bluuebunny/crossref_metadata_2025 huggingface dataset:
DEVELOPMENT OF STRESS AND SURVIVAL OF SALMONELLA TYPHIMURIUM ATCC 7136 IN A TAPIOCA SOYSTARCH PRODUCT CONTAINING POTASSIUM SORBATE
Authors: LaROCCO KATHLEEN A. , MARTIN SCOTT E.
Published: April 2007

The effects of reduced water activity and 0.1% sorbate on Salmonella typhimurium ATCC 7136 in a soy‐starch product were examined. The formulated product (final pH 6.7), was inoculated with cells to give a final concentration of approximately 2 × 106 cells/g. Ten gram samples were placed in a series of desiccators over saturated salt solutions and stored at either 22°C or 40°C. Water activities ranged from 0.79 to 0.97. Samples were withdrawn at prescribed intervals and appropriate dilutions made. A dual plating procedure was used to monitor growth (tryptic soy agar) and development of injury (Levine's Eosin Methylene Blue Agar supplemented with 2% NaCl and 0.05% sodium desoxycholate). Cells stored at 22°C remained viable longer at an aw of 0.79 than at aw values of 0.96 to 0.97. As storage time increased, cells were stressed at a faster rate at higher aw values. This effect was accelerated at 40°C and as storage time increased.
REGULATORY SIGNIFICANCE OF AEROMONAS IN FOODS
Authors: ARCHER DOUGLAS L. , KVENBERG JOHN E.
Published: April 2007

Aeromonas hydrophila and other Aeromonas spp. are commonly found in fresh water and in foods. Although their isolation from stools of persons with diarrhea has implicated them as a cause of diarrheal disease, these microbes have failed to produce disease, even at very high doses, in voluntary human feeding studies. The presence of A. hydrophila in foods destined for cancer patients is certainly contraindicated, but at present Aeromonas spp. should be considered putative causes of acute gastroenteritis in normal persons. However, regulatory action based on health concerns seems insupportable at this time.
DETERMINATION OF ETHYL CARBAMATE IN COMMERCIAL PROTEIN BASED CONDIMENT SAUCES BY GAS CHROMATOGRAPHY‐MASS SPECTROMETRY
Authors: HARTMAN THOMAS G. , ROSEN ROBERT T.
Published: April 2007

Commercially obtained protein based condiments, including soy sauces, were analyzed for the presence of ethyl carbamate (urethane) using combined gas chromatography‐mass spectrometry (GC‐MS). Samples were spiked with 100 parts‐per‐billion (ppb) of t‐butyl carbamate internal standard, extracted with methylene chloride and concentrated prior to GC‐MS analysis. For quantitation, the ratio of the pseudomolecular ions produced during isobutane chemical ionization (CI) at m/z 90 (ethyl carbamate) and m/z 118 (t‐butyl carbamate) were monitored by mass chromatography. Response factors for ethyl carbamate versus the internal standard were determined in both the electron ionization (EI) and chemical ionization modes. The CI mode was used for quantitation as it was more sensitive and interference free. Samples testing positive by CI‐MS were subsequently scanned by EI‐MS for confirmation of identity as the CI spectra did not contain fragment ions necessary for adequate specificity. This method proved simple and reliable with detection limits less than 1 ppb. Limits of confirmation were 10 ppb. The recovery of internal standard was 86.7%± 5.6%. Only fermented products were found to contain ethyl carbamate.
EFFECT OF SOME PRESERVATIVES AND FUNGICIDES IN ARRESTING FUNGAL INFESTATION OVER MARKETED BETEL NUT (ARECA CATECHU L.)
Authors: RAISUDDIN  , MISRA J. K.
Published: April 2007

Betel nut, a common masticatory, extensively chewed in India and other countries, is usually infested by a number of fungi. Many of them produce toxins. Attempts were made to control the fungal infestation of betel nuts by temperature treatment, and the use of preservatives and fungicides. Varying degrees of control of fungal infestation were seen. A temperature treatment of 60°C for 6 h totally inhibited fungi. Boric and propionic acids at 5% and 1%, respectively, were effective in completely suppressing the fungal growth on nuts in 4 weeks. Except for potassium metabisulphite, which inhibited fungal populations up to 80%, other salts at .5% to 1% inhibited fungal infestation 50 to 70%. Among the fungicides, Dithane M‐45 was quite effective at 0.2%, and was totally inhibitory at 5% in four weeks.
GAMMA IRRADIATION, HOT WATER AND IMAZALIL TREATMENTS ON DECAY ORGANISMS AND PHYSICAL QUALITY OF STORED NETTED MUSKMELON FRUIT
Authors: LESTER GENE
Published: April 2007

Nonchemical treatments of gamma irradiation (2 Kilograys) and hot water (57°C) and the fungicide imazalil (1000 ppm) were compared with and without shrink‐film wrap for effects on decay and physical quality of netted muskmelon fruit stored at 4°C for 0 through 60 days. Gamma irradiation was ineffective in controlling decay and surface molds, and injurious to physical quality by decreasing firmness, increasing fresh weight loss, membrane leakage and vein track browning. Hot water treatment coupled with shrink‐film wrap was effective in controlling decay activity and maintaining physical quality up to 20 days storage. Imazalil coupled with shrink‐film wrap controlled the incidence and severity of decay and maintained fruit firmness, moisture loss, membrane permeability and vein track browning for almost 60 days storage.
REDUCING MICROBIAL POPULATIONS ON BEEF TISSUES: CONCENTRATION AND TEMPERATURE OF LACTIC ACID
Authors: ANDERSON M.E. , MARSHALL R.T.
Published: April 2007

Cylindrical samples of beef semitendinosus muscle were dipped in inocula of diluted (1:8) fresh bovine manure or suspensions of Escherichia coli or Salmonella typhimurium. After air drying 15 min, samples were sanitized by dipping in lactic acid(0, 1, 2 or 3%)for 15 s at 25, 40, 55 or 70°C. The most effective treatment was dipping the lean beef muscle in 3% lactic acid solution at 70°C. In general, as the temperature of acid at each concentration was increased from 25 to 70°C, numbers of surviving test organisms were increasingly reduced. Overall, concentration was an insignificant variable at the higher temperatures but became significant as temperature was lowered. Treatment tended to affect aerobes most and E. coli least. Bacterial injury was shown to be a factor to be considered when conducting sanitizing studies.
EXTINCTION OF LISTERIA MONOCYTOGENES IN SINGLE‐STRENGTH ORANGE JUICE: COMPARISON OF METHODS FOR DETECTION IN MIXED POPULATIONS1
Authors: PARISH M. E. , HIGGINS D. P.
Published: April 2007

The FDA method of selective enrichment followed by selective plating on modified McBride agar was capable of detecting the presence of L. monocytogenes inoculated into a typical, commerical, reconstituted, single‐strength orange juice at the 100 cfu/mL level. The KOH shock treatment, formerly recommended in the FDA protocol, negatively affected recovery of Listeria at 100 and 101 levels in juice which also had a low background microflora (102 cfu/mL total count); however, KOH treatment was required for Listeria detection in juice which had high background microflora (108 cfu/mL). Two other protocols for detection of Listeria which utilized cold enrichment or different selective enrichment media were less effective than the FDA procedure due to heavy growth of background microflora. No Listeria was detected in 100 commerical orange juice samples from dairy and nondairy processors in geographically distinct areas of North America using the FDA method.
RESTAURATEUR REACTION TO IRRADIATED SHELLFISH
Authors: JAROSZ L. A. , TIMMER J. , RACH E. C.
Published: April 2007

Forty‐two restaurateurs in Wisconsin were interviewed to determine their awareness of food irradiation and use of shellfish. The restaurateurs were divided into control and test groups; the latter heard an explanation that favorably explained the process of food irradiation. This explanation had no effect (P< .05) on the reaction to six statements regarding food irradiation and contamination. Only 8% of all the respondents knew that the shellfish served in his/her restaurant were purchased from shippers listed on the approved interstate shellfish shippers’list. In addition, 24% of the respondents disagreed with the statement “I think that shellfish are carriers of organisms that can cause illness” and 57% had never heard of food irradiation. This pilot study showed that educational activities regarding food irradiation and shellfish purchasing and handling are needed for these important wholesale consumers of shellfish.
ANALYSIS OF DITHIOCARBAMATE AND NICKEL RESIDUES IN LETTUCE AND PEPPERS GROWN IN SOIL CONTAINING PHOTODEGRADABLE PLASTIC MULCH
Authors: WOLFE DAVID W. , BACHE CARL A. , LISK DONALD J.
Published: April 2007

Photodegradable plastic, which contains nickel and dithiocarbamates as active ingredients, controls weeds and conserves moisture during the growth of vegetables after which it may be plowed into the soil to decompose. Lettuce and green peppers were grown in the greenhouse and field in soil into which was incorporated photodegraded plastic at rates equivalent of up to 30 years of repetitive annual plastic use. Dithiocarbamate residues were not detectable in the harvested crop or soil samples. Residues of nickel showed no consistent differences between treated or control crop and soil samples.
DETERMINATION OF PIRIMIPHOS‐METHYL IN PASTA BY GAS CHROMATOGRAPHY/CHEMICAL IONIZATION MASS SPECTROMETRY
Authors: MATTERN GREGORY C. , WINSTON MARVIN , ROSEN JOSEPH D.
Published: April 2007

A method for the determination of pirimiphos‐methyl residues in pasta has been developed. The pesticide was extracted from pasta using the Luke procedure modified for low moisture, nonfatty food products. The extracts were analyzed by capillary column gas chromatography using an ion trap mass spectrometer in the chemical ionization mode as the detector. Quantification was performed using fluorene as the internal standard. The limit of detection was 0.005 ppm. Recoveries from spaghetti were 83.0% at the 0.100 ppm level and 93.3% at the 0.010 ppm level. Of 48 spaghetti samples analyzed, 38 contained detectable residues between trace (>0.005 ppm) and 0.180 ppm. Electron ionization (EI) was used to confirm residues as low as 0.016 ppm in more concentrated extracts.
TEMPERATURE SHIFT EFFECTS ON INJURY AND DEATH IN LISTERIA MONOCYTOGENES SCOTT A
Authors: SMITH J. L. , MARMER B. S.
Published: April 2007

Exposure of Listeria monocytogenes Scott A grown at 37°C to a 1 h heat treatment at 52°C resulted in little death of the cells (< 0.5 log). However, as the temperature of growth decreased, there was an increase in the extent of death (> 4 logs at 10°C growth temperature). Heat induced injury, however, decreased as the growth temperature decreased. Shifting L. monocytogenes grown at 10, 19, or 28°C to 37°C for periods up to 5 h led to cells with increased heat tolerance. However, there was little effect on injury by the shift‐up procedure. Presence of chloramphenicol during the shift‐up period inhibited the gain in heat tolerance. L. monocytogenes grown at low temperatures (< 28°C), were more susceptible to killing by heat, but this susceptibility could be lost if cells grown at low temperatures are given a short incubation at 37°C. The data obtained here suggest that if foods containing L. monocytogenes are temperature‐abused for even short periods, the organisms will acquire an increased heat tolerance and will require higher inactivation temperatures or longer processing times.
RAPID METHOD FOR DETECTION OF SALMONELLAE ATTACHED TO CHICKEN SKIN1
Authors: TSAI HSIU‐CHUAN SONIA , SLAVIK MICHAEL F.
Published: April 2007

A rapid, sensitive nitrocellulose membrane lifting technique was developed to identify Salmonella typhimurium attached to chicken skin. Basically, this method used a nitrocellulose membrane to remove salmonellae attached to chicken skin. The membrane with attached salmonellae was then incubated on xylose lysine deoxycholate (XLD) agar for 18 h at 37°C. Appearance of black colonies on the white membrane was considered a positive presumptive test for salmonellae. Immunostaining of colonies on the nitrocellulose membrane was then used to confirm presence or absence of salmonellae. This technique can be used to identify salmonellae contamination of chicken skin in less than 24 h and was shown to be more sensitive than presently used swabbing or washing techniques.
SHELF‐LIFE EXTENSION AND SAFETY CONCERNS ABOUT FRESH FISHERY PRODUCTS PACKAGED UNDER MODIFIED ATMOSPHERES: A REVIEW
Authors: REDDY N. R. , ARMSTRONG D. J. , RHODEHAMEL E. J. , KAUTTER D. A.
Published: April 2007

Shelf‐life and quality of fresh fishery products can be extended by the use of a modified atmosphere (MA) and high barrier film packaging coupled with refrigerated storage. MAs with elevated levels of carbon dioxide inhibit or slow the growth of various aerobic spoilage bacteria of fishery products by extending the lag phase. However, at the same time, MAs provide conditions for the growth of Grampositive bacteria and food pathogens within the package. The extension of the storage life of the refrigerated MA products may enable the slower‐growing Gram‐positive bacteria to reach high populations. The shelf‐life of fishery products packaged under MAs rich in carbon dioxide coupled with storage at 8.0°C or below can be extended more than 100%. Major safety concerns regarding the risk of foodborne botulism can result from MA packaging of fresh fishery products that contain the spores of nonproteolytic C. botulinum and are subsequently temperature‐abused. Minimizing the risk of foodborne botulism by including inhibitory factors such as antimicrobial agents before packaging fishery products under MAs and strict adherence to refrigerated storage temperatures are discussed.
N‐NITROSOPROLINE AND N‐NITROSOSARCOSINE IN ESTONIAN FOODSTUFFS
Authors: HAMBURG ANDRES , HAMBURG ANU
Published: April 2007

The N‐nitrosoamino acids (NNA) N‐nitrosoproline (NPRO) and N‐nitrososarcosine (NSAR) are precursors of the carcinogenic N‐nitrosamines. Methodology using gas chromatography for their determination and data on their contents in 52 food products are presented. Food products consisted of smoked meats (12), smoked (9) and boiled (11) sausage, cheese (10), fish (7) and beer (3). Results showed that NNA formed during processing, particularly in meat, where levels of NPRO were as high as 353μg/kg. The compounds accumulated in the adipose tissue and surface portion of the product. Smoking caused increased formation of NPRO, while the use of liquid smoke minimized it. NPRO in meat products in natural casings was higher than in synthetic ones, and frying of boiled sausage and hams further enchanced NPRO formation. Like meat, smoked cheese and fish showed consistently higher NNA levels than the non‐smoked products. These data indicate means of reducing NNA contents in foods by modification of processing techniques.
EFFECTIVENESS OF CARNOBACTERIUM PISCICOLA LK5 FOR CONTROLLING THE GROWTH OF LISTERIA MONOCYTOGENES SCOTT A IN REFRIGERATED FOODS1
Authors: BUCHANAN R.L. , KLAWITTER L.A.
Published: April 2007

The potential for controlling the growth of Listeria monocytogenes in refrigerated foods using Carnobacterium piscicola LK5, a bacteriocin‐producing strain originally isolated from raw ground beef, was studied using co‐culture techniques. Eight foods, including UHT milk, canned “all‐beef”dog food (cooked meat), raw ground beef, irradiation‐sterilized raw ground beef, chicken roll, pasteurized crabmeat, canned creamed corn, and frankfurters, were inoculated with 103 cfu/g L. monocytogenes Scott A, with and without 104cfu/g LK5, and incubated at 5 and 19C. Samples were removed periodically and assayed for total aerobic plate count using Brain Heart Infusion Agar and L. monocytogenes using Vogel‐Johnson Agar or Modified Vogel Johnson Agar. The growth of L. monocytogenes was suppressed in milk, dog food, crabmeat, creamed corn, and frankfurters stored at 5C. The microorganism was less inhibitory at 19C. In sterile raw ground beef, LK5 inactivated the pathogen at 5C and prevented its growth at 19C. No activity attributable to LK5 was observed in refrigerated nonsterile ground beef or chicken roll; however, these products did not support the psychrotrophic growth of the pathogen even in the absence of LK5. LK5 was most effective in products where the background microflora was reduced by either thermal processing or irradiation treatment. The results indicate that C. piscicola LK5 has potential as a means for preventing the growth of L. monocytogenes in a variety of refrigerated food products.
CONSUMER FOOD SAFETY CONCERNS AND INTEREST IN PESTICIDE‐RELATED INFORMATION
Authors: BRUHN CHRISTINE M. , DIAZ‐KNAUF KATHERINE , FELDMAN NANCY , HARWOOD JAN , HO GENEVIEVE , IVANS ERNESTINE , KUBIN LAUREL , LAMP CATHI , MARSHALL MARY , OSAKI SUSAN , STANFORD GWENDOLYN , STEINBRING YVONNE , VALDEZ ISELA , WILLIAMSON EUNICE , WUNDERLICH EVELYN
Published: April 2007

Consumer food safety concerns and interest in pesticide related information was measured by personal interviews with 479 consumers in 14 counties in California. Although concern about pesticide safety was noted by almost half of the respondents, nutritional considerations had the greatest impact on food selection criteria. Of those who volunteered pesticide safety concerns, 15% indicated they sought organic produce and 13% said they avoided or reduced produce purchases. In addition to information about the human health effects of pesticide use, consumers expressed high interest in the environmental effects of pesticide use. Consumers currently use television and newspapers as information sources and prefer these to other sources.
INHIBITION OF LISTERIA MONOCYTOGENES BY LACTOCOCCUS LACTIS SUBSP. LACTIS ISOLATED FROM ITALIAN RAW HAM
Authors: STECCHINI MARA LUCIA , AQUILI VALERIA , SARAIS ILEANA , PITOTTI ANNA
Published: April 2007

A total of 168 strains of lactic acid bacteria were isolated from Italian raw ham and screened for antagonistic activity against Listeria monocytogenes by using an agar spot assay. Only one strain of Lactococcus lactis subsp. lactis produced antagonistic effects other than inhibition by low pH and hydrogen peroxide. The proteinaceous nature of the compound produced by L. lactis B10 was demonstrated by its inactivation by proteolytic enzymes. The cell‐free culture super‐natants (filtered and heat‐treated) showed a bactericidal mode of action. Bacteriocin produced by L. lactis B10 was inhibitory to other lactic acid bacteria and one strain of Staphylococcus aureus, but not to the gram‐negative bacteria tested.
CONSUMER WILLINGNESS TO PAY FOR SAFER FOOD PRODUCTS1
Authors: SHIN SEUNG‐YOULL , KLIEBENSTEIN JAMES , HAYES DERMOT J. , SHOGREN JASON F.
Published: April 2007

Existing estimates of societal costs of food‐borne pathogens use only out‐of‐pocket expenses, such as hospital charges, and ignore the cost of (or willingness to pay to avoid) the pain and suffering associated with a food‐borne disease. This paper develops and implements a method to determine consumers’willingness to pay for safer food products. The results show that, for each meal that may be contaminated, participants in this study would pay 55 cents to eliminate Salmonella and 81 cents to eliminate Trichinella spiralis.
SEAFOOD ALLERGY: PREVALENCE AND TREATMENT
Authors: LEHRER SAMUEL B. , HELBLING ARTHUR , DAUL CAROLYN B.
Published: April 2007

Seafood is a common cause of food allergy. Allergic reactions are reported by consumers following ingestion of seafood meat and by processing workers after occupational exposure to seafood by inhalation of vapors generated during cooking. Although seafood allergy is commonly observed in clinical practice, its precise prevalence is not established. Based on our estimates, approximately 100,000 to 250,000 Americans are at risk of developing allergic reactions to seafood products. In this study, skin testing, in vitro assays and double‐blind, placebo‐controlled food challenge were employed to investigate seafood allergy in shrimp‐allergic individuals. As in most food allergy studies only 1/3 of the alleged shrimp‐sensitive subjects had a positive shrimp challenge test. The combination of a positive shrimp skin test and shrimp RAST (>11% bound) had the best predictive value (87%) for a positive challenge response. Although occupational seafood allergy is not well‐studied, based on a Canadian investigation, it can be estimated that 57,000 American seafood workers are at risk of developing work‐related allergic reactions. Since seafood is a major food allergen in consumers and industrial workers, further studies are necessary. Despite developments of new antiallergic therapies, avoidance continues to be the best “treatment”for allergic ingestive, inhalative and occupational disease.
RESPONSE SURFACE MODELS FOR THE EFFECTS OF TEMPERATURE, pH, SODIUM CHLORIDE, AND SODIUM NITRITE ON THE AEROBIC AND ANAEROBIC GROWTH OF STAPHYLOCOCCUS AUREUS 196E1
Authors: BUCHANAN R.L. , SMITH J.L. , MCCOLGAN C. , MARMER B.S. , GOLDEN M. , DELL B.
Published: April 2007

The effects and interactions of temperature (12–45C), initial pH (4.5–9.0), NaCl (0.5–16.5%), and sodium nitrite (1–200 μg/ml) on the aerobic and anaerobic growth of Staphylococcus aureus 196E were studied using 50 ml portions of Brain Heart Infusion Broth in 250ml unsealed and sealed trypsinizing flasks, respectively. The flasks were inoculated to a level of approximately 103 cfu/ml, incubated on a rotary shaker, sampled periodically, and enumerated on Tryptic Soy Agar. Growth curves were generated by fitting the data to the Gompertz function using nonlinear regression analysis. The general growth characteristics of S. aureus in response to the five environmental variables were similar to those observed by other investigators including (1) enhanced growth in the presence of oxygen, (3) ability to grow at high sodium chloride concentrations, and (3) dependence of the bacteriostatic activity of sodium nitrite on pH and oxygen availability. Supplemental studies indicated that growth kinetics were independent of inoculum size, which allowed the Gompertz A term to be treated as a constant. However, the maximum population density (MPD) achieved by the cultures was dependent on the independent variables, requiring that it be modeled in addition to the Gompertz B and M terms. The MPD was then used to calculate the Gompertz C term. Quadratic and cubic response surface models were generated using various data transformations. Quadratic models using and LN‐transformation provided reasonable predictions of the effects of the four variables on the growth kinetics of S. aureus, and should prove useful for providing initial estimates of the behavior of S. aureus in foods.
GROWTH OF LISTERIA MONOCYTOGENES, AEROMONAS HYDROPHILA AND YERSINIA ENTEROCOLITICA ON COOKED MUSSEL TISSUE UNDER REFRIGERATION AND MILD TEMPERATURE ABUSE
Authors: HUDSON J. ANDREW , AVERY SHERYL M.
Published: April 2007

Strains of the psychrotrophic bacteria Listeria monocytogenes, Aeromonas hydrophila and Yersinia enterocolitica were inoculated onto samples of cooked mussel tissue and incubated at 5 and 10C under both aerobic and anaerobic conditions. These organisms were enumerated over a time course and data were analyzed to give values for the lag and generation times. All species grew under all conditions, and the rate of growth was similar under aerobic and anaerobic incubation. Predicted growth kinetic values from response surface models and measured growth rates for L. monocytogenes and A. hydrophila were in reasonable agreement, but similar comparisons for Y. enterocolitica gave shorter predicted lag and generation times than were measured. A combination of models from different sources would have given more accurate predictions than any one individual model.
INHIBITION OF STAPHYLOCOCCUS AUREUS IN BUFFER, CULTURE MEDIA AND FOODS BY LACIDIN A, A BACTERIOCIN PRODUCED BY LACTOBACILLUS ACIDOPHILUS OSU133
Authors: LIAO CHII‐CHERNG , YOUSEF AHMED E. , CHISM GRADY W. , RICHTER EDWARD R.
Published: April 2007

Thirty seven strains of lactobacilli and leuconostocs were screened for bacteriocin production. A bacteriocin‐like substance (designated lacidin A) was detected in culture filtrate of Lactobacillus acidophilus OSU133. Lacidin A inhibited Enterococcus faecalis, L. acidophilus, Lactobacillus delbrueckii subsp. lactis, and Staphylococcus aureus. The bacteriocinogenic nature of lacidin A was confirmed by eliminating the inhibitory effects of acid, hydrogen peroxide and phage and by loss of activity upon hydrolysis with proteolytic enzymes. The bacteriocin is relatively heat‐stable and has considerable bactericidal action against S. aureus in phosphate buffer. Lacidin A also demonstrated bacteriostatic action against S. aureus in brain heart infusion and heat‐treated milk and liquid whole egg.
MATHEMATICAL MODELING OF MICROBIAL GROWTH: A REVIEW
Authors: SKINNER GUY E. , LARKIN JOHN W. , RHODEHAMEL E. JEFFERY
Published: April 2007

The use of mathematical modeling of microbiological behavior to predict and evaluate food safety or shelf life is receiving considerable interest. Researchers are attempting to use mathematical equations that incorporate such critical growth factors as pH, aw, and NaCl content to predict microbial growth and/or toxin production in order to replace traditional time‐intensive challenge studies. Predictive equations can be divided into probabilistic, regression, Arrhenius, and square root models. Models vary greatly in theory and complexity. Predictive models are used to monitor processes ranging from temperature during distribution to inventory control. They have been shown to be useful in product development and shelf‐life estimation when safety is not an issue. Most models are generated by regression analysis of data obtained from laboratory experiments. Statistically based models, even when conservatively derived, are not appropriate as the only criterion for evaluating food safety.
ENRICHMENT OF SEVERELY AND MODERATELY HEAT‐INJURED LISTERIA MONOCYTOGENES CELLS
Authors: WANG SHU‐YING , HITCHINS ANTHONY D.
Published: April 2007

Recovery of injured cells of a 90% heat kill of Listeria monocytogenes strain Lm82 in Trypticase soy yeast extract broth (TSBYE) at 30C was determined in enrichment broth and modified enrichment broth. Although the surviving population was heterogeneous with respect to degree of damage, two fractions of surviving cells defined as moderately and severely damaged were considered. Progeny of moderately damaged survivors (NaCl‐sensitive but not enrichment medium‐sensitive) increased about 100‐fold in 5 h; severely damaged cells (enrichment medium‐ and NaCl‐sensitive) did not grow in this time period. Most of the severely damaged cells required 20 h or longer to recover in TSBYE and even longer in TSBYE plus selective agents. Recovery was accelerated either by adding sodium pyruvate or by reducing the oxygen level. The results were used to design a Mark I preenrichment/enrichment protocol based on the U.S. Food and Drug Administration's selective enrichment broth.
SHELF‐LIFE EXTENSION BY PHENYLGLYOXAL OF CLOSTRIDIUM SPOROGENES‐INOCULATED VACUUM‐PACKAGED GROUND BEEF
Authors: BOWLES BOBBY L. , MILLER ARTHUR J.
Published: April 2007

Phenylglyoxal (PG), an aromatic α‐dicarbonyl, is used in a variety of industrial, medical, and biological research applications. The compound delays spore germination and inhibits vegetative cells of both aerobic and anaerobic sporeforming bacteria, interacts with several critical bacterial growth factors, and is structurally similar to a number of approved food flavoring agents. Previous research demonstrated inhibitory activity against Clostridium sporogenes in model systems. Therefore, we investigated the shelf‐life enhancing effectiveness of PG in C. sporogenes‐inoculated vacuum‐packaged ground beef at 32C. During extended incubation under temperature abuse conditions, PG delayed undesirable color changes and prevented organoleptic spoilage. Five μg PG/g inhibited proteolysis, while 156 μg PG/g delayed conversion of myoglobin to metmyoglobin, prevented H2S production, maintained product quality and texture for 25 days, and reduced thermal resistance of C. sporogenes spores at 90C. The observed activity of PG suggests that similar activity might be found with currently approved α‐dicarbonyls. Furthermore, the compound's effect on thermal resistance may serve as an example of compounds that could be used to reduce thermal processing requirements of heat‐sensitive and/or minimally processed foods.
INFLUENCE OF LACTIC ACID AND MODIFIED ATMOSPHERE ON THERMAL DESTRUCTION OF LISTERIA MONOCYTOGENES IN CRAWFISH TAIL MEAT HOMOGENATE1
Authors: DORSA WARREN J. , MARSHALL DOUGLAS L.
Published: April 2007

Precooked homogenized crawfish tail meat was inoculated with Listeria monocytogenes, treated with lactic acid, and packaged in various atmospheres for D value determinations at 60C. D60 values using 0.0, 0.5, 0.75, and 1.0% lactic acid (LA) treated meat were 4.68, 4.41, 3.46, and 2.49 min, respectively. LA increased sensitivity of L. monocytogenes to heat but this was not solely due to a reduction of pH. Sensory analyses of odor, color, taste, and texture of uninoculated whole crawfish tail meat demonstrated no significant differences (P > 0.05) between LA treated samples and controls. D60 values for the bacterium in crawfish tail meat homogenate packed in air, O2, CO2, or N2 were 10.58, 9.22, 11.68, or 12.97 min, respectively, which were not significantly different (P > 0.05). When 1% LA was added, significant decreases (P < 0.05) in D60 values were observed in each packaging atmosphere. Similar (P > 0.05) D60 values for crawfish tail meat treated with 1% LA and packed in air, O2, CO2, or N2 were 3.44, 3.88, 3.48, or 3.08, respectively. These results show that heat treatments of 60C were lethal to L. monocytogenes in packaged crawfish tail meat homogenate regardless of package atmosphere. Additionally, LA increased the lethality of heat to the bacterium in all tested package atmospheres.
EFFECT OF POLYPHOSPHATES AND NaCl ON AEROMONAS HYDROPHILA K144
Authors: PALUMBO SAMUEL A. , CALL JEFFREY E. , COOKE PETER H. , WILLIAMS AARON C.
Published: April 2007

Polyphosphates are multifunctional ingredients added to many foods, particularly meat products. In addition to their moisture‐binding properties, polyphosphates have been reported to inhibit various bacteria. In the current study, four food‐grade polyphosphates were evaluated for their effects on the growth of Aeromonas hydrophila K144 in both a model system and a food system. Since polyphosphates can interact with other food factors, effect of these compounds were studied at different NaCl levels and temperatures. The model system was BHI Broth modified by the addition of polyphosphates (sodium pyrophosphate, sodium tripolyphosphate, Hexaphos, or Sodaphos) and NaCl; incubation was aerobic at 5 or 28C. The food system was ground pork with NaCl and polyphosphate added and inoculated with A. hydrophila. Individually, the polyphosphates were relatively noninhibitory in both BHI broth and ground pork, but NaCl and temperature interacted with the polyphosphates in the model system to increase generation and lag times of A. hydrophila. In BHI broth, a combination of 2% of any of the polyphosphates tested and 3.5% NaCl inactivated the bacterium; this inactivation was temperature‐dependent. By both a plating system and electron microscopy, the polyphosphate‐NaCl combination was shown to injure the bacterium. In the ground pork, the polyphosphate‐NaCl combination limited growth of the bacterium during refrigerated storage. These results suggest that polyphosphates could be useful to control the presence of A. hydrophila in certain foods.
CHARACTERIZATION OF AEROMONAS SPECIES ISOLATED FROM FOOD
Authors: RASHAD FERIAL M. , ABDEL‐KAREEM HUSSEIN
Published: April 2007

Characterization of ten Aeromonas spp. isolates from local foods and A. hydrophila ATCC 7965, revealed that all strains of A. hydrophila, A. sobria and one strain of A. caviae showed strong hemolytic activity. All of them were protease producers except one A. caviae strain. Some A. hydrophila and A. caviae strains fermented lactose, coagulated milk and reduced litmus. The majority of strains were resistant to at least 5 of 14 antibiotics tested. All the strains grew over the range of 5–42C except those of A. caviae which failed to grow at 42C. Frozen storage at ‐16C greatly decreased the viability of the tested strains. Radiation D10values of strains ranged from 0.109–0.253 kGy in nutrient broth and increased when some strains were irradiated in ground meat at room temperature. Both strains of A. hydrophila (ATCC andFI), A. sobria FI and A. caviae FI grew normally in the presence of 1 and 3% salt. Only A. hydrophila FI tolerated 6.5% salt. These four strains were able to grow in the presence of 0.05–0.3% potassium sorbate at pH 7.0, while at pH 5.0 the presence of sorbate prevented their growth.
INFLUENCE OF MODIFIED ATMOSPHERE PACKAGING ON GROWTH OF CLOSTRIDIUM PERFRINGENS IN COOKED TURKEY
Authors: JUNEJA VIJAY K. , MARMER BENNE S. , CALL JEFFREY E.
Published: April 2007

Clostridium perfringens containing samples of sterile ground turkey were studied to assess growth under modified atmosphere conditions. Samples were packaged under various atmospheres (CO2/O2/N2: 75/5/20, 75/10/15, 75/20/5, 25/20/55, 50/20/30), stored at 4, 15 and 28C, and sampled periodically for growth. Diluted samples were plated on Shahidi Ferguson perfringens agar (Difco Laboratories, Detroit, MI) to determine vegetative cell counts. Temperature abuse (cyclic and static) of the turkey product was also investigated. The results showed that the growth of C. perfringens was slowest under 25–50% CO2/20% O2/balance N2 at 15 and 28C. There was no growth at 4C for up to 28 days. Temperature abuse (28C storage) of refrigerated products for 8 h did not permit C. perfringens growth. Use of 25–50% CO2/20% O2/balance N2 may extend the shelf‐life of turkey, but in the absence of proper refrigeration, it cannot be relied upon to eliminate the risk of C. perfringens food poisoning.
THERMAL RESISTANCE OF BACILLUS CEREUS SPORES AS AFFECTED BY ADDITIVES IN THE RECOVERY MEDIUM
Authors: GONZÁLEZ ISAAC , LÓPEZ MERCEDES , MAZAS MARGARITA , GONZÁLEZ JOSEFA , BERNARDO ANA
Published: April 2007

The effects of the addition of starch, glucose, sodium chloride, sodium citrate, monopotassium phosphate and disodium phosphate to the recovery medium on apparent heat resistance of Bacillus cereus spores (ATCC 4342, 7004 and 9818) were investigated. Sodium citrate, monopotassium and disodium phosphate at concentrations of 0.1% were effective inhibitory agents for heat injured B. cereus spores especially for strain 9818, although only monopotassium and disodium phosphate caused a significant reduction (p < 0.05) in D‐values obtained for strain 9818. Sodium chloride also had a marked effect on the recovery of heat injured spores. Concentration as low as 0.5% caused a significant reduction in the recovery rates for strains 9818 and 7004. In all cases, increasing the salt levels from 0.5 to 4% resulted in a progressive decrease in spore recovery. D‐values gradually decreased as the salt content increased, although the concentrations which produced statistically significant differences (p < 0.05) varied among strains. The addition of starch at 0.1% resulted in a significant increase in the counts for strains 9818 and 7004. In contrast, glucose (0.1%), did not significantly modify the counts obtained Neither of these compounds affected decimal reduction times. No statistical significance (p>0.05) differences were detected among z‐values for the spores of the three strains recovered in the presence of different additives assayed. z‐Values ranged from 6.67 to 8.32, with a mean value of 7.56 ± 0.46C.
THE EFFECTS OF CHEMICAL PRESERVATIVES AND PASTEURIZATION ON THE MICROBIAL SPOILAGE AND SHELF‐LIFE OF KUNUN‐ZAKI
Authors: EFIUVWEVWERE B.J.O. , AKOMA O.
Published: April 2007

“Kunun‐zaki” was produced using pasteurization alone or in combination with chemical preservatives. Diverse microbial genera (Lactobacillus, Bacillus, Aspergillus and Saccharomyces) dominated the untreated control samples but only two microbial genera (Bacillus and Lactobacillus) were isolated from the samples subjected to preservation treatments with Lactobacillus being the predominant genus. The effects of pasteurization alone were comparable to the combined effects of pasteurization and chemical preservative treatments in reducing microbial populations. Of all the treatments, sodium benzoate (0.08% w/v) with pasteurization was most effective, reducing the total viable counts by approximately 4.5 log at the end of the storage period. In contrast, the combination of potassium sorbate (0.06%w/v) with pasteurization was least beneficial, resulting in only 2.6 log reduction. Shelf‐life (based on sensory overall acceptability and microbial quality) of the samples varied with the treatments, but combination of 0.08% w/v sodium benzoate with pasteurization extended the shelf life by approximately 4 days whereas samples pasteurized without preservatives showed marginally enhanced shelf‐life of about 2 days. However, untreated control samples exhibited remarkably high microbial loads and were virtually unacceptable 24h after production. Pasteurization alone would therefore be adequate for small scale production and commercialization.
RECOVERY OF ESCHERICHIA COLI FROM POTENTIALLY LETHAL RADIATION DAMAGE: CHARACTERIZATION OF A RECOVERY PHENOMENON
Authors: LUCHT L. , BLANK G. , BORSA J.
Published: April 2007

The recovery of Escherichia coli ATCC 11775 following irradiation in phosphate buffer at OC was assessed using a two‐stage incubation protocol. In the first stage survivors were recovered on basal yeast extract agar (BYEA) plates and incubated at 18C (18C‐resuscitation) for specified time intervals (0 to 48 h). In the second stage, the incubation temperature was increased to 37C and the survivors were incubated for an additional 24 h to promote colony development. Controls consisted of survivors which were directly incubated at 37C on BYEA for time intervals equivalent to the total times used in the two‐stage incubation protocol. The ratio of colony‐forming units obtained with and without (control) the 18C‐resuscitation protocol was used to calculate recovery factors (RF). Depending on the applied dose, RFs ranged from ca. 2.5 (0.44 kGy) to 15–18 (0.76 kGy) following an optimal resuscitation time of 24–28 h. Irreparable damage, incurred by incubating survivors directly at 37C (37C‐damage) for 10 min prior to their recovery using the two‐stage protocol, was minimal regardless of dose; however, extending 37C‐damage to 60 min decreased RFs by ca. two‐thirds. RFs for cells increased from 1.6 to 375 following irradiation at 0.25 and 0.53 kGy, respectively. In ground beef, RFs for cells treated at the highest dose (1.50kGy) increased by ca. 100‐fold following 18C‐resuscitation. In contrast, the 18C‐resuscitation protocol exhibited minimal effects when E. coli was irradiated in trypticase soy broth. Survivor levels for E. coli following either gamma or electron beam irradiation appeared similar; however, both appeared higher following the 18C‐resuscitation protocol.
INFLUENCE OF MOISTURE CONTENT AND STORAGE TEMPERATURE ON THE PRODUCTION OF AFLATOXIN BY ASPERGILLUS FLAVUS EA‐81 IN MAIZE AFTER EXPOSURE TO GAMMA RADIATION
Authors: HASSAN ATEF AHMED , AZIZ NAGY HALIM
Published: April 2007

The effect of gamma radiation on aflatoxin production by Aspergillus flavus EA‐81 in maize with different initial moisture levels was determined over a 15‐day period. The viability of A. flavus on maize decreased over time with increasing moisture contents and storage at 8C. After 45 days at 28C, levels of viable conidiospores of A. flavus increased from 4.5 × 107 to about 3.0 × 108 per gram of maize. Levels of aflatoxin B1 produced by A. flavus were 10 μg kg‐1 in the maize stored at 8C after 45 days. Production of aflatoxin was highest at 40% moisture and 28C. Irradiation of 1.0 or 2.0 kGy greatly reduced the level of mold growth relative to unirradiated controls. A dose of 4.0 kGy eliminated all viable fungi. Aflatoxin B1 production decreased with increased levels of irradiation and was negligible at 4.0 kGy. When maize was inoculated after irradiation and stored, the spore counts and aflatoxin levels were higher than in unirradiated and inoculated controls after 30 days. Apparently, the natural competitive microflora prevented growth and thus limited higher concentrations of aflatoxin in maize.
HEAT RESISTANCE IN DIFFERENT HEATING MEDIA OF LISTERIA MONOCYTOGENES ATCC 15313 GROWN AT DIFFERENT TEMPERATURES
Authors: PAGÁN R. , MAÑAS P. , ALVAREZ I. , SALA F.J.
Published: April 2007

This paper examines the influence of growth temperature on thermal resistance of Listeria monocytogenes ATCC 15313. Regardless of the incubation temperature, the heat resistance of Listeria monocytogenes increased during incubation until the stationary phase of growth was reached. The maximum heat resistance of cells grown at 4C, 20C or 37C was attained after 14 days, 36 h and 18 h of incubation, respectively. After longer incubation times the heat resistance of cells grown at 4C and 20C did not change but that of cells grown at 37C decreased. The maximum heat resistance was usually greater at higher incubation temperatures. However, the magnitude of these differences depended on the pH and composition of heating media. By raising the incubation temperature from 4C to 37C, the D62 value in pH 7 citrate‐phosphate buffer increased from 0.13 to 0.34 min. However, when skimmed milk was used as menstruum this difference was not observed. Cells grown at 37C attained maximum heat resistance at pH 7 but those grown at 4C, at pH 6. The magnitude of the effect of the incubation temperature on heat resistance was constant at all heating temperatures tested (z = 6 ± 0.8C). The higher heat resistance of cells grown at higher temperatures was not due to a greater capacity of heat damage repair
SOURCES OF CONTAMINATION DURING SLAUGHTER AND MEASURES FOR CONTROL
Authors: SHERIDAN J.J.
Published: April 2007

This paper is concerned with processes and procedures involved in the contamination of beef, lamb and pork carcasses during slaughter. The hides of beef and the fleece of sheep are major sources of carcass contamination. The spread of pathogens from beef hides to the carcass, operatives and surfaces in the abattoir is demonstrated. Efforts to clean the hide of cattle and the fleece of sheep are outlined, with reference to the success of these treatments in reducing carcass contamination. The effect of bringing very dirty or dungy animals to slaughter is considered in terms of the effect on carcass contamination after slaughter. The influence of tying the bung (or rectum) in reducing carcass contamination is discussed, as is the use of plastic bags as an additional control in preventing pathogen spread on pig carcasses. The relationship of this revised procedure in reducing the occurrence of yersiniosis in Norway is shown. The use of a commercially automated system to tie beef bungs is discussed in relation to reducing carcass contamination. A comparison between the removal of faecal contamination on carcasses by trimming or using a new steam‐vacuumized system is presented. The effect of preevisceration washing of beef carcasses is described and the rationale relating to bacterial removal using this treatment is discussed. The influence of evisceration as a source of carcass contamination is demonstrated in relation to sheep slaughter. The processes of carcass decontamination using washing with water at different temperatures, steam pasteurization and hot lactic acid are compared in relation to their ability to remove bacteria from beef carcass surfaces. Finally, the effect of line speed and the impact of technology advances on beef and sheep carcass contamination is reviewed.
SPOILAGE AND HISTAMINE IN WHOLE PACIFIC HERRING (CLUPEA HARENGUS PALLASI) AND PINK SALMON (ONCORHYNCHUS GORBUSCHA) FILLETS
Authors: CRAPO CHARLES , HIMELBLOOM BRIAN
Published: April 2007

Fresh pink salmon (Oncorhynchus gorbuscha) fillets and whole Pacific herring (Clupea harengus pallasi) were stored for two weeks at 10C to determine if significant amounts of histamine were produced before the fish spoiled. Spoilage odors in salmon were moderate by day 4 and intense by day 7, while herring had detectable spoilage by day 4 and became potent by day 6. Aerobic bacterial counts increased from 4.0 × 102/g initially to 3.6 × 108/g in salmon fillets by day 14 and from 2.3 × 103/g initially to 2.7 × 107/g in whole herring by day 14. Total volatile nitrogen increased from 1.8 to 78.5 mg N/100 g in salmon and 2.2 to 23.6 mg N/100 g in herring. Histamine was not detected in salmon, while concentrations reached 54.9 ppm in herring at day 14. However, herring were considered spoiled by day 6.
IMMUNOLOGICAL AND CYTOPATHOGENIC PROPERTIES OF LISTERIA MONOCYTOGENES ISOLATED FROM NATURALLY CONTAMINATED MEATS
Authors: AMORIL J.G. , BHUNIA A.K.
Published: April 2007

Meat products have been implicated as the potential source of Listeria monocytogenes infection in humans. Here, we investigated the incidence of this organism in raw beef and poultry meat products and assessed their biochemical, immunological and cytopathogenic properties. Forty meat samples (20 beef and 20 poultry) were analyzed and the isolates were tested for sugar fermentation, hemolysin production, phospholipase activity, serotype profile, abilities to react with Listeria‐specific monoclonal antibodies (MAbs) EM‐7G1 and C11E9, and cytotoxic effects on hybridoma Ped‐2E9 cells. Thirteen (6 beef and 7 poultry) meat samples (32.5%) were positive for L. monocytogenes. A total of 276 Listeria isolates were obtained, of which 182 (66%) were confirmed to be L. monocytogenes, 80 (29%) were L. innocua, 12 (4.3%) were L. welshimeri and 2 (0.7%) were identified as L. grayi. Fifty six percent of the L. monocytogenes isolates were serotype 4, while 42% were serotype 1, and 2% were untypeable. All but two L. monocytogenes isolates were hemolytic and phospholipase positive (99%). In the ELISA assay, MAb C11E9 showed reaction with L. monocytogenes isolates from all 13 positive meat samples (100%), while MAb EM‐7G1 reacted positively with 12 of 13 positive meat samples (92.3%). Hemolysin‐positive L. monocytogenes isolates were cytopathogenic to Ped‐2E9 cells, while hemolysin‐negative strains showed no effect. This study demonstrated that 32.5% of commercially purchased raw meat products were contaminated with cytopathogenic L. monocytogenes strains, and could be a potential source for infection in susceptible populations if these meats were not processed or cooked properly.
A MICROBIOLOGICAL SAFETY CONSUMER SURVEY ON THE HOUSEHOLD USE OF EGGS IN BELGIUM
Authors: GRIJSPEERDT KOEN , HERMAN LIEVE , BILLIET LUITGARDE
Published: April 2007

A survey of parents of higher education college students assessed the purchasing behavior, storage conditions and consumption of hen eggs in the household, to quantify microbiological unsafe handling. Analysis of the questionnaires indicates an average consumption of 6.4 eggs per month, which are kept at an average temperature of 9.7C for 2 weeks. An additional spot check showed that the interviewees probably underestimate the keeping temperature. The questionnaire also listed a series of egg dishes, which were afterwards categorized according to risk. The distributions of storage temperature, keeping time and type of dish were combined using a Monte Carlo resampling technique, which resulted in a hazard distribution. This distribution showed that the majority of the samples (98.2%) fell into a low hazard category.