SEARCH · PubMed Health

Results for “Pasteurization”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources

PubMed1980

Plasma and red cell folacin in cow's milk-fed infants and children during the first 2 years of life: the significance of boiling pasteurized cow's milk.

Plasma and red blood cell folacin concentrations (Lactobacillus casei activity) and other pertinent parameters have been studied in 10 infants and children fed home-made cow's milk mixtures until 5 months of age. The folacin concentrations have been estimated in 44 samples of pasteurized cow's milk before and after pretreatment with conjugase. The effect of boiling on the folacin concentration has been studied in 11 samples of pasteurized cow's milk. During the time the infants were fed home-made cow's milk mixtures they developed signs of folacin deficiency, as judged from the plasma and red cell folacin concentrations as well as from other hematologic studies. The mean folacin concentration in pasteurized cow's milk was 168.9 SEM 7.80, and range 72 to 262 nmol/liter. Pretreatment with conjugase did not increase the folacin concentrations. During boiling for 1 min 2/3 of the folacin activity was lost. This could be prevented by adding ascorbic acid, 1 mg/ml, before the boiling procedure. The folacin deficiency observed in the infants is probably secondary to loss of folacin activity in connection with the preparation of the cow's milk mixtures.

Adult↗

PubMed1984

Lactose malabsorption from yogurt, pasteurized yogurt, sweet acidophilus milk, and cultured milk in lactase-deficient individuals.

The use of fermented dairy foods is common in areas of the world where lactase deficiency is prevalent. Recently, we have shown that the digestion of lactose from yogurt is enhanced as compared to that from milk. This enhanced digestion is apparently due to inherent B-galactosidase in yogurt which is active in the gastrointestinal tract after consumption of the yogurt. Furthermore, yogurt is well tolerated by lactase-deficient subjects resulting in little or no gastrointestinal distress. Since other fermented and microbial-containing dairy foods are consumed worldwide and may also contain some "lactase" activity, we chose to evaluate the digestion of lactose from three of these products: pasteurized yogurt, cultured milk (buttermilk), and sweet acidophilus milk. Breath hydrogen techniques were used to evaluate lactose malabsorption in nine lactase-deficient subjects. The studies demonstrated that yogurt is unique among the products tested in enhancing the digestion of lactose. Furthermore, pasteurization of yogurt eliminated the enhanced digestion of lactose, reduced the inherent lactase activity of the yogurt by 10-fold and reduced cell counts by 100-fold. Interestingly, eight of nine subjects fed cultured milk experienced gastrointestinal distress, whereas all subjects fed pasteurized yogurt were symptom free, even though the amount of malabsorbed lactose was similar.

Adult↗

PubMed1996

Physical mapping of Mycobacterium bovis BCG pasteur reveals differences from the genome map of Mycobacterium tuberculosis H37Rv and from M. bovis.

A Dral restriction map of the approximately 4.35 Mb circular chromosome of the vaccine strain Mycobacterium bovis BCG Pasteur was constructed by linking all 21 Dral fragments, ranging in size from 6 to 820 kb, using specific clones that spanned the Dral recognition sites as hybridization probes. The positions of 20 known genes were also established. Comparison of the resultant genome map with that of the virulent tubercle bacillus Mycobacterium tuberculosis H37Rv revealed extensive global conservation of the genomes of these two members of the M. tuberculosis complex. Possible sites of evolutionary rearrangements were localized on the chromosome of M. bovis BCG Pasteur by comparing the Asnl restriction profile with that of M. tuberculosis H37Rv. When selected cosmids from the corresponding areas of the genome of M. tuberculosis H37Rv were used as hybridization probes to examine different BCG strains, wild-type M. bovis and M. tuberculosis H37Rv, a number of deletions up to 10 kb in size, insertions and other polymorphisms were detected. In addition to the known deletions covering the genes for the protein antigens ESAT-6 and mpt64, other genetic loci exhibiting polymorphisms or rearrangements were detected in M. bovis BCG Pasteur.

BCG Vaccine↗

PubMed1984

Detection of post-pasteurization contamination of cream by impedimetric methods.

Impedimetric methods for evaluating post-pasteurization contamination and shelf-life of cream were assessed. Over 94% of the samples tested were in agreement, using selected cut-offs of 20 h for detection time measured at 21 degrees C with creams containing inhibitors for the growth of Gram positive bacteria on standard plate count agar as growth media, and 3.2 X 10(7) cfu/g for plate counts obtained on cream which had been pre-incubated in the presence of inhibitors for the growth of Gram positive organisms, and on cream stored at 6 degrees C for 7 d. Agreement between the impedimetric method and plate count was not as good if either Brain Heart Infusion or Milk Agar was used in place of Plate Count Agar in the former technique. A poor correlation was obtained between plate count methods for enumerating post-pasteurization contamination and keeping quality with impedimetric measurements on cream alone. It was possible, with a reasonable degree of certainty, to determine if cream had suffered post-pasteurization contamination within 20 h of production.

Bacteria↗

PubMed1986

Factors contributing to the seasonal variation of Bacillus spp. in pasteurized dairy products.

The seasonal variation in the spoilage of pasteurized products, especially double cream, by spore-forming bacteria was due to a number of factors. By far the most important was the seasonal variation in the types of organisms isolated from raw milks. Psychrotrophic spore-formers predominated in the summer-autumn months and these strains were able to germinate rapidly and grow in refrigerated dairy products. There was evidence that the concentration of one or more factors which promoted germination of psychrotrophic strains of Bacillus spp. in milk was higher during the summer than in the winter. This again may contribute to seasonal differences in spoilage by spore-forming bacteria. Post-heat treatment contamination by spores of Bacillus spp. may also be more prevalent in the summer-autumn period and evidence was obtained that spores associated with post-pasteurization contamination could germinate and grow more rapidly than those introduced into the product from the raw material. Thus, the increased spoilage of pasteurized products by Bacillus spp. observed in the June to October period may be due to a combination of factors. The relative contribution that each makes is not easily resolved.

Animals↗

PubMed1993

Classification of the spoilage flora of raw and pasteurized bovine milk, with special reference to Pseudomonas and Bacillus.

Eighty-one bacterial strains isolated from refrigerated raw milk, 124 from pasteurized milk and cream stored at 5 degrees C and 7 degrees C, and 19 type and reference strains of Pseudomonas spp. and Bacillus spp. were characterized by numerical phenotypic analysis. Data were processed with simple matching (SSM) and Jaccard (SJ) coefficients, and UPGMA clustering. Fourteen clusters of Gram-negative bacteria were formed at SJ = 79% (SSM = 90%). Raw milk was exclusively spoilt by Gram-negative bacteria, the majority of which were Pseudomonas fluorescens biovar I, Ps. fragi, Ps. lundensis and Ps. fluorescens biovar III. Minor groups in raw milk included Enterobacteriaceae spp. and Acinetobacter spp. Pasteurized milk was spoilt by essentially the same Gram-negative organisms in 65% (5 degrees C) and 50% (7 degrees C) of the cases. The phenotypic characteristics of Gram-negative bacteria are given. Bacillus polymyxa (both temperatures) and B. cereus (only at 7 degrees C) were responsible for 77% of samples spoiled by the Gram-positive organisms. Minor milk spoilage groups included other Bacillus spp. and lactic acid bacteria. All Bacillus spp. grew fermentatively in milk, and most strains denitrified. It is suggested that: (i) industrial recontamination tests of pasteurized milk are directed against Pseudomonas; (ii) milk is stored at 5 degrees C or lower to avoid growth of B. cereus; and (iii) the significance of gas-producing and nitrate/nitrite-reducing Bacillus strains is recognized in cheese production.

Animals↗

PubMed1988

Allergic reactions to raw, pasteurized, and homogenized/pasteurized cow milk: a comparison. A double-blind placebo-controlled study in milk allergic children.

Five children aged 12-40 months with IgE-mediated adverse reactions to cow milk (immediate onset clinical pattern of cow milk allergy) were orally challenged double-blind in random order with three different milk preparations processed from the same batch of milk 1) raw untreated cow milk, 2) pasteurized cow milk, 3) homogenized and pasteurized cow milk, and 4) Nutramigen (a commercial hypoallergenic infant formula based on hydrolysed casein) as placebo. Skin prick tests with the same preparations were also performed. On oral challenge the three different processed milk types provoked significant and similar allergic reactions in each child, and no adverse reactions followed the challenge with placebo (Nutramigen). Skin prick test with the same milk products were positive in all children and comparable to the results with an extract of purified raw cow milk protein (Soluprick), whereas Nutramigen did not elicit any skin reactions. A tendency towards a lower threshold of reaction and larger skin reactions induced by the processed milk preparations might indicate an increased ability of pasteurized and homogenized/pasteurized milk to evoke allergic reactions in patients allergic to milk.

Animals↗

PubMed1985

Biological and physical properties of fibronectin pasteurized in the presence of stabilizers.

Interest in human plasma fibronectin (Fn) as a potential clinical product for replacement therapy in septic patients has prompted the search for stabilizers to protect the protein from heat denaturation during pasteurization designed to inactivate hepatitis viruses. Fn was pasteurized (60 degrees C, 10 h) in the presence of either citrate, tricarballylate, sucrose or four mixtures of lysine, glucarate, gluconate or citrate which had been found to increase the denaturation temperature of Fn by greater than or equal to 19 degrees C. All but a citrate/gluconate mixture were effective in preventing aggregation as measured by dye fluorescence, light scattering, gel filtration and electrophoresis. Binding to gelatin was retained and immunological activity was only slightly diminished compared to a sample heated without stabilizers. Opsonic activity was measured as ability to mediate the uptake of 125I-gelatin-coated polystyrene beads by attached human monocytes. Fn heated without stabilizers underwent a transient increase in activity which was traced to formation of aggregates having elevated specific activities. Pasteurized samples had slightly elevated opsonic activities with no detectable aggregates present, while the unstabilized control was inactive. These results indicate that the physical properties of Fn as well as the functional activities of the gelatin- and cell-binding domains can be protected against thermal denaturation by various compounds.

Blood Transfusion↗

PubMed1996

Liquid pasteurization of an immunoglobulin preparation without stabilizer: effects on its biological and biochemical properties.

Intravenous immunoglobulins (IVIg) purified by cold ethanol fractionation have a very good safety record with regard to the transmission of many viruses. However, a few cases of non-A-non-B hepatitis have been described after intravenous injection of some immunoglobulin preparations. To ensure even higher safety for our IVIg, an additional virus inactivation step, based on pasteurization, was developed. The heating of aqueous IVIg was performed without stabilizer, and at a very low salt concentration (< 1 mM) at acidic pH. No generation of polymer was detected after pasteurization and a significant decrease in the proportion of dimers was observed. Analysis of the secondary structure by circular dichroism showed a very slight change in the secondary structure. The biological properties of the Fc region as well as the Fab region were not affected by the pasteurization. Our method has several advantages: (1) improvement of viral safety; (2) there is no need to add stabilizer which may stabilize viral particles, and (3) the absence of any hypotensive effect and low anticomplementary activity indicates a good clinical tolerance of IgG preparation.

Animals↗

PubMed1983

Role of phosphate in the regulation of the Pasteur effect in Saccharomyces cerevisiae.

The occurrence of the Pasteur effect in Saccharomyces cerevisiae in several conditions has been examined. In these conditions measurements of a series of metabolites potentially involved in the regulation of the effect were performed. These included, among others, adenine nucleotides, citrate, fructose 2,6-bisphosphate and phosphate. Only phosphate changed in a consistent way, increasing in anaerobiosis when the Pasteur effect occurred. It is concluded that, with the available data, only phosphate may be considered as a regulator of the Pasteur effect in this microorganism.

Aerobiosis↗

PubMed1987

Intravesical BCG therapy in the management of multiple superficial bladder carcinoma. Comparison between Glaxo and Pasteur strains.

Intravesical Bacillus Calmette-Guérin (BCG) therapy in the treatment and prophylaxis of superficial bladder cancer has shown encouraging results in North America but disappointing results have been reported in Great Britain. This was attributed to differences in quality between BCG (Glaxo strain) used in Great Britain and BCG (Pasteur and Tice strains) used in North America. Twenty-one patients with multiple superficial recurrent transitional cell carcinoma of the bladder were entered into a pilot study comparing the efficacy of BCG Glaxo (Evans Medical Ltd, Dunstable, UK) and Pasteur (L'Institut Pasteur, France) strains. Comparable and encouraging results were demonstrated, indicating that this mode of therapy is effective.

Administration, Intravesical↗

PubMed1994

Marker tumour response to Evans and Pasteur bacille Calmette-Guérin in multiple recurrent pTa/pT1 bladder tumours: report from the Medical Research Council Subgroup on Superficial Bladder Cancer (Urological Cancer Working Party).

OBJECTIVE: To compare the efficacy of Evans bacille Calmette-Guérin (BCG) and Pasteur BCG in eradicating marker bladder tumours and to compare the toxicity of the two strains. PATIENTS AND METHODS: Ninety-nine patients with multiple recurrent pTa or pT1 bladder tumours were allocated at random to six instillations at weekly intervals of either Evans BCG or Pasteur BCG. All tumours were resected except one marker tumour. At cystoscopy 3 months after randomization all tumours including the marker tumour, if still present, were resected. RESULTS: The incidence of adverse events was similar in the two groups but numbers were small and only large differences would have been detected. No statistically significant difference in efficacy regarding the response of the marker tumour or the appearance of other tumours at 3 months was noted in the two groups. There was no evidence of stage progression of the marker tumours. CONCLUSIONS: In multiple recurrent pTa or pT1 bladder tumours clearing the bladder of all except one marker tumour provides a safe and convenient way of measuring the response to intravesical therapy. No significant difference in efficacy or toxicity was detected between Evans BCG and Pasteur BCG.

Administration, Intravesical↗

PubMed2006

Vero-cytotoxigenic Escherichia coli O157 in pasteurized milk containers at the point of retail: a qualitative approach to exposure assessment.

Dairies within the United Kingdom are classified into two groups, namely, off-farm and on-farm dairies (the latter often being small scale). We propose a model for the probability of milk sold as pasteurized reaching the point of retail contaminated with Vero-cytotoxigenic Escherichia coli (VTEC) O157 from each of these two pathways. We evaluate qualitatively the exposures inherent in each, and compare and contrast the two situations. The model framework is generic, in that it can in principle be used, with the relevant data modifications, to provide a qualitative assessment of the likely exposure from milk sold as pasteurized to any potentially milk-borne pathogenic organism. Furthermore, the methodological approaches presented are widely applicable in the microbial risk assessment field. The specific example presented will be of particular interest to the UK dairy and public health communities: we conclude that the exposure potential per liter consumed from milk processed in off-farm dairies is negligible, whereas the exposure potential per liter consumed from milk processed on-farm is low, but not sufficiently small to be regarded as negligible. We also identify areas of data sparsity, which need to be addressed for quantitative risk assessment to proceed, and highlight the critical points in the pasteurized milk production chain, which, in the event of a breakdown, have the potential to increase the risk to the consumer.

Animals↗

PubMed1996

IS900 PCR to detect Mycobacterium paratuberculosis in retail supplies of whole pasteurized cows' milk in England and Wales.

IS900 PCR for Mycobacterium paratuberculosis was applied to cream, whey, and pellet fractions of centrifuged whole cows' milk. The test and simultaneous control reactions gave correct results for spiked milk and for native milk samples obtained directly from M. paratuberculosis-free, subclinically infected, and clinically infected cows. The test was then applied to units of whole pasteurized cows' milk widely obtained from retail outlets throughout central and southern England from September 1991 to March 1993. With peak periods in January to March and in September to November, when up to 25% of units were affected, an overall 22 of 312 samples (7%) tested positive for M. paratuberculosis. In 18 of the 22 positive samples (81%), the PCR signal segregated to the cream or pellet fractions or both, consistent with the presence of intact mycobacteria. Nine of 18 PCR-positive milk samples (50%) and 6 of 36 PCR-negative milk samples (16%) yielded long-term liquid cultures which tested positive for M. paratuberculosis after 13 to 40 months of incubation, despite overgrowth by other organisms. Taken together with data on the prevalence of M. paratuberculosis infection in herds in the United Kingdom, the known secretion of M. paratuberculosis in milk from subclinically infected animals, and the inability of laboratory conditions simulating pasteurization to ensure the killing of all these slowly growing or unculturable organisms, there is a high risk, particularly at peak times, that residual M. paratuberculosis will be present in retail pasteurized cows' milk in England.

Animals↗

PubMed2001

Effect of turbulent-flow pasteurization on survival of Mycobacterium avium subsp. paratuberculosis added to raw milk.

A pilot-scale pasteurizer operating under validated turbulent flow (Reynolds number, 11,050) was used to study the heat sensitivity of Mycobacterium avium subsp. paratuberculosis added to raw milk. The ATCC 19698 type strain, ATCC 43015 (Linda, human isolate), and three bovine isolates were heated in raw whole milk for 15 s at 63, 66, 69, and 72 degrees C in duplicate trials. No strains survived at 72 degrees C for 15 s; and only one strain survived at 69 degrees C. Means of pooled D values (decimal reduction times) at 63 and 66 degrees C were 15.0 +/- 2.8 s (95% confidence interval) and 5.9 +/- 0.7 s (95% confidence interval), respectively. The mean extrapolated D72 degrees C was <2.03 s. This was equivalent to a >7 log10 kill at 72 degrees C for 15 s (95% confidence interval). The mean Z value (degrees required for the decimal reduction time to traverse one log cycle) was 8.6 degrees C. These five strains showed similar survival whether recovery was on Herrold's egg yolk medium containing mycobactin or by a radiometric culture method (BACTEC). Milk was inoculated with fresh fecal material from a high-level fecal shedder with clinical Johne's disease. After heating at 72 degrees C for 15 s, the minimum M. avium subsp. paratuberculosis kill was >4 log10. Properly maintained and operated equipment should ensure the absence of viable M. avium subsp. paratuberculosis in retail milk and other pasteurized dairy products. An additional safeguard is the widespread commercial practice of pasteurizing 1.5 to 2 degrees above 72 degrees C.

Animals↗

PubMed1963

Effect of Pasteurization on Survival of Certain Psychrophilic Bacteria.

The effect of pasteurization on survival in milk of four strains of psychrophilic pseudomonads and of one strain of Alcaligenes was determined. Cell numbers were very low immediately after pasteurization, but increased after storage. The survival of psychrophilic bacteria in pasteurized milk appeared to depend on the initial number of organisms, and detection depended partly on the length of time of storage at 3 to 5 C.

Journal Article↗

PubMed1974

Survival studies with spores of Clostridium botulinum type E in pasteurized meat of the blue crab Callinectes sapidus.

Clostridium botulinum type E studies reported in this paper include the incidence of the organism in selected Chesapeake Bay areas, growth and toxin production in crabmeat homogenates, and the effect of pasteurization upon varying levels of spores in crabmeat. Type E spores were detected in 21 of 24 bottom mud samples taken at locations from which blue crabs were being harvested. Sterilized crabmeat homogenates inoculated with as little as five spores per 10 g became toxic after 8 days at 50 F, 2 days at 75 F, and 1 day at 85 F. Growth at 50 F and above was accompanied by gas production and a slightly sour odor. Growth and toxin production at 40 F required 55 days or longer and inocula of 10(3) spores or higher per 10 g of homogenate. At 40 F gas production was usually not apparent and no off odors could be detected. A recommended minimum pasteurization of 1 min at 185 F internal meat temperature reduced type E spore levels in inoculated packs of crabmeat from 10(8) spores per 100 g to 6 or less spores per 100 g, and the pasteurized meat remained nontoxic during 6 months of storage at 40 F.

Brachyura↗

PubMed2004

Cytomegalovirus (CMV) inactivation in breast milk: reassessment of pasteurization and freeze-thawing.

Breast-feeding mothers frequently transmit cytomegalovirus (CMV) to preterm infants of very low birth weight. Current recommendations for prevention of virus transmission are based on data published 20 y ago in the context of human milk banking. Two recent clinical trials examined storage of breast milk at -20 degrees Celsius to reduce virus transmission. However, in both studies, CMV transmission occurred. Using sensitive tools like quantitative PCR, CMV pp67 late mRNA assay, and a high-speed, centrifugation-based microculture assay for quantification of CMV infectivity, we reassessed the virological and biochemical characteristics of freeze-storing breast milk at -20 degrees Celsius, compared it with traditional Holder pasteurization (30 min at 62.5 degrees Celsius), and a new short-term pasteurization (5 s at 72 degrees Celsius) based on the generation of a milk film. Both heat treatment procedures were able to destroy viral infectivity and pp67 RNA completely. Preliminary results showed short-term heat inactivation below 72 degrees Celsius was less harmful in reducing the activity of marker enzymes than Holder pasteurization. Freezing breast milk preserved the biochemical and immunologic quality of the milk; however, late viral RNA and viral infectivity was also preserved. Compared with viral DNA, CMV-RNA more directly reflects infectious CMV in human milk samples. Further studies are necessary to evaluate short-term heat treatment below 72 degrees Celsius as an effective tool for prevention of CMV transmission.

Cold Temperature↗