bluuebunny/crossref_metadata_2025 huggingface dataset:
THE LIPOLYTIC ACTIVITY OF SOME INDIGENOUS SPANISH MOLDS ISOLATED FROM MEAT PRODUCTS1
Authors: OCKERMAN H.W. , SÁNCHEZ F.J. CÉSPEDES , MARISCAL M.A. ORTEGA , LEÓN‐CRESPO F.
Published: May 2007

The fungi growth on Spanish ham surfaces is involved in flavor development. However, there is a lack of information about the metabolism of these molds. Five mold strains belonging to the Penicillium genera, isolated from Spanish ham surface, were used to evaluate their lipolytic activity in a meat substratum having a similar composition to that existing on the surface of this traditional Spanish product. The samples were held at different temperatures (3, 8 and 12C) and relative humidities (75%, 85% and 95%) during 30 days. The lipolytic activity of all mold strains was clearly affected by the time and temperature of incubation. P. camemberti strains have the highest acidity index (A.I.) among the molds tested. However, samples inoculated with P. chrysogenum showed the highest thiobarbituric acid index (TBA).
VISUAL ACCEPTABILITY AND CONSUMER PURCHASE INTENT OF ENHANCED PORK LOIN ROASTS
Authors: BREWER M.S. , JENSEN J. , PRESTAT C. , ZHU L.G. , MCKEITH F.K.
Published: May 2007

Pork loins were pumped to 0, 6, 12 or 18% over initial weight (0.4% sodium tripolyphosphate, 0.4% sodium chloride), and vacuum‐packaged. In retail supermarkets, consumers (n = 196) evaluated acceptability of color, purge in the package, texture appearance, overall appearance acceptability, and purchase intent. Seventy percent of these consumers were 26 to 55 years of age; 70% were female; 70% consumed pork at least twice per month, usually at home (>88%). More than 36% of the consumers would purchase “enhanced” pork, but expressed concern about ingredients on the label: phosphate (60%), salt (74%), and water (26%). Based on visual evaluation, 57% of the consumers “probably” or “definitely would buy” the unpumped product. The percentage of consumers rating loins in the higher two purchase intent categories decreased as pump level increased from 57% for 0% pump to 46% for 18% pump. Percentages of the ratings falling in the higher two categories for acceptability of liquid in the package decreased from 58% for 0% pump to 42% for 6% pump, and <37% for 12% and 18% pump.
TENDERNESS IMPROVEMENT OF BOVINE BICEPS FEMORIS MUSCLE BY CALCIUM CHLORIDE INJECTION
Authors: PAZOS A.A. , SALITTO V.A. , LASTA J.A. , BOLONDI A. , GUIDI S.M. , CARDUZA F.J. , GONZALEZ C.B.
Published: May 2007

Injection of 0.25 M calcium chloride solution in less tender muscles, such as Biceps femoris, from relatively old animals produced tenderness increase in a shorter aging time (2 days). Protein degradation obtained after submitting muscle samples to the combination of calcium treatment plus two days of aging, was comparable to the proteolysis observed after 7 days of aging (Light Microscopy, Transmission Electron Microscopy, Polyacrylamide Gel Electrophoresis). Consumers were not only able to detect the resulting tenderness increment but also preferred calcium treated samples. The practice of calcium treatment on this widely used muscle ‐which is less tender, or with tenderness inconsistencies‐ has a benefit for both the industry and consumers.
CHARACTERISTICS OF PORK WITH DOCOSAHEXAENOIC ACID SUPPLEMENTED IN THE DIET
Authors: MARRIOTT N.G. , GARRETT J.E. , SIMS M.D. , WANG H. , ABRIL J.R.
Published: May 2007

The omega‐3 fatty acid, docosahexaenoic acid (DHA) was added to the basal diet of market pigs at 0, 0.125 and 0.250 kg/pig for 22–42 days. There were three consecutive pens per block with 10 blocks for a total of 30 pens assigned to each treatment group. No differences were found in off‐flavor, juiciness, and overall flavor of the semimembranosus muscle and cured bacon among the three treatment groups. Furthermore, weight loss during storage and cooking did not differ among the three treatments. Objective evaluation results for oxidative rancidity did not differ between hams from control pigs and those from pigs receiving 0.250 kg/pig DHA. Shear force of cured bacon did not differ among the three treatments. These data suggest that DHA, when fed at 0.125 and 0.250 kg/pig, causes no adverse effects on carcass characteristics, sensory attributes, and tenderness of market size pigs.
LOCALIZATION OF PARATROPOMYOSIN IN CHICKEN SKELETAL MUSCLE MYOFIBRILS AND ITS BEHAVIOR DURING POSTMORTEM STORAGE OF MUSCLES REVEALED BY IMMUNOELECTRON MICROSCOPY
Authors: HATTORI A. , FUJIMOTO S. , NISHIMURA T. , TATSUMI R. , WAKAMATSU J. , ITO T.
Published: May 2007

Paratropomyosin is a minor myofibrillar protein which in freshly prepared myofibrils is exclusively localized at the A‐I junction region of sarcomeres. We investigated the ultrastructural localization of paratropomyosin in intact and postrigor myofibrils by immunoelectron microscopy. Paratropomyosin was localized as two distinct stripes at the A‐I junction in intact myofibrils. It also was localized at the position corresponding to the original A‐I junction in thick filament‐free myofibrils (I‐Z‐I brushes). However, following postmortem storage, paratropomyosin was found broadly distributed in thin filaments of myofibrils.
INFLUENCE OF LOW FAT FISHMEAL ON FATTY ACID COMPOSITION AND SENSORY QUALITY OF PORK
Authors: JONSDOTTIR R. , VALDIMARSDOTTIR T. , BALDURSDOTTIR B. , THORKELSSON G.
Published: May 2007

Four groups of growing‐finishing pigs, were fed low fat fishmeal together with an increased level of fish oil. Additional fish oil increased the content of long‐chain n‐3 fatty acids in subcutaneous fat and muscle when feeding up to 9 g fish oil kg‐1 diet. Sensory quality of fresh meat was not affected by the increased level of fish oil in diets but the intensity of off‐flavor/odor and rancid flavor/odor of fat increased after six months of frozen storage. Partial least square regression of rancid flavor/odor after six months of frozen storage using the significant variables C20:1, C20:5 (EPA), C22:5 (DPA) and C22:6 (DHA) in subcutaneous fat gave correlation coefficients as high as 0.92. Based on these results, the use of low fat fishmeal is acceptable but the content of fish oil should be limited to 3 g fish oil kg‐1 diet for growing‐finishing pigs.
GROWTH KINETICS of LISTERIA IN the PRESENCE of OXYRASETM ENZYME IN A BROTH MODEL SYSTEM1
Authors: YU LINDA S.L. , FUNG DANIEL Y.C.
Published: May 2007

The growth of Listeria monocytogenes and other Listeria species (L. innocua, L. ivanovii, L. seeligeri, and L. welshimeri) (initial inocula of 103‐103 CFU/mL) at 35C in the absence (as controls) or presence of OxyraseTM enzyme was studied using Fraser broth. the results showed that the generation times of these organisms ranged from 35.5 to 54.4 min for the studies with OxyraseTM and from 39.4 to 72.7 min for the studies without OxyraseTM. the degree of growth enhancement by OxyraseTM was dependent on species/strains of Listeria and population of inocula. an earlier initial increase in populations of three strains of L. monocytogenes at 35C was observed in Fraser broth with OxyraseTM added, and the lag phase durations computed for LM 101M, LM 103M, and Scott A were shown to be 3.2, 1.6, and 2.4 h shorter in the presence of OxyraseTM than in the controls. For the range of 0 to 0.8 unit/mL added OxyraseTM tested, the growth of L. monocytogenes demonstrated a dose‐response to the amount of OxyraseTM in the broth system.
USE of SPIRAL PLATER and LASER COLONY SCANNER FOR ENUMERATION of MICROORGANISMS IN MEAT1
Authors: MANNINEN M.T. , FUNG D.Y.C.
Published: May 2007

Microbial analyses of pork loin surfaces and minced beef samples were done using aerobic plate count (APC) and spiral plate (Spiral) methods and manual counting (MC) and laser counting (LC) procedures.

Connecting APC and Spiral techniques together was convenient, when analyzing pork surface swab samples. If APC plates were “too numerous to count,” Spiral plates could be used to get an estimation of the microbial numbers/cm2. Conversely when microbial numbers were too low for the Spiral technique, APC plates were easy to count.

Good correlation was found among Spiral and APC plates counted manually and with the laser for both sample materials. For minced beef samples, Spiral‐MC and Spiral‐LC methods gave higher numbers than APC‐MC (63% of samples) and APC‐LC (49% of samples) (not significant at 0.05 level). When APC and Spiral results for minced beef samples were analyzed, LC gave higher microbial numbers compared to MC: 65% of the APC‐LC results were higher than APC‐MC results (statistically significant at 0.05 level), and 56% of Spiral‐LC results were higher than Spiral‐MC results (not significant at 0.05 level). Most minced beef results by all combinations of methods (APC‐MC / APC‐LC / Spiral‐MC / Spiral‐LC) were within a ± 0.5 logarithmic range, and all were within a ± 1.0 range.
A METHOD FOR the DETERMINATION of STRANDEDNESS of DNA FRAGMENTS CLONED IN PHAGE M13
Authors: BHADURI SAUMYA
Published: May 2007

Recombinant M13Hol phage containing Eco R1 restriction endonuclease fragments B, E, and F of adenovirus type 2 (Ad2) DNA were constructed by cloning into the unique Eco R1 site of the replicative form of the phage M13Hol176 DNA. Polarity of the adenovirus inserts in recombinant molecules was deduced by the following procedures: Viral DNA fragments obtained from Ad2 DNA molecules were purified, denatured, and subjected to electrophoresis. the separated DNA strands were transferred from agarose to nitrocellulose by the Southern procedure and hybridized with radioactive 3′‐end labeled Hae III fragments of the recombinant phage DNAs. This procedure provided a rapid test for assaying strandedness of the cloned fragments.
EVALUATION OF OXYRASE METHOD FOR CAMPYLOBACTER ISOLATION FROM CHICKEN CARCASSES1
Authors: RABEN DENNIS , SLAVIK MIKE
Published: May 2007

One hundred fresh chickens were purchased from an area grocery store and assayed for campylobacters by comparing four different isolation methods. In all methods, recovery of campylobacter involved pre‐enrichment in broths for 18–24 h and selective plating for isolation. The four campylobacter isolation methods evaluated included: (1) FSIS method, (2) FDA‐BAM method, (3) modified FDA‐BAM method, and (4) oxyrase‐supplemented Brucella broth enrichment method. Each of the four methods detected campylobacters in over 90% of the chicken carcasses tested. The oxyrase method, however, was found to be more rapid and less labor intensive than the other three methods.
AUTOMATED 35S‐LABELLED PROTEIN ELECTROPHORESIS FOR IDENTIFICATION OF STRAINS OF RHIZOBIUM LEGUMINOSARUM bv. TRIFOLII
Authors: STONE C.E. , COOPER J.E.
Published: May 2007

A technique for strain‐level identification within a Rhizobium biovar is described, based on automated sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) of 35S‐labelled proteins, offering substantial improvements on existing SDS‐PAGE methods particularly in the areas of standardization of electrophoresis conditions and rapidity of positive identification. Gels were analysed with a β‐scanner, the beta particle emission data being directly relayed to an IBM PC/AT computer for subsequent manipulation. Analysis of the total protein profiles obtained by this method revealed regions of variability between strains of R. leguminosarum bv. trifolii. Automated comparison of these regions enabled identification of strains. The method was successfully used for identifying root nodule isolates obtained from competition studies between known pairs of R. leguminosarum bv. trifolii strains inoculated onto Trifolium repens.
DETERMINATION AND SIGNIFICANCE OF GENETIC DIVERSITY IN LISTERIA ISOLATED FROM FOOD AND ENVIRONMENT
Authors: PATEL T.R.
Published: May 2007

Listeriosis in humans and animals is caused by the opportunistic bacterium Listeria monocytogenes. The repeated outbreaks in 1980s have increased the interest in the epidemiology of the disease. The organism is widely distributed in the environment, and healthy carriers are found among humans and animals. It has been isolated from a variety of foods including chicken, cheese, milk, sausages, and smoked, fermented and marinated fish products.

The ubiquity of L. monocytogenes and risk to the target populations make study of the epidemiology of the etiological agent important. Phage and serotyping have been employed in conjunction with other methods in modern molecular biology to isolate, identify and type the various strains of L. monocytogenes. Information regarding the genetic diversity among different species of the genus Listeria and among the same species is lacking. This report attempts to address this problem.
INFLUENCE OF TEMPERATURE ON THE FATTY ACID PROFILE OF LISTERIA MONOCYTOGENES
Authors: JUNEJA V.K. , DAVIDSON P.M.
Published: May 2007

Variation in the fatty acid profile of two Listeria monocytogenes strains grown at varying temperatures was determined. The fatty acid profiles varied greatly at different temperatures. General decreases in relative percentages of branched and medium chain (up to C16:0) fatty acids and variable changes in long chain fatty acids were found with increasing growth temperature. Individual fatty acid percentages between strains were variable. The relative percentages of unknown long chain fatty acids, detected in both strains at various temperatures, were greatest in Scott A (7.07%) and ATCC 19114 (13.15%) at 35C. Results demonstrated that L. monocytogenes had altered fatty acid profile in response to changes in growth temperature.
FOOD GRADE OXYGEN REDUCING MEMBRANE BOUND ENZYMES 1
Authors: TUITEMWONG K. , FUNG D.Y.C. , TUITEMWONG P.
Published: May 2007

A commercial oxygen reducing membrane fraction obtained from Escherichia coli (OxyraseTM) has been shown in our laboratory to stimulate growth of many facultative anaerobic organisms, including starter cultures. The purpose of this study was to isolate “Food Grade” membrane fractions from Acetobacter xylinum and Gluconobacter oxydans and to compare their activities with the membrane fractions from E. coli prepared in our laboratory and Oxyrase. Cells were grown in afermentor, harvested by centrifugation, and disrupted by a French press (ca. 15,000 psi). The suspension was fractionated and filtered before use. The maximum activity of membrane fractions of Gluconobacter and Acetobacter were from cultures grown to 24 and 44 h, respectively. Formate, lactate, succinate, and α‐glycerophosphate were tested as H‐donors for enzyme activity. When lactate and α‐glycerophosphate were used as substrates, Acetobacter membrane fractions were able to deplete 100% oxygen in 5 min. It required 8 and 30 min, respectively, when succinate and formate were used. Gluconobacter membrane fractions were effective with lactate and α‐glycerophosphate. With succinate and formate, they took about 60 min or longer to reduce O2 completely. E. coli membrane fractions made in our laboratory depleted O2 more effectively (1 min) than Oxyrase (3–5 min) when formate was used as a H‐donor.
ACCELERATION OF YOGURT FERMENTATION BY BACTERIAL MEMBRANE FRACTION BIOCATALYSTS
Authors: TUITEMWONG K. , FUNG D.Y.C. , TUITEMWONG P.
Published: May 2007

Bacterial membrane fraction biocatalysts obtained from Escherichia coli (E‐8), Gluconobacter oxydans (Gox) and Acetobacter xylinum (Acx), as well as the commercial oxygen scavenger OxyraseTM, at concentrations of 0.1–2.0 U/ml effectively stimulated cell growth of Lactobacillus bulgaricus and Sreptococcus thermophilus, and lactic acid production during yogurt fermentation. The membrane fractions scavenged oxygen in the fermented milk to an optimal oxygen tension for growth of yogurt cultures. The yogurt culture populations with membrane fraction(s) increased faster than those without. Total counts in the presence of yogurts with Oxyrase, E‐8, Gox, and Acx were 0.5–1, 0.5, 1.5, or 1.2 log cycles, respectively, greater than counts of the control after 3 h of fermentation. The commercial membrane fraction Oxyrase reduced the fermentation time by 1 h needed to reach pH 4.5 compared to the controls, while E‐8, Gox, and Acx reduced time by about 0.5 h, 1.5 h and 1–1.5 h, respectively, depending on the membrane concentrations. The titratable acidity was corresponded well with the reduction in pH. Ratios of rods to cocci among the samples with and without membrane fraction supplementation were not different (P > .05). Each membrane fraction biocatalyst enhanced the depletion rate of dissolved oxygen in a yogurt mix differently.
RAPID DETECTION OF MYCOPLASMA INFECTIONS IN CHICKENS WITH A FLUORESCENCE CONCENTRATION IMMUNOASSAY 1
Authors: SLAVIK MICHAEL F. , TSAI HSIU‐CHUAN SONIA
Published: May 2007

Mycoplasma gallisepticum infection in chickens was detected with a fluorescence concentration immunoassay (FCIA) using intact mycoplasmal cells as the reacting particles. The antigen and test chicken antisera were directly pipetted into the wells of a 96‐well fluoricon assay plate and incubated 30 min at ambient temperature in the chamber of a fluorescence concentration analyzer. The antigen‐antibody bound complexes and free components automatically were separated by vacuum filtrations and washings through the membrane filter equipped at the base of the wells. Fluorescein isothiocyanate (FITC) was used as the tracer via FITC‐goat‐anti‐chicken IgG which was incubated with the above formed antigen‐antibody complexes in the wells for another 30 min. After the vacuum filtrations and washings, the fluorescent signal was read at a wavelength of 485/535 nm and was reported in a numerical arbitrary fluorescence unit (AFU). The positive cutoff AFU value was calculated by adding 2 standard deviations to the average AFU of the negative control. Samples with AFU above the cut‐off value were scored positive indicating the infection. It was found the FCIA method was comparable in sensitivity to the Agritech ELISA method and more sensitive than the serum plate agglutination (SPA) test or hemagglutination‐inhibition (HI) test. Forty‐seven/51 sera from M. gallisepticum inoculated chickens were scored positive using FCIA or ELISA methods, while 36/51 and 40/51 were indicated positive by HI and SPA tests respectively. The specificity of the FCIA assay using sera from M. gallisepticum inoculated chickens was shown to be comparable to the HI test. Cross‐reactivity occurred at 35%, 8% and 11% in SPA, HI and FCIA tests respectively. The FCIA assay can be completed in less than 2 h with a total of 24 samples including one negative control and one positive control sera assayed in one plate.
COMPETITIVE ENZYME IMMUNOASSAY FOR THE RAPID IDENTIFICATION OF SALMONELLA
Authors: TSANG RAYMOND S.W. , NIELSEN KLAUS H. , BALSEVICIUS SOPHIA , KELLY LINDA , KHAKHRIA RASIK , JOHNSON WENDY M.
Published: May 2007

A competitive enzyme immunoassay using a murine monoclonal antibody M105 directed against a genus‐specific epitope in the Salmonella lipopolysaccharide was used to identify over 200 strains of Salmonella submitted to the National Laboratory for Enteric Pathogens. The immunoassay rapidly identified 208 strains of Salmonella representative of subspecies I, II, IIIa, IIIb, IV, and V, including 89 different serotypes from 26 O serogroups. The competitive enzyme immunoassay did not give positive results with 3 strains of Citrobacter freundii and 4 strains of Escherichia coli which were submitted to our laboratory as suspect Salmonella.
A METHOD FOR ISOLATION OF CAMPYLOBACTER SPP. (JEJUNI, COLI AND LARI) FROM SHELLFISH AND THE MARINE ENVIRONMENT
Authors: ABEYTA CARLOS , KAYSNER CHARLES A. , HUNT JAN M. , WEKELL MARLEEN M.
Published: May 2007

A method has been developed to detect thermophilic species of Campylobacter in shellfish, marine and tributary waters, sediment and farm runoff by‐products such as manure and silage. The method consists of a 48 h enrichment incubation and subcultured to selective agars. Presumptive colonies confirmed with a latex agglutination (antibodies) to common flagellar antigens of C. jejuni, C. coli and C. lardi. Over an 8 year period, West Coast estuaries (Washington, Oregon, and California) were sampled, resulting in analysis of a total of 512 samples. Results suggest that Campylobacter spp. are well distributed in the marine environment. Two enrichment broths were compared for the recovery of campylobacters from environmental samples. The method described in the Food and Drug Administration Bacteriological Analytical Manual (FDA/BAM) (1984), was compared to a modified method. Use of the modified method described here resulted in higher recovery rates of Campylobacter spp. Recoveries of campylobacters from sediment, shellfish, and water were 10,13, and 28% higher for the modified method, respectively.
CYCLOHEXIMIDE AS A MEDIA AMENDMENT FOR ENUMERATING BACTERIAL POPULATIONS IN ANIMAL FEEDS
Authors: HA S.D. , PILLAI S.D. , MACIOROWSKI K.G. , RICKE S.C.
Published: May 2007

The present study was designed to evaluate cycloheximide as a potential media amendment for differential bacterial and fungal enumeration of animal feeds. The objectives of this study were to determine the effect of cycloheximide on bacterial growth rates and to evaluate its efficacy for the reduction of indigenous spreading fungi when enumerating bacterial populations in three types of feeds and after short or long‐term storage. Escherichia coli, Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes and Pseudomonas fluorescens were grown in tryptic soy broth containing cycloheximide to determine its effect on bacterial specific growth rates. Growth rates of B. cereus and S. aureus were significantly decreased by the addition of 600 and 1000 mg/L cycloheximide respectively, but other pure cultures were not significantly influenced by cycloheximide addition. Intrinsic bacterial populations from feed were not significantly affected by cycloheximide additions at concentrations from 10 to 300 mg/L, but the indigenous spreading molds from feeds were significantly decreased by these cycloheximide concentrations and were decreased below detection levels by 300 mg/L of cycloheximide. The addition of 300 mg/L of cycloheximide effectively eliminates fungal growth for accurate enumeration of bacterial populations in feeds.
EVALUATION OF CULTURE PROTOCOLS AND OXYRASETM SUPPLEMENTATION FOR ARCOBACTER SPP.
Authors: LIU X. , PHEBUS R.K. , FUNG D.Y.C. , KASTNER C.L.
Published: May 2007

Growth of Arcobacter butzleri was evaluated in Brain Heart Infusion broth incubated aerobically, microaerobically, and with OxyraseTM supplementation (anaerobically). At initial concentrations of101 to 103 cells/mL, A. butzleri populations reached 7.5 to 8.0 log CFU/ml in 48h at 37C in OxyraseTM ‐supplemented broth. The organism quickly declined in the other two systems to undetectable levels during the initial 24h of incubation. Only moderate population levels (ca. 3 log CFU/ml) could be detected in aerobic and microaerobic systems after 56h incubation. Growth of five Arcobacter spp. strains was evaluated at 30C in Brucella‐blood broth, modified Cary and Blair Transport Medium, and a biphase cultural system. Strains were inoculated at a level of ca. 103 cells/ml and incubated with and without OxyraseTM supplementation to the system for 36h. Both the Brucella‐blood broth and the biphase system supported good growth of the strains, with counts reaching ca. 8 to 9 log CFU/ml. Modified Cary and Blair Transport Medium was the least effective cultural system. OxyraseTM provided slight to moderate stimulation of growth for most strains.
RAPID METHOD FOR SCREENING THE TOLERANCE OF YEASTS TO ZINC (II) AND CHROMIUM (III)
Authors: BATIČ MARTIN , LENARČIČ DARJA , ŠTUPAR JANEZ , RASPOR PETER
Published: May 2007

Rapid screening of the tolerance of yeasts to zinc (II) and chromium (III) was performed by an agar diffusion test. A rapid and reliable procedure for the determination of metal ion concentration gradients on agar plates was developed. Different species of yeasts from the following genera were investigated: Arthroascus, Bulera, Dekkera, Debaryomyces, Dipodascopsis, Eremothecium, Candida, Hansenula, Kluyveromyces, Hormoacus, Geotrichum, Lipomyces, Pachysolen, Pichia, Saccharomyces, Schizosaccharomyces, Schizoblastosporion, Schwan‐niomyces, Sporobolomyces, Yarrowia, Torulaspora, Zygosaccharomyces and Williopsis. The experimental conditions were defined as a constant volume of malt agar 32 cm3, and a temperature of 29C. After periods of 24, 47 and 72 h, the concentration intervals of growth inhibition were determined, and the yeasts investigated were grouped in different classes according to their tolerance to Zn (II) and Cr (III). Yeasts were found to be tolerant to significantly higher zinc (II) concentrations in the malt agar medium (5.9 mM to 20 mM) in comparison to chromium (III) (1.5 mM to 6.9 mM). Yeasts showed inter‐ and intra‐generic differences in zinc (II) and chromium (III) tolerance.
RAPID IDENTIFICATION AND SEROTYPING OF SALMONELLA ENTERITIDIS
Authors: HOORFAR J. , THORNS C.J.
Published: May 2007

A latex agglutination kit for S. enteritidis was evaluated on 155 field isolates from 29 serotypes from Denmark, All but one of the S. enteritidis isolates were correctly identified by the kit, and none of the isolates of other serotypes tested were identified as S. enteritidis. The results indicate a very high degree of specificity and sensitivity for the SEF14 monoclonal antibody, which forms the basis of the test.
SURVIVAL OF AN UNIRRADIATED SALMONELLA TYPHIMURIUM MARKER STRAIN INOCULATED IN POULTRY FEEDS AFTER IRRADIATION
Authors: HA S.D. , JONES F.T. , KWON Y.M. , RICKE S.C.
Published: May 2007

The present study was designed to compare unirradiated Salmonella typhimurium survival during storage after inoculation in either irradiated or unirradiated poultry feed. The effects of irradiation (5 kGy) on the indigenous feed microflora and on the survival of marker strain of S. typhimurium contaminated after irradiation treatment were determined during 56 days of storage of either soybean meal (SBM) or meat and bone meal (MBM) based feeds. The initial aerobic bacterial populations were reduced more than 90% in both SBM (4.96 to 4.08 ± 0.03 log10 CPU/g feed) and MBM (5.12 to 3.90 ± 0.03) by irradiation. Irradiation treatment reduced the average fungal counts during 56 days of storage in both SBM (4.24 to 2.74 ± 0.03) and MBM (4.38 to 2.15 ± 0.03) containing feeds. However, unirradiated S. typhimurium populations inoculated after irradiation of the feed were not different in either irradiated or nonirradiated SBM and MBM based feeds. Therefore, the differences in fungal versus bacterial sensitivity among the feed types and storage times suggests that gamma irradiation can alter the makeup of indigenous microbial populations in feed but this does not appear to have a discernible influence on subsequent survival of unirradiated S. typhimurium added as a dry inoculum after irradiation.
DETECTION OF SALMONELLA SPP. CONTAMINATION IN RAW MATERIALS AND COSMETICS/PHARMACEUTICAL PRODUCTS USING THE BAXTM SYSTEM, A PCR‐BASED ASSAY
Authors: JIMENEZ L. , SMALLS S. , SCALICI C. , BOSKO Y. , IGNAR R. , ENGLISH D.
Published: May 2007

Abstract A system utilizing the polymerase chain reaction (PCR), the BAXTM, was compared and validated against standard selective/enrichment assays to detect the presence of Salmonella spp. in artificially contaminated samples of raw materials and cosmetic/pharmaceutical products. After a 24 h incubation in lactose broth or lactose broth with Tween 20, the inoculated samples were analyzed both by the BAXTM system and by standard enrichment/selective methods. Standard enrichment assays required 5–7 days to confirm the presence and identification of Salmonella typhimurium, while the BAXTM system reduced the detection time to 30 h. The BAXTM system allowed a faster quality control evaluation of those raw materials and cosmetic/pharmaceutical formulations that require Salmonella spp. screening.
DETECTION AND DEMONSTRATION OF INHIBITORY ACTIVITIES OF BACTERIOCINS BY ISOELECTRIC FOCUSING
Authors: ZHENG G. , SLAVIK M.F.
Published: May 2007

A technique utilizing isoelectric focusing (IEF) was developed and compared with a modified Bhunia's sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) method for directly detecting antimicrobial activities of inhibitory peptides or proteins (bacteriocins). In IEF, the gel containing separated peptide or protein bands was directly overlaid with indicator bacteria without any fixation or rinsing as done in the SDS‐PAGE method. The IEF gave clear zones of inhibition surrounding inhibitory bands. Bhunia's method was modified to reduce the time for fixation and rinsing, and a 15‐min fixation followed by 2‐h rinsing with dd H2O was determined to be necessary for a detection similar to the IEF. In addition, results of this study showed that denaturation of bacteriocins and, subsequently, failure to detect the presence of a bacteriocin could occur in the SDS‐PAGE analysis while little denaturation was observed in the IEF assay. Therefore, the IEF assay developed in this study was more rapid and less destructive as compared with the SDS‐PAGE method.
SUITABILITY OF SELECTIVE MEDIA FOR RECOVERY AND ENUMERATION OF SUBLETHALLY HEAT‐ AND ACID‐INJURED LISTERIA MONOCYTOGENES
Authors: WILLIAMS ROBERT C. , GOLDEN DAVID A.
Published: May 2007

The suitability of PALCAM and modified Oxford (MOX) agars for recovering sublethally heat‐ and lactic acid‐injured Listeria monocytogenes was investigated. L. monocytogenes LM101M, LM103M (meat isolates), and Scott A were suspended in tryptose phosphate broth (TPB), heated for up to 40 min at 54C, and surface plated onto tryptose phosphate agar (TPA), TPA + 4% NaCl (TPAS), PALCAM, and MOX. TPA and TPAS were used to determine total viable and sublethally injured populations, respectively. Heat‐injured LM103M was recovered in the highest numbers on all media, followed by Scott A and LM101M (P<0.01). TPA allowed best recovery of all test strains, followed by PALCAMand MOX which were not different, and TPAS (P<0.01). For acid‐injury studies, uninjured and heat‐injured (54C for 20 min) test strains were suspended in phosphate‐buffered TPB + 0.85% lactic acid (bTPBLA) at 25C for up to 24 h and plated as described above. Uninjured and heat‐injured L. monocytogenes were recovered better from bTPBLA on MOX than on PALCAM (P<0.05). Heat injured L. monocytogenes LM103M was recovered better than LM101M but similar to Scott A on MOX and PALCAM (P<0.05), whereas Scott A was recovered similarly to LM101M and LM103M on MOX and PALCAM (P>0.05). Acid‐injury of L. monocytogenes LM103M was enhanced by prior heat stress.
HANDS‐FREE, “POP‐UP,” ADHESIVE TAPE METHOD FOR MICROBIAL SAMPLING OF MEAT SURFACES
Authors: FUNG DANIEL Y.C. , THOMPSON LESLIE K. , CROZIER‐DODSON BETH ANN , KASTNER CURTIS L
Published: May 2007

Microbial contamination of food is a concern to both food producers and consumers. For the food production industry surface sampling of foods is one of the simplest ways to monitor the microbial load. The objective of this experiment was to investigate the feasibility of using the less expensive and quicker “Pop‐up” tape method instead of the conventional swab/rinse method for the microbial sampling of meat surfaces. An analyst can place the unit on the wrist and then use both hands to lay out all the necessary materials and take the sample with one hand. The “Pop‐up” tape method was able to measure microbial loads up to 2.2 log CFU/cm2 on meat surfaces. The conventional swab/rinse method was able to measure up to 8.3 log CFU/cm2 on meat surfaces. The correlation coefficient (R) between the two methods was 0.91 (n=42). These data show that the “Pop‐up” tape method is a viable alternative to other methods for estimating microbial surface contamination.
A REVIEW OF ANALYTICAL SEPARATION, CONCENTRATION AND SEGREGATION TECHNIQUES IN MICROBIOLOGY
Authors: PATEL PRADIP
Published: May 2007

There are several major factors responsible for accentuating the need for real‐time detection techniques for foodborne pathogens. These include: (1) the general upward trends in the reported statistics of food‐poisoning worldwide and emergence of foodborne diseases (e.g. Salmonella enteritidis, Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes and Yersinia enterocolitica); (2) the strict national and international food safety and hygiene regulations, including the US Pathogen reduction Act (e.g. setting zero tolerance classification by the USDA FSIS of E. coli O157:H7) and implementation of mandatory standards for microorganisms in the recent EEC directives for shell‐fish, dairy products and eggs; (3) and the progressive introduction of a range of quality assurance and quality management programs (such as BS 5750, ISO 9000 and TQM) to enhance the efficiency and streamline modern food production and distribution systems.

Increasing adoption of the HACCP approach to food production together with the recent information derived from a range of mathematical models for prediction of growth and survival of food‐poisoning microorganisms can effectively reduce the potential risks by microbial contamination. Microbiological testing should be considered in the context of properly evaluated and implemented safety assurance systems. The role of microbiological testing in relation to HACCP has been discussed and considered in detail elsewhere (Hall 1994).

Over the past ten years, a plethora of new methods for the microbiological examination of food has become available. The performance of these methods, outside of the originating laboratory, has to be effective and reliable, and this can only be assessed by proper validation of the methods. Validated methods are used by food control laboratories to analyze commodities to verify regulatory compliance. There are several international schemes available for validation of modem microbiological methodr, including AOAC International. IDF procedures, EMMAS and Microval (Anon. 1996). In order to produce consistently reliable data, a laboratory must ensure appropriate quality assurance measures are in place. These include filly documented methodr, proper trained laboratory staff and participation in a proficiency testing scheme, many of which are currently available.
APPLICATION OF A DOUBLE TUBE SYSTEM FOR ENUMERATION OF CLOSTRIDIUM TYROBUTYRICUM
Authors: SCHMIDT KAREN A. , THAKUR RENÉE HART , JIANG GUANCHENG , FUNG DANIEL Y.C.
Published: May 2007

Clostridium tyrobutyricum, a spore‐forming, gram‐positive, anaerobic bacterium, is considered to be the main organisms responsible for the late spoilage of cheese by gas formation. Most methods for detecting C. tyrobutyricum are based on spore germination and vegetative growth and take 4–7 days plus an identification step for confirmation. The purpose of this study was to develop a faster detection method using a Double Tube System. Because no selective medium is available for detection of C. tyrobutyricum, three media (Reinforced Clostridial, AC, and Tomato Juice) were compared using two strains of C. tyrobutyricum and one strain of C. sporogenes. Each 4 day‐old test strain was inoculated on duplicated plates of each agar that were then placed in anaerobic jars or in the double‐tube systems for 2–4 days at 30 or 37C. All three agars consistently supported growth of the test strains. Counts did not differ with incubation at 30 or 37C and were comparable using the conventional anaerobic jar or a Double Tube System. However, in the Double Tube System, colonies could be counted accurately at least 6 h earlier than on the plates in anaerobic jars.
EFFECT OF OXYRASETM ON THE METABOLIC PROCESSES OF LACTIC ACID BACTERIA IN FROZEN YOGURT MIX1
Authors: ORDONEZ GUSTAVO A. , FUNG DANIEL Y.C. , JEON IKE J.
Published: May 2007

The effect of OxyraseTM (a bacterial cell material containing oxygen‐reducing membrane fractions) on the metabolic processes of lactic acid bacteria during fermentation of a frozen yogurt mix was studied. Frozen yogurt mixes that were treated with 0.5 units of OxyraseTM per gram were inoculated with commercial culture organisms of Bifidobacterium bifidum, Lactobacillus acidophilus, and a mixed culture of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus and incubated at 40C for 8 h. Results showed that OxyraseTM significantly affected the development of titratable acidity (TA) and pH as well as the rates of bacterial growth. The TA increased from 0.23 to 0.87% with OxyraseTM during 8 h, whereas it increased only to 0.52% without OxyraseTM In the same period, pH decreased from 6.8 to 5.15 with OxyraseTM but only to 6.12 without OxyraseTM. In all cultures, OxyraseTM enhanced the bacterial growth rate (μ) and reduced generation time (g) (P < 0.05). The greatest effect of OxyraseTM on growth was observed with B. bifidum, followed by the mixed yogurt culture and L. acidophilus.
EFFICACY OF AN IMMUNO‐MAGNTIC SEPARATION SYSTEM FOR RECOVERING CRYPTOSPORIDIUM OOCYSTS FROM SOILS
Authors: McELROY WYNDI , CABELLO ELISSETTE , PILLAI SURESH D.
Published: May 2007

Studies were conducted to determine the efficacy of the commercially available immuno‐magnetic system by DynalTM to recover C. parvum oocysts from silty clay, sandy clay loam and clay soils. Each soil type was spiked with known numbers of oocysts and their recovery using percoll‐sucrose gradient centrifugation in combination with immuno‐magnetic separation system was evaluated. The recoveries varied significantly. The silty clay loam soil had the highest recovery ranging between 91% and 26%, while the sandy clay loam had the lowest recovery ranging between 30% and 2%. The results indicate that though the DynalTM IMS system is capable of recovering oocysts from soils, the recovery efficiencies can vary significantly.
A MEMBRANE SEPARATOR/BIOREACTOR COUPLED WITH ABSORBANCE MEASUREMENT FOR DETECTION OF Escherichia coli O157:H7
Authors: LIU YONGCHENG , YE JIANMING , LI YANBIN
Published: May 2007

A membrane separator/bioreactor system was developed for rapid detection of Escherichia coli O157:H7. The system consisted of a membrane separator/bioreactor (0.45 μm of the pore size) to separate the‐complexes of E. coli O157:H7 and alkaline phosphatase‐conjugated anti‐E. coli O157:H7 antibodies from the sample and to produce p‐nitrophenol through the enzymatic reaction (p‐nitrophenyl phosphate hydrolysis), and an optical detector for measuring the p‐nitrophenol absorbance at 400 nm. The membrane material and the flow rate of the substrate for the enzymatic hydrolysis had great effects on the absorbance of p‐nitrophenol. The optimum conditions for the enzymatic reaction were determined as 1.0 M Tris buffer, pH 8.0, and 0.1 M MgCl2 for this system. The detection range was 104± 107 CFU/mL with a relative standard deviation of 4.3 ± 14.2%, and whole procedure could be completed in 50 min without any enrichment and culture. Other bacteria such as Salmonella typhimurium, Campylobacter jejuni and Listeria monocytogenes had no significant interference with the detection of E. coli O157:H7.
DEVELOPMENT OF A PCR ASSAY SUITABLE FOR CAMPYLOBACTER SPP. MASS SCREENING PROGRAMS IN BROILER PRODUCTION
Authors: BANG DANG DUONG , PEDERSEN KARL , MADSEN MOGENS
Published: May 2007

Campylobacter is the most common cause of human acute bacterial gastroenteritis worldwide. In order to comply with the demands of consumers for food free of bacterial pathogens, a mass screening program for Campylobacter in Danish broilers has been carried out based on conventional bacterial culture techniques since 1998. However, using conventional culture methods is time consuming and laborious, and therefore a Polymerase Chain Reaction (PCR) Campylobacter detection assay suitable for mass screening of cloacal swab samples from broilers was developed. By comparing the PCR detection with conventional culture methods, significantly more samples were found positive for Campylobacter with the PCR method. The PCR method is rapid, sensitive and suitable for mass screening for Campylobacter in poultry. Using this PCR method Campylobacter can be detected within 15 h. Notably, the method can be applied to detect Campylobacter directly from chicken feces at the species level.
RAPID PURIFICATION OF SALMONELLA DNA IN MINCED MEAT AND DETECTION BY REAL‐TIME PCR
Authors: JENÍKOVÁ G. , JENSEN A.N. , DEMNEROVÁ K. , HOORFAR J.
Published: May 2007

Four rapid and simple DNA purification and sample treatment protocols were evaluated for detection of Salmonella enterica in spiked minced meat, using a fluorogenic 5’nuclease (TaqMan) PCR assay in an ABI‐Prism 7700 Sequence Detector. The detection limit with the single separation treatment of DNeasy was found to be 6–8 CFU in just 19 end‐point fluorescence (Ct) values, while this was 22 Ct for a combination of DNeasy and BactXtractor. Extraction by DNeasy resulted in Ct <22, indicating a detection limit of <10 Salmonella cells per 25g, when the samples were inoculated with Salmonella before the overnight preenrichment. The method is currently being adapted to a BioRobot 3000 platform. However, the use of paramagnetic beads (DNA Direct) resulted in poor and variable detection limit.
EFFECT OF SUPPLEMENTS ON CAMPYLOBACTER GROWTH IN ENRICHMENT MEDIA1
Authors: WONGLUMSOM WIJIT , FUNG DANIEL Y.C.
Published: May 2007

Supplementation of Niroomand and Fung broth (NFB) and Hunt broth (HB) with Oxyrase®, sheep blood, hemin or yeast extract for recovery of Campylobacter was evaluated. Five strains of C. jejuni and one strain of C. coli were cultured in HB with or without Oxyrase®, NFB with or without Oxyrase®, NFB without hemin, and NFB plus yeast extract without hemin. The HB without Oxyrase® was evacuated and flushed three times with mixed gas (5% O2, 10% CO2, and 85% N2) prior to incubation. The effect of blood in HB supplemented with Oxyrase® on the growth of Campylobacter was also examined. Hunt broth showed significantly better performance than NFB (p<0.05). Supplementation of 0.2% hemin and 0.6% yeast extract stimulated growth by up to 2 log CFU/mL depending on strains. Addition of 7% lysed blood enhanced growth of C. jejuni, and differences were significant at 6 h and 24 h of incubation. At 20 h of incubation, broth containing 0.6 units/mL of Oxyrase® yielded Campylobacter counts of 8.6 to 10.9 log CFU/mL, and the broth flushed with mixed gas provided counts of 9.4 to 11.0 log CFU/mL. No statistical difference (p>0.05) was found between the Oxyrase® method and gas replacement method at incubation times of 12h, 20h, 28h, and 36h for all strains tested. Dissolved oxygen levels of all enrichment media were less than 1.5 mg/L. Using Oxyrase® supplemented HB without the cumbersome gassing step provides a simple and time‐saving procedure for culturing Campylobacter jejuni and C. coli.
POTENTIAL RAPID BIOASSAY FOR ALIMET® USING A METHIONINE ESCHERICHIA COLI AUXOTROPH
Authors: FROELICH C.A. , DÍAZ I.B. ZABALA , RICKE S.C.
Published: May 2007

A potential rapid bioassay for methionine hydroxy analog (MHA) feed additive (ALIMET®) was examined using a methionine auxotroph E. coli strain. Bacterial cells were grown in minimal media containing a concentration range of 0 to 26.8 μM of either L‐methionine or MHA as ALIMET®. Increasing either methionine or MHA concentration increased the growth rate of the methionine auxotroph. The estimated substrate affinities for methionine compared to MHA were not significantly different (P > 0.13) and the maximum growth rate estimates were also similar (P > 0.34). Methionine and MHA standard curves yielded linear responses (R2= 0.96) to increasing concentrations of the respective substrate. Based on these results it appears that the E. coli methionine auxotroph would have potential utility for further development of a rapid bioassay of ALIMET®.
COMPARISON OF EGG‐YOLK‐FREE TRYPTOSE SULFITE CYCLOSERINE AND SHAHIDI‐FERGUSON‐PERFRINGENS MEDIA FOR ENUMERATION OF CLOSTRIDIUM PERFRINGENS IN MEAT PRODUCTS AND PEPTONE WATER USING FUNG'S DOUBLE TUBE METHOD1
Authors: SABAH J.R. , FUNG D.Y.C.
Published: May 2007

This study compared the ability of Clostridium perfringens to recover in Fung's Double Tube (FDT) system using either tryptose‐sulfite‐cycloserine without egg yolk (TSC) or Shahidi‐Ferguson‐perfringens (SFP) agar both in three typical meat products and peptone water. A three‐strain cocktail of C. perfringens spores (ATCC 10388, NCTC 8238, and NCTC 8239) was inoculated in each food system at three inoculum levels: 102, 104, and 106 cfu/g or mL. FDT system consists of a smaller glass test tube inserted into a larger glass test tube in which sample and agar have been poured. By inserting the inner tube, the agar squeezes between the exterior wall of the small tube and the interior wall of the larger tube to form a thin agar layer, which creates an anaerobic environment. Tubes are then incubated in aerobic incubators. There were no significant differences in enumeration of C. perfringens between the two media in any of the meat products and peptone water at any inoculation level. Thus, the use of SFP, which is less expensive and easier to prepare than TSC, is recommended as an alternative agar for analyses of C. perfringens in FDT system. Compared to the petri dish method, the FDT method generates greater anaerobiosis, is easier to prepare, more compact, and eliminates the need for an overlay and an anerobic chamber or jar. Combined together, the use of SFP in the FDT system provides an efficient, easy‐to‐use method that is less expensive than the conventional method to detect and enumerate C. perfringens in foods.
ADAPTATION OF A METHIONINE AUXOTROPH ESCHERICHIA COLI GROWTH ASSAY TO MICROTITER PLATES FOR QUANTITATING METHIONINE
Authors: DÍAZ I.B. ZABALA , FROELICH C.A. , RICKE S.C.
Published: May 2007

A rapid microtiter methionine assay was developed using a methionine auxotroph E. coli strain. The bacterial strain was first grown on rich media to promote extensive bacterial growth and the cells were depleted to exhaust all endogenous methionine. After depletion, cells were transferred to minimal media with increasing concentrations of methionine and microtiter plates were incubated at 37C for 6 h. Methionine microtiter standard curves yielded linear growth responses to increasing concentrations of methionine in the range of 0 to 26.8 μM. Addition of different antibiotic and antifungal agents to the media did not significantly alter the linear growth response observed in the microtiter assay. This microtiter plate E. coli methionine assay has potential as a rapid in vitro assay method for quantifying methionine.
DEVELOPMENT OF ARTIFICIAL NEURAL NETWORKS CAPABLE OF IDENTIFYING CRYPTOSPORIDIUM PARVUM OOCYSTS STAINED WITH 4′, 6 DIAMIDINO‐2‐PHENYLINDOLE
Authors: WIDMER KENNETH W.
Published: May 2007

Cryptosporidium parvum is a coccidian protozoan parasite capable of infecting a variety of mammalian hosts, and can cause gastro‐enteric disease within humans. C. parvum oocysts were stained with varying concentrations of 4′, 6 diamidino‐2‐phenylindole (DAPI). After microscopic observation, objects of interest were captured using a CCD color digital camera. The microscopic images were classified based on their DAPI stain properties as either DAPI positive or negative. Individual oocysts were cropped, converted to grayscale, applied to a binary threshold filter, and were further processed into a numerical data array. DAPI positive and negative images (100 each) were randomly removed for artificial neural network (ANN) testing. The remaining image data were used for ANN training using a commercially available software program. After training experimentation, a final network design was implemented possessing 95 input, 400 hidden, and 2 output neurons. Additional control image sets (ranging from 165 to 119 images) were collected to better ascertain ANN performance. These images consisted of DAPI positive oocysts and two types of DAPI negative images (either formalin treated oocysts or algal cultures). Selected ANN correctly identified, as a range, 82.4–93.8% of the DAPI positive oocysts, 97–98.2% of the DAPI negative oocysts, and 52.9–57% of the DAPI negative algal cells. The control image sets were unique data, never presented during ANN training. Because of this, combined with the high number of correct image identifications for certain image sets, ANN technology may provide a means to identify C. parvum oocysts through automated analysis.