Fast-responding thermal-death-time tubes for the determination of thermal bacteria inactivation

2011 ◽  
Vol 12 (1) ◽  
pp. 109-112 ◽  
Author(s):  
Christin Büchner ◽  
Susann Thomas ◽  
Doris Jaros ◽  
Harald Rohm
Keyword(s):  
Death Time ◽  
Thermal Death ◽  
Bacteria Inactivation ◽  
Thermal Death Time

Determination of the Thermal Death Time of Vibrio cholerae in Blue Crabs (Callinectes sapidus)

1984 ◽  
Vol 47 (1) ◽  
pp. 4-6 ◽  
Author(s):  
LAWRENCE M. SHULTZ ◽  
JAMES E. RUTLEDGE ◽  
ROBERT M. GRODNER ◽  
STANLEY L. BIEDE
Keyword(s):  
Vibrio Cholerae ◽  
Callinectes Sapidus ◽  
Death Time ◽  
Thermal Death ◽  
Peptone Water ◽  
Heat Penetration ◽  
D Values ◽  
Thermal Death Time ◽  
Crab Meat

The D-values of Vibrio cholerae were determined in peptone water and in crab meat homogenate. In peptone water, the D-values in minutes were 1.70 at 49°C, 1.04 at 54°C, 0.63 at 60°C and 0.36 at 63°C. In crab meat homogenate, the D-values in minutes were 8.15 at 49°C, 5.02 at 54°C, 2.65 at 60°C, 1.60 at 66°C and 0.30 at 71°C. Whole crabs injected with 106 V. cholerae were cooked by boiling or steaming. No V. cholerae was recovered from crabs cooked in boiling water (100°C) for 15 min or in steam (100, 115.6 or 121.1°C) for 10 min when V. cholerae was injected into the crab's dorsal swim fin muscle. The rate of heat penetration during cooking of crabs was also determined.

Comparison of Two Models for Process Holding Time Calculations: Convection System

1985 ◽  
Vol 48 (4) ◽  
pp. 359-363 ◽  
Author(s):  
B. MANJI ◽  
F. R. VAN DE VOORT
Keyword(s):  
Kinetic Parameters ◽  
Actual Process ◽  
Correct Process ◽  
Chemical Systems ◽  
Death Time ◽  
Thermal Death ◽  
Microbial Destruction ◽  
Thermal Death Time ◽  
Relationship Of ◽  
The Relationship

The reaction kinetics of microbial destruction in food products are generally determined by the Thermal Death Time method (TDT), while chemical changes have traditionally been calculated by the more widely accepted Arrhenius approach. These two methods do not reconcile mathematically, and simply stated, one is the inverse of the other. It was of interest therefore to consider the relationship of these methods relative to each other on a mathematically simulated and experimental basis. The kinetic parameters of Saccharomyces uvarum were determined experimentally and used to calculate simulated processes in accordance to the relationships dictated by the TDT and Arrhenius models. The simulation results indicated a discrepancy between the methods, the Arrhenius approach requiring about 16% more time to complete a process. Based on five processing trials carried out using S. uvarum the actual process times were compared to those predicted by the TDT and Arrhenius methods. The Arrhenius method predicted the correct process times on the average, while the TDT predictions were short by about 8% in terms of time. From a microbiological standpoint, these differences are not likely to be singificant, however, they may be important if the TDT method is used to characterize the kinetic parameters of more rigerously defined chemical systems.

Thermal Inactivation of Escherichia coli in Camel Milk

2003 ◽  
Vol 66 (9) ◽  
pp. 1708-1711 ◽  
Author(s):  
SHLOMO SELA ◽  
RIKY PINTO ◽  
UZI MERIN ◽  
BARUCH ROSEN
Keyword(s):  
Escherichia Coli ◽  
Thermal Inactivation ◽  
Bovine Milk ◽  
Milk Composition ◽  
Camel Milk ◽  
E Coli ◽  
Death Time ◽  
Thermal Death ◽  
Milk Industry ◽  
Thermal Death Time

Camels subsist and produce milk in desert pastures not utilized by other domesticated herbivores. Developing the camel milk industry can improve the economy of desert inhabitants. To comply with sanitary ordinances, camel milk is pasteurized by procedures specified for bovine milk. It is widely accepted that milk composition might affect bacterial thermal death time (TDT). Camel and bovine milks markedly differ in their chemical composition, yet data regarding TDT values of bacteria in camel milk is missing. As a first step toward developing specific heat treatments appropriate for camel milk, TDT curves of Escherichia coli in artificially contaminated camel and cow milks have been compared. Heating the milks to temperatures ranging from 58 to 65°C yields similar thermal death curves and derived D- and z-values. These findings suggest that, in this temperature range, E. coli might behave similarly in bovine and camel milk. Additional TDT studies of various pathogenic species in camel milk are required before establishing pasteurization conditions of camel milk.

Heat Resistance of Juice Spoilage Microorganisms

2002 ◽  
Vol 65 (8) ◽  
pp. 1271-1275 ◽  
Author(s):  
ADRIENNE E. H. SHEARER ◽  
ALEJANDRO S. MAZZOTTA ◽  
ROLENDA CHUYATE ◽  
DAVID E. GOMBAS
Keyword(s):  
Heat Resistance ◽  
Process Conditions ◽  
Citrate Buffer ◽  
Ph Values ◽  
Death Time ◽  
High Fructose ◽  
Thermal Death ◽  
Challenge Tests ◽  
D Values ◽  
Thermal Death Time

The heat resistance of various yeasts (Saccharomyces cerevisiae, Rhodotorula mucilaginosa, Torulaspora delbrueckii, and Zygosaccharomyces rouxii), molds (Penicillium citrinum, Penicillium roquefortii, and Aspergillus niger), and lactic acid bacteria (Lactobacillus fermentum and Lactobacillus plantarum) obtained from spoiled acid or acidified food products was determined in 0.1 M citrate buffer at pH values of 3.0, 3.5, and 4.0. S. cerevisiae was the most heat resistant of the microorganisms in citrate buffer, and its heat resistance was further evaluated in apple, grapefruit, calcium-fortified apple, and tomato juices as well as in a juice base with high fructose corn syrup. Decimal reduction times (D-values) and changes in temperature required to change the D-value (z-values) for S. cerevisiae were higher in the juices than in citrate buffer at all pH values tested. The D57°C(135°F)-values varied from 9.4 min in the juice product with pH 2.8 to 32 min in a calcium-added apple juice with pH 3.9. The S. cerevisiae strain used in this study can be used in thermal-death-time experiments in acidic products to calculate process conditions and in challenge tests to validate the calculated temperatures and hold times during processing.

Ascaris lumbricoides suum: Thermal death time of unembryonated eggs

1987 ◽  
Vol 64 (1) ◽  
pp. 120-122 ◽  
Author(s):  
Robert J. Barnard ◽  
Jeffrey W. Bier ◽  
George J. Jackson ◽  
Foster D. McClure
Keyword(s):  
Ascaris Lumbricoides ◽  
Death Time ◽  
Thermal Death ◽  
Thermal Death Time

SIGNIFICANCE OF VARIATIONS IN OBSERVED SLOPES OF THERMAL DEATH TIME CURVES FOR PUTREFACTIVE ANAEROBES

1954 ◽  
Vol 19 (1-6) ◽  
pp. 173-181 ◽  
Author(s):  
ARTHUR M. KAPLAN ◽  
HOWARD REYNOLDS ◽  
HAROLD LICHTENSTEIN
Keyword(s):  
Death Time ◽  
Thermal Death ◽  
Thermal Death Time
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