Thermal Resistance of Aeromonas hydrophila in Liquid Whole Egg†

1997 ◽  
Vol 60 (3) ◽  
pp. 231-236 ◽  
Author(s):  
JAMES D. SCHUMAN ◽  
BRIAN W. SHELDON ◽  
PEGGY M. FOEGEDING
Keyword(s):  
Thermal Resistance ◽  
Aeromonas Hydrophila ◽  
Animal Origin ◽  
Inactivation Kinetics ◽  
Processing Plant ◽  
Decimal Reduction Time ◽  
Heat Resistant ◽  
Liquid Whole Egg ◽  
D Values ◽  
Whole Egg

Aeromonas hydrophila (AH) is a psychrotrophic spoilage bacterium and potential pathogen which has been isolated from a variety of refrigerated foods of animal origin, including raw milk, red meat, poultry, and commercially broken raw liquid whole egg (LWE). Decimal reduction times (D values) of 4 strains of AH (1 egg isolate, 2 egg processing plant isolates, 1 ATCC type strain) were determined in LWE using an immersed sealed capillary tube (ISCT) procedure. Initial populations (7.0 to 8.3 log CFU/tube in 0.05 ml LWE) were heated at 48, 51, 54, 57, and 60°C, and survivors were plated onto starch ampicillin agar (48 h at 28°C). D values ranged from 3.62 to 9.43 min (at 48°C) to 0.026 to 0.040 min (at 60°C). Both processing plant isolates were more heat resistant than the ATCC strain. Decimal reduction time curves (r2 ≤ 0.98) yielded ZD values of 5.02 to 5.59°C, similar to those for other non-spore-forming bacteria. D values of the most heat resistant AH strain were also determined in LWE at 48, 51, and 54°C using a conventional capped test tube procedure (10 ml/tube). Cells heated in test tubes yielded nonlinear (tailing) survivor curves and larger (P ≤ 0.05) apparent D values at each temperature than those obtained using the ISCT method. This study provides the first thermal resistance data for AH in LWE and the first evidence that straight-line semilogarithmic thermal inactivation kinetics may be demonstrated for Aeromonas using the ISCT procedure.

Thermal Inactivation Kinetics of Salmonella spp. within Intact Eggs Heated Using Humidity-Controlled Air

2001 ◽  
Vol 64 (7) ◽  
pp. 934-938 ◽  
Author(s):  
R. E. BRACKETT ◽  
J. D. SCHUMAN ◽  
H. R. BALL ◽  
A. J. SCOUTEN
Keyword(s):  
Thermal Inactivation ◽  
Inactivation Kinetics ◽  
Glass Capillary ◽  
Salmonella Spp ◽  
Shell Eggs ◽  
Log Reduction ◽  
Liquid Whole Egg ◽  
D Values ◽  
Kinetics Of ◽  
Whole Egg

The heat resistance of six strains of Salmonella (including Enteritidis, Heidelberg, and Typhimurium) in liquid whole egg and shell eggs was determined. Decimal reduction times (D-values) of each of the six strains were determined in liquid whole egg heated at 56.7°C within glass capillary tubes immersed in a water bath. D-values ranged from 3.05 to 4.09 min, and significant differences were observed between the strains tested (α = 0.05). In addition, approximately 7 log10 CFU/g of a six-strain cocktail was inoculated into the geometric center of raw shell eggs and the eggs heated at 57.2°C using convection currents of humidity-controlled air. D-values of the pooled salmonellae ranged from 5.49 to 6.12 min within the center of intact shell eggs. A heating period of 70 min or more resulted in no surviving salmonellae being detected (i.e., an 8.7-log reduction per egg).

Inactivation of Listeria innocua Inoculated in Liquid Whole Egg by High Hydrostatic Pressure

1998 ◽  
Vol 61 (1) ◽  
pp. 119-122 ◽  
Author(s):  
E. PONCE ◽  
R. PLA ◽  
M. MOR-MUR ◽  
R. GERVILLA ◽  
B. GUAMIS
Keyword(s):  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Prolonged Exposure ◽  
Microbial Inactivation ◽  
Listeria Innocua ◽  
Decimal Reduction Time ◽  
First Order Kinetics ◽  
Liquid Whole Egg ◽  
D Values ◽  
Whole Egg

The resistance of Listeria innocua, as a model microorganism for Listeria monocytogenes, to high hydrostatic pressure in liquid whole egg was studied at several pressures (300, 350, 400, and 450 MPa), temperatures (−15, 2, and 20°C), and times (5, 10, and 15 min). Listeria innocua was added to liquid whole egg at approximately 106 CFU/ml. Listeria innocua was not totally inactivated in any of the treatments. In general, reduction was better at 2°C than at room temperature, but the greatest inactivation was obtained at 450 MPa at 20°C for 15 min (over 5 log of reduction). The results indicate that microbial inactivation was increased with prolonged exposure to pressure. D values for Listeria innocua were obtained at 400 MPa for two temperatures (2 and 20°C), and different times (0 to 20 min). The microbial inactivation followed apparent first-order kinetics, exhibiting a decimal reduction time of 7.35 min at 2°C and 8.23 min at 20°C.

Heat Resistance and Growth of Listeria monocytogenes in Liquid Whole Egg1,2

1990 ◽  
Vol 53 (1) ◽  
pp. 9-14 ◽  
Author(s):  
PEGGY M. FOEGEDING ◽  
SUSAN B. LEASOR
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Growth Temperature ◽  
Generation Times ◽  
Liquid Whole Egg ◽  
D Values ◽  
Whole Egg

Listeria monocytogenes F5069, ATCC 19111, Scott A, and two L. monocytogenes strains isolated from egg were evaluated for growth and thermal resistance in liquid whole egg. Each strain grew in liquid whole egg at temperatures between 4 and 30°C, except Scott A which did not grow at 4 or 10°C. Generation times ranged from 24 h for F5069 to 51 h for ATCC 19111 at 4°C and from 7.8 h for one of the egg isolates to 31 h for ATCC 19111 at 10°C. Maximum populations for each strain increased with increasing growth temperature and were between 105 and 3 × 108 CFU/g. Decimal reduction times (D-values) of each L. monocytogenes strain in raw liquid whole egg were similar to D-values reported in milk. The heat resistance of all strains was similar. For L. monocytogenes F5069, D-values ranged from 22.6 min at 51°C to 0.20 min at 66°C. The zD-value for F5069 was 7.2°C. Minimal pasteurization parameters (60°C, 3.5 min) for liquid whole egg would result in 99 to 99.9% inactivation (populations reduced 2 to 3 log cycles) of the L. monocytogenes strains tested.

Heat Tolerances of Salmonella, Cronobacter sakazakii, and Pediococcus acidilactici Inoculated into Galactooligosaccharide

2017 ◽  
Vol 80 (7) ◽  
pp. 1123-1127 ◽  
Author(s):  
Jihyun Bang ◽  
Moonkak Choi ◽  
Haeseok Jeong ◽  
Sangseob Lee ◽  
Yoonbin Kim ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Microbial Population ◽  
Heating Time ◽  
Pathogenic Microorganisms ◽  
Pediococcus Acidilactici ◽  
Cronobacter Sakazakii ◽  
Decimal Reduction Time ◽  
Treatment Conditions ◽  
Heat Treated ◽  
D Values

ABSTRACT Food-grade galactooligosaccharide (GOS) with low water activity (aw of ca. 0.7) is used as an ingredient in various foods. We evaluated heat tolerances of Salmonella, Cronobacter sakazakii, and Pediococcus acidilactici at temperatures (70 to 85°C) used during the saturation process of GOS by comparing decimal reduction time (D-values) and thermal resistance constants (z-values). To determine the D- and z-values, GOS containing Salmonella (5.1 to 5.8 log CFU/g) or C. sakazakii (5.3 to 5.9 log CFU/g) was heat treated at 70, 77.5, or 85°C for up to 40, 25, or 15 s, respectively, and GOS containing P. acidilactici (6.1 to 6.5 log CFU/g) was heat treated at 70, 77.5, or 85°C for up to 150, 75, or 40 s, respectively. The D-values were calculated using a linear model for heating time versus microbial population for each bacterium. When the D-values for Salmonella, C. sakazakii, and P. acidilactici in GOS were compared, the thermal resistance of all bacteria decreased as the temperature increased. Among the three bacteria, P. acidilactici had higher D-values than did Salmonella and C. sakazakii. The z-values of Salmonella, C. sakazakii, and P. acidilactici were 30.10, 33.18, and 13.04°C, respectively. Overall order of thermal resistance was P. acidilactici > Salmonella ≈ C. sakazakii. These results will be useful for selecting appropriate heat treatment conditions for the decontamination of pathogenic microorganisms during GOS manufacturing.

Nisin Reduces the Thermal Resistance of Listeria monocytogenes Scott A in Liquid Whole Egg

1999 ◽  
Vol 62 (9) ◽  
pp. 999-1003 ◽  
Author(s):  
KELLEY P. KNIGHT ◽  
FRANCIS M. BARTLETT ◽  
ROBIN C. McKELLAR ◽  
LINDA J. HARRIS
Keyword(s):  
Heat Treatment ◽  
Listeria Monocytogenes ◽  
Logistic Equation ◽  
Glass Ampoule ◽  
Log Reduction ◽  
Egg Products ◽  
Current Minimum ◽  
Liquid Whole Egg ◽  
D Values ◽  
Whole Egg

D-values (decimal reduction times) and z-values (increase in temperature required for a 1-log change in D-value) for Listeria monocytogenes Scott A were determined in liquid whole egg with nisin (0 or 10 μg ml−1) and NaCl (0 or 10%) by a submerged glass ampoule procedure. Samples were plated onto nonselective agar at appropriate intervals, and D-values were determined using a modified biphasic logistic equation. Addition of NaCl increased D-values at all temperatures tested. The addition of nisin to unsalted liquid whole egg resulted in a rapid 4-log reduction in viable counts within the first hour. Nisin significantly (P ≤ 0.05) decreased D-values at lower (<58°C) temperatures in both unsalted and salted liquid whole egg but had little effect on the D-values at current minimum U.S. and Canadian pasteurization temperatures (60°C without NaCl; 63°C with NaCl). However, when nisin was added 2 h prior to heat treatment, D-values were significantly (P ≤ 0.05) reduced at these temperatures. Inhibitory levels of nisin were detected in the liquid whole egg postpasteurization. Nisin could have a favorable impact on the control of L. monocytogenes in pasteurized liquid egg products.

Desiccation and Thermal Resistance of Escherichia coli O121 in Wheat Flour

2019 ◽  
Vol 82 (8) ◽  
pp. 1308-1313 ◽  
Author(s):  
QUINCY J. SUEHR ◽  
NATHAN M. ANDERSON ◽  
SUSANNE E. KELLER
Keyword(s):  
Escherichia Coli ◽  
Thermal Resistance ◽  
Wheat Flour ◽  
Shiga Toxin ◽  
Salmonella Enteritidis ◽  
Thermal Inactivation ◽  
The United States ◽  
Inactivation Kinetics ◽  
E Coli ◽  
D Values

ABSTRACT Non-O157 Shiga toxin–producing Escherichia coli infections have recently been associated with wheat flour on two separate accounts in the United States and Canada. However, there is little information regarding the thermal resistance and longevity of non-O157 Shiga toxin–producing Escherichia coli during storage in low-moisture environments. The objectives of this study were to determine the thermal inactivation kinetics of E. coli O121 in wheat flour and to compare the thermal inactivation rates with those of other pathogens. Wheat flour, inoculated with E. coli O121, was equilibrated at 25°C to a water activity of 0.45 in a humidity-controlled conditioning chamber. Inoculated samples were treated isothermally at 70, 75, and 80°C, and posttreatment population survivor ratios were determined by plate counting. D- and z-values calculated with a log-linear model, were compared with those obtained in other studies. At 70, 75, and 80°C, the D-values for E. coli O121 were 18.16 ± 0.96, 6.47 ± 0.50, and 4.58 ± 0.40 min, respectively, and the z-value was 14.57 ± 2.21°C. Overall, E. coli O121 was observed to be slightly less thermally resistant than what has been previously reported for Salmonella Enteritidis PT30 in wheat flour as measured under the same conditions with the same methods.

Effects of Inoculation Procedures on Variability and Repeatability of Salmonella Thermal Resistance in Wheat Flour

2016 ◽  
Vol 79 (11) ◽  
pp. 1833-1839 ◽  
Author(s):  
IAN M. HILDEBRANDT ◽  
BRADLEY P. MARKS ◽  
ELLIOT T. RYSER ◽  
ROSSANA VILLA-ROJAS ◽  
JUMING TANG ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Water Activity ◽  
Wheat Flour ◽  
Thermal Inactivation ◽  
Culture Method ◽  
Isothermal Treatment ◽  
Inactivation Kinetics ◽  
Inoculation Methods ◽  
Low Moisture Foods ◽  
D Values

ABSTRACT Limited prior research has shown that inoculation methods affect thermal resistance of Salmonella in low-moisture foods; however, these effects and their repeatability have not been systematically quantified. Consequently, method variability across studies limits utility of individual data sets and cross-study comparisons. Therefore, the objective was to evaluate the effects of inoculation methodologies on stability and thermal resistance of Salmonella in a low-moisture food (wheat flour), and the repeatability of those results, based on data generated by two independent laboratories. The experimental design consisted of a cross-laboratory comparison, both conducting isothermal Salmonella inactivation studies in wheat flour (~0.45 water activity, 80°C), utilizing five different inoculation methods: (i) broth-based liquid inoculum, (ii) lawn-based liquid inoculum, (iii) lawn-based pelletized inoculum, (iv) direct harvest of lawn culture with wheat flour, and (v) fomite transfer of a lawn culture. Inoculated wheat flour was equilibrated ~5 days to ~0.45 water activity and then was subjected to isothermal treatment (80°C) in aluminum test cells. Results indicated that inoculation method impacted repeatability, population stability, and inactivation kinetics (α = 0.05), regardless of laboratory. Salmonella inoculated with the broth-based liquid inoculum method and the fomite transfer of a lawn culture method exhibited instability during equilibration. Lawn-based cultures resulted in stable populations prior to thermal treatment; however, the method using direct harvest of lawn culture with wheat flour yielded different D-values across the laboratories (α = 0.05), which was attributed to larger potential impact of operator variability. The lawn-based liquid inoculum and the lawn-based pelletized inoculum methods yielded stable inoculation levels and repeatable D-values (~250 and ~285 s, respectively). Also, inoculation level (3 to 8 log CFU/g) did not affect D-values (using the lawn-based liquid inoculum method). Overall, the results demonstrate that inoculation methods significantly affect Salmonella population kinetics and subsequent interpretation of thermal inactivation data for low-moisture foods.

scholarly journals A laboratory determination of the destruction of α-amylase and salmonellae in whole egg by heat pasteurization

1962 ◽  
Vol 60 (2) ◽  
pp. 153-162 ◽  
Author(s):  
D. H. Shrimpton ◽  
J. B. Monsey ◽  
Betty C. Hobbs ◽  
Muriel E. Smith
Keyword(s):  
Resistant Strain ◽  
Heating Period ◽  
Routine Test ◽  
Heat Resistant ◽  
Laboratory Determination ◽  
Liquid Whole Egg ◽  
Heat Pasteurization ◽  
Whole Egg

The conditions of heating necessary to destroy salmonellae in liquid whole egg have been compared with those necessary to destroy the activity of the α-amylase of whole egg. All conditions of pasteurizing from the mildest at 61·1° C. (142° F.) for 1 min. to the most severe at 65·5° C. (150° F.) for 5 min. eliminated Salm. typhimurium. The heat-resistant strain of Salm. senftenberg N.C.T.C. 9959 (775 W) was not recovered after heating at 64·4° C. (148° F.) for 2½ min. and at the lower temperatures when the heating period was 3 min. or more. The activity of α-amylase was also destroyed by heating at 64·4° C. (148° F.) for 2½ min. but not at lower temperatures.Because the baking properties of egg are not impaired by heating at 64·4° C. (148° F.) for 2½ min. it is proposed that the inactivation of the α-amylase of whole egg can be used as a test for controlling the pasteurization process, and a routine test has been developed which can be completed within 1 hr.

Thermal Inactivation of Conidia From Aspergillus flavus and Aspergillus parasiticus

1975 ◽  
Vol 38 (11) ◽  
pp. 678-682 ◽  
Author(s):  
M. P. DOYLE ◽  
E. H. MARTH
Keyword(s):  
Thermal Resistance ◽  
Heat Resistance ◽  
Aspergillus Flavus ◽  
Positive Relationship ◽  
Thermal Inactivation ◽  
Aspergillus Parasiticus ◽  
Moist Heat ◽  
Heat Resistant ◽  
D Values ◽  
Strain Dependent

Thermal resistance at 45, 50, 55, and 60 C of conidia from various strains of Aspergillus flavus and Aspergillus parasiticus was determined using a heating menstruum buffered at pH 7.0 with KH2PO4-NaOH. Heat resistance of conidia from both molds was strain-dependent. With moist heat at 45 C, D-values for conidia from various strains ranged from 14 to >161 h, whereas at 60 C the range was from 8 to 59 sec. At 50 and 55 C, D values ranged from 16 to 987 and 3 to 29 min, respectively. There appeared to be a positive relationship between the degree of heat resistance of conidia and the amount of aflatoxin produced by the different aspergilli. Conidia that were 15 and 20 days old were less resistant to heat than when they were 7 or 10 days old. Conidia that were produced on a substrate low in protein and high in glucose were more heat resistant than were those produced on a more proteinaceous substrate that contained little glucose.

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