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Results for “Pasteurization”

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PubMed1987

Effect of homogenization and pasteurization on the allergenicity of bovine milk analysed by a murine anaphylactic shock model.

In a factorial design study a murine anaphylactic shock model was used to analyse the effect of homogenization, pasteurization, and fat content on the ability of bovine milk to induce anaphylactic reactions. Mice were sensitized by either oral or subcutaneous immunizations with various types of bovine milk. In spite of a significantly higher antibody titre in the mice sensitized subcutaneously, there was no difference in the sensitivity between orally and subcutaneously immunized mice with respect to anaphylactic reactions. Pasteurization did not seem to change the ability of milk to induce anaphylactic reactions. However, increasing fat contents in combinations with homogenization resulted in an increase of the ability of the milk to induce anaphylactic reactions.

Anaphylaxis↗

PubMed1984

Use of the Direct Epifluorescent Filter Technique for predicting the keeping quality of pasteurized milk within 24 hours.

The keeping quality (KQ) of pasteurized milk stored at 5 degrees C and 11 degrees C was predicted within 24 h by pre-incubating samples and counting bacteria by the Direct Epifluorescent Filter Technique (DEFT). For samples from 5 degrees C storage, 0.03% (w/v) benzalkonium chloride and 0.002% (w/v) crystal violet (final concentration) were added to inhibit the growth of Gram positive bacteria during pre-incubation. The samples from milk stored at 11 degrees C were pre-incubated without the addition of inhibitors. After pre-incubation there was a satisfactory relationship between the DEFT count and the KQ of milks at both 5 degrees C and 11 degrees C. The DEFT count following pre-incubation correctly classified greater than 80% of pasteurized milks on the basis of KQ.

Animals↗

PubMed1986

Prediction of the keeping quality of pasteurized milk by the detection of cytochrome c oxidase.

The keeping quality (KQ) of pasteurized milk samples stored at 5 degrees C and 10 degrees C was satisfactorily predicted after 18 h pre-incubation with 0.05% benzalkonium chloride at 20 degrees C, by estimating the numbers of Gram-negative psychrotrophic bacteria using the simple, cheap and rapid (5 min) assay of cytochrome c oxidase. Correlation coefficients for the relationship between cytochrome c oxidase activity at 20 degrees C and KQ at 5 degrees C or 10 degrees C of -0.89 and -0.84 respectively were obtained. The method correctly predicted the KQ of more than 89% of the samples of pasteurized milk. The assay was not satisfactory for use on samples after pre-incubation at 30 degrees C.

Animals↗

PubMed1986

The incidence of Yersinia enterocolitica and Yersinia enterocolitica-like organisms in raw and pasteurized milk in Northern Ireland.

Yersinia enterocolitica and Y. enterocolitica-like bacteria were frequently isolated from samples of both raw bulked milk (34/150) and farm bottled (raw) milk (5/20). These bacteria were also found to contaminate creamery pasteurized milk (6/100 samples) and farm pasteurized milk (4/50 samples). Although Y. enterocolitica was the most commonly isolated species, Y. intermedia and Y. frederiksenii were also frequently obtained (52, 31 and 15% of isolates, respectively). Also, one atypical strain was identified as Y. aldovae. The Y. enterocolitica strains were largely biotype 1 (20/27) including five strains which could ferment lactose. One third of the Y. enterocolitica strains were not typable, but of those which were, the serotypes were 0:34 (18.5%), 0:5.27 (18.5%), 0:6.3 (15%), 0:4 (11%) and 0:7 (4%). Pre-enrichment in trypticase-soy broth (TSB) (at 22 degrees C for 24 h) followed by selective enrichment in bile-oxalate-sorbose broth (at 22 degrees C for 6 d) allowed the recovery of 92.3% of all isolates, as compared with 15.4% using cold enrichment in TSB at 4 degrees C for 21 d.

Animals↗

PubMed1987

Survival of Listeria monocytogenes in raw milk treated in a pilot plant size pasteurizer.

The survival of Listeria monocytogenes in raw milk treated in a pilot plant size pasteurizer was investigated. Raw milk was inoculated with different initial concentrations of L. monocytogenes and heated at temperatures ranging from 69 degrees to 73 degrees C. Listerias were not isolated from any of the milk samples immediately after thermal treatment. They were isolated, however, from 46.6% of heated samples (none from samples heated at 73 degrees C) after variable periods at refrigeration temperature. The results suggest that a low number of listerias survive some thermal treatments, but a cold enrichment is necessary to repair the thermally injured cells and detect these organisms in milk. The importance of the isolation technique in the recovery of listerias from pasteurized milk samples is discussed.

Animals↗

PubMed1984

Pasteurization of C1 inactivator in the presence of citrate salts.

Conditions have been determined under which the C1 inactivator (C1-INA) can be pasteurized to reduce the risk of transfusion hepatitis associated with its use for replacement therapy in patients with genetic or acquired deficiencies. Recovery of 90% of the biological and immunological activity of a C1-INA concentrate was achieved following heat treatment for 10 h at 60 degrees C in the presence of 3 M potassium citrate. Crossed immunoelectrophoresis in heparinized agarose was used to demonstrate the ability of the pasteurized C1-INA to bind heparin and to form a precipitation pattern with antibody which was almost indistinguishable from that of an unheated control. High pressure liquid chromatography and enhancement of the fluorescence of 1,8-anilinonaphthalene sulfonate were used to show that other proteins present in the concentrate were also stabilized.

Citrates↗

PubMed1985

A pasteurized antithrombin III concentrate for clinical use.

A method for large-scale production of a pasteurized antithrombin III (AT III) concentrate for therapeutic use has been adapted from published methods. It includes the following steps: (1) batchwise adsorption onto heparin-Sepharose from plasma depleted of cryoprecipitate and prothrombin complex; (2) chromatographic elution at high salt concentration; (3) pasteurization for 10 h at 60 degrees C in the presence of added citrate ion; (4) desalting on Sephadex G-25, and (5) sterile filtration and freeze-drying. Seven batches prepared in this manner gave a mean yield of 269 U AT III/kg plasma. The product passed all the usual animal safety and pyrogenicity tests and has been used successfully in several courses of treatment of congenital deficiencies.

Adsorption↗

PubMed1996

Thermal inactivation of several Mycobacterium spp. in milk by pasteurization.

The thermal inactivation of Mycobacterium avium, Myco. bovis, Myco. fortuitum, Myco. intracellulare and Myco. kansaii in milk at 63.5 degrees C was investigated. Survivors were enumerated after heating for 0, 5, 10, 15, 20 and 30 min and thermal death curves were constructed for each species. Mycobacterium bovis and Myco. fortuitum were found to exhibit linear thermal death curves and neither species demonstrated any survival after heating at 63.5 degrees C for 30 min (equivalent to holder pasteurization). In contrast, Myco. avium, Myco. intracellulare and Myco. kansasii yielded thermal death curves which exhibited significant 'tailing' and all three strains survived holder pasteurization.

Animals↗

PubMed1990

Effects of growth temperature and strictly anaerobic recovery on the survival of Listeria monocytogenes during pasteurization.

Listeria monocytogenes F5069 was suspended in either Trypticase soy broth-0.6% yeast extract (TSBYE) or sterile, whole milk and heated at 62.8 degrees C in sealed thermal death time tubes. Severely heat-injured cells were recovered in TSBYE within sealed thermal death time tubes because of the formation of reduced conditions in the depths of the TSBYE. Also, the use of strictly anaerobic Hungate techniques significantly increased recovery in TSBYE containing 1.5% agar compared with aerobically incubated controls. The exogenous addition of catalase, but not superoxide dismutase, slightly increased the recovery of heat-injured cells in TSBYE containing 1.5% agar incubated aerobically. Growth of cells at 43 degrees C caused a greater increase in heat resistance as compared with cells heat shocked at 43 degrees C or cells grown at lower temperatures. Growth of L. monocytogenes at 43 degrees C and enumeration by the use of strictly anaerobic Hungate techniques resulted in D62.8 degrees C values that were at least sixfold greater than those previously obtained by using cells grown at 37 degrees C and aerobic plating. Results indicate that, under the conditions of the present study, high levels of L. monocytogenes would survive the minimum low-temperature, long-time treatment required by the U.S. Food and Drug Administration for pasteurizing milk. The possible survival of low levels of L. monocytogenes during high-temperature, short-time pasteurization and enumeration of injured cells by recovery on selective media under strictly anaerobic conditions are discussed.

Anaerobiosis↗

PubMed1992

Thermotolerance of heat-shocked Listeria monocytogenes in milk exposed to high-temperature, short-time pasteurization.

The effect of prior heat shock (48 degrees C for 15 min) on the thermotolerance of Listeria monocytogenes at the minimal high-temperature, short-time (71.7 degrees C for 15 s) parameters required by the Pasteurized Milk Ordinance was examined. The mean D71.7 degrees C value for heat-shocked L. monocytogenes was 4.6 +/- 0.5 s (control D = 3.0 +/- 1.0 s); the ratio of D to control D was 1.5. The increased thermotolerance of heat-shocked Listeria cells was not significant and appeared unlikely to have practical implications, in terms of risk assessment, for the safety of pasteurized milk.

Animals↗

PubMed1997

Heat inactivation of Mycobacterium paratuberculosis in raw milk: are current pasteurization conditions effective?

Currently, it is not known whether commercial pasteurization effectively kills Mycobacterium paratuberculosis in contaminated raw milk. Results from holder test tube experiments indicated that a residual population of viable bacteria remained after treatment at 65, 72, 74, or 76 degrees C for 0 to 30 min. Use of a laboratory-scale pasteurizer unit demonstrated that treatment of raw milk at 72 degrees C for 15 s effectively killed all M. paratuberculosis.

Animals↗

PubMed2002

Inducible gene expression by nonculturable bacteria in milk after pasteurization.

The viability of bacteria in milk after heat treatments was assessed by using three different viability indicators: (i) CFU on plate count agar, (ii) de novo expression of a gfp reporter gene, and (iii) membrane integrity based on propidium iodide exclusion. In commercially available pasteurized milk, direct viable counts, based on dye exclusion, were significantly (P < 0.05) higher than viable cell counts determined from CFU, suggesting that a significant subpopulation of cells in pasteurized milk are viable but nonculturable. Heating milk at 63.5 degrees C for 30 min resulted in a >4-log-unit reduction in the number of CFU of Escherichia coli and Pseudomonas putida that were marked with lac-inducible gfp. However, the reduction in the number of gfp-expressing cells of both organisms under the same conditions was <2.5 log units. These results demonstrate that a substantial portion of cells rendered incapable of forming colonies by heat treatment are metabolically active and are able to transcribe and translate genes de novo.

Animals↗

PubMed1970

Bacteriological and shelf-life characteristics of canned, pasteurized crab cake mix.

The bacteriological spoilage characteristics of a canned, pasteurized crab cake mix product stored at various temperatures were investigated. A large number of bacteria, both mesophilic and psychrophilic, survived the pasteurization process. Bacillus and Micrococcus were found to predominate when the product was stored at 30 C (86 F) and 18 C (64 F), whereas Alcaligenes predominated at 2 C (36 F). The product was found to be free of Escherichia coli. Bacterial counts, trimethylamine nitrogen, volatile reducing substances, and ammonia determinations were evaluated as indices of quality for the product. Close correlation was observed between bacterial counts, volatile reducing substance values, and organoleptic tests when the product was stored at 30 C (86 F). The shelf-life of the product was approximately 6 months at 2 C (36 F), 4 days at 18 C (64 F), and 27 hr at 30 C (86 F).

Alcaligenes↗

PubMed1980

Comparison of Pasteur and Behringwerke antivenoms in envenoming by the carpet viper (Echis carinatus).

Bites and envenoming by the carpet viper Echis carinatus are common medical emergencies in parts of Nigeria, but the most effective use of the various commercially produced antivenoms in treatment has not been established. Pasteur Paris Echis monospecific and Behringwerke West and North Africa Bitis-Echis-Naja polyspecific antivenoms were compared in two groups of seven patients with incoagulable blood after E carinatus bites. In both groups spontaneous bleeding stopped within a few hours and local swelling subsided within two weeks after the initial antivenom injection. Pasteur antivenom (20-40 ml) restored blood coagulability within 12 hours in all cases, but 60--180 ml of Behringwerke antivenom was effective in only four cases. Persisting venom procoagulant activity was observed in the remaining three cases. Despite its potency in the mouse protection test, Behringwerke antivenom is unreliable and unpredictable in neutralising venom procoagulant in humans bitten by E carinatus.

Adult↗

PubMed2005

Immunologic factors in human milk: the effects of gestational age and pasteurization.

This study compared concentrations of total protein, lysozyme, and immunoglobulins (IgA, IgG, IgM) in samples of colostrum (n=101) obtained from mothers of infants<32 weeks, 32 to 36(6) 7 weeks, and >or=37 weeks gestational age, both before and after pasteurization. Total protein was measured by refraction index, lysozyme by the lysoplate method, and immunoglobulins through the radial immunodiffusion technique. The total protein concentration was greater in colostrum of the <32 weeks and 32 to 36(6) 7 weeks categories compared to full-term (P<.001), while concentrations of lysozyme and IgM were similar. IgA concentrations were higher in the <32 weeks group compared to the full-term and similar to the 32 to 36(6) 7 weeks group (P<.05). The IgG was higher in the <32 weeks category compared to 32 to 36(6) 7 weeks, and both were similar to the full-term (P<.05). Pasteurization significantly decreased all of the factors analyzed.

Adult↗

PubMedDate not supplied

[Isolation of pathogenic bacteria in pasteurized type C milk sold in Recife City, Pernambuco, Brazil].

In order to improve information about the microbiological quality of the milk commercially available in the city of Recife, 250 samples of pasteurized type-C milk and 50 samples of raw milk were analyzed for Yersinia enterocolitica and Listeria monocytogenes and verify the possible occurrence of Yersinia enterocolitica and Listeria monocytogenes. These bacteria can develop in refrigeration temperatures and are responsible for food-born diseases. Neither Y. enterocolitica nor L. monocytogenes were found in the samples analyzed. However, the presence of Y. intermedia and Y. frederiksenii was detected, these environmental species behave as opportunist pathogens. Through the methodology used for Listeria isolation, one isolate of Salmonella Montevideo was obtained from a sample of pasteurized milk and another isolated from one sample of raw milk. Besides these, several other bacteria species were found. It is likely that the large microbiota present in the samples and the procedures employed to destroy it could have hindered the isolation of Y. enterocolitica and L. monocytogenes.

Animals↗

PubMedDate not supplied

[Pasteur Institute of São Paulo: battling rabies for one hundred years].

The Pasteur Institute of São Paulo is currently celebrating its centennial. The article first paints a brief history of Pasteur's institutional trajectory, emphasizing its main contributions to science and public health. The second part describes the exhibit that marks this anniversary - its goals, organization, and sources - and comments on aspects of the material on display.

Academies and Institutes↗

PubMed2003

Models and microbiology: Pasteur and the body.

Louis Pasteur developed a model of the body as a culture vessel in the late 1870s as an explanation of both natural and acquired immunity, and other investigators quickly applied the model in the explanation of other microbiological phenomena, principally the tissue tropism seen in the normal and the pathological flora. This paper will argue that although Pasteur quickly abandoned the model, it persisted as an explanation of tissue tropism for nearly 70 years, structuring the interpretation of data by and guiding the research of a diverse group of microbiological researchers.

Equipment and Supplies↗