Thermal and Pressure-Assisted Thermal Destruction Kinetics for Spores of Type A Clostridium botulinum and Clostridium sporogenes PA3679

2016 ◽  
Vol 79 (2) ◽  
pp. 253-262 ◽  
Author(s):  
N. RUKMA REDDY ◽  
EDUARDO PATAZCA ◽  
TRAVIS R. MORRISSEY ◽  
GUY E. SKINNER ◽  
VIVIANA LOEZA ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
High Temperatures ◽  
Clostridium Botulinum ◽  
Pilot Scale ◽  
Inactivation Kinetics ◽  
Clostridium Sporogenes ◽  
Log Reduction ◽  
Pressure Test ◽  
D Values

ABSTRACT The purpose of this study was to determine the inactivation kinetics of the spores of the most resistant proteolytic Clostridium botulinum strains (Giorgio-A and 69-A, as determined from an earlier screening study) and of Clostridium sporogenes PA3679 and to compare the thermal and pressure-assisted thermal resistance of these spores. Spores of these strains were prepared using a biphasic medium method. C. sporogenes PA3679 spores were heat treated before spore preparation. Using laboratory-scale and pilot-scale pressure test systems, spores of Giorgio-A, 69-A, and PA3679 suspended in ACES [N-(2-acetamido)-2-aminoethanesulfonic acid] buffer (pH 7.0) were exposed to various combinations of temperature (93 to 121°C) and pressure (0.1 to 750 MPa) to determine their resistance. More than a 5-log reduction occurred after 3 min at 113°C for spores of Giorgio-A and 69-A and after 5 min at 117°C for spores of PA3679. A combination of high temperatures (93 to 121°C) and pressures yielded greater log reductions of spores of Giorgio-A, 69-A, and PA3679 compared with reduction obtained with high temperatures alone. No survivors from initial levels (>5.0 log CFU) of Giorgio-A and 69-A were detected when processed at a combination of high temperature (117 and 121°C) and high pressure (600 and 750 MPa) for <1 min in a pilot-scale pressure test system. Increasing pressure from 600 to 750 MPa at 117°C decreased the time from 2.7 to 1 min for a >4.5-log reduction of PA3679 spores. Thermal D-values of Giorgio-A, 69-A, and PA3679 spores decreased (i.e., 29.1 to 0.33 min for Giorgio-A, 40.5 to 0.27 min for 69-A, and 335.2 to 2.16 min for PA3679) as the temperature increased from 97 to 117°C. Pressure-assisted thermal D-values of Giorgio-A, 69-A, and PA3679 also decreased as temperature increased from 97 to 121°C at both pressures (600 and 750 MPa) (i.e., 17.19 to 0.15 min for Giorgio-A, 9.58 to 0.15 min for 69-A, and 12.93 to 0.33 min for PA3679 at 600 MPa). At higher temperatures (117 or 121°C), increasing pressure from 600 to 750 MPa had an effect on pressure-assisted thermal D-values of PA3679 (i.e., at 117°C, pressure-assisted thermal D-value decreased from 0.55 to 0.28 min as pressure increased from 600 to 750 MPa), but pressure had no effect on pressure-assisted thermal D-values of Giorgio-A and 69-A. When compared with Giorgio-A and 69-A, PA3679 had higher thermal and pressure-assisted thermal D-values. C. sporogenes PA3679 spores were generally more resistant to combinations of high pressure and high temperature than were the spores of the C. botulinum strains tested in this study.

Effect of Packaging Systems and Pressure Fluids on Inactivation of Clostridium botulinum Spores by Combined High Pressure and Thermal Processing

2013 ◽  
Vol 76 (3) ◽  
pp. 448-455 ◽  
Author(s):  
EDUARDO PATAZCA ◽  
TRAVIS R. MORRISSEY ◽  
VIVIANA LOEZA ◽  
N. RUKMA REDDY ◽  
GUY E. SKINNER ◽  
...  
Keyword(s):  
High Pressure ◽  
Thermal Processing ◽  
Clostridium Botulinum ◽  
Pilot Scale ◽  
Test System ◽  
High Pressure Processing ◽  
Laboratory Scale ◽  
Packaging System ◽  
Test Systems ◽  
Pressure Test

Several studies have been published on the inactivation of bacterial spores by using high pressure processing in combination with heat. None of the studies investigated the effect of the packaging system or the pressurizing fluid on spore inactivation. The objective of this study was to select and validate an appropriate packaging system and pressure transfer fluid for inactivation of Clostridium botulinum spores by using high pressure processing in combination with thermal processing. Inactivation of spores packaged in three packaging systems (plastic pouches, cryovials, and transfer pipettes) was measured in two pressure test systems (laboratory-scale and pilot-scale) at 700 MPa and >105°C. Total destruction (>6.6-log reduction) of the spores packaged in the graduated tube part of transfer pipettes was obtained after processing for up to 10 min at 118°C and 700 MPa in both pressure test systems, compared with the spores packaged either in plastic pouches or cryovials. Reduction of spores packaged in plastic pouches was lowest (<4.8 log) for both pressure test systems when processed at the same conditions (i.e., 700 MPa and 118°C). Within the pilot-scale pressure system, increasing the process temperature from 118 to 121°C at 700 MPa for 10 min resulted in only a small increase in spore reduction (<5.1 log) for spores packaged in plastic pouches, whereas there were no recoverable spores for either of the other two packaging systems. Use of plastic pouches for packaging spores in inactivation kinetic studies could lead to erroneous conclusions about the effect of high pressure in combination with heat. BioGlycol is the pressure–heat transfer fluid of choice, as compared with Duratherm oil, to maximize the temperature response rate during pressurization within the laboratory-scale pressure test system.

Determination of the Thermal Inactivation Kinetics of Listeria monocytogenes, Salmonella enterica, and Escherichia coli O157:H7 and non-O157 in Buffer and a Spinach Homogenate

2015 ◽  
Vol 78 (8) ◽  
pp. 1467-1471 ◽  
Author(s):  
EMEFA ANGELICA MONU ◽  
MALCOND VALLADARES ◽  
DORIS H. D'SOUZA ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Thermal Inactivation ◽  
Inactivation Kinetics ◽  
Mild Heat ◽  
Log Reduction ◽  
D Values ◽  
Heat Processes ◽  
Kinetics Of

Produce has been associated with a rising number of foodborne illness outbreaks. While much produce is consumed raw, some is treated with mild heat, such as blanching or cooking. The objectives of this research were to compare the thermal inactivation kinetics of Listeria monocytogenes, Salmonella enterica, Shiga toxin–producing Escherichia coli (STEC) O157:H7, and non-O157 STEC in phosphate-buffered saline (PBS; pH 7.2) and a spinach homogenate and to provide an estimate of the safety of mild heat processes for spinach. Five individual strains of S. enterica, L. monocytogenes, STEC O157:H7, and non-O157 STEC were tested in PBS in 2-ml glass vials, and cocktails of the organisms were tested in blended spinach in vacuum-sealed bags. For Listeria and Salmonella at 56 to 60°C, D-values in PBS ranged from 4.42 ± 0.94 to 0.35 ± 0.03 min and 2.11 ± 0.14 to 0.16 ± 0.03 min, respectively. D-values at 54 to 58°C were 5.18 ± 0.21 to 0.53 ± 0.04 min for STEC O157:H7 and 5.01 ± 0.60 to 0.60 ± 0.13 min for non-O157 STEC. In spinach at 56 to 60°C, Listeria D-values were 11.77 ± 2.18 to 1.22 ± 0.12 min and Salmonella D-values were 3.51 ± 0.06 to 0.47 ± 0.06 min. D-values for STEC O157:H7 and non-O157 STEC were 7.21 ± 0.17 to 1.07 ± 0.11 min and 5.57 ± 0.38 to 0.99 ± 0.07 min, respectively, at 56 to 60°C. In spinach, z-values were 4.07 ± 0.16, 4.59 ± 0.26, 4.80 ± 0.92, and 5.22 ± 0.20°C for Listeria, Salmonella, STEC O157:H7, and non-O157 STEC, respectively. Results indicated that a mild thermal treatment of blended spinach at 70°C for less than 1 min would result in a 6-log reduction of all pathogens tested. These findings may assist the food industry in the design of suitable mild thermal processes to ensure food safety.

scholarly journals Synthesis of Star-Shaped Boron Carbide Micro-Crystallites under High Pressure and High Temperatures

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 448
Author(s):  
Vladimir Filonenko ◽  
Pavel Zinin ◽  
Igor Zibrov ◽  
Alexander Anokhin ◽  
Elena Kukueva ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Boron Carbide ◽  
Carbon Content ◽  
High Temperatures ◽  
Low Carbon

We synthesized star-shaped pentagonal microcrystals of boron carbide with an extremely low carbon content (~5%), from m-carborane under high pressure (7 GPa) and high temperature (1370–1670 K). These crystals have five-fold symmetry and grow in the shape of stars. A 5-fold symmetry in large micron-sized crystals is extremely rare making this a striking observation.

The Heat Resistance of Spores of Clostridium botulinum 213B Heated at 121–130°C in Acidified Mushroom Extract

1992 ◽  
Vol 55 (11) ◽  
pp. 913-915 ◽  
Author(s):  
K. L. BROWN ◽  
A. MARTINEZ
Keyword(s):  
Citric Acid ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
High Temperatures ◽  
Clostridium Botulinum ◽  
Mushroom Extract ◽  
D Values

Spores of Clostridium botulinum 213B were heated in mushroom extract acidified to pH 6 with citric acid or glucono-deltalactone at temperatures of 121.1, 125, and 130°C using a thermoresistometer. Decimal reduction times were similar in acidified and natural pH (6.7) mushroom extract. At 121.1, 125, and 130°C, D values were in the range 2.44 – 2.55 s, 0.91–1.45 s, and 0.51–0.75 s, respectively. There was no evidence that mild acidification reduced thermal resistance at high temperatures.

Combined High Pressure and Thermal Processing on Inactivation of Type E and Nonproteolytic Type B and F Spores of Clostridium botulinum

2014 ◽  
Vol 77 (12) ◽  
pp. 2054-2061 ◽  
Author(s):  
GUY E. SKINNER ◽  
KRISTIN M. MARSHALL ◽  
TRAVIS R. MORRISSEY ◽  
VIVIANA LOEZA ◽  
EDUARDO PATAZCA ◽  
...  
Keyword(s):  
High Pressure ◽  
Thermal Processing ◽  
Clostridium Botulinum ◽  
High Pressures ◽  
Genetic Relatedness ◽  
Test System ◽  
High Pressure Processing ◽  
Type B ◽  
Genetic Fingerprint ◽  
D Values

The aim of this study was to determine the resistance of multiple strains of the three nonproteolytic types of Clostridium botulinum (seven strains of type E, eight of type B, and two of type F) spores exposed to combined high pressure and thermal processing. The resistance of spores suspended in N-(2-acetamido)-2-aminoethanesulfonic acid (ACES) buffer (0.05 M, pH 7) was determined at a process temperature of 80°C with high pressures of 600, 650, and 700 MPa using a laboratory-scale pressure test system. Spores of C. botulinum serotype E strains demonstrated less resistance than nonproteolytic spores of type B or F strains when processed at 80°C and 600 MPa for up to 15 min. All C. botulinum type E strains were reduced by >6.0 log units within 5 min under these conditions. Among the nonproteolytic type B strains, KAP 9-B was the most resistant, resulting in reductions of 2.7, 5.3, and 5.5 log, coinciding with D-values of 7.7, 3.4, and 1.8 min at 80°C and 600, 650, and 700 MPa, respectively. Of the two nonproteolytic type F strains, 610F was the most resistant, showing 2.6-, 4.5-, and 5.3-log reductions with D-values of 8.9, 4.3, and 1.8 min at 80°C and 600, 650, and 700 MPa, respectively. Pulsed-field gel electrophoresis was performed to examine the genetic relatedness of strains tested and to determine if strains with similar banding patterns also exhibited similar D-values. No correlation between the genetic fingerprint of a particular strain and its resistance to high pressure processing was observed.

Combined High Pressure and Thermal Processing on Inactivation of Type A and Proteolytic Type B Spores of Clostridium botulinum

2013 ◽  
Vol 76 (8) ◽  
pp. 1384-1392 ◽  
Author(s):  
N. RUKMA REDDY ◽  
KRISTIN M. MARSHALL ◽  
TRAVIS R. MORRISSEY ◽  
VIVIANA LOEZA ◽  
EDUARDO PATAZCA ◽  
...  
Keyword(s):  
High Pressure ◽  
Thermal Processing ◽  
Clostridium Botulinum ◽  
High Pressures ◽  
Type A ◽  
Test System ◽  
High Pressure Processing ◽  
Type B ◽  
Botulinum Type ◽  
D Values

The aim of this study was to determine the resistance of multiple strains of Clostridium botulinum type A and proteolytic type B spores exposed to combined high pressure and thermal processing and compare their resistance with Clostridium sporogenes PA3679 and Bacillus amyloliquefaciens TMW-2.479-Fad-82 spores. The resistance of spores suspended in N-(2-acetamido)-2-aminoethanesulfonic acid (ACES) buffer (0.05 M, pH 7.0) was determined at a process temperature of 105°C, with high pressures of 600, 700, and 750 MPa by using a laboratory-scale pressure test system. No surviving spores of the proteolytic B strains were detected after processing at 105°C and 700 MPa for 6 min. A >7-log reduction of B. amyloliquefaciens spores was observed when processed for 4 min at 105°C and 700 MPa. D-values at 105°C and 700 MPa for type A strains ranged from 0.57 to 2.28 min. C. sporogenes PA3679 had a D-value of 1.48 min at 105°C and 700 MPa. Spores of the six type A strains with high D-values along with C. sporogenes PA3679 and B. amyloliquefaciens were further evaluated for their pressure resistance at pressures 600 and 750 MPa at 105°C. As the process pressure increased from 600 to 750 MPa at 105°C, D-values of some C. botulinum strains and C. sporogenes PA3679 spores decreased (i.e., 69-A, 1.91 to 1.33 min and PA3679, 2.35 to 1.29 min). Some C. botulinum type A strains were more resistant than C. sporogenes PA3679 and B. amyloliquefaciens to combined high pressure and heat, based on D-values determined at 105°C. Pulsed-field gel electrophoresis (PFGE) was also performed to establish whether strains with a similar restriction banding pattern also exhibited similar D-values. However, no correlation between the genomic background of a strain and its resistance to high pressure processing was observed, based on PFGE analysis. Spores of proteolytic type B strains of C. botulinum were less resistant to combined high pressure and heat (700 MPa and 105°C) treatment when compared with spores of type A strains.

Pyrite form of group-14 element pernitrides synthesized at high pressure and high temperature

2017 ◽  
Vol 46 (30) ◽  
pp. 9750-9754 ◽  
Author(s):  
K. Niwa ◽  
H. Ogasawara ◽  
M. Hasegawa
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
High Temperatures ◽  
High Pressures ◽  
Group 14

The incompressible pyrite form of group 14 elemental pernitrides synthesized at high pressures and high temperatures.

A computational model for temperature and sterility distributions in a pilot-scale high-pressure high-temperature process

AIChE Journal ◽  
2007 ◽  
Vol 53 (11) ◽  
pp. 2996-3010 ◽  
Author(s):  
Kai Knoerzer ◽  
Pablo Juliano ◽  
Simon Gladman ◽  
Cornelis Versteeg ◽  
Peter J. Fryer
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Computational Model ◽  
Pilot Scale ◽  
High Temperature Process ◽  
High Pressure High Temperature

scholarly journals The High Temperature and High Pressure Test of Pressure Vessel for the Irradiation Test

2008 ◽  
Vol 10 (4) ◽  
pp. 1-6
Author(s):  
박국남 ◽  
JUN HYUNG GIL ◽  
Timothy C. Kennedy ◽  
이기홍 ◽  
Youngki Kim ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Pressure Vessel ◽  
Irradiation Test ◽  
Pressure Test

Reciprocating Shaft Seals for High-Temperature and High-Pressure Applications: A Review

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Michael McKee ◽  
Faramarz Gordaninejad
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
High Temperatures ◽  
High Pressures ◽  
Fiber Reinforcement ◽  
Shaft Seals ◽  
Scientific Topic ◽  
Temperature Applications

This study reviews the work performed in the field of reciprocating shaft seals from the advent of the scientific topic in the 1940s. Concepts of leakage, film layers, friction, wear, and other concerns with shaft seals are discussed. The importance of shaft seals as it pertains to liquid springs is brought to light along with issues requiring a need for these seals to withstand high temperatures and high pressures. Issues resulting from a seal exposure to high temperatures, such as thermosetting and embrittlement, are discussed in conjunction with materials and properties that allow seals to operate in high-temperature environments. High-pressure sealing challenges are identified along with the techniques currently employed to overcome these issues, such as fiber reinforcement and backup rings. Sealing solutions have been implemented independently for both high-pressure and high-temperature applications; however, the combination of high pressures coupled with high temperatures is still a challenge today.

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