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 55 records · Page 3Linked to original sources

PubMed2003

The effect of Pretoria Pasteurization on bacterial contamination of hand-expressed human breastmilk.

One of the challenges facing the development of programs to reduce mother to child transmission of HIV in developing countries remains the problem of infant feeding. One of the alternative feeding methods under investigation for infants of HIV-infected mothers is heat treatment of expressed breastmilk by Pretoria Pasteurization. The objective of this study was to determine the effect of Pretoria Pasteurization on commensal and pathogenic bacteria in hand-expressed human breastmilk, and to determine the duration of time for which milk can be kept safely without refrigeration after Pretoria Pasteurization. Samples of milk were hand expressed by lactating women in the postnatal ward. The samples were split into control and pasteurized specimens. The pasteurized specimens underwent Pretoria Pasteurization. All samples were stored at room temperature and were sampled for bacterial culture every 4 h, up to 12 h. Clinically significant levels of bacterial contamination occurred in 59 per cent of control and 7.8 per cent of pasteurized samples. Four pasteurized samples showed significant contamination. There is strong evidence that the contaminating organisms in these samples were introduced by handling after pasteurization. The 53 (91 per cent) pasteurized samples that had no contamination at 4 h remained sterile for the remainder of the standing period of 12 h. Forty-one per cent of control samples already had significant growth after standing at room temperature for 4 h. In conclusion, Pretoria Pasteurization kills pathogenic and commensal bacteria in hand-expressed breastmilk. Expressed breastmilk that has undergone Pretoria Pasteurization can be kept without refrigeration for up to 12 h with minimal probability of bacterial contamination provided that it is kept in the pasteurization container and is not handled.

Colony Count, Microbial↗

PubMed2005

Effects of pasteurization of potato slurry by-product fed in corn-or barley-based beef finishing diets.

Pasteurization of vegetable by-products such as potato slurry (PS) before feeding may be necessary to prevent the spread of pathogens and beef carcass blemishes. We hypothesized that pasteurization would increase ruminal fermentability of PS starch. Four ruminally cannulated crossbred beef steers (initial BW = 432) were used in a 4 x 4 Latin square experiment with a 2 x 2 factorial arrangement of treatments to examine the main effects and interactions of pasteurization (54.4 degrees C for 2 h) of PS and grain type (GT; dry-rolled corn and barley) on ruminal and total tract digestion of beef finishing diets. Diets contained 7% alfalfa hay and 14% PS (DM basis) and were fed ad libitum three times daily. Corn-based diets had 71.7% corn, whereas barley-based diets had 60% barley and 11.7% corn. Pasteurization resulted in greater (P = 0.004) soluble, rapidly degradable starch (34.3 vs. 26.7% for pasteurized and nonpasteurized PS, respectively). Ruminal fluid pH was more acidic (P < 0.07) for corn-based diets than for barley-based diets (P = 0.07) at 0200 and 2100 (sample time x GT; P < 0.05). Ruminal fluid pH was more acidic (P = 0.06) at 1400 for corn-based diets containing pasteurized PS compared with other dietary treatments (sample time x pasteurization x GT; P = 0.04). Minimum and maximum ruminal pH were greater (P < 0.10) for barley-based diets than for corn-based diets. Ruminal fluid pH was < 6.0 for a greater (P = 0.04) proportion of the day for corn-based compared with barley-based diets. In vitro incubation measurements revealed that pasteurization of PS resulted in lower (P = 0.06) ruminal fluid ammonia N concentration. Ruminal fluid ammonia N concentration was lower (P = 0.11) for barley-based diets than for corn-based diets. Steers fed barley-based diets had greater (P = 0.02) DMI and lesser (P < 0.05) total tract digestibility of DM and ADF compared with steers fed corn diets. Pasteurization increased (P = 0.10) total tract starch digestibility. Results indicate pasteurization increased rapidly degradable starch, ruminal starch fermentability, and total tract starch digestibility of PS. Grain type interacted with pasteurization such that feeding corn-based diets containing pasteurized PS resulted in periodic reductions in ruminal pH. Feeding management may be more critical when feeding pasteurized PS in beef finishing diets.

Animal Feed↗

PubMed2005

A study on the application of pasteurization of medical equipment.

OBJECTIVES: To study the need of pasteurization of medical equipment and the possibility of production of pasteurizer in Thailand. MATERIAL AND METHOD: The need of pasteurization of medical equipment was studied by a set of questionnaires to heads of the central sterile supply department (CSSD) and head ward nurses in 29 hospitals across Thailand. Efficacy of pasteurization was demonstrated by disinfection with an imported pasteurizer. A pasteurizer was later produced by the researchers and had it tested for efficacy in disinfection. RESULTS: There were 26 items of medical equipment that could be disinfected by pasteurization. The number of the equipment was 6.2 pieces per bed per week. Disinfection of the equipment was done in C.S.S.D. as well as in patient's wards. The imported pasteurizer was efficacious in disinfection. The pasteurizer made by researchers was convenient for use, not expensive to manufacture and the operating cost for disinfection was 2 to 6 folds less than that done by ethylene oxide gas. CONCLUSION: Pasteurization is effective in disinfection and is applicable to certain heat labile medical equipments. A pasteurizer is not difficult to produce, cheap and the operating cost is low. Pasteurization should be more widely applied in Thailand

Central Supply, Hospital↗

PubMed1996

Survival of Mycobacterium paratuberculosis and preservation of immunoglobulin G in bovine colostrum under experimental conditions simulating pasteurization.

OBJECTIVE: To determine whether Mycobacterium paratuberculosis could survive in colostrum after pasteurization. Additionally, this study investigated the effect pasteurization had on IgG concentration in colostrum. ANIMALS: Colostrum samples were collected from cattle (beef and dairy) owned by the state of Ohio. PROCEDURE: Colostrum was divided into aliquots and inoculated with variable concentrations of M paratuberculosis (ATCC No. 19698: 10(4), 10(3), and 10(2) colony-forming units/ml). Half the samples at each concentration were subjected to pasteurization temperatures (63 C) for 30 minutes and the remainder were kept at approximately 20 to 23 C. All samples were incubated (Herrold's egg yolk medium with and without mycobactin J) and observed for growth during the next 16 weeks. Additionally, the IgG concentration of colostrum was determined by radioimmunoassay before and after pasteurization. Samples that coagulated at pasteurization temperatures were mechanically resuspended before measurement of IgG concentration. RESULTS: Growth of M paratuberculosis was retarded but not eliminated by pasteurization. Growth was observed in all unpasteurized samples incubated on Herrold's egg yolk medium with mycobactin J but in only 2 of 18 pasteurized samples similarly cultured. Growth from pasteurized samples appeared 5 to 9 weeks after growth was observed from nonpasteurized samples. Mean colostral IgG concentration was 44.4 g/L in nonpasteurized samples and 37.2 g/L in pasteurized samples, a decrease of 12.3%. High-quality colostrum (> 48 g of IgG/L) had a significantly greater loss of IgG concentration than did colostrum of lesser quality (P = 0.002). CONCLUSIONS: Pasteurization lessened, but did not eliminate, growth of M paratuberculosis from experimentally inoculated colostrum samples. Pasteurization resulted in a significant decrease in colostral IgG concentration but not to an unmanageable level that would preclude the colostrum's use for passive transfer of immunity. CLINICAL RELEVANCE: Colostrum is macrophage rich and may serve as a source of M paratuberculosis infection to calves. Pasteurization of colostrum may lessen the risk of infection, but will not totally eliminate M paratuberculosis.

Animals↗

PubMed2002

Microbiological and organoleptic qualities of vacuum-packaged ground beef prepared from pasteurized manufacturing beef.

Manufacturing beef was pasteurized by immersion in water of 85 degrees C for 60 s, or was not pasteurized before being coarsely ground. The coarsely ground beef was vacuum-packaged and stored at 2 degrees C for up to 6 weeks. Before storage and at weekly intervals, three packs of pasteurized and three of unpasteurized beef were opened. The meat from each pack was finely ground and displayed in two overwrapped packs at 4 degrees C for 3 days after storage for up to 3 weeks, or for 2 days after longer storage times. Samples for microbiological analysis were obtained at the times of preparation of display packs and at the end of display. Displayed meat was assessed daily for colour, discolouration and retail acceptability, and for odour intensity and acceptability at the end of display. Before storage, the numbers of total aerobic bacteria, presumptive pseudomonads and presumptive Brochothrix thermosphacta recovered from pasteurized meat were >1 log unit less than the corresponding numbers recovered from unpasteurized meat, but the numbers of presumptive lactic acid bacteria and presumptive enterobacteria were <1 log unit less from pasteurized than from unpasteurized meat. After all periods of storage and display, the numbers of bacteria recovered from pasteurized and unpasteurized meat at each time were mostly similar. The colour of pasteurized meat was perceived as being paler than that of unpasteurized meat, but discolouration and retail acceptability of pasteurized and unpasteurized meat were perceived as similar at most times. The odours of displayed, pasteurized and unpasteurized meat were perceived to be similar at all times that odours were assessed. The findings indicate that pasteurizing of manufacturing beef to improve the microbiological safety of ground beef would not unacceptability degrade the appearance of the ground product, but that the storage life of ground beef would not be greatly extended by the treatment.

Animals↗

PubMed1990

A survey of the microflora of raw and pasteurized milk and the sources of contamination in a milk processing plant in Addis Ababa, Ethiopia.

The microorganisms present in raw and pasteurized milk and the sources of contamination in the milk after it had arrived at the processing plant in Addis Ababa were studied. The lowest count registered for raw milk samples was 4 X 10(7) cfu/ml while the highest was 1 X 10(9) cfu/ml. Pasteurized milk had mesophilic aerobic counts of 7 X 10(5) cfu/ml as it left the pasteurizing unit, but the population increased 2- to 4-fold as a result of subsequent contamination. Of the total counts in raw milk, psychrophilic, thermoduric and thermophilic organisms made up 98.1, 1.4 and 0.5% respectively. In pasteurized milk, the amounts were 53.0, 39.5 and 7.5% respectively. Samples of milk pasteurized in the laboratory contained only 74.5% thermoduric and 25.5% thermophilic organisms. The isolates mostly belonged to the genera Bacillus, Streptococcus, Lactobacillus, Arthrobacter, Alcaligenes, Aeromonas and Pseudomonas. Cocci were more predominant than rod-shaped bacteria. Of the rod-shaped bacteria, 73% were Gram-negative. The utensils holding the raw and pasteurized milk and the plastic sheets used for bagging the pasteurized milk contributed unusually high numbers of bacteria which were either thermoduric or thermophilic. More isolates were obtained from the pasteurized than the raw milk. The keeping quality of the pasteurized milk was found to be much lower than that of the laboratory-pasteurized milk.

Animals↗

PubMed2003

Effect of on-farm commercial batch pasteurization of colostrum on colostrum and serum immunoglobulin concentrations in dairy calves.

The objectives were to describe the effect of on-farm commercial batch pasteurization on immunoglobulin (IgG) concentrations and the fluid and feeding characteristics of colostrum and to compare serum IgG concentrations in calves fed fresh versus pasteurized colostrum. Newborn calves (123) were systematically allocated to dietary treatments of either fresh or pasteurized colostrum at both the first and second colostrum feedings. The IgG concentrations were measured for batches of colostrum fed fresh and in pre and postpasteurized samples for batches of colostrum fed after being pasteurized and in calf serum. Pasteurization reduced colostrum IgG concentration, with the percentage reduction averaging 58.5 and 23.6% for 95-L and 57-L batches, respectively. Pasteurizing high quality colostrum in 57-L (vs. 95-L) batches resulted in higher IgG concentrations in the end product. Pasteurization of 57-L batches produced colostrum of normal or only mildly thickened consistency that could be fed to calves. Serum IgG concentrations were higher for calves fed fresh colostrum and for calves with a shorter time interval (< or = 6 h) between first and second colostrum feedings. After controlling for the time interval between feedings, serum IgG concentrations were significantly higher for 40 calves fed unpasteurized (19.1 mg/ml) vs. 55 calves fed pasteurized colostrum (9.7 mg/ml) for calves fed 2 L at first feeding. By contrast, there was no difference in serum IgG concentrations between 8 calves fed unpasteurized (16.1 mg/ml) and 20 calves fed pasteurized colostrum (13.5 mg/ml) after calves were fed 4 L at the first feeding. While the latter results suggest that pasteurizing colostrum may work for producers with excellent colostrum management, these results are preliminary and should be interpreted with caution, given the fewer number of calves and batches of colostrum involved with this second comparison.

Animals↗

PubMed2005

Effectiveness of steam pasteurization in controlling microbiological hazards of cull cow carcasses in a commercial plant.

The purpose of the study, carried out in a beef processing plant, was to evaluate the effectiveness of a new prototype for steam pasteurization treatment in controlling microbiological hazards. Samples were taken by swabbing randomly selected sites before and after pasteurization and again after chilling to obtain total aerobic counts (TAC), total coliform counts (TCC), and generic Escherichia coli counts (ECC) on Petrifilm plates and to determine the prevalence of Salmonella spp., Listeria monocytogenes, and E. coli O157:H7 using standard enrichment techniques. Escherichia coli and L. monocytogenes strains were tested for various factors associated with their virulence by using colony hybridization and polymerase chain reaction (PCR), respectively. Antimicrobial susceptibility was determined for each isolate that was potentially pathogenic to humans by using the disk-diffusion method. Mean values for TAC, TCC, and ECC were 2.18, 0.16, and 0.06 log10 CFU/cm2, respectively, before pasteurization; 1.17, 0.03, and 0.01 log10 CFU/cm2 after pasteurization; and 0.89, 0.02, and 0.01 log10 CFU/cm2 after chilling. Prevalence of L. monocytogenes, Salmonella spp., and E. coli O157:H7 on carcasses was 0.8%, 0.0%, and 0.0%, respectively, before pasteurization; 2.6%, 0.0%, and 0.0% after pasteurization; and 3.1%, 0.1%, and 0.0% after chilling. The prevalence of E. coli containing > or = 1 virulence gene was 14.7%. More specifically, 11.88% of the isolates obtained before pasteurization, 22.2% obtained after pasteurization, and 31.2% obtained after chilling had virulence genes. All L. monocytogenes isolates tested positive for the presence of 3 major virulence factors (hlyA, inlB, and plcB). Antibiograms showed that certain isolates were susceptible to all antibiotics, some showed an intermediate sensitivity, and others were multiresistant. Overall, these results suggest that steam pasteurization is an effective means of improving safety quality of beef carcasses. However, pasteurization may indirectly contribute to the growth of some pathogenic microorganisms, such as L. monocytogenes.

Abattoirs↗

PubMed2002

Incidence of Mycobacterium paratuberculosis in bulk raw and commercially pasteurized cows' milk from approved dairy processing establishments in the United Kingdom.

Over a 17-month period (March 1999 to July 2000), a total of 814 cows' milk samples, 244 bulk raw and 567 commercially pasteurized (228 whole, 179 semi-skim, and 160 skim), from 241 approved dairy processing establishments throughout the United Kingdom were tested for the presence of Mycobacterium paratuberculosis by immunomagnetic PCR (to detect all cells living and dead) and culture (to detect viable cells). Overall, M. paratuberculosis DNA was detected by immunomagnetic PCR in 19 (7.8%; 95% confidence interval, 4.3 to 10.8%) and 67 (11.8%; 95% confidence interval, 9.0 to 14.2%) of the raw and pasteurized milk samples, respectively. Confirmed M. paratuberculosis isolates were cultured from 4 (1.6%; 95% confidence interval, 0.04 to 3.1%) and 10 (1.8%; 95% confidence interval, 0.7 to 2.8%) of the raw and pasteurized milk samples, respectively, following chemical decontamination with 0.75% (wt/vol) cetylpyridinium chloride for 5 h. The 10 culture-positive pasteurized milk samples were from just 8 (3.3%) of the 241 dairy processing establishments that participated in the survey. Seven of the culture-positive pasteurized milk samples had been heat treated at 72 to 74 degrees C for 15 s; the remainder had been treated at 72 to 75 degrees C for the extended holding time of 25 s. When typed by restriction fragment length polymorphism and pulsed-field gel electrophoresis methods, some of the milk isolates were shown to be types distinct from those of laboratory strains in regular use within the testing laboratory. From information gathered at the time of milk sample collection, all indications were that pasteurization had been carried out effectively at all of the culture-positive dairies. That is, pasteurization time and temperature conditions complied with the legal minimum high-temperature, short-time process; all pasteurized milk samples tested phosphatase negative; and post-process contamination was considered unlikely to have occurred. It was concluded that viable M. paratuberculosis is occasionally present at low levels in commercially pasteurized cows' milk in the United Kingdom.

Animals↗

PubMed2002

Study of the healing process after transplantation of pasteurized bone grafts in rabbits.

Different bone allografts (pasteurized, autoclaved, and frozen) were compared based on their osteoinductive properties. Our primary purpose was to examine the biologic qualities of pasteurized allografts, as pasteurization inactivates most viruses transmitted by transplantation. Frozen, pasteurized, and autoclaved allografts were packed into a standard defect of rabbit ulna. The animals were sacrificed at 2 and 4 weeks after surgery. The parts of bones with experimental defects were explored en bloc, and a roentgenogram was carried out. Ulna bone samples were then embedded in methyl-methacrylate. Roentgenograms showed that after 2 weeks, calluses were well-formed, but irregular in shape in all 3 types of allografts. After 4 weeks, the calluses were regular in shape in all but the autoclaved grafts. After 2 weeks, the healing processes had begun in the frozen and pasteurized grafts, with the reaching approximately the same stage, while in the autoclaved grafts these processes were not seen and the bone particles were surrounded by connective tissue without any changes. After 4 weeks, osteoinductive processes were very strong, with the first signs of complete bone remodeling at the bone edges of the defect in pasteurized and frozen allografts. The osteoinductive values of these 2 types were very high and similar. Autoclaved allografts, on the other hand, had very low osteoinductive values, as they were still at the very beginning of the healing process. Histomorphometric analysis revealed a significant difference in both newly formed osteoid thickness and osteoblast number per microm of bone surface in all experimental groups (P < 0.005). Values of osteoid thickness and osteoblast number were significantly higher in both frozen and pasteurized grafts when compared with the autoclaved ones (P < 0.005). Osteogenic properties of pasteurized bone allografts were preserved, and the allografts have been gradually replaced with newly formed bone. As such, pasteurized bone grafts from a bone bank have approximately the same biologic validity as frozen grafts, while autoclaved grafts impair bone healing.

Animals↗

PubMed2005

Economic analysis of feeding pasteurized nonsaleable milk versus conventional milk replacer to dairy calves.

OBJECTIVE: To determine growth, morbidity, and mortality rates in dairy calves fed pasteurized nonsaleable milk versus commercial milk replacer and compare economics of feeding pasteurized nonsaleable milk versus commercial milk replacer in dairy calves. DESIGN: Clinical trial. ANIMALS: 438 dairy calves. PROCEDURE: Calves were assigned at 1 to 2 days of age to be fed pasteurized nonsaleable milk or a commercial milk replacer until weaned. Body weight was measured at the time of study enrollment and at the time of weaning, and any medical treatments administered and deaths that occurred prior to weaning were recorded. A partial budget model was developed to examine the economics of feeding pasteurized nonsaleable milk versus commercial milk replacer. RESULTS: Calves fed conventional milk replacer had significantly lower rates of gain (-0.12 kg/d [-0.26 lb/d]), lower weaning weights (-5.6 kg [-12.3 lb]), higher risk for treatment during the summer and winter months (odds ratio [OR], 3.99), and higher risk of death during the winter months (OR, 29.81) than did calves fed pasteurized nonsaleable milk. The estimated savings of feeding pasteurized nonsaleable milk, compared with milk replacer, was dollars 0.69/calf per day. The estimated number of calves needed to economically justify the nonsaleable milk pasteurization system was 23 calves/d. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that dairy calves fed pasteurized nonsaleable milk have a higher growth rate and lower morbidity and mortality rates than do calves fed conventional milk replacer. Feeding pasteurized nonsaleable milk could be an economically viable strategy for dairy calf producers.

Animal Feed↗

PubMed1995

[The Pasteur network].

Inspired by Louis Pasteur, the international network of Pasteur Institutes forms an original body of research institutes whose vitality has grown steadily since Albert Calmette first created the Saigon Institute in 1891. The dynamic development of the 23 Pasteur Institutes currently implanted throughout the world was made possible by three driving forces. First of all, Pasteur's own teaching--"Advance only what you can prove experimentally"--the founding principle of modern research. Secondly, the international missions headed by leading collaborators including Thuillier who worked on cholera in Egypt, Loir who initiated antirabies research in Australia and Russia, Calmette in Saigon, and others in Rio de Janeiro, Dalat, Tunis and Alger. And finally Pasteur's own personal renown. Today the Pasteur Institutes fill a vital need in their respective countries developing and producing vaccines locally, serving often as the only competent medical laboratory in developing countries and helping improve standards of hygiene adapted to local situations. Fundamental research has always been at the heart of Pasteur Institutes, coupled with essential training for technicians and researchers alike. Despite political incertitudes and turmoil, the international network of Pasteur Institutes has held its place as the leader in scientific progress for over a century, setting the place for modern international research. The Cantacuzene Institute in Bucarest and the Pasteur Institute in Saint-Petersburg which joined the network in 1991 and 1993 are the most recent examples of the fundamental principle of exchange and cooperation so important for further development.

Academies and Institutes↗

PubMed1997

[Critical control points in the pasteurized milk processing fluxogram].

With the aim of evaluating the microbiological quality of raw and pasteurized milk and confirm the critical control points in a dairy processing industry (Recife-PE, Brazil), 84 samples of milk were collected from four points of the flow-chart considered critical (raw milk storage tank, outlet of the pasteurizer unit, pasteurized milk storage tank and packing filling machine). All samples were evaluated for the presence of mesophilic and psychotrophics microorganisms. The most probable number (MPN) of total and faecal coliforms were determined. Samples of raw and pasteurized milk (collected from the packing filling machine) were also assessed for the presence of Staphylococcus aureus. The preservation temperature of raw and pasteurized milk in the storage tanks and the MPN of total and faecal coliforms present in the water used by the industry were simultaneously evaluated. High counts of mesophilic and psychotrophics microorganisms, total and faecal coliforms and S. aureus were detect in raw milk production and processing. The pasteurization process reduced the microorganisms to acceptable numbers in the Brazilian standards, however, the statistics analysis showed that the number of microorganisms increased significantly (p < 0.01) in the pasteurized milk storage tank, representing an important point of contamination. The probable reason for this findings was the presence of coliforms in 60% samples of water which was used to clean the milk equipment and the inadequate temperatures in the storage tank. Therefore, the results of the microbiological analysis confirm that the milk maintenance temperature in the storage tanks, the pasteurization and the packaging are critical control points in the pasteurized milk processing fluxogram.

Animals↗

PubMed1990

The source of Yersinia spp. in pasteurized milk: an investigation at a dairy.

Pasteurized bottled milk supplied by a single dairy was frequently found to be contaminated with Yersinia spp. Investigations were carried out at the dairy in an effort to pinpoint the source of these organisms. Viable counts obtained from milk bottle rinses indicated that bottle washing was often unsatisfactory, and on one occasion Y. frederiksenii was isolated from the pooled rinse water of six bottles. Samples of milk were taken on arrival at the dairy and at various stages following pasteurization. Heat resistance tests carried out on strains of yersinia isolated from pasteurized milk indicated that they would not survive the pasteurization process. However two strains of yersinia were isolated from a sample of milk taken immediately after pasteurization but before bottling. The thermograph indicated that the time/temperature conditions applied during pasteurization were adequate. The presence of yersinia strains in the milk at this stage therefore suggests that undetectable levels of raw milk were being allowed to contaminate the pasteurized milk. The absence of yersinia in cartoned samples produced on the same day as contaminated bottled samples indicated that environmental contamination of the bottle filler valve also may have occurred at times. Results of this investigation indicate that increased vigilance is required to ensure proper operation of pasteurizers and bottle washers.

Animals↗

PubMed2001

Challenge testing of the lactoperoxidase system in pasteurized milk.

AIMS: To determine the role of lactoperoxidase (LP) in inhibiting the growth of micro-organisms in pasteurised milk. METHODS AND RESULTS: Four micro-organisms of importance in the spoilage of pasteurized milk were challenged in lactoperoxidase (LP)-enriched ultra-heat treated (UHT) milk after subsequent pasteurization. Milk samples were stored at the optimum temperatures for growth of the individual bacteria. Pasteurization was carried out at 72 degrees C/15 s and 80 degrees C/15 s to determine the effect of the LP system on the micro-organisms. An active LP system was found to greatly increase the keeping quality (KQ) of milks inoculated with Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus thermophilus and pasteurized at 72 degrees C, but had little or no effect in milks heated at 80 degrees C, presumably due to virtual inactivation of LP at 80 degrees C. However, pasteurization temperature had no effect on the KQ of milks challenged with Bacillus cereus spores. CONCLUSIONS: This study suggests that the LP system, rather than heat-shocking of spores, is responsible for the greater KQ of milk pasteurized at 72 degrees C/15 s compared with 80 degrees C/15 s. SIGNIFICANCE AND IMPACT OF THE STUDY: The study emphasizes the care required in selecting pasteurization temperatures in commercial practice and to avoid the temptation to compensate for inferior quality of raw milk by increasing pasteurization temperature.

Animals↗

PubMed2001

The effect of shell egg pasteurization on the protein quality of albumen.

The effect of a low-temperature, extended-time, in-shell pasteurization process on the protein quality of egg albumen was evaluated. Ten dozen fresh chicken eggs were pasteurized in a hot-air oven at 55 C for 180 min. The eggs were refrigerated and broken out for analysis on Days 0, 7, 14, 28, 42, and 56 following pasteurization. There were no significant differences in total or soluble protein over the experimental period for the pasteurized or unpasteurized albumen. Mean protein content was 80.6 +/- 0.5% for the pasteurized albumen and 80.9 +/- 0.5% for the unpasteurized albumen. In vitro digestibility, as measured by the AOAC method, was 82.4 +/- 0.7% for the pasteurized albumen and 81.7 +/- 0.6% for the unpasteurized albumen. There were no significant differences over the experimental period in the digestibility of the samples. Free amino acids and discriminant-computed protein efficiency ratio (DC-PER) also did not differ between the pasteurized and unpasteurized albumens or over the experimental period. The in-shell pasteurization process used had no effect on the protein quality of albumen.

Amino Acids↗

PubMed2005

Efficacy of various pasteurization time-temperature conditions in combination with homogenization on inactivation of Mycobacterium avium subsp. paratuberculosis in milk.

The effect of various pasteurization time-temperature conditions with and without homogenization on the viability of Mycobacterium avium subsp. paratuberculosis was investigated using a pilot-scale commercial high-temperature, short-time (HTST) pasteurizer and raw milk spiked with 10(1) to 10(5) M. avium subsp. paratuberculosis cells/ml. Viable M. avium subsp. paratuberculosis was cultured from 27 (3.3%) of 816 pasteurized milk samples overall, 5 on Herrold's egg yolk medium and 22 by BACTEC culture. Therefore, in 96.7% of samples, M. avium subsp. paratuberculosis had been completely inactivated by HTST pasteurization, alone or in combination with homogenization. Heat treatments incorporating homogenization at 2,500 lb/in2, applied upstream (as a separate process) or in hold (at the start of a holding section), resulted in significantly fewer culture-positive samples than pasteurization treatments without homogenization (P < 0.001 for those in hold and P < 0.05 for those upstream). Where colony counts were obtained, the number of surviving M. avium subsp. paratuberculosis cells was estimated to be 10 to 20 CFU/150 ml, and the reduction in numbers achieved by HTST pasteurization with or without homogenization was estimated to be 4.0 to 5.2 log10. The impact of homogenization on clump size distribution in M. avium subsp. paratuberculosis broth suspensions was subsequently assessed using a Mastersizer X spectrometer. These experiments demonstrated that large clumps of M. avium subsp. paratuberculosis cells were reduced to single-cell or "miniclump" status by homogenization at 2,500 lb/in2. Consequently, when HTST pasteurization was being applied to homogenized milk, the M. avium subsp. paratuberculosis cells would have been present as predominantly declumped cells, which may possibly explain the greater inactivation achieved by the combination of pasteurization and homogenization.

Animals↗

PubMed2004

Effect of prepackage and postpackage pasteurization on postprocess elimination of Listeria monocytogenes on deli turkey products.

Surface pasteurization for inactivation of Listeria monocytogenes was evaluated for radiant heat prepackage pasteurization, submersed water postpackage pasteurization, and combinations of the two techniques on various types of ready-to-eat deli turkey products obtained from at least four different manufacturers. Products were inoculated either by in-package liquid inoculum or surface sponge-contact with approximately 10(9) CFU of L. monocytogenes. Additional testing of radiant heat pasteurization was performed with low-level inoculation of product undersides with approximately 100 CFU of L. monocytogenes followed by enrichment recovery after pasteurization. Prepackage pasteurization provided 2.0 to 2.8 log reductions when processed for 60 s and 2.8 to 3.8 log reductions when processed for 75 s. An improved radiant oven provided 3.53 (60 s) and 4.76 (75 s) log reductions of L. monocytogenes. No positive samples were detected after enrichment when 40 samples of deli turkey (4 to 4.5 kg) undersides were inoculated at low levels and processed for 75 s. Submersed water postpackage pasteurization provided 1.95 to 3.0 log reductions when processed for 2, 3, 4, or 5 min, and combinations of the two processes gave 3.0 to 4.0 log inactivation of L. monocytogenes using either 60 + 60 s or 60 + 90 s for the prepackage and postpackage pasteurization processes, respectively. These processes, either individually or in combination, can provide postprocess elimination of bacteria for the manufacture of safe ready-to-eat deli meats.

Animals↗