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At least 343 records · Page 19Linked to original sources
PubMed1987

Conventional taxonomy of lactobacilli surviving radurization of meat.

All of the 113 catalase-negative, Gram-positive, rod-shaped strains isolated from radurized minced beef (5 kGy) were homofermentative, non-thermophilic, and belonged to the sub-genus Streptobacterium. The majority of the strains (100) were identified as Lactobacillus sake. These were divided into four sub-groups based on their sugar fermentation pattern: group IA1 (melibiose (+), maltose (-), amygdalin (-), 76 strains); group IA2 (melibiose (+), maltose (-), amygdalin (+), 14 strains); group IB1 (melibiose (+), maltose (+), amygdalin (+), four strains); group IB2 (melibiose (+), maltose (+), amygdalin (-), six strains). Of the remaining strains, two produced L(+)-lactic acid and were identified as L. farciminis, three were identified as L. curvatus and eight showed characteristics of both L. sake and L. curvatus and were designated 'L. sake/curvatus.' With one exception, all strains were aciduric and relatively insensitive to the chemical preservatives tested. Most L. sake strains produced significant amounts of H2O2. Electron microscopy confirmed a possible relationship between the thickness of the cells and radiation resistance. The problems and limitations of this type of taxonomic study and possible reasons for the predominance of L. sake species in radurized meat are discussed.

Animals↗
PubMed1980

Transformation assay for identification of psychrotrophic achromobacters.

The finding that many psychrotrophic, gram-negative, nonmotile, oxidase-positive coccobacilli (achromobacters) are competent for genetic transformation made possible the development of a transformation assay that permits recognition of genetically related strains. It has been demonstrated that 109 independently isolated achromobacters are genetically related since deoxyribonucleic acid samples from all of these organisms were able to transform a single competent auxotrophic strain to prototrophy. Genetically interacting bacteria included strains that lacked one or more of the characteristics typical for most achromobacters. An oxidase-negative mutant of one of these strains reacted positively in the transformation assay, unlike other oxidase-negative bacteria. Achromobacters were derived from fish, poultry, irradiated foods, seawater, and other sources. One strain previously classified as Micrococcus cryophilus has been shown to be related to the achromobacters. Two achromobacters had an optimum growth temperature of 35 degrees C and behaved as typical mesophiles. The moraxellae and Acinetobacter were shown to be unrelated to the achromobacters by using the transformation assay. The ready demonstration of genetic relatedness provides a new basis for taxonomic grouping of the psychrotrophic achromobacters.

Journal Article↗
PubMed1999

Pulsed-light inactivation of food-related microorganisms.

The effects of high-intensity pulsed-light emissions of high or low UV content on the survival of predetermined populations of Listeria monocytogenes, Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus were investigated. Bacterial cultures were seeded separately on the surface of tryptone soya-yeast extract agar and were reduced by up to 2 or 6 log10 orders with 200 light pulses (pulse duration, approximately 100 ns) of low or high UV content, respectively (P < 0.001).

Colony Count, Microbial↗
PubMed1967

Fate of free amino acids and nucleotides in spoiling beef.

Fresh beef allowed to undergo microbial spoilage at 7 C showed decreases in quantity and types of amino acids as well as decreases in nucleotides when the initial number of bacteria per gram was high. When the initial number of bacteria was low, decreases were either not detectable or of low orders. It seems, therefore, that low-molecular-weight compounds of the above type support the growth of beef-spoilage bacteria rather than primary beef proteins. These low-molecular-weight compounds provide the probable sources of ammonia, hydrogen sulfide, and other such compounds associated with beef allowed to spoil at low temperatures.

Amino Acids↗
PubMed1973

Food additives.

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Animal Feed↗
PubMed2000

Parasites.

Ill health related to food-borne infection transcends all geographical, political and cultural boundaries. The incidence of food-borne diseases continues to adversely affect the health and productivity of populations in most countries, especially non-industrialised ones. However, since the 1950s, the emphasis in the industrialised world had shifted away from addressing public health problems, to problems of chemical contaminants etc., but recently food-borne infections have again become of increasing concern to governments and the food industry. Improvements in international transportation means food can be distributed throughout the world, but so can the parasitic pathogens which contaminate foods. Alternatively, tourists are being affected abroad and possibly transmitting the pathogen to others at home. Thus, an increasing number of food-related illnesses are international in scope. In this review parasitic contamination of foods of animal origin, particularly meat and fish, will be discussed together with potential problems associated with water and unwashed fruits and vegetables.

Animals↗
PubMed1997

Decontamination of chicken carcasses artificially contaminated with Salmonella.

A study was conducted to evaluate the efficacy of three chemical disinfectants and of ionising radiation in reducing the level of contamination in chicken carcasses which had been artificially contaminated with Salmonella Virchow. Chicken carcasses were obtained from a local abattoir. Five carcasses and one control carcass were used to test each concentration of disinfectant and the radiation. The amount of contaminant employed was 0.5 ml of 10(4) colony-forming units per ml of S. Virchow spread over the thigh, breast and wing areas. All treatments were conducted in duplicate. The three disinfectants used were as follows: calcium hypochlorite, at concentrations of 20 ppm, 50 ppm, 100 ppm and 200 ppm of available chlorine. Lactic acid at concentrations of 0.5%, 0.75% and 1%. Hydrogen peroxide compound at concentrations of 1%, 2% and 3%. Five inoculated carcasses were immersed at a time in one disinfectant concentration for 15 min, while the control carcasses were simultaneously immersed in water free from disinfectants. Five carcasses, each in a plastic bag, were subjected to varying ascending doses (from 2 to 7 k gray [kGy]) of ionising radiation from radioactive isotopes of cobalt 60. A bacteriological examination of each carcass was conducted after the treatment to determine the presence or absence of S. Virchow. The number of carcasses which gave positive results showing the presence of Salmonella decreased after chemical treatment, but the organism was not completely eliminated. However, in those carcasses subjected to 7 kGy of radiation, Salmonella was eliminated and no changes in the appearance, colour or smell of the carcasses were observed.

Animals↗
PubMed1998

Rheological properties and lipid oxidation of rice decontaminated with low-energy electrons.

Microbial load and quality of rice grains which were exposed to electrons at different acceleration voltages of 170 to 200 kV were examined to evaluate the efficacy of decontaminating rice with low-energy electrons. Electrons at any acceleration voltage between 170 and 200 kV reduced microbial loads of brown rice grains to levels lower than 10 colony-forming units (CFU)/g. Higher acceleration voltages resulted in a lower viscosity and a higher thiobarbituric acid value (TBA). Milling at a yield of 90 or 88% after electron treatment made the viscosity and TBA of rice treated with electrons at 170 kV almost the same as untreated rice. Low and high compression analyses of rice grains which were exposed to electrons at 170 to 180 kV and milled at a yield of 90% followed by cooking showed almost the same hardness and stickiness as untreated grains which were milled at 90%. The results indicate that milling at a yield of 90% or lower removes the portion of rice exposed to electrons at 170 kV and that treatment of brown rice with low-energy electrons enables the preparation of milled rice with extremely low levels of microbial load and little quality deterioration.

Decontamination↗
PubMed2000

Efficacy of ultraviolet light for reducing Escherichia coli O157:H7 in unpasteurized apple cider.

This study examined the efficacy of UV light for reducing Escherichia coli O157:H7 in unpasteurized cider. Cider containing a mixture of acid-resistant E. coli O157:H7 (6.3 log CFU/ml) was treated using a thin-film UV disinfection unit at 254 nm. Dosages ranged from 9,402 to 61,005 microW-s/cm2. Treatment significantly reduced E. coli O157:H7 (P < or = 0.0001). Mean reduction for all treated samples was 3.81 log CFU/ml. Reduction was also affected by the level of background microflora in cider. Results indicate that UV light is effective for reducing this pathogen in cider. However, with the dosages used in this experiment, additional reduction measures are necessary to achieve the required 5-log reduction.

Beverages↗
PubMed2003

Response of Salmonella and Escherichia coli O157:H7 to UV energy.

To determine the efficacy of a UV light treatment at 253.7 nm (UVC light) on microbial growth, plates containing tryptic soy agar plus 50 ppm of nalidixic acid (TSAN) were inoculated with known concentrations of five-strain cocktails of Salmonella and Escherichia coli O157:H7 and subjected to different UVC treatments. The concentration of the cocktail inoculum was determined with TSAN prior to inoculation. Serial dilutions were carried out, and inoculation levels of 10(0) to 10(8) CFU/ ml were tested for each pathogen. Multiple replications of doses of UV light ranging from 1.5 to 30 mW/cm2 were applied to different cocktail concentrations, and doses of > 8.4 mW/cm2 resulted in a 5-log reduction of Escherichia coli O157:H7, while a 5-log reduction of Salmonella was observed with doses of > 14.5 mW/cm2. Results for both organisms yielded sigmoidal inactivation curves. UVC light is effective in reducing microbial populations of pathogens on agar surfaces.

Colony Count, Microbial↗
PubMed2004

Efficiency of pulsed UV light for microbial decontamination of food powders.

The aim of this study was to evaluate the efficiency of pulsed light on the destruction of dried microorganisms on fluidized glass beads and to determine treatment parameters (energy level, water activity, final product quality) for process optimization. The applied drying method allowed microorganisms to remain viable on glass beads or dried powdered products with viability yields approaching 100%. The pulsed UV light system enabled an efficient fluidization of food powders, even for granular products (up to 5 mm diameter) and avoided shadowed areas. For Saccharomyces cerevisiae decontamination, the dose effect of UV rays was preponderant with glass beads and quartz plate, and in this case, 58 J/cm2 were required to decrease the microbial population by 7 log. For colored food powders (black pepper and wheat flour), the thermal effect of pulsed light dominated the UV effect.

Consumer Product Safety↗