STREET‐VENDED FOODS IN JOHANNESBURG, SOUTH AFRICA
Authors: MOSUPYE F.M. , LINDSAY D. , DAMELIN L.H. , VON HOLY A.
Published: April 2007

Twenty‐one isolates each of Bacillus (B.) cereus, B. licheniformis and B. subtilis from street foods, collected in central Johannesburg, were randomly selected to test for cytotoxicity against McCoy 5A Mouse cells using a 3‐(4,5‐dimethylthizol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay, and observation by confocal scanning laser microscopy (CSLM) and scanning electron microscopy (SEM). Forty‐eight percent of B. cereus, 33% of B. licheniformis and 19% of B. subtilis strains produced cytotoxic compounds. For B. cereus strains, all supernatants exhibiting cytotoxic effects were inactivated by heat treatment at 121C for 15 min. By contrast, 24% of B. licheniformis and 10% of B. subtilis supernatants exhibited cytotoxic effects following heat treatment. CSLM and SEM showed that McCoy cells treated with cytotoxic supernatants exhibited leakage and necrosis. Presence of B. cereus, B. licheniformis and B. subtilis in street foods in high numbers may pose potetnial safety risks due to production of cytotoxic compounds.
INACTIVATION OF ESCHERICHIA COLI O157:H7 ON INOCULATED ALFALFA SEEDS WITH OZONATED WATER UNDER PRESSURE1
Authors: SHARMA RATNA R. , DEMIRCI ALI , BEUCHAT LARRY R. , FETT WILLIAM F.
Published: April 2007

Alfalfa seeds inoculated with Escherichia coli O157:H7 (∼105 CFU/g) were subjected to low hydrostatic pressure. Seeds immersed in ozonated water at 4C were held at 8 and 12‐psi ozone pressure for 2, 4, 8, 16, 32, and 64 min. Alternatively, seeds were continuously sparged with ozone for up to 64 min and then held at 12 psi for 5 min. Controls consisted of sparging and pressurization with air. Thirty‐two minute treatments of continuous ozone sparging followed by pressurization of seeds at 12 psi for 5 min were repeated with the addition of four surfactants (Tween 20, Tween 80, SPAN 20, and SPAN 80) in the treatment water. Enumeration of E. coli O157:H7 on treated, untreated, and control seeds was done on tryptic soy agar supplemented with 50 μg/mL of nalidixic acid. The reduction in population of E. coli O157:H7 on seeds treated with the 8 and 12 psi hydrostatic pressure in ozonated water ranged from 0.74 −1.56 log10 CFU/g and 0.72 – 1.62 log10 CFU/g, respectively. Control treatments carried out with air pressurization of seeds resulted in maximum population reductions of 1.55 log10 and 1.83 log10 CFU/g for 8 and 12 psi, respectively. For seeds treated with continuous ozone sparging (2 – 64 min) followed by pressurization at 12 psi for 5 min, the highest reduction was 2.03 log10 CFU/g. Reductions were, however, not significantly different (P > 0.05) from control treatment (with air) which reduced the populations by 0.57 – 2.19 log10 CFU/g. The presence of surfactants during continuous sparging of water followed by pressurization at 12 psi was not beneficial. None of the treatments adversely affected the germination of the seeds.
HYGIENIC PARAMETERS, TOXINS AND PATHOGEN OCCURRENCE IN RAW MILK CHEESES
Authors: DE REU K. , DEBEUCKELAERE W. , BOTTELDOORN N. , DE BLOCK J. , HERMAN L.
Published: April 2007

In total, 71 samples of retail raw milk cheeses produced or imported in Belgium and samples of Belgian farmhouse cheeses were examined for cotiforms, β‐glucuronidase positive Escherichia coli, Escherichia coli O157, Staphylococcus aureus, Salmonella spp., Listeria spp. and Listeria monocytogenes. The presence of staphylococcal enterotoxins was investigated on samples with S. aureus counts higher than 103 cfu/g. The incidence of coliforms, β‐glucuronidase positive E. coli and S. aureus was higher in soft than in blue veined, semi‐hard, hard and fresh cheeses. Four mold‐ripened soft cheeses were positive for E. coli O157. One of the 4 cheeses was positive for verotoxin VT2. Staphylococcal enterotoxins were detected in 1 soft redsmear cheese, which was positive for L. monocytogenes. L. monocytogenes was also detected in one fresh cheese. Salmonella was not detected in any of the 71 raw milk cheeses.
EFFECT OF CHILLING AND FREEZING ON SURVIVAL OF VIBRIO PARAHAEMOLYTICUS ON FISH FILLETS1
Authors: VASUDEVAN PRADEEP , MAREK PATRICK , DAIGLE SCOTT , HOAGLAND THOMAS , VENKITANARAYANAN KUMAR S.
Published: April 2007

Vibrio parahaemolyticus is a foodborne pathogen isolated from coastal waters of the United States, and from seafoods including fish. No information is available on the viability of V. parahaemolyticus on raw, chilled and frozen fish. A three‐strain mixture of V. parahaemolyticus was inoculated on fish fillets (pH 6.4) to obtain a bacterial load of 104 (high) or 103 (low) CFU/fillet, and stored at 4C or 8C for 9 days or at – 18C for seven weeks. At 4C and 8C, and at both levels of inoculation, V. parahaemolyticus survived on the fillets for the entire duration of the study. However, there was a significant reduction (P < 0.01) in V. parahaemolyticus population on the fillets by 9 days of storage. In the frozen fillets, there was a sharp decline (P < 0.01) in the population of V. parahaemolyticus by day 5 of storage. Although chilling and freezing significantly (P < 0.01) inactivated high numbers of V. parahaemolyticus on fish, they cannot be relied upon as a method to reduce V. parahaemolyticus on fish, since the time and magnitude of reduction depends on the initial load of the pathogen and the storage temperature.
IN VITRO COMPARISON OF ANAEROBIC AND AEROBIC GROWTH RESPONSE OF SALMONELLA TYPHIMURIUM TO ZINC ADDITION
Authors: PARK S.Y. , WOODWARD C.L. , BIRKHOLD S.G. , KUBENA L.F. , NISBET D.J. , RICKE S.C.
Published: April 2007

Zinc supplemented diets have been used to provide zinc as a nutrient and higher concentrations have been used to induce molt in laying hens. It is not known if the zinc in these diets would inhibit Salmonella spp growth. This study examines the effects of zinc compounds on the growth of S. typhimurium poultry isolate under aerobic and anaerobic conditions. The aerobic growth response of S. typhimurium was determined either in tryptic soy broth (TSB) or minimal (M9) broth containing five different concentrations (0.67, 2.01, 3.35, 4.69, and 6.03% [wt/vol]) of either Zn acetate [Zn(C2H2O2)22H2O] or Zn sulfate [ZnSO47H2O] while anaerobic growth response was determined in M9 broth with or without reductants (L‐cysteine hydrochloride [C3H7NO2SHCl], and sodium sulfide [Na2S 9H2O]). Aerobic growth rates inhibited (P < 0.05) by Zn acetate than by Zn sulfate in TSB medium. The Zn source and concentration decreased (P < 0.05) aerobic growth response of S. typhimurium poultry isolate in M9 medium. The growth rates of S. typhimurium under anaerobic growth conditions were less responsive to Zn salts but were generally lower (P < 0.05) in the presence of reductant than in the absence of reductants at each concentration of Zn compound. The results in this study provide evidence that Zn may inhibit S. typhimurium under in vitro aerobic or anaerobic atmospheric conditions and S. typhimurium grows less optimally under anaerobic growth conditions.
EFFECTIVENESS OF CHLORINE AND NISIN‐EDTA TREATMENTS OF WHOLE MELONS AND FRESH‐CUT PIECES FOR REDUCING NATIVE MICROFLORA AND EXTENDING SHELF‐LIFE1
Authors: UKUKU DIKE O. , FETT WILLIAM F.
Published: April 2007

Efficacy of nisin‐EDTA treatments as a sanitizing treatment for reducing native microflora of whole melons and extending shelf‐life of fresh‐cut pieces was compared to chlorine treatments. Whole cantaloupe and honeydew melons were washed with water, nisin (10 μg/mL)‐EDTA (0.02 M), or 200 ppm chlorine for 5 min at ∼ 20C before fresh‐cut preparation and storage at 5C for 15 days with periodic microbiological sampling. In addition, some fresh‐cut pieces were washed with 10 μg/mL nisin‐EDTA or 50 ppm chlorine for 1 min before storage. Changes in appearance, odor, overall acceptability and the shelf‐life of the minimally processed fresh‐cut melons were investigated. Preliminary studies indicated that water washes, EDTA (0.002 to 0.2 M) or nisin (5 to 10 μg/mL) were not effective in reducing the microflora of whole melon when used individually. Nisin‐EDTA and chlorine treatments were significantly (P < 0.05) more effective in reducing native microflora than water washes. Nisin‐EDTA treatments were significantly (P < 0.05) more effective than chlorine in reducing populations of yeast and mold and Pseudomonas spp. on whole melon surfaces but were not as effective as chlorine treatments for reducing aerobic mesophilic bacteria, lactic acid bacteria and total gram‐negative bacteria. Microbial contaminants on fresh‐cut pieces washed with 50 ppm chlorine or nisin‐EDTA were further reduced. However, microbial populations increased throughout refrigerated storage irrespective of treatments. Odor, appearance, and overall acceptability ratings for cantaloupe and honeydew fresh‐cut pieces treated with nisin‐EDTA or chlorine were not significantly (P > 0.05) different from each other throughout the storage period (15 to 21 days). However, both treatments led to significantly (P < 0.05) improved ratings compared to the controls for the fresh‐cut pieces at 9 to 12 days of storage and thereafter. The results of this study suggest that treatments with nisin‐EDTA before and after fresh‐cut processing would improve the quality and extend the shelf‐life of fresh‐cut melon.
ANTIMICROBIAL PROPERTIES OF NISIN‐COATED POLYMERIC FILMS AS INFLUENCED BY FILM TYPE AND COATING CONDITIONS
Authors: LEUNG PATSY P. , YOUSEF AHMED E. , SHELLHAMMER THOMAS H.
Published: April 2007

Polymeric films were coated with nisin, an antimicrobial peptide, for potential application in shelf‐life extension of food. Five commercial packaging films with varying surface energies were compared. The highest antimicrobial activity was observed on the most hydrophobic nisin‐coated films (surface energy ± 32 dyne/cm). The binding affinity of nisin to the surface of ethylene acrylic acid copolymer (surface energy = 32 dyne/cm) was investigated. Films were coated in nisin solutions under varying conditions including nisin concentration, contact time, solution's volume to film area ratio, pH of coating solution and temperature during coating. Stronger nisin activity was detected on films as the coating time increased from 30 s to 2 h. Higher nisin coating concentration also promoted the binding of nisin to films with saturation level observed at 250 μg/mL. Films coated with nisin using a higher solution to film area ratio (0.84 compared to 0.14 and 0.28 mL/cm2) also exhibited higher nisin activity.