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PubMed2004

Evaluation of biogenic amines and microbial counts throughout the ripening of goat cheeses from pasteurized and raw milk.

The effect of the hygienic quality of milk on changes in microbial counts and biogenic amine content was evaluated during ripening of goat cheeses manufactured from pasteurized and raw milks at 1, 14, 30, 60 and 90 d. The original milk, rennet, curd and whey were also included in the study. The pH, salt content and extent of proteolysis in the cheese were also evaluated. Spermidine and spermine were the main amines in raw milk, while they were minor amines in cheeses. Other amines increased markedly during ripening, tyramine being the main amine in cheese made from raw milk and cadaverine and putrescine in those produced from pasteurized milk. Enterobacteriaceae counts decreased during ripening whereas those of lactic acid bacteria increased, especially lactobacilli and enterococci. Cheese made from raw milk showed higher microbial counts during ripening than those made from pasteurized milk, especially for Enterobacteriaceae and enterococci, counts being 2 or 3 log units higher. Raw milk cheese showed remarkably higher biogenic amines compared with pasteurized milk cheeses. Therefore, pasteurization of milk causes a decrease in final biogenic amine content of cheese as a result of the reduction of its microbial counts.

Animals↗

PubMed2006

Carotenoid profile modification during refrigerated storage in untreated and pasteurized orange juice and orange juice treated with high-intensity pulsed electric fields.

A comparative study was made of the evolution and modification of various carotenoids and vitamin A in untreated orange juice, pasteurized orange juice (90 degrees C, 20 s), and orange juice processed with high-intensity pulsed electric fields (HIPEF) (30 kV/cm, 100 micros), during 7 weeks of storage at 2 and 10 degrees C. The concentration of total carotenoids in the untreated juice decreased by 12.6% when the juice was pasteurized, whereas the decrease was only 6.7% when the juice was treated with HIPEF. Vitamin A was greatest in the untreated orange juice, followed by orange juice treated with HIPEF (decrease of 7.52%) and, last, pasteurized orange juice (decrease of 15.62%). The decrease in the concentrations of total carotenoids and vitamin A during storage in refrigeration was greater in the untreated orange juice and the pasteurized juice than in the juice treated with HIPEF. During storage at 10 degrees C, auroxanthin formed in the untreated juice and in the juice treated with HIPEF. This carotenoid is a degradation product of violaxanthin. The concentration of antheraxanthin decreased during storage, and it was converted into mutatoxanthin, except in the untreated and pasteurized orange juices stored at 2 degrees C.

Beverages↗

PubMed1998

Effect of high-temperature, short-time (HTST) pasteurization on milk containing low numbers of Mycobacterium paratuberculosis.

The efficacy of high-temperature, short-time (HTST) pasteurization (72 degrees C/15 s) when low numbers (< or = 10(3) cfu ml-1) of Mycobacterium paratuberculosis are present in milk was investigated. Raw cows' milk spiked with Myco. paratuberculosis (10(3) cfu ml-1, 10(2) cfu ml-1, 10 cfu ml-1, and 10 cfu 50 ml-1) was subjected to HTST pasteurization using laboratory pasteurizing units. Ten bovine strains of Myco. paratuberculosis were tested in triplicate. Culture in BACTEC Middlebrook 12B radiometric medium detected acid-fast survivors in 14.8% and 10% of HTST-pasteurized milk samples at the 10(3) and 10(2) cfu ml-1 inoculum levels, respectively, whereas conventional culture on Herrold's egg yolk medium containing mycobactin J detected acid-fast survivors in only 3.7% and 6.7% of the same milk samples. IS900-based PCR confirmed that these acid-fast survivors were Myco. paratuberculosis. No viable Myco. paratuberculosis were isolated from HTST-pasteurized milk initially containing either 10 cfu ml-1 or 10 cfu 50 ml-1.

Animals↗

PubMed2004

Target selection in designing pasteurization processes for shelf-stable high-acid fruit products.

This study is focused on the search for targets and criteria for the design of pasteurization processes for high-acid shelf-stable fruit products, such as juices, nectars, pastes, purees, concentrates, jams, jellies, etc. First, an overview of pasteurization is presented and then, frequently used targets for pasteurization processes are reviewed Enzymes naturally present in fruits, in decreasing order of heat resistance, were pectinesterase, peroxidase, and polyphenoloxidase, and they may be used as pasteurization targets. The heat resistance of each enzyme is strongly dependent on its fruit origin. The most heat resistant micro-organisms capable of spoiling high acid fruit products include ascospores of Neosartorya fischeri, Byssochlamys nivea, Talaromyces flavus, Eupenicillium javanicum, and Byssochlamys fulva moulds, as well as bacterial spores of Clostridium butyricum, Bacillus coagulans, and Bacillus megaterium. These micro-organisms, spores, and enzymes were, in general, less heat resistant than the spores of a particular spoilage micro-organism named Alicyclobacillus acidoterrestris, which has been causing problems in the fruit industry. Therefore, the use of Alicyclobacillus acidoterrestris spores as a reference micro-organism in the design of pasteurization processes for high-acid shelf-stable fruit products is suggested.

Food Microbiology↗

PubMed1998

Effects of human milk pasteurization and sterilization on available fat content and fatty acid composition.

BACKGROUND: Human milk is frequently heat treated in hospitals to reduce bacterial contamination, particularly in banked milk fed to preterm infants. Pasteurization and sterilization may induce oxidative losses of unsaturated lipids and vitamins and may inactivate enzymes and immunologic factors. This study was designed to examine the effects of pasteurization and sterilization on milk fat content available to the recipient infant and on fatty acid composition. METHODS: In fresh, pasteurized (62.5 degrees C for 30 minutes), and sterilized (120 degrees C for 30 minutes) milk samples (5 ml) of 12 mothers (days 5-35 of lactation), fat content was determined gravimetrically and the contribution of 30 fatty acids was determined by gas-liquid chromatography. RESULTS: The coefficients of variation for measurements of milk fat content were 0.7% and of fatty acids accounting for more than 0.09% of weight, 0.1-3.0%. Available fat content was 3.1+/-1.4 g/dl (mean +/- SD) in fresh human milk and 3.1+/-1.4 g/dl (not significant) in pasteurized human milk. Fat content declined to 2.7+/-1.1 g/dl (p < 0.001 vs. fresh) in sterilized human milk, because of increased fat adherence to the container surface after sterilization. The percentage composition of saturated, monounsaturated, and polyunsaturated fatty acids of the n-6 (C18:3, C20:2, C20:3, and C22:4) and the n-3 series (C18:3 C20:5, C22:5, and C22:6) was not affected by thermal treatment. Milk sterilization caused a slight decrease of linoleic (-0.7% vs. fresh milk; p = 0,006) and arachidonic (-2,6%; p = 0.045) acids. CONCLUSIONS: Pasteurization of human milk does not influence fat content and composition, but sterilization may reduce available fat content by more than 10%, whereas there are only slight changes in fatty acid composition.

Arachidonic Acid↗

PubMed2007

Pasteurized intercalary autogenous bone graft combined with vascularized fibula.

The optimal reconstruction procedure after wide resection of bone tumors is debatable. We reviewed pasteurized intercalary autogenous bone graft combined with a vascularized fibula graft in 15 patients with malignant bone tumors, and assessed whether this procedure would improve bone union and function. The mean duration until bone union of the pasteurized autogenous bone was 13.5 months and duration until union of the vascularized fibula was 7.7 months. Complete bone union between the pasteurized autogenous bone and the vascularized fibula eventually was achieved in 13 patients (86.7%). In the remaining two patients, fibula union was achieved but union of the pasteurized autogenous bone was not attributable to infection. Postoperative complications included two fractures and two infections. Three patients with delayed union eventually achieved bone union using an autogenous cancellous bone graft. The mean Musculoskeletal Tumor Society score was 80.6% and it was comparable to scores from other procedures. Our results suggest a pasteurized autogenous bone graft combined with a vascularized fibula graft can be a useful reconstruction method in selected patients with large bone defects after wide resection of malignant bone tumors.

Adolescent↗

PubMed1984

Pasteurization of naturally contaminated water with solar energy.

A solar box cooker (SBC) was constructed with a cooking area deep enough to hold several 3.7-liter jugs of water, and this was used to investigate the potential of using solar energy to pasteurize naturally contaminated water. When river water was heated either in the SBC or on a hot plate, coliform bacteria were inactivated at temperatures of 60 degrees C or greater. Heating water in an SBC to at least 65 degrees C ensures that the water will be above the milk pasteurization temperature of 62.8 degrees C for at least an hour, which appears sufficient to pasteurize contaminated water. On clear or partly cloudy days, with the SBC facing magnetic south in Sacramento, bottom water temperatures of at least 65 degrees C could be obtained in 11.1 liters of water during the 6 weeks on either side of the summer solstice, in 7.4 liters of water from mid-March through mid-September, and in 3.7 liters of water an additional 2 to 3 weeks at the beginning and end of the solar season. Periodic repositioning of the SBC towards the sun, adjusting the back reflective lid, and preheating water in a simple reflective device increased final water temperatures. Simultaneous cooking and heating water to pasteurizing temperatures was possible. Additional uses of the SBC to pasteurize soil and to decontaminate hospital materials before disposal in remote areas are suggested.

Enterobacteriaceae↗

PubMed1996

Effect of pasteurization on infectivity of Cryptosporidium parvum oocysts in water and milk.

Cryptosporidium parvum is a major cause of diarrheal disease in humans and has been identified in 78 other species of mammals. The oocyst stage, excreted in feces of infected humans and animals, has been responsible for recent waterborne outbreaks of human cryptosporidiosis. High temperature and long exposure time have been shown to render oocysts (suspended in water) noninfectious, but for practical purposes, it is important to know if high-temperature--short-time conditions (71.7 degrees C for 15 s) used in commercial pasteurization are sufficient to destroy infectivity of oocysts. In this study, oocysts were suspended in either water or whole milk and heated to 71.7 degrees C for 15, 10, or 5 s in a laboratory-scale pasteurizer. Pasteurized and nonpasteurized (control) oocysts were then tested for the ability to infect infant mice. No mice (0 of 177) given 10(5) oocysts pasteurized for 15, 10, or 5 s in either water or milk were found to be infected with C. parvum on the basis of histologic examination of the terminal ileum. In contrast, all (80 of 80) control mice given nonpasteurized oocysts were heavily infected. These data indicate that high-temperature--short-time pasteurization is sufficient to destroy the infectivity of C. parvum oocysts in water and milk.

Animals↗

PubMed2005

Mycobacterium avium subspecies paratuberculosis cultured from locally and commercially pasteurized cow's milk in the Czech Republic.

Between November 2002 and April 2003, 244 bottles and cartons of commercially pasteurized cow's milk were obtained at random from retail outlets throughout the Czech Republic. During the same period, samples of raw milk and of milk that was subsequently subjected to a minimum of 71.7 degrees C for 15 s in a local pasteurization unit were also obtained from two dairy herds, designated herds A and B, with low and high levels, respectively, of subclinical Mycobacterium avium subsp. paratuberculosis infection, and from one herd, herd C, without infection. Infection in individual cows in each herd was tested by fecal culturing. Milk samples were brought to the Veterinary Research Institute in Brno, Czech Republic, processed, inoculated onto Herrold's egg yolk slants, and incubated for 32 weeks. Colonies were characterized by morphology, Ziehl-Neelsen staining, mycobactin J dependency, and IS900 PCR results. M. avium subsp. paratuberculosis was cultured from 4 of 244 units (1.6%) of commercially pasteurized retail milk. M. avium subsp. paratuberculosis was also cultured from 2 of 100 (2%) cartons of locally pasteurized milk derived from infected herds A and B and from 0 of 100 cartons of milk from uninfected herd C. Raw milk from 1 of 10 (10%) fecal culture-positive cows in herd A and from 13 of 66 (19.7%) fecal culture-positive cows in herd B was culture positive for M. avium subsp. paratuberculosis. These findings confirm that M. avium subsp. paratuberculosis is present in raw milk from subclinically infected dairy cows. The culture of M. avium subsp. paratuberculosis in the Czech Republic from retail milk that had been pasteurized locally or commercially to the required national and European Union standards is in agreement with similar research on milk destined for consumers in the United Kingdom and the United States and shows that humans are being exposed to this chronic enteric pathogen by this route.

Animals↗

PubMed2002

11 January 1887, the day medicine changed: Joseph Grancher's defense of Pasteur's treatment for rabies.

The Pasteur treatment for rabies is generally seen in terms of a triumphant penetration of laboratory science into clinical medicine. Similarly, the debates challenging the Pastorians have been interpreted as retrograde and inevitably vain efforts by a few disgruntled clinicians to resist scientific progress. This article revises the standard account by showing that the defenders of Pasteur perceived a serious threat to their enterprise and acted expeditiously to counter a potential crisis by adopting clinical strategies and tactics to argue for the relative safety of their method and to account for the rare failures resulting in deaths. An extensive unpublished source, the correspondence of Dr. Joseph Grancher with Pasteur, reveals this physician's leading role in successfully orchestrating the defense of Pasteur's antirabies method in January 1887 in the National Academy of Medicine. In responding to Dr. Michel Peter's accusations that the method could be dangerous and had been fatal in certain cases, Grancher invoked notions of risk inherent in all medical therapy, along with individual variability and predisposition to disease. Grancher's unpublished correspondence, supplemented by other manuscript letters, permits a textured understanding of the urgency experienced by Pasteur's team and their interactions as they worked out a strategy to defend their pioneering entry into human medicine. The suppression of autopsy evidence in one fatal case is apparent. More important, the strategy of the Pastorians implied a complementarity between the "clinic" and laboratory science, rather than any opposition.

History, 19th Century↗

PubMed2001

Effect of pasteurization of Ewe's milk and use of a native starter culture on the volatile components and sensory characteristics of roncal cheese.

The effect of pasteurization of milk and use of a native starter culture on the volatile components and sensory characteristics of a Spanish ewe's-milk cheese were examined. Three cheese batches were made, one from raw milk, another from pasteurized milk, and a third from pasteurized milk with an added native starter culture in addition to the commercial starter. Cheeses were analyzed at 1, 120, and 240 d of ripening. Analysis of the volatile components was by purge and trap connected to a gas chromatograph with a mass spectrometer and disclosed a total of 76 components belonging to the following chemical families: hydrocarbons, fatty acids, esters, sulfur and carbonyl compounds, and, in particular, alcohols. Pasteurization lowered the levels of certain volatile components, especially alcohols, aldehydes, and ketones. The cheeses made from pasteurized milk showed lower scores for attributes of characteristic taste and aftertaste, as well as a characteristic aroma at 240 d of ripening. These results suggest that the components present in higher concentrations in the cheeses made from the raw milk were necessary for development of characteristic Roncal cheese aroma. The new native starter culture tested did not exert a significant effect on any of the parameters considered, with the exception of certain isolated components, for which higher or lower quantities were recorded in the cheeses made with that starter culture, although the differences did not have a definite effect on the sensory characteristics of the cheeses.

Animals↗

PubMed1999

Combined effects of carbon dioxide addition and barrier films on microbial and sensory changes in pasteurized milk.

The growth of psychrotrophic microorganisms is an important factor in the deterioration of refrigerated pasteurized milk. Dissolved CO2 inhibits certain spoilage microorganisms in foods provided that the packaging offers a sufficient barrier to CO2 evolution. The objectives of this work were, first, to estimate the sensory threshold for dissolved CO2 in 2% milk and, second, to determine the relationship between microbial growth and package barrier properties for pasteurized milk to which CO2 had been added at concentrations near the flavor threshold. The sensory threshold, as determined by a trained panel, for CO2 in 2% pasteurized milk was > 2.8 mM and < 9.1 mM. Pasteurized milk was inoculated with a cocktail of spoilage microorganisms, packaged in different barrier film pouches, and stored at 6.1 degrees C for up to 28 d. The addition of CO2 at concentrations of 8.7 and 21.5 mM increased the time needed to reach 10(6) cfu/ml from 6.4 d (no CO2) to 8.0 and 10.9 d, respectively, in low barrier pouches. In high barrier pouches, the time needed to reach 10(6) cfu/ml was increased to 9.7 and 13.4 d, respectively, at CO2 concentrations of 8.7 and 21.5 mM. This increase represents an increase in shelf-life of approximately 25 to 200%. Microbial counts had longer lag times and lower growth rates and took longer to reach stationary growth as the concentration of CO2 increased in all films than did the control milk. The control milk curdled in less than 17 d, but the test milk in the high barrier packaging had not curdled at 28 d. These data suggest that the shelf-life of pasteurized refrigerated milk could be extended by at least 25 to 200% at CO2 concentrations near the sensory threshold. The major variables in shelf-life are the amount of added CO2 and the barrier properties of the package.

Animals↗

PubMed1996

Comparison between irradiated and thermally pasteurized liquid egg white on functional, physical, and microbiological properties.

A comparative study was undertaken to determine the effect of irradiation and thermal pasteurization on the functional, physical, and microbiological properties of liquid egg white (LEW). The LEW was irradiated or thermally pasteurized then stored at 4 C for 3 mo. Both treatments destroyed the inoculum, Salmonella typhimurium. The microbial growth rate was slower in the irradiated LEW than in the thermally pasteurized treatment. Irradiated samples had 47% lower foam drainage and more stable viscosity than samples that were thermally pasteurized. Volume of angel food cake prepared with irradiated or pasteurized LEW decreased 48 and 57%, respectively, after 90 d. Color did not differ between treatments. Ionizing radiation is an alternative processing method that inhibits microbial growth and helps maintain functionality of LEW.

Animals↗

PubMed2004

Polyphenol oxidase activity as a potential intrinsic index of adequate thermal pasteurization of apple cider.

In response to increasing concerns about microbial safety of apple cider, the U.S. Food and Drug Administration has mandated treatment of cider sufficient for a 5-log reduction of the target pathogen. Pasteurization has been suggested as the treatment most likely to achieve a 5-log reduction, with Escherichia coli O157:H7 as the target pathogen. Regulators and processors need a reliable method for verifying pasteurization, and apple cider polyphenol oxidase (PPO) activity was studied as a potential intrinsic index for thermal pasteurization. The effect of pasteurization conditions and apple cider properties on PPO activity and survival of three pathogens (E. coli O157:H7, Salmonella, and Listeria monocytogenes) was studied using a Box-Behnken response surface design. Factors considered in the design were pasteurization conditions, i.e., hold temperature (60, 68, and 76 degrees C), preheat time (10, 20, 30 s), and hold time (0, 15, 30 s), pH, and sugar content ((o)Brix) of apple cider. Response surface contour plots were constructed to illustrate the effect of these factors on PPO activity and pathogen survival. Reduction in PPO activity of at least 50% was equivalent to a 5-log reduction in E. coli O157:H7 or L. monocytogenes for cider at pH 3.7 and 12.5 (o)Brix. Further studies, however, are needed to verify the relationship between PPO activity and pathogen reduction in cider with various pH and (o)Brix values.

Beverages↗

PubMed2006

Hot water postprocess pasteurization of cook-in-bag turkey breast treated with and without potassium lactate and sodium diacetate and acidified sodium chlorite for control of Listeria monocytogenes.

Surface pasteurization and food-grade chemicals were evaluated for the ability to control listeriae postprocess on cook-in-bag turkey breasts (CIBTB). Individual CIBTB were obtained directly from a commercial manufacturer and surface inoculated (20 ml) with a five-strain cocktail (ca. 7.0 log) of Listeria innocua. In each of two trials, the product was showered or submerged for up to 9 min with water heated to 190, 197, or 205 degrees F (ca. 87.8, 91.7, or 96.1 degrees C) in a commercial pasteurization tunnel. Surviving listeriae were recovered from CIBTB by rinsing and were then enumerated on modified Oxford agar plates following incubation at 37 degrees C for 48 h. As expected, higher water temperatures and longer residence times resulted in a greater reduction of L. innocua. A ca. 2.0-log reduction was achieved within 3 min at 205 and 197 degrees F and within 7 min at 190 degrees E In related experiments, the following treatments were evaluated for control of Listeria monocytogenes on CIBTB: (i) a potassium lactate-sodium diacetate solution (1.54% potassium lactate and 0.11% sodium diacetate) added to the formulation in the mixer and 150 ppm of acidified sodium chlorite applied to the surface with a pipette, or (ii) a potassium lactate-sodium diacetate solution only, or (iii) no potassium lactate-sodium diacetate solution and no acidified sodium chlorite. Each CIBTB was inoculated (20 ml) with ca. 5 log CFU of a five-strain mixture of L. monocytogenes and then vacuum sealed. In each of two trials, half of the CIBTB were exposed to 203 degrees F water for 3 min in a pasteurization tunnel, and the other half of the CIBTB were not; then, all CIBTB were stored at 4 degrees C for up to 60 days, and L. monocytogenes was enumerated by direct plating onto modified Oxford agar. Heating resulted in an initial reduction of ca. 2 log CFU of L. monocytogenes per CIBTB. For heated CIBTB, L. monocytogenes increased by ca. 2 log CFU per CIBTB in 28 (treatment 1), 28 (treatment 2), and 14 (treatment 3) days. Thereafter, pathogen levels reached ca. 7 log CFU per CIBTB in 45, 45, and 21 days for treatments 1, 2, and 3, respectively. In contrast, for nonheated CIBTB, L. monocytogenes levels increased from ca. 5 log CFU per CIBTB to ca. 7 log CFU per CIBTB in 28, 21, and 14 days for treatments 1, 2, and 3, respectively. Lastly, in each of three trials, we tested the effect of hot water (203 degrees F for 3 min) postprocess pasteurization of inoculated CIBTB on the lethality of L. monocytogenes and validated that it resulted in a 1.8-log reduction in pathogen levels. Collectively, these data establish that hot water postprocess pasteurization alone is effective in reducing L. monocytogenes on the surface of CIBTB. However, as used in this study, the potassium lactate-sodium diacetate solution and acidified sodium chlorite were only somewhat effective at controlling the subsequent outgrowth of this pathogen during refrigerated storage.

Acetates↗

PubMed2006

Surface pasteurization of vacuum-sealed precooked ready-to-eat meat products.

Pathogens may contaminate ready-to-eat meat products after cooking but before packaging. Listeria monocytogenes is a formidable contaminant in the food processing environment and is relatively heat resistant compared with other non-spore-forming pathogens. As a consequence, this microorganism is commonly chosen for evaluation in postpackage pasteurization studies. The aim of this study was to review information on the thermal surface pasteurization of vacuum-sealed precooked ready-to-eat meat products, bearing in mind the conditions of commercial production lines, and to formulate a guideline for pasteurization intensity. Review of the literature revealed that fewer microorganisms were killed at the product surface than would be expected based on the results of volumetric thermal resistance studies. Mathematical modeling studies indicated that this low kill might be due to surface imperfections that shield bacteria from the heat. More information on contamination with L. monocytogenes (and other possible pathogens) in process lines and their potential migration into product surface irregularities is urgently required. Studies involving destructive sampling (surface shaving) methods and inoculation with pathogens, both at realistic and inflated levels, should be performed with various product types. Published reports suggest that postpackage pasteurization of fully cooked meat products (weighing up to 9 kg) by water submersion (96 degrees C) for about 10 min should achieve a 2- to 4-log destruction of L. monocytogenes on the product surface. If heating at this temperature and duration is not feasible for product quality or logistic reasons, the inherent bacteriological stability of the product should be increased so that the intensity of surface pasteurization can safely be reduced.

Animals↗

PubMed1995

[Do objects have history? A meeting between Pasteur and Whitehead in a lactic-acid bath].

Did Pasteur discover, construct, invent lactic acid? This Gordian knot in social studies of the sciences is happily cut when the scene played out at Lille in 1857 is peopled with Whiteheadean conceptual characters. The Nature addressed by Pasteur does not speak the language of scientific utterances but neither is it mute; it is imbued with propositions. Insofar as Pasteur plays the character of a scientist, he is 'acted on' by a singular proposition -- "a tale that perhaps might be told," as Whitehead would say, but that will only be true or false if Pasteur manages to make a real world correspond to this proposition, a world capable of providing logical subjects, and thus offering proof to "whomever judges with impartiality." A hybrid-mediator-translator of Pasteurian and microorganismic propositions, the experimental environment "makes the event," in an encounter from which a new Pasteur and a new yeast emerge, partners of a new history.

Acids↗

PubMed2002

Establishment of the European Pharmacopoeia Biological Reference Preparation (Ph. Eur. BRP) for hepatitis A vaccine type B (Aventis Pasteur) batch 2.

A collaborative study was organised by the European Directorate for the Quality of Medicines with the goal to calibrate a candidate European Pharmacopoeia Biological Reference Preparation (Ph. Eur. BRP) for hepatitis A vaccine (adsorbed, inactivated) type B (Aventis Pasteur) batch 2 against the International Standard using the antigen content- and immunogenicity assay. Nine laboratories participated in the study; seven carried out both assays. Three samples were to be assayed, sample A, the 1st International Standard for hepatitis A vaccine (inactivated), sample B, the candidate BRP and sample C, the hepatitis A vaccine BRP type B (Aventis Pasteur) batch 1. Samples B and C represent the currently marketed vaccine and contain an antigen that is formalin inactivated and alum adjuvanted. For samples B and C, desorption was necessary prior to the antigen content assay; a proprietary desorption procedure had to be used. Due to an insufficient number of samples, sample C could only be tested in the antigen content assay. Samples A and B had to be tested in 3 independent experiments in the immunogenicity assay; an assay had to be used that produced a dose response curve. All three samples had to be tested also in three independent experiments in the antigen content assay using a standard method. The results from the immunogenicity assays were submitted to probit analyses, the results from the antigen content assays to parallel line analyses on log transformed responses. Based on the results of the collaborative study, the candidate BRP batch 2 appeared suitable as reference preparation for the immunogenicity assay of adsorbed, inactivated hepatitis A vaccines from Aventis Pasteur. A potency value of 262 IU/ml was assigned based on the calibration against the 1st International Standard. The attempt to reproduce the in vitro potency of the BRP batch 1 in the current study failed; only about 50% of the previously established potency was found. It was hypothesised that this loss in potency might be due to ageing of the antigen which changed adsorption behaviour, and subsequently would lead to reduced desorption and lower in vitro potency. Additional experiments were performed to investigate this hypothesis. For older vaccines a much lower degree of desorption and thus a much lower in vitro potency was found, when using the proprietary desorption method. With more vigorous desorption procedures, this problem could only partly be overcome. Thus the results obtained in the antigen content assay in the collaborative study and in the additional experiments did not allow proposing the candidate reference preparation for use in the antigen content assay for hepatitis A vaccine from Aventis Pasteur. The candidate BRP was adopted by the European Pharmacopoeia Commission at its session in March 2002 as Ph. Eur. BRP for hepatitis A vaccine (adsorbed, inactivated) type B (Aventis Pasteur) batch 2 to be used for the immunogenicity assay.

Europe↗