Статті в журналах: "Ultrahigh temperature milk"

1

WADSWORTH, K. D., and R. BASSETTE. "Laboratory-Scale System to Process Ultrahigh-Temperature Milk1." Journal of Food Protection 48, no. 6 (June 1, 1985): 530–31. http://dx.doi.org/10.4315/0362-028x-48.6.530.

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A laboratory-scale, indirect, ultrahigh-temperature (UHT) system was constructed using stainless steel tubing (6.35 mm) as the barrier between the heating agent and the product. Nitrogen gas under 80 psi pressure propelled milk through the tubing of the system. The milk was preheated in a hot water bath, brought to sterilization temperature in an oil bath, and held at this temperature in a holding tube. After leaving the holding tube, the milk was cooled rapidly in an ice-water bath and aseptically collected in 250-ml amber colored glass bottles in a glove box. The system effectively sterilized milk with carefully controlled temperature and time.

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2

D'AMICO, DENNIS J., TODD M. SILK, JUNRU WU, and MINGRUO GUO. "Inactivation of Microorganisms in Milk and Apple Cider Treated with Ultrasound." Journal of Food Protection 69, no. 3 (March 1, 2006): 556–63. http://dx.doi.org/10.4315/0362-028x-69.3.556.

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Nonthermal technologies are emerging as promising alternatives to heat treatment for food processing. Ultrasound, defined as sound waves with a frequency greater than 20 kHz, has proven bactericidal effects, especially when combined with other microbial-reduction strategies such as mild heating. In this study, ultrasound treatment (sonifier probe at 20 kHz, 100% power level, 150 W acoustic power, 118 W/cm2 acoustic intensity) with or without the effect of mild heat (57°C) was effective at reducing microbial levels in raw milk, Listeria monocytogenes levels inoculated in ultrahigh-temperature milk, and Escherichia coli O157:H7 in apple cider. Continuous flow ultrasound treatment combined with mild heat (57°C) for 18 min resulted in a 5-log reduction of L. monocytogenes in ultrahigh-temperature milk, a 5-log reduction in total aerobic bacteria in raw milk, and a 6-log reduction in E. coli O157:H7 in pasteurized apple cider. Inactivation regressions were second-order polynomials, showing an initial period of rapid inactivation, eventually tailing off. Results indicate that ultrasound technology is a promising processing alternative for the reduction of microorganisms in liquid foods.

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3

BRIÑEZ, WILFIDO JOSÉ, ARTUR X. ROIG-SAGUÉS, M. MANUELA HERNÁNDEZ HERRERO, and BUENAVENTURA GUAMIS LÓPEZ. "Inactivation of Listeria innocua in Milk and Orange Juice by Ultrahigh-Pressure Homogenization." Journal of Food Protection 69, no. 1 (January 1, 2006): 86–92. http://dx.doi.org/10.4315/0362-028x-69.1.86.

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The aim of this work was to evaluate the bactericidal efficacy of ultrahigh-pressure homogenization (UHPH) against Listeria innocua ATCC 33090 inoculated into milk and orange juice. We also intended to study the effect of inlet temperature on the lethality and production of sublethal injuries in this microorganism and its ability to survive, repair, and grow in refrigerated storage after UHPH treatment. Samples of ultrahigh-temperature whole milk and ultrahigh-temperature orange juice inoculated at a concentration of approximately 7.0 log (CFU per milliliter) were immediately pressurized at 300 MPa on the primary homogenizing valve and at 30 MPa on the secondary valve, with inlet temperatures of 6.0 ± 1.0°C and 20 ± 1.0°C. L. innocua viable counts and injured cells were measured 2 h after UHPH treatment and after 3, 6, and 9 days of storage at 4°C for milk and after 3, 6, 9, 12, 15, 18, and 21 days of storage at 4°C for orange juice. Both the inlet temperature and the food matrix influenced significantly (P < 0.05) the inactivation of L. innocua, which was higher in whole milk at the 20°C inlet temperature. The UHPH treatment caused few or no sublethal injuries in L. innocua. During storage at 4°C after treatments, counts increased by approximately 2 logarithmic units from day 0 to 9 in whole milk, whereas in orange juice counts diminished by approximately 2.5 logarithmic units from day 0 to 18.

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4

WADSWORTH, K. D., and R. BASSETTE. "Effect of Oxygen on Development of Off-Flavors in Ultrahigh-Temperature Milk1." Journal of Food Protection 48, no. 6 (June 1, 1985): 487–93. http://dx.doi.org/10.4315/0362-028x-48.6.487.

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The role of dissolved oxygen as a contributor to flavor deterioration in sterile milk during storage was investigated. Before processing, a concentrated aqueous solution of Tenox-2 was added to half of a batch of pasteurized-homogenized milk to give a final concentration of 400 ppm BHA on a fat basis in the milk. The other half was untreated. Half of each of those batches was treated to reduce oxygen concentrations by a combination of nitrogen sweep and sonication. The remaining two samples (Tenox-2 added and no-Tenox-2) did not receive the deoxygenation treatment. Oxygen levels in the preprocessed deoxygenated milk were lower (4.6 ppm) than those in the untreated milk (6.9 ppm). All four lots were UHT-sterilized at 135°C for 5 s in an indirect UHT system constructed at Kansas State University. Sterilized milk was collected aseptically in a glove box in 250-ml amber glass bottles, which were closed with either Teflon-lined caps or sterile cotton plugs. Samples from each treatment were stored at 7° and 32°C for 4 months. Samples in capped bottles maintained relatively low (<4 ppm) dissolved oxygen concentrations, whereas those in cotton-plugged bottles had relatively high (7–7.5 ppm) dissolved oxygen concentrations. Dissolved oxygen affected the rate of stale flavor development. Sterile milk in bottles with cotton plugs, which had relatively high concentrations of dissolved oxygen during storage, developed a stale flavor sooner and with greater intensity than milks with lower levels of oxygen. However, acetaldehyde, propanal, n-pentanal, and n-hexanal, which are most likely products of lipid oxidation, did not appear to be principal contributors to staling in sterile milk during storage in this study. Furthermore, the stale flavor development did not parallel changes in thiobarbituric acid (TBA) values. Although antioxidant (40 ppm BHA on fat basis from Tenox-2) did retard oxidation slightly, it did not control staling. A decrease in the concentration of several volatile materials throughout the storage period probably was caused by dissipation of the volatile material through the cotton plug or by their interaction with other compounds in the milk. Acid degree values increased in sterile milk at 32°C during prolonged storage, but changes in ADVs did not parallel development of the stale flavor.

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5

Dupont, Didier, Damien Lugand, Odile Rolet-Repecaud, and Jacques Degelaen. "ELISA To Detect Proteolysis of Ultrahigh-Temperature Milk upon Storage." Journal of Agricultural and Food Chemistry 55, no. 17 (August 2007): 6857–62. http://dx.doi.org/10.1021/jf070694w.

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6

McLean, Sarah K., Louise A. Dunn, and Enzo A. Palombo. "Phage Inhibition ofEscherichia coliin Ultrahigh-Temperature-Treated and Raw Milk." Foodborne Pathogens and Disease 10, no. 11 (November 2013): 956–62. http://dx.doi.org/10.1089/fpd.2012.1473.

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7

BELLOQUE, JOSEFINA, ALFONSO V. CARRASCOSA, and ROSINA LÓPEZ-FANDIÑO. "Changes in Phosphoglyceride Composition during Storage of Ultrahigh-Temperature Milk, as Assessed by 31P-Nuclear Magnetic Resonance: Possible Involvement of Thermoresistant Microbial Enzymes." Journal of Food Protection 64, no. 6 (June 1, 2001): 850–55. http://dx.doi.org/10.4315/0362-028x-64.6.850.

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Soluble phosphoglycerides were studied in ultrahigh-temperature (UHT) milk by 31P-nuclear magnetic resonance. It was shown that, during storage of UHT milk, manufactured from raw milk with poor microbial quality, glycerophosphocholine and glycerophosphoethanolamine disappeared in parallel with an increase in α-glycerophosphate (GP). Storage at 10, 20, and 30°C showed a faster transformation as the temperature increased. UHT milk samples manufactured from raw milks with better microbial quality and submitted to severe heat processes did not display changes in phosphoglycerides during storage. Screening of commercial UHT milks showed variations regarding the presence of GP, while in pasteurized milk samples, the appearance of GP occurred when the commercial life had been exceeded. Inoculation of sterile milk with Pseudomonas fluorescens NCIB9046 and incubation at 10°C supported that changes in phosphoglycerides could be the consequence of a phosphodiesterase activity of bacterial origin, able to survive UHT processing. A similar behavior was observed between this activity and proteolytic activity. The potential application of the detection of these compounds as spoilage predictor indices is discussed.

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8

BLAKE, M. R., B. C. WEIMER, D. J. MCMAHON, and P. A. SAVELLO. "Sensory and Microbial Quality of Milk Processed for Extended Shelf Life by Direct Steam Injection†." Journal of Food Protection 58, no. 9 (September 1, 1995): 1007–13. http://dx.doi.org/10.4315/0362-028x-58.9.1007.

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Heat treatments of milk between 100 and 145°C produce a new type of product with a shelf life of 15 to 30 days at 7°C, which is termed extended shelf life (ESL) milk. Little information is available on the safety and sensory qualities of this product. Extended shelf life milk is being processed commercially to expand the distribution area of fluid milk products. After arrival at market, this product still has the shelf life of a pasteurized product. In this study milk was processed by direct steam injection at temperatures between 100 and 140°C for 4 or 12 s. Holding time did not significantly affect the sensory quality of the milk. A trained taste panel found cooked flavor and other off flavors varied significantly with increasing processing temperature and storage time. There were no significant differences noted in cooked or off flavors between 132 and 140°C. Psychrotrophic Bacillus species were isolated from milk processed at and below 132°C, while no organisms were isolated from milk processed at temperatures at or above 134°C. Consumer preference panels indicated consumers preferred milk processed at 134°C for 4 s to ultrahigh-temperature (UHT) processed milk, although there was a slight preference for high-temperature short-time processed (HTST) milk compared to milk processed at 134°C for 4 s. Higher temperatures had a less destructive effect on lipase activity, while storage time did not significantly affect lipase activity.

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9

Snoj, Tomaz, Gregor Majdic, Silvestra Kobal, Monika Zuzek та Nina Cebulj-Kadunc. "Estrone, 17β-estradiol and progesterone concentrations in processed milk with different fat contents". Veterinarski glasnik 71, № 1 (2017): 35–43. http://dx.doi.org/10.2298/vetgl170324006s.

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Introduction. The aim of this study was to determine estrone (E1), 17?-estradiol (E2) and progesterone (P4) concentrations in processed milk with different fat contents and to compare the concentrations of these hormones in commercial ultrahigh temperature (UHT) processed milk and commercial pasteurized milk. Materials and Methods. Commercial milks with different fat contents (UHT 0.5 %, UHT 1.5 %, UHT 3.5 % and pasteurized 3.5 % (10 samples of each type of milk)) were purchased in local stores. E1, E2 and P4 concentrations were determined by commercial ELISA kits. Results and Conclusions. E1 concentrations were below the limit of detection (15 pg mL-1) in all milks except in two UHT 3.5 % (out of 10) and two pasteurized 3.5 % (out of 10) milk samples. Mean E2 and P4 concentrations in UHT 3.5 % milk (25.37 ? 1.15 pg mL-1 and 10.76 ? 0.43 ng mL-1, respectively) were significantly higher than in UHT 0.5 % milk (19.38 ? 0.79 pg mL-1 and 7.06 ? 0.26 ng mL-1, respectively). Significant positive correlations were determined between hormone concentrations and milk fat contents. Relatively high E2 and P4 concentrations indicate that the bulk of milk in the commercial milks examined originated from pregnant cows.

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10

SHI, RUNJIA, ZHONGNA YU, WEI WU, HARVEY HO, JUN WANG, YUTAO WANG, and RONGWEI HAN. "A Survey of 61 Veterinary Drug Residues in Commercial Liquid Milk Products in China." Journal of Food Protection 83, no. 7 (March 16, 2020): 1227–33. http://dx.doi.org/10.4315/jfp-20-048.

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ABSTRACT To investigate the drug residue status in commercial liquid milk products in China, 190 samples, including ultrahigh temperature milk (n = 168) and pasteurized milk (n = 22) samples, were collected in 2019. Milk samples were analyzed for the presence of any of the 61 veterinary drugs in them by using a screening assay combined with an ultraperformance liquid chromatography–tandem mass spectrometry analysis. Ten (5.26%) samples were found positive for β-lactams, tetracyclines, and aminoglycosides, and six (3.16%) samples were confirmed residual for penicillin G (n = 6; 3.16%), tetracycline (n = 1; 0.53%), and oxytetracycline (n = 1; 0.53%), with the maximum concentration of 2.85, 40.64, and 12.35 μg kg−1, respectively. Drug residue detection rate in group II (4.55%; the local city domestic brands) was higher than that in group I (2.70%; the major brands of China) and group III (2.78%; the imported brands into China) and higher in domestic samples (3.39%) than that in imported samples (2.78%), and higher in pasteurized milk samples (9.09%) than in ultrahigh temperature milk samples (2.38%). All drug residue levels were far below the regulated maximum residue limits. However, based on some veterinary drug residues detected in the samples, there is a potential veterinary drug risk in liquid milk products in the Chinese market, and this situation deserves the attention of governments and consumers. HIGHLIGHTS

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11

Xu, Sa, Theodore P. Labuza, and Francisco Diez-Gonzalez. "Thermal Inactivation of Bacillus anthracis Spores in Cow's Milk." Applied and Environmental Microbiology 72, no. 6 (June 2006): 4479–83. http://dx.doi.org/10.1128/aem.00096-06.

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ABSTRACT Decimal reduction time (time to inactivate 90% of the population) (D) values of Bacillus anthracis spores in milk ranged from 3.4 to 16.7 h at 72ï¿½C and from 1.6 to 3.3 s at 112ï¿½C. The calculated increase of temperature needed to reduce the D value by 90% varied from 8.7 to 11.0ï¿½C, and the Arrhenius activation energies ranged from 227.4 to 291.3 kJ/mol. Six-log-unit viability reductions were achieved at 120ï¿½C for 16 s. These results suggest that a thermal process similar to commercial ultrahigh-temperature pasteurization could inactivate B. anthracis spores in milk.

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12

Quaglia, N. C., A. Dambrosio, G. Normanno, A. Parisi, A. Firinu, V. Lorusso, and G. V. Celano. "Survival of Helicobacter pylori in artificially contaminated ultrahigh temperature and pasteurized milk." Food Microbiology 24, no. 3 (May 2007): 296–300. http://dx.doi.org/10.1016/j.fm.2006.04.008.

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13

Giacometti, Federica, Andrea Serraino, Frederique Pasquali, Alessandra De Cesare, Elisabetta Bonerba, and Roberto Rosmini. "Behavior ofArcobacter butzleriandArcobacter cryaerophilusin Ultrahigh-Temperature, Pasteurized, and Raw Cow's Milk Under Different Temperature Conditions." Foodborne Pathogens and Disease 11, no. 1 (January 2014): 15–20. http://dx.doi.org/10.1089/fpd.2013.1597.

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14

Coulibaly, Kelegoun, and Ike J. Jeon. "Solid-phase extraction of less volatile flavor compounds from ultrahigh-temperature processed milk." Journal of Agricultural and Food Chemistry 40, no. 4 (April 1992): 612–16. http://dx.doi.org/10.1021/jf00016a017.

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15

Liu, Yanhong, and Amy Ream. "Gene Expression Profiling of Listeria monocytogenes Strain F2365 during Growth in Ultrahigh-Temperature-Processed Skim Milk." Applied and Environmental Microbiology 74, no. 22 (September 19, 2008): 6859–66. http://dx.doi.org/10.1128/aem.00356-08.

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ABSTRACT To study how Listeria monocytogenes survives and grows in ultrahigh-temperature-processed (UHT) skim milk, microarray technology was used to monitor the gene expression profiles of strain F2365 in UHT skim milk. Total RNA was isolated from strain F2365 in UHT skim milk after 24 h of growth at 4°C, labeled with fluorescent dyes, and hybridized to “custom-made” commercial oligonucleotide (35-mers) microarray chips containing the whole genome of L. monocytogenes strain F2365. Compared to L. monocytogenes grown in brain heart infusion (BHI) broth for 24 h at 4°C, 26 genes were upregulated (more-than-twofold increase) in UHT skim milk, whereas 14 genes were downregulated (less-than-twofold decrease). The upregulated genes included genes encoding transport and binding proteins, transcriptional regulators, proteins in amino acid biosynthesis and energy metabolism, protein synthesis, cell division, and hypothetical proteins. The downregulated genes included genes that encode transport and binding proteins, protein synthesis, cellular processes, cell envelope, energy metabolism, a transcriptional regulator, and an unknown protein. The gene expression changes determined by microarray assays were confirmed by real-time reverse transcriptase PCR analyses. Furthermore, cells grown in UHT skim milk displayed the same sensitivity to hydrogen peroxide as cells grown in BHI, demonstrating that the elevated levels of expression of genes encoding manganese transporter complexes in UHT skim milk did not result in changes in the oxidative stress sensitivity. To our knowledge, this report represents a novel study of global transcriptional gene expression profiling of L. monocytogenes in a liquid food.

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16

Banik, Sourav Kumar, Kamal Kanta Das, and Md Aftab Uddin. "Microbiological quality analysis of raw, pasteurized, UHT milk samples collected from different locations in Bangladesh." Stamford Journal of Microbiology 4, no. 1 (March 27, 2015): 5–8. http://dx.doi.org/10.3329/sjm.v4i1.22753.

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Present study attempted to determine the microbiological quality of raw, pasteurized and UHT (Ultra High Temperature-processed) milk samples collected from different locations in Bangladesh. A total of 46 samples were studied including 22 raw milk samples from the local dairy markets and 24 different brands of pasteurized and ultrahigh temperature (UHT) treated milk manufactured in different beverage industries. The samples were examined for determining the total viable bacterial count (TVBC) and total coliform count (TCC). Results revealed that the raw milk samples were substandard in terms of TVBC and TCC. The range of TVBC and TCC in raw milk samples was 5.2×108 to 1.3×107 cfu/ml and 4.2×104 to 1.0×104 cfu/ml, respectively. On the contrary, the quality of pasteurized and UHT-treated milks was excellent. The TVBC range in pasteurized milk samples was from 1.8×103 to 1.1×102 cfu/ml, slightly lower than that recommended by the Bangladesh Standards and Testing Institution (BSTI). Interestingly sample numbers P-6, P-10 and P-12 of pasteurized milk samples had no growth at all both in terms of TVBC and TCC and none of the UHT processed milk contained any bacteria. So from the consumer point of view, both types of processed milk can be considered safe for consumption within the mentioned expiry date. DOI: http://dx.doi.org/10.3329/sjm.v4i1.22753 Stamford Journal of Microbiology, Vol.4(1) 2014: 5-8

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17

WIRJANTORO, T. I., M. J. LEWIS, A. S. GRANDISON, G. C. WILLIAMS, and J. DELVES-BROUGHTON. "The Effect of Nisin on the Keeping Quality of Reduced Heat-Treated Milks." Journal of Food Protection 64, no. 2 (February 1, 2001): 213–19. http://dx.doi.org/10.4315/0362-028x-64.2.213.

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Milk was subjected to a combination process involving reduced heat treatment (RHT) of 117°C for 2 s and nisin (75 and 150 IU ml−1). The microbial activity and other quality aspects were compared with a RHT control (without nisin) and with a ultrahigh temperature (UHT) milk processed at 142°C for 2 s. Nisin was found to inhibit microbial growth for products stored without refrigeration, and RHT-nisin samples stored at 30°C showed very low spoilage rates during 150 days, although not low enough to satisfy requirements for commercial sterility. RHT-nisin samples could be distinguished from and were preferred to the UHT control. Significant browning occurred during storage at 30°C and above but was less in the RHT-nisin milk samples compared with the UHT milk. In RHT-nisin milk samples stored at 20 and 10°C, no microbial activity could be detected in most samples after storage for 1 year. The effectiveness of this combination of RHT, nisin, and low storage temperatures against gram-positive spore-forming bacteria suggests potential for use of nisin in extended shelf life products.

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18

López-Enríquez, Lorena, David Rodríguez-Lázaro, and Marta Hernández. "Quantitative Detection of Clostridium tyrobutyricum in Milk by Real-Time PCR." Applied and Environmental Microbiology 73, no. 11 (April 20, 2007): 3747–51. http://dx.doi.org/10.1128/aem.02642-06.

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ABSTRACT We developed a real-time PCR assay for the quantitative detection of Clostridium tyrobutyricum, which has been identified as the major causal agent of late blowing in cheese. The assay was 100% specific, with an analytical sensitivity of 1 genome equivalent in 40% of the reactions. The quantification was linear (R 2 > 0.9995) over a 5-log dynamic range, down to 10 genome equivalents, with a PCR efficiency of >0.946. With optimized detergent treatment and enzymatic pretreatment of the sample before centrifugation and nucleic acid extraction, the assay counted down to 300 C. tyrobutyricum spores, with a relative accuracy of 82.98 to 107.68, and detected as few as 25 spores in 25 ml of artificially contaminated raw or ultrahigh-temperature-treated whole milk.

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19

STABEL, J. R., and A. LAMBERTZ. "Efficacy of Pasteurization Conditions for the Inactivation of Mycobacterium avium subsp. paratuberculosis in Milk." Journal of Food Protection 67, no. 12 (December 1, 2004): 2719–26. http://dx.doi.org/10.4315/0362-028x-67.12.2719.

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Mycobacterium avium subsp. paratuberculosis, the causative agent of a chronic enteritis in ruminants (Johne's disease), has been linked to Crohn's disease in humans. This microorganism is shed by infected animals primarily in the feces but is also shed in the milk at much lower levels. Therefore, dairy products from infected animals may be one mode of transmission of this animal pathogen. This study was designed to evaluate the effectiveness of the holder and high-temperature short-time pasteurization standards on the destruction of M. paratuberculosis. One hundred eighty experiments were conducted in this study using a slug-flow pasteurizer unit and a laboratory scale pasteurizer unit. Ultrahigh-temperature milk was inoculated at two concentrations, 108 and 105 CFU/ml, with three different field strains of M. paratuberculosis. Five different time-temperature combinations were evaluated: 62.7°C for 30 min, 65.5°C for 16 s, 71.7°C for 15 s, 71.7°C for 20 s, and 74.4°C for 15 s. Three replicates of each experiment were run for the pasteurizer unit, time-temperature combination, and strain of M. paratuberculosis. Treatment of milk regardless of bacterial strain or pasteurizer unit resulted in an average 5.0- and 7.7-log kill for the low and high concentrations of inoculum, respectively. Milk treated for cheese production (65.5°C for 16 s) resulted in a much lower and more variable kill. Results from this study indicate that the current U.S. minimum standards for batch and high-temperature short-time pasteurization of grade A milk significantly reduced the survivability of M. paratuberculosis, but some bacteria survived subpasteurization heat treatment of milk used for cheese manufacture.

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20

KESWANI, J., and J. F. FRANK. "Thermal Inactivation of Mycobacterium paratuberculosis in Milk." Journal of Food Protection 61, no. 8 (August 1, 1998): 974–78. http://dx.doi.org/10.4315/0362-028x-61.8.974.

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Thermal inactivation of Mycobacterium paratuberculosis, a suspected human pathogen, was determined in ultrahigh-temperature whole milk. Three strains of M. paratuberculosis were examined for survival at temperatures from 55 to 75°C using a submerged glass capillary tube method. Clumped and declumped suspensions of the cultures were used to determine the rate of heat inactivation and survival at pasteurization temperatures. Methods for declumping M. paratuberculosis included the use of glass beads, vortexing, and passing the cells through a 26-gauge needle. The latter procedure was found to be superior over other methods and did not affect the viability of cells. Capillary tubes filled with milk containing 4 × 106 to 3 × 107 CFU/ml were heated at temperatures ranging from 55 to 75°C. At 55°C, minimal thermal inactivation was observed for clumped and declumped cells. At 58°C, thermal inactivation ranging from 0.3 to 0.7 log reduction was observed for both clumped and declumped suspensions. D values at 60°C ranged from 8.6 to 11 min and 8.2 to 14.1 min for clumped and declumped cells, respectively. At 63°C, the D values ranged from 2.7 to 2.9 and 1.6 to 2.5 min for clumped and declumped cells, respectively. Survival of M. paratuberculosis at initial levels ranging from 44 to 105 CFU/ml at pasteurization treatment (63°C for 30 min and 72°C for 15 s) was also determined. No survivors were observed after incubating plates for up to 4 months on Middlebrook 7H11 agar and up to 2 months on Herrold's egg yolk medium. The sensitivity of the plating method was 1 CFU/250 μl. These results demonstrate that low levels of M. paratuberculosis, as might be found in raw milk, will not survive pasteurization treatments.

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21

Clements, Richard S., David M. Wyatt, Michael H. Symons, and Kenneth N. Ewings. "Inhibition Enzyme-Linked Immunosorbent Assay for Detection of Pseudomonas fluorescens Proteases in Ultrahigh-Temperature-Treated Milk." Applied and Environmental Microbiology 56, no. 4 (1990): 1188–90. http://dx.doi.org/10.1128/aem.56.4.1188-1190.1990.

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22

Kokkinidou, Smaro, and Devin G. Peterson. "Control of Maillard-Type Off-Flavor Development in Ultrahigh-Temperature-Processed Bovine Milk by Phenolic Chemistry." Journal of Agricultural and Food Chemistry 62, no. 32 (August 5, 2014): 8023–33. http://dx.doi.org/10.1021/jf501919y.

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23

Grabowski, NT, B. Ahlfeld, A. Brix, A. Hagemann, C. von Münchhausen, and G. Klein. "Similarities and differences among fluid milk products: traditionally produced, extended shelf life and ultrahigh-temperature processed." Food Science and Technology International 19, no. 3 (March 11, 2013): 235–41. http://dx.doi.org/10.1177/1082013212442200.

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24

Colahan-Sederstrom, Paula M., and Devin G. Peterson. "Inhibition of Key Aroma Compound Generated during Ultrahigh-Temperature Processing of Bovine Milk via Epicatechin Addition." Journal of Agricultural and Food Chemistry 53, no. 2 (January 2005): 398–402. http://dx.doi.org/10.1021/jf0487248.

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25

Jansson, Therese, Hanne B. Jensen, Ulrik K. Sundekilde, Morten R. Clausen, Nina Eggers, Lotte B. Larsen, Colin Ray, Henrik J. Andersen, and Hanne C. Bertram. "Chemical and Proteolysis-Derived Changes during Long-Term Storage of Lactose-Hydrolyzed Ultrahigh-Temperature (UHT) Milk." Journal of Agricultural and Food Chemistry 62, no. 46 (November 6, 2014): 11270–78. http://dx.doi.org/10.1021/jf504104q.

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26

Chaves, Jeane Q., Eislaine P. de Paiva, Leon Rabinovitch, and Adriana M. Vivoni. "Molecular Characterization and Risk Assessment of Bacillus cereus Sensu Lato Isolated from Ultrahigh-Temperature and Pasteurized Milk Marketed in Rio de Janeiro, Brazil." Journal of Food Protection 80, no. 7 (May 30, 2017): 1060–65. http://dx.doi.org/10.4315/0362-028x.jfp-16-448.

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ABSTRACT The presence of Bacillus cereus in milk is a major concern in the dairy industry. In this study 27 Bacillus cereus sensu lato isolates from pasteurized and ultrahigh-temperature (UHT) milk (24 whole UHT and 4 pasteurized samples) collected at supermarket chains in Rio de Janeiro, Brazil, were evaluated to assess the potential risk for food poisoning. Toxigenic and virulence profiles were defined by gene-specific PCR. Affiliation to phylogenetic groups was assigned by panC sequencing. Microbiological analysis revealed the presence of B. cereus s.l. in eight (33.3%) brands (six brands of UHT and two brands of pasteurized milk). Twenty-seven isolates were recovered (13 B. cereus and 14 Bacillus thuringiensis). Predominant toxigenic patterns were type I (contains all toxin genes except ces) and type II (does not contain cytK and ces), with seven (25.9%) isolates each. Predominant virulence patterns were type 2 (does not contain hlyII or shp) and type 3 (contains all virulence genes), with five (18.5%) isolates each. All isolates belonged to phylogenetic groups III and IV. Presence of hbl, piplc, and sph was associated with group IV isolates. Our results suggest that B. thuringiensis and B. cereus sensu stricto should be considered potential foodborne pathogens. Because the majority of the milk isolates studied have the potential to cause food poisoning because of the high prevalence of toxin and virulence genes and the specific phylogenetic group affiliations, these milk products can be potentially hazardous for human consumption.

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Troise, Antonio Dario, Alberto Fiore, Antonio Colantuono, Smaro Kokkinidou, Devin G. Peterson, and Vincenzo Fogliano. "Effect of Olive Mill Wastewater Phenol Compounds on Reactive Carbonyl Species and Maillard Reaction End-Products in Ultrahigh-Temperature-Treated Milk." Journal of Agricultural and Food Chemistry 62, no. 41 (October 3, 2014): 10092–100. http://dx.doi.org/10.1021/jf503329d.

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28

UEDA, Yasuko, Sadaki ASAKUMA, Eiko NEMOTO, Tomoko OSHITA, Yasuhiro AOKI, and Kenji SUDO. "Sensory evaluations of ultrahigh temperature milk and drinkable yogurt produced from milk obtained from ear-corn silage-fed cows, assessed by untrained panel." Nihon Chikusan Gakkaiho 90, no. 2 (May 25, 2019): 133–40. http://dx.doi.org/10.2508/chikusan.90.133.

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29

Abbes, Chiraz, Ahlem Mansouri, and Ahmed Landoulsi. "Synergistic Effect of the Lactoperoxidase System and Cinnamon Essential Oil on Total Flora andSalmonellaGrowth Inhibition in Raw Milk." Journal of Food Quality 2018 (2018): 1–6. http://dx.doi.org/10.1155/2018/8547954.

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Despite its antibacterial and antipathogenic effects, the heat treatment of milk induces undesirable changes that can be noted in the overall properties of ultrahigh temperature (UHT) milk, such as changes in nutritional and organoleptic properties. Our goal is to find new nonthermal antibacterial technologies for the preservation of raw milk (RM). This study investigates the possible synergistic effect of using a combination of the lactoperoxidase system (LS) and 3 μg mL−1of cinnamon essential oil (cinnamon EO) to inactivate the total flora of milk andSalmonellaHadar (S. Hadar). The LS was activated with 30 mg L−1sodium percarbonate and 14 mg L−1of sodium thiocyanate. Using this approach, we obtained a synergistic effect with a complete inhibition of the activity of the total flora of the milk andS.Hadar after 12 hours at 25°C. In addition, the attainment of synergy was defined when the inhibitory effect of the two compounds together was greater than the effect observed by each compound added alone. Moreover, the monitoring of the synergistic effect at 4°C for 5 days showed complete inhibition of total flora for 3 days and forS. Hadar it was up to 5 days. To summarize, the current study clearly identified a new inhibitory combination that may be used in food-based applications.

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30

BAYNES, R. E., R. LYMAN, K. L. ANDERSON, and C. F. BROWNIE. "A Preliminary Survey of Antibiotic Residues and Viable Bacteria in Milk from Three Caribbean Basin Countries." Journal of Food Protection 62, no. 2 (February 1, 1999): 177–80. http://dx.doi.org/10.4315/0362-028x-62.2.177.

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There is widespread concern about the presence of antimicrobial drugs in milk. The presence of drug residues in milk may have public health implications. Milk samples (n = 25 to 65/country) were collected from bulk tanks and commercial vendors in Barbados, Costa Rica, and Jamaica between February 1996 and August 1997. Bulk tank samples were collected from high milk-producing regions of Jamaica and Costa Rica and from 26 dairy farms in Barbados. Milk pH, bacterial growth (total CFU/ml and the presence of Streptococcus agalactiae and Staphylococcus aureus), and the presence of antimicrobials were determined. Milk samples were tested by a microbial inhibition test (Delvotest-P, Gist-Brocades Food Ingredients, Inc.) to screen for antimicrobial drugs. All positives were retested for the presence of β-lactam antibiotics after incubating with penicillinase and some positives were identified by high-pressure liquid chromatography–UV. Mean pH values ranged from 6.5 to 6.7. S. aureus was identified in bulk tank samples from Costa Rica (52%), Barbados (44%), and Jamaica (46%). S. agalactiae was identified in bulk tank samples from Costa Rica (28%), Barbados (8 and 16%), and Jamaica (18%). Antimicrobial residues were detected in some bulk tank samples from Barbados (8%) and Jamaica (10%) but not in samples from Costa Rica. All positives in milk from Jamaica and Barbados were determined to be β-lactams. No residues were detected in pasteurized milk samples from Barbados or ultrahigh-temperature milk from Jamaica. The presence of β-lactam residues in some of these samples suggests the appropriateness of testing milk prior to processing for consumption.

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GAYSINSKY, SYLVIA, T. MATTHEW TAYLOR, P. MICHAEL DAVIDSON, BARRY D. BRUCE, and JOCHEN WEISS. "Antimicrobial Efficacy of Eugenol Microemulsions in Milk against Listeria monocytogenes and Escherichia coli O157:H7." Journal of Food Protection 70, no. 11 (November 1, 2007): 2631–37. http://dx.doi.org/10.4315/0362-028x-70.11.2631.

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The antimicrobial activity of eugenol microemulsions (eugenol encapsulated in surfactant micelles) in ultrahigh-temperature pasteurized milk containing different percentages of milk fat (0, 2, and 4%) was investigated. Antimicrobial micro-emulsions were prepared from a 5% (wt) aqueous surfactant solution (Surfynol 485W) with 0.5% (wt) eugenol. Two strains each of Listeria monocytogenes and Escherichia coli O157:H7 previously shown to be the least and most resistant to the microemulsion in microbiological media were used to inoculate sterile milk (104 CFU/ml). Samples were withdrawn and plated at 0, 1, 3, 6, 12, and 24 h for enumeration. Microemulsions completely prevented growth of L. monocytogenes for up to 48 h in skim milk and reduced both strains of E. coli O157:H7 to less than detectable levels in less than 1 h. Similarly, in 2% fat milk, eugenol-Surfynol combinations reduced both strains of E. coli O157:H7 to less than detectable levels in less than 1 h but only increased the lag phase of both strains of L. monocytogenes. In full-fat milk (4% fat), microemulsions inhibited growth of the least resistant strains of L. monocytogenes and E. coli but were ineffective against the two resistant strains. Unencapsulated eugenol was slightly more or as inhibitory as microemulsions against target pathogens. Results were attributed to diffusional mass transport of antimicrobials from microemulsions to the macroemulsion (milk). Results suggest that food composition, especially fat level, may affect the efficiency of targeting of foodborne pathogens with surfactant-encapsulated antimicrobials.

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Pandey, Sadanand, Corli De Klerk, Joonwoo Kim, Misook Kang, and Elvis Fosso-Kankeu. "Eco Friendly Approach for Synthesis, Characterization and Biological Activities of Milk Protein Stabilized Silver Nanoparticles." Polymers 12, no. 6 (June 24, 2020): 1418. http://dx.doi.org/10.3390/polym12061418.

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Today, the overall occurrence of re-emerging and rising illnesses has been a serious load on economies as well as public health. Here, we describe a simple, nontoxic and eco-friendly method for the synthesis of milk protein (MP)-stabilized silver nanoparticles (MP-s-AgNPs) using ultrahigh-temperature full cream milk. Highly stable AgNPs were prepared with a fair control over their size, without using any reducing or stabilizing agent, and their formation was attributed to the presence of the MP casein. Ag+ ion reduction was possibly caused by the MPs. The synthesized MP-s-AgNPs were characterized in detail by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering. MP-s-AgNPs showed inhibitory activity against both Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative microorganisms (Salmonella typhi and Escherichia coli). Moreover, MP-s-AgNPs were found to be more toxic to bacteria than to fungi (Aspergillus fumigatus, Aspergillus ochraceus and Penicillium chrysogenum).

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Dalabasmaz, Sevim, Jennifer Ebner та Monika Pischetsrieder. "Identification of the Peptide PyroQ-βCasein194–209as a Highly Specific and Sensitive Marker to Differentiate between Ultrahigh-Temperature Processed (UHT) Milk and Mildly Heated Milk". Journal of Agricultural and Food Chemistry 65, № 49 (30 листопада 2017): 10781–91. http://dx.doi.org/10.1021/acs.jafc.7b03801.

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34

Yuan, Shaohong, Sam K. C. Chang, Zhisheng Liu, and Baojun Xu. "Elimination of Trypsin Inhibitor Activity and Beany Flavor in Soy Milk by Consecutive Blanching and Ultrahigh-Temperature (UHT) Processing." Journal of Agricultural and Food Chemistry 56, no. 17 (September 10, 2008): 7957–63. http://dx.doi.org/10.1021/jf801039h.

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35

Tachon, Sybille, Johannes Bernhard Brandsma, and Mireille Yvon. "NoxE NADH Oxidase and the Electron Transport Chain Are Responsible for the Ability of Lactococcus lactis To Decrease the Redox Potential of Milk." Applied and Environmental Microbiology 76, no. 5 (December 28, 2009): 1311–19. http://dx.doi.org/10.1128/aem.02120-09.

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ABSTRACT The redox potential plays a major role in the microbial and sensorial quality of fermented dairy products. The redox potential of milk (around 400 mV) is mainly due to the presence of oxygen and many other oxidizing compounds. Lactococcus lactis has a strong ability to decrease the redox potential of milk to a negative value (−220 mV), but the molecular mechanisms of milk reduction have never been addressed. In this study, we investigated the impact of inactivation of genes encoding NADH oxidases (noxE and ahpF) and components of the electron transport chain (ETC) (menC and noxAB) on the ability of L. lactis to decrease the redox potential of ultrahigh-temperature (UHT) skim milk during growth under aerobic and anaerobic conditions. Our results revealed that elimination of oxygen is required for milk reduction and that NoxE is mainly responsible for the rapid removal of oxygen from milk before the exponential growth phase. The ETC also contributes slightly to oxygen consumption, especially during the stationary growth phase. We also demonstrated that the ETC is responsible for the decrease in the milk redox potential from 300 mV to −220 mV when the oxygen concentration reaches zero or under anaerobic conditions. This suggests that the ETC is responsible for the reduction of oxidizing compounds other than oxygen. Moreover, we found great diversity in the reducing activities of natural L. lactis strains originating from the dairy environment. This diversity allows selection of specific strains that can be used to modulate the redox potential of fermented dairy products to optimize their microbial and sensorial qualities.

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36

MATHEW, FINNY P., and ELLIOT T. RYSER. "Competition of Thermally Injured Listeria monocytogenes with a Mesophilic Lactic Acid Starter Culture in Milk for Various Heat Treatments." Journal of Food Protection 65, no. 4 (April 1, 2002): 643–50. http://dx.doi.org/10.4315/0362-028x-65.4.643.

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Overnight tryptose broth cultures of three L. monocytogenes strains were combined, centrifuged, suspended in 200 ml of tryptose phosphate broth, and heated at 56°C for 20 min and at 64°C for 2 min to obtain low-heat-injured (LHI) and high-heat-injured (HHI) cells, respectively, showing >99.0% injury. Flasks containing 200 ml of raw, low-heat-treated (56°C for 20 min), high-heat-treated (64°C for 2 min), pasteurized, and ultrahigh-temperature (UHT) milk were tempered to 31.1°C and inoculated to contain 104 to 106 CFU/ml of LHI, HHI, or healthy L. monocytogenes cells and a commercial Lactococcus lactis subsp. lactis–Lactococcus lactis subsp. cremoris starter culture at levels of 0.5, 1.0, and 2.0%. Numbers of healthy and injured L. monocytogenes cells and starter organisms were determined using tryptose phosphate agar with or without 4.0% NaCl at selected intervals during 24 h of incubation at 31.1°C. The presence of L. monocytogenes did not adversely affect the growth of the starter culture at any inoculation level. Overall, L. monocytogenes survived the 24-h fermentation period and grew to some extent. In starter-free controls, 76 to 81% of LHI cells and 59 to 69% of HHI cells were repaired after 8 h of incubation, with the lowest repair rates being observed for raw rather than heat-treated or pasteurized milk. Increased injury was observed for healthy L. monocytogenes cells at the 1.0 and 2.0% starter levels, with less injury seen for LHI and HHI cells. Raw and subpasteurized milk allowed less of a decrease in the percentage of injury and also showed higher numbers of injured cells than did pasteurized and UHT milks. These findings may have important implications for the survival of Listeria spp. in certain cheeses that can be prepared from raw or heat-treated milk.

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McCLEMENTS, J. M. J., M. F. PATTERSON, and M. LINTON. "The Effect of Growth Stage and Growth Temperature on High Hydrostatic Pressure Inactivation of Some Psychrotrophic Bacteria in Milk." Journal of Food Protection 64, no. 4 (April 1, 2001): 514–22. http://dx.doi.org/10.4315/0362-028x-64.4.514.

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The effect of high hydrostatic pressure on the survival of the psychrotrophic organisms Listeria monocytogenes, Bacillus cereus, and Pseudomonas fluorescens was investigated in ultrahigh-temperature milk. Variation in pressure resistance between two strains of each organism were studied. The effect of growth stage (exponential and stationary phase), growth temperature (8 and 30°C) on pressure resistance, and sublethal pressure injury were investigated. Exponential-phase cells were significantly less resistant to pressure than stationary-phase cells for all of the three species studied (P < 0.05). Growth temperature was found to have a significant effect at the two growth stages studied. Exponential cells grown at 8°C were more resistant than those grown at 30°C, but for stationary-phase cells the reverse was true. B. cereus stationary-phase cells grown at 30°C were the most pressure resistant studied. L. monocytogenes showed the most sublethal damage compared to B. cereus and P. fluorescens. B. cereus spores were more resistant to pressure than vegetative cells. Pressure treatment at 400 MPa for 25 min at 30°C gave a 0.45-log inactivation. Pressure treatment at 8°C induced significantly less spore germination than at 30°C. This study indicates the importance of the history of a bacterial culture prior to pressure treatment and that bacterial spores require more severe pressure treatments, probably in combination with other preservation techniques, to ensure inactivation.

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38

Pompei, Carlo, and Margherita Rossi. "Use of a Model Solution for the Evaluation of Heat Damage in Milk Treated in an Ultrahigh-Temperature Heat Exchanger." Journal of Agricultural and Food Chemistry 42, no. 2 (February 1994): 360–65. http://dx.doi.org/10.1021/jf00038a024.

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39

HAYMAN, MELINDA M., RAMASWAMY C. ANANTHESWARAN, and STEPHEN J. KNABEL. "Heat Shock Induces Barotolerance in Listeria monocytogenes." Journal of Food Protection 71, no. 2 (February 1, 2008): 426–30. http://dx.doi.org/10.4315/0362-028x-71.2.426.

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The aim of this study was to investigate the effect of heat shock on the resistance of Listeria monocytogenes to high pressure processing (HPP). L. monocytogenes ATCC 19115 was grown to stationary phase at 15°C and inoculated into whole ultrahigh-temperature milk at ~107 CFU/ml. Milk samples (5 ml) were placed into plastic transfer pipettes, which were heat sealed and then heated in a water bath at 48°C for 10 min. Immediately after heat shock, the milk was cooled in water (20°C) for 25 min and then placed on ice. The samples were high pressure processed at ambient temperature (~23°C) at 400 MPa for various times up to 150 s. Following HPP, the samples were spread plated on tryptic soy agar supplemented with yeast extract. Heat shock significantly increased the D400 MPa-value of L. monocytogenes from 35 s in non–heat-shocked cells to 127 s in heat-shocked cells (P < 0.05). Addition of chloramphenicol before heat shock eliminated the protective effect of heat shock (P < 0.05). Heat shock for 5, 10, 15, or 30 min at 48°C resulted in maximal barotolerance (P < 0.05); increasing the time to 60 min significantly decreased survival compared with that at 5, 10, 15, or 30 min (P < 0.05). These results indicate that prior heat shock significantly increases the barotolerance of L. monocytogenes and that de novo protein synthesis during heat shock is required for this enhanced barotolerance.

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Cruciata, Margherita, Ciro Sannino, Danilo Ercolini, Maria L. Scatassa, Francesca De Filippis, Isabella Mancuso, Antonietta La Storia, Giancarlo Moschetti, and Luca Settanni. "Animal Rennets as Sources of Dairy Lactic Acid Bacteria." Applied and Environmental Microbiology 80, no. 7 (January 17, 2014): 2050–61. http://dx.doi.org/10.1128/aem.03837-13.

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ABSTRACTThe microbial composition of artisan and industrial animal rennet pastes was studied by using both culture-dependent and -independent approaches. Pyrosequencing targeting the 16S rRNA gene allowed to identify 361 operational taxonomic units (OTUs) to the genus/species level. Among lactic acid bacteria (LAB),Streptococcus thermophilusand some lactobacilli, mainlyLactobacillus crispatusandLactobacillus reuteri, were the most abundant species, with differences among the samples. Twelve groups of microorganisms were targeted by viable plate counts revealing a dominance of mesophilic cocci. All rennets were able to acidify ultrahigh-temperature-processed (UHT) milk as shown by pH and total titratable acidity (TTA). Presumptive LAB isolated at the highest dilutions of acidified milks were phenotypically characterized, grouped, differentiated at the strain level by randomly amplified polymorphic DNA (RAPD)-PCR analysis, and subjected to 16S rRNA gene sequencing. Only 18 strains were clearly identified at the species level, asEnterococcus casseliflavus,Enterococcus faecium,Enterococcus faecalis,Enterococcus lactis,Lactobacillus delbrueckii, andStreptococcus thermophilus, while the other strains, all belonging to the genusEnterococcus, could not be allotted into any previously described species. The phylogenetic analysis showed that these strains might represent different unknown species. All strains were evaluated for their dairy technological performances. All isolates produced diacetyl, and 10 of them produced a rapid pH drop in milk, but only 3 isolates were also autolytic. This work showed that animal rennet pastes can be sources of LAB, mainly enterococci, that might contribute to the microbial diversity associated with dairy productions.

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Zhang, Wei, Mahesha M. Poojary, Valentin Rauh, Colin A. Ray, Karsten Olsen та Marianne N. Lund. "Quantitation of α-Dicarbonyls and Advanced Glycation Endproducts in Conventional and Lactose-Hydrolyzed Ultrahigh Temperature Milk during 1 Year of Storage". Journal of Agricultural and Food Chemistry 67, № 46 (31 жовтня 2019): 12863–74. http://dx.doi.org/10.1021/acs.jafc.9b05037.

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SCHLESSER, JOSEPH E., and BRIAN PARISI. "Inactivation of Yersinia pseudotuberculosis 197 and Francisella tularensis LVS in Beverages by High Pressure Processing." Journal of Food Protection 72, no. 1 (January 1, 2009): 165–68. http://dx.doi.org/10.4315/0362-028x-72.1.165.

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In 2003, the U.S. Department of Health and Human Services announced a new research program to develop technologies and strategies to prevent and minimize potential food safety and security threats. The threat of terrorist attacks against the nation's food supplies has created the need to study microorganisms not typically associated with foodborne illness. High-pressure processing has been proposed as a treatment to reduce Yersinia pestis and Francisella tularensis LVS levels in beverages. The objectives of this work were to determine the pressure resistance of Y. pseudotuberculosis 197 (surrogate for Y. pestis) and F. tularensis LVS (vaccine strain). For each bacterium, samples of ultrahigh-temperature pasteurized skim milk and pasteurized reduced-acid orange juice (pH ca. 4.2) were inoculated at a minimum level of 5 log CFU/ml. Ten-milliliter samples of the inoculated product were vacuum sealed in polyester pouches and subjected to pressures of 300 and 500 MPa for holding times ranging from 30 s to 6 min. One set of trials was performed at an initial temperature of 10°C and another at 25°C. Processed samples were immediately plated and enumerated. A pressure treatment of 300 MPa at 25°C for less than 6 min was not sufficient to achieve a 5-log reduction of Y. pseudotuberculosis 197 or F. tularensis LVS in milk. However, a pressure treatment of 500 MPa was effective at hold times as low as 30 s. Overall, F. tularensis LVS demonstrated less pressure resistance than Y. pseudotuberculosis 197. Based on these findings, a high-pressure process designed to inactivate 5 log CFU of Y. pseudotuberculosis 197 per ml and F. tularensis LVS in orange juice or milk should be set at or above 500 MPa with a hold time of 2 min or greater.

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Scheldeman, Patsy, Annelies Pil, Lieve Herman, Paul De Vos, and Marc Heyndrickx. "Incidence and Diversity of Potentially Highly Heat-Resistant Spores Isolated at Dairy Farms." Applied and Environmental Microbiology 71, no. 3 (March 2005): 1480–94. http://dx.doi.org/10.1128/aem.71.3.1480-1494.2005.

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ABSTRACT The presence of highly heat-resistant spores of Bacillus sporothermodurans in ultrahigh-temperature or sterilized consumer milk has emerged as an important item in the dairy industry. Their presence is considered undesirable since they hamper the achievement of commercial sterility requirements. By using a selective 30-min heat treatment at 100°C, 17 Belgian dairy farms were screened to evaluate the presence, sources, and nature of potentially highly heat-resistant spores in raw milk. High numbers of these spores were detected in the filter cloth of the milking equipment and in green crop and fodder samples. About 700 strains were isolated after the selective heating, of which 635 could be screened by fatty acid methyl ester analysis. Representative strains were subjected to amplified ribosomal DNA restriction analysis, 16S rRNA gene sequencing, percent G+C content, and DNA-DNA reassociations for further identification. The strain collection showed a remarkable diversity, with representatives of seven aerobic spore-forming genera. Bacillus licheniformis and Bacillus pallidus were the most predominant species overall. Twenty-three percent of the 603 spore-forming isolates proved to belong to 18 separate novel species. These findings suggest that the selective heating revealed a pool of unknown organisms with a higher heat-resistant character. This study showed that high spore counts can occur at the dairy farm and that feed and milking equipment can act as reservoirs or entry points for potentially highly heat-resistant spores into raw milk. Lowering this spore load by good hygienic measures could probably further reduce the contamination level of raw milk, in this way minimizing the aerobic spore-forming bacteria that could lead to spoilage of milk and dairy products. Assessment and characterization of this particular flora are of great importance to allow the dairy or food industry to adequately deal with newly arising microbiological problems.

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Xu, Baojun, and Sam K. C. Chang. "Isoflavones, Flavan-3-ols, Phenolic Acids, Total Phenolic Profiles, and Antioxidant Capacities of Soy Milk As Affected by Ultrahigh-Temperature and Traditional Processing Methods." Journal of Agricultural and Food Chemistry 57, no. 11 (June 10, 2009): 4706–17. http://dx.doi.org/10.1021/jf900687j.

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45

DEHKORDI, NEGIN HEYDARIAN, HOSSEIN TAJIK, MEHRAN MORADI, SEYEDEH ALALEH KOUSHEH, and RAHIM MOLAEI. "Antibacterial Interactions of Colloid Nanosilver with Eugenol and Food Ingredients." Journal of Food Protection 82, no. 10 (September 23, 2019): 1783–92. http://dx.doi.org/10.4315/0362-028x.jfp-19-174.

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ABSTRACT This study was conducted to investigate antibacterial properties of the colloidal silver nanoparticles (SNPs) and eugenol, alone and in combination, on Staphylococcus aureus and Salmonella Typhimurium and their interactions with food constituents (fat, protein, and carbohydrate). We examined antibacterial activities of SNPs and eugenol in Luria-Bertani (LB) broth and 1.5 and 3% fat ultrahigh-temperature (UHT) milk. MICs of eugenol and SNPs (particle size of 31.3 nm) were also investigated in the presence of sunflower oil, meat extract, and starch at concentrations of 2, 5, and 10% to examine the interactions between food constituents and antimicrobial agents. MICs and MBCs of eugenol and SNPs for both bacteria were at 2,500 and 25 μg/mL, respectively. Combinations of the two substances had additive and synergistic effects on Salmonella Typhimurium and S. aureus, respectively. Both compounds had bactericidal activity. In food matrices, results indicated that eugenol only in sunflower oil at 5 and 10% concentrations had significant antibacterial activity. A similar result was achieved for SNPs with 10% meat extract. In LB broth, eugenol at 2,500 and 5,000 μg/mL achieved 6-log reductions in the microbial population of both bacteria after 3 h, while SNPs achieved the same effect after 9 h. In UHT milk with 1.5% fat, eugenol at 5,000 μg/mL and SNPs at 25 μg/mL achieved 6-log reductions in bacterial populations after 24 h. Thus, the antimicrobial activity of both eugenol and SNPs depended on the medium in which the experiment was conducted, and the combination of both antimicrobial agents increased the antimicrobial effect.

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CHEN, HAIQIANG, ROLF D. JOERGER, DAVID H. KINGSLEY та DALLAS G. HOOVER. "Pressure Inactivation Kinetics of Phage λ cI 857". Journal of Food Protection 67, № 3 (1 березня 2004): 505–11. http://dx.doi.org/10.4315/0362-028x-67.3.505.

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Inactivation curves of phage λ cI 857 inactivated by high hydrostatic pressure were obtained at three pressure levels (300, 350, and 400 MPa) in buffered media and ultrahigh-temperature 2% reduced fat milk. Pressurization of phage λ in buffered media at 300 MPa for 300 min, 350 MPa for 36 min, and 400 MPa for 8 min reduced the titer of phage λ by 7.5, 6.7, and 7.7 log, respectively. Pressurization of phage λ in milk at 300 MPa for 400 min, 350 MPa for 80 min, and 400 MPa for 20 min reduced the titer of phage λ by 5.4, 6.4, and 7.1 log, respectively. Tailing was observed in all inactivation curves, indicating that the linear model was not adequate for describing these curves. Among the three nonlinear models studied, the Weibull and log-logistic models consistently produced best fits to all inactivation curves, and the modified Gompertz model the poorest. Because there were no significant differences in the values of shape factor (n) for suspension medium buffer, we reduced the number of parameters in the Weibull model from two to one by setting n at the mean value. The simplified Weibull model produced a fit comparable to the full model. Additionally, the simplified Weibull model allowed predictions to be made at pressures different from the experimental pressures. Menstruum was found to significantly affect the pressure resistance of phage λ. Comparison of pressure inactivation of hepatitis A virus and phage λ indicated that phage λ is more sensitive to pressure than hepatitis A virus in Dulbecco's modified Eagle medium with 10% fetal bovine sera.

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Grutsch, Alyssa A., Pierre S. Nimmer, Rachel H. Pittsley, Katherine G. Kornilow, and John L. McKillip. "Molecular Pathogenesis of Bacillus spp., with Emphasis on the Dairy Industry." Fine Focus 4, no. 2 (December 21, 2018): 203–22. http://dx.doi.org/10.33043/ff.4.2.203-222.

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The bacterial species Bacillus cereus accounts for 1.4-12% of foodborne illness outbreaks worldwide, a statistic that is certainly an underestimate. This bacterial genus is capable of contaminating a wide range of food products, including rice, chicken, vegetables, spices, and dairy products. B. cereus endospores are partially resistant to pasteurization, dehydration, gamma radiation, and other physical stresses used in food processing, and their adhesive characteristics promote biofilm-forming capability on a variety of substrates in dairy operations. B. cereus and other closely-related species produce several types of exotoxins, including at least four hemolysins, three phospholipases, a heat/acid stable emetic toxin called cereulide, and three well-studied heat-labile enterotoxins that all cause gastroenteritis following ingestion. While a great deal of information on virulence gene presence and expression is known in B. cereus, very little has been done to explore the virulence potential of thermoduric spore-formers that may be found in ultrahigh temperature (UHT) pasteurized milk, and their ability to produce biofilms. Biofilm production is understood to be under similar regulation as toxins and other extracellular virulence determinants. This chapter describes the current status of knowledge with Bacillus spp. relevant to the dairy industry, virulence potential, and biofilm production from the perspective of food safety.

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48

HIGGINBOTHAM, KRISTEN L., KELLIE P. BURRIS, SVETLANA ZIVANOVIC, P. MICHAEL DAVIDSON, and C. NEAL STEWART. "Antimicrobial Activity of Hibiscus sabdariffa Aqueous Extracts against Escherichia coli O157:H7 and Staphylococcus aureus in a Microbiological Medium and Milk of Various Fat Concentrations." Journal of Food Protection 77, no. 2 (February 1, 2014): 262–68. http://dx.doi.org/10.4315/0362-028x.jfp-13-313.

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Hibiscus sabdariffa L. calyces are widely used in the preparation of beverages. The calyces contain compounds that exhibit antimicrobial activity, yet little research has been conducted on their possible use in food systems as antimicrobials. Aqueous extracts prepared from the brand “Mi Costenita” were sterilized by membrane filtration (0.22-μm pore size) or autoclaving (121°C, 30 min) and tested for antimicrobial activity against the foodborne pathogens Escherichia coli O157:H7 strains ATCC 43894 and Cider and Staphylococcus aureus strains SA113 and ATCC 27708 in a microbiological medium and ultrahigh-temperature-processed milk with various fat percentages. Extracts heated by autoclaving exhibited greater activity than did filtered extracts in a microbiological medium. Against E. coli, results of 20 mg/ml filtered extract were not different from those of the control, whereas autoclaved extracts reduced viable cells ca. 3 to 4 log CFU/ml. At 60 mg/ml, both extracts inactivated cells after 24 h. There were reduced populations of both strains of S. aureus (ca. 2.7 and 3 log CFU/ml, respectively) after 24 h of incubation in 40 mg/ml filtered extracts. When grown in autoclaved extracts at 40 mg/ml, both strains of S. aureus were inactivated after 9 h. Autoclaved extracts had decreased anthocyanin content (2.63 mg/liter) compared with filtered extracts (14.27 mg/liter), whereas the phenolic content (48.7 and 53.8 mg/g) remained similar for both treatments. Autoclaved extracts were then tested for activity in milk at various fat concentrations (skim [<0.5%], 1%, 2%, and whole [>3.25%]) against a 1:1 mixture of the two strains of E. coli O157:H7 and a 1:1 mixture of the two strains of S. aureus. Extracts at 40 mg/ml inactivated S. aureus after 168 h in skim and whole milk, and E. coli was inactivated after 96 h in 60 mg/ml extract in all fat levels. These findings show the potential use of Hibiscus extracts to prevent the growth of pathogens in foods and beverages.

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CHEN, HAIQIANG, DONGSHENG GUAN, and DALLAS G. HOOVER. "Sensitivities of Foodborne Pathogens to Pressure Changes." Journal of Food Protection 69, no. 1 (January 1, 2006): 130–36. http://dx.doi.org/10.4315/0362-028x-69.1.130.

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Eight foodborne pathogens were suspended in ultrahigh-temperature whole milk and treated at pressure levels of 0.1 to 690 MPa at 21.5°C for 10 min. There was no clear trend in pressure resistance between gram-negative and gram-positive organisms. The order of the single strains tested, from most to least pressure sensitive, was Vibrio parahaemolyticus < Yersinia enterocolitica < Listeria monocytogenes < Salmonella enterica serovar Typhimurium < S. enterica serovar Enteritidis < Escherichia coli O157:H7 ≃ Staphylococcus aureus < Shigella flexneri. For each organism there existed a pressure range in which log(number of survivors) had a near linear relationship when plotted versus treatment pressure level. In this study, a decimal reduction pressure (DP) value was defined and used to measure the sensitivity of these pathogens to pressure changes. L. monocytogenes and V. parahaemolyticus were most sensitive to pressure changes, and S. flexneri was most resistant. The DP values were 16.3 MPa for L. monocytogenes, 21.7 MPa for V. parahaemolyticus, and 127.0 MPa for S. flexneri. The most pressure-resistant gram-negative bacterium, S. flexneri, and most pressure-resistant gram-positive bacterium, S. aureus, were treated at 50°C and pressures of 0.1 to 650 MPa for 10 min. High temperature considerably enhanced pressure inactivation of these two organisms and affected their sensitivities to pressure changes. The effect of treatment time on the DP values of L. monocytogenes and V. parahaemolyticus was also determined, and it was found that it did not significantly affect their DP values.

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50

GENSLER, CATHERINE A., STEPHANIE R. B. BROWN, SULAIMAN F. ALJASIR, and DENNIS J. D'AMICO. "Compatibility of Commercially Produced Protective Cultures with Common Cheesemaking Cultures and Their Antagonistic Effect on Foodborne Pathogens." Journal of Food Protection 83, no. 6 (February 10, 2020): 1010–19. http://dx.doi.org/10.4315/jfp-19-614.

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ABSTRACT The documented survival of pathogenic bacteria, including Listeria monocytogenes (LM), Shiga toxin–producing Escherichia coli (STEC), and Salmonella during the manufacture and aging of some cheeses highlights the need for additional interventions to enhance food safety. Unfortunately, few interventions are compliant with the Standards of Identity for cheese. Protective bacterial cultures (PCs) represent actionable, natural interventions. However, supportive data for commercially produced PCs regarding their efficacy against pathogens and potential antagonism with each other and cheesemaking cultures are scant, thereby impeding their potential use by the cheese industry. The overall objective of this study was to identify commercially produced PCs that exert antimicrobial activity toward pathogens with minimal impact on beneficial cheese microbes. Direct antagonism and agar well diffusion assays were used to determine the impact of 10 commercially produced PCs on the growth of starter cultures and cultures of ripening bacteria and fungi. Deferred antagonism was used to evaluate the potential for antimicrobial effects against LM, STEC, and Salmonella. PCs and starter cultures were cocultured in ultrahigh-temperature-processed milk to determine the effects of coculture on starter acidification profiles when incubated according to a simulated cheesemaking temperature profile (4 h at 35°C followed by 20 h at 20°C). Compatibility assays suggest that PC antagonism is microbe and strain specific. Only one PC negatively impacted the acidification of the starters tested. PC antagonism of ripening bacteria and fungi growth varied but was consistent within species. All PCs displayed deferred inhibition of LM, STEC, and Salmonella growth, but to varying degrees. These data identify commercial PCs with potential for the control of pathogens and characterize their compatibility with cheesemaking cultures for future use by cheesemakers and investigations of their efficacy in the production of cheese. HIGHLIGHTS

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