Thermal resistance of Listeria monocytogenes and background microbiota in unsalted and 10% salted liquid egg yolk

2019 ◽  
Vol 39 (4) ◽  
Author(s):  
Lihan Huang
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Egg Yolk

Thermal Resistance of Salmonella spp. and Listeria monocytogenes in Liquid Egg Yolk and Egg Yolk Products†

1995 ◽  
Vol 58 (9) ◽  
pp. 960-966 ◽  
Author(s):  
MARY S. PALUMBO ◽  
SHARON M. BEERS ◽  
SAUMYA BHADURI ◽  
SAMUEL A. PALUMBO
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Minimum Temperature ◽  
Salmonella Enteritidis ◽  
Egg Yolk ◽  
Salmonella Spp ◽  
Egg Products ◽  
D Values ◽  
Unit Reduction ◽  
D Value

The effectiveness of various pasteurization procedures in destroying Listeria monocytogenes and Salmonella enteritidis in liquid egg products was evaluated. Survivor studies were perfonned on individual strains of L. monocytogenes and L. innocua in commercially broken raw egg yolk samples after heating at 61.1, 63.3, and 64.4°C using submerged vials, and on Salmonella spp. at 60.0, 61.1, and 62.2°C. Surviving bacteria were enumerated on TSA and results expressed as D-values. The influence of aw -lowering ingredients such as salt and sugar on thermal resistance in yolk was investigated using a five-strain mixture of L. monocytogenes or a mixture of Salmonella spp. (four strains of S. enteritidis, one stain each of S. senftenberg and S. typhimurium) at 61.1°C to 66.7°C. At 61.1°C (present minimum temperature for pasteurization of plain egg yolk), a 7-log-unit reduction of Salmonella took 1.4 to 2.4 min, whereas a 7-log-unit reduction of L. monocytogenes took 4.9 to 16.1 min. The D-value for L. monocytogenes at 64.4°C increased from 0.44 min in plain yolk to 8.26 min after a 21.5-min lag (total time to achieve 1-log-unit reduction was 30.7 min) in yolk with 10% salt and 5% sugar, and 27.3 min after a 10.5-min lag (total time 37.8 min for 1-log-unit reduction) in yolk with 20% salt. The D-value for Salmonella in egg yolk at 64.4°C was < 0.2 min, but when 10% salt was added, the D-value was 6.4 min. Aw -lowering solutes in liquid egg yolk increased the thermal resistance of Salmonella and L. monocytogenes.

Thermal resistance of Listeria monocytogenes in inoculated and naturally contaminated raw milk

1988 ◽  
Vol 7 (4) ◽  
pp. 277-286 ◽  
Author(s):  
J.M. Farber ◽  
G.W. Sanders ◽  
J.I. Speirs ◽  
J.-Y. D'Aoust ◽  
D.B. Emmons ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Raw Milk

Thermal Resistance of Listeria monocytogenes Scott A in Ultrafiltered Milk as Related to the Effect of Different Milk Components

2010 ◽  
Vol 73 (11) ◽  
pp. 2110-2115 ◽  
Author(s):  
KINGA SZLACHTA ◽  
SUSANNE E. KELLER ◽  
ARLETTE SHAZER ◽  
STUART CHIRTEL
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Milk Fat ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Single Measure ◽  
Total Solids ◽  
Whole Milk ◽  
Milk Components

Pasteurization parameters for grade A milk are well established and set by regulation. However, as solids levels increase, an increased amount of heat is required to destroy any pathogens present. This effect is not well characterized. In this work, the effect of increased dairy solids levels on the thermal resistance of Listeria monocytogenes was examined through the use of ultrafiltered (UF) milk, reconstituted milk powder, and the milk components lactose and caseinate. From the results obtained, lactose and caseinate did not appear to affect thermal resistance. In addition, the level of milk fat, up to 10% of the total solids in UF whole milk, did not result in statistically significant changes to thermal resistance when compared with UF skim milk. Reconstituted skim milk powder at 27% total solids (D62-value = 1.16 ± 0.2 [SD] min, z = 5.7) did result in increased thermal resistance, as compared with reconstituted skim milk powder at 17.5% (D62-value = 0.86 ± 0.02 min, z = 5.57) and UF whole milk at 27% total solids (D62-value = 0.66 ± 0.07 min, z = 5.16). However, that increase appeared to be due to the increase in salt levels, not to increases in caseinate, fat, or lactose. Consequently, total solids, as a single measure, could not be used to predict increased thermal resistance of L. monocytogenes in concentrated milk.

Behavior of Psychrotropic Pathogens Listeria monocytogenes, Yersinia enterocolitica, and Aeromonas hydrophila in Commercially Pasteurized Eggs Held at 2, 6.7 and 12.8° C.

1992 ◽  
Vol 55 (1) ◽  
pp. 8-12 ◽  
Author(s):  
JOHN P. ERICKSON ◽  
PHYLLIS JENKINS
Keyword(s):  
Listeria Monocytogenes ◽  
Yersinia Enterocolitica ◽  
Aeromonas Hydrophila ◽  
Egg Yolk ◽  
Egg White ◽  
Competitive Growth ◽  
Growth Responses ◽  
Egg Products ◽  
Spoilage Microflora ◽  
Whole Egg

Four commercially pasteurized liquid egg products were individually inoculated with Listeria monocytogenes, Yersinia enterocolitica, and Aeromonas hydrophila. They were unsalted whole egg blend, unsalted egg white, 5% NaCl whole egg blend, and 10% NaCl egg yolk. The inoculated samples and uninoculated controls were held at 2, 6.7, and 12.8°C (temperature abuse) for 14 d. Psychrotropic pathogen growth or survival risks in the unsalted and NaCl supplemented eggs were Y. enterocolitica > A. hydrophila > L. monocytogenes, and L. monocytogenes > Y. enterocolitica > A. hydrophila, respectively. Y. enterocolitica produced delayed (≥4 d) growth responses in unsalted eggs held at ≤6.7°C but was inhibited by ≥5% NaCl at all three holding temperatures. L. monocytogenes growth was prevented at ≤6.7°C in the unsalted and NaCl supplemented eggs. The organism rapidly increased in the temperature abused 5% NaCl whole egg blend. L. monocytogenes and A. hydrophila were inactivated in the unsalted egg white and NaCl supplemented eggs, respectively. Psychrotropic pathogen behavior was unaffected by the competitive growth of indigenous spoilage microflora including pseudomonads, Serratia spp., and NaCl tolerant micrococci. Properly refrigerated and hygienically handled pasteurized liquid eggs are microbiologically safe against a broad range of psychrotropic pathogen strains.

Thermal Resistance of Listeria monocytogenes in Dairy Products

1987 ◽  
Vol 50 (7) ◽  
pp. 543-544 ◽  
Author(s):  
J. G. BRADSHAW ◽  
J. T. PEELER ◽  
J. J. CORWIN ◽  
J. M. HUNT ◽  
R. M. TWEDT
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Dairy Products ◽  
Skim Milk ◽  
Ice Cream ◽  
Milk Samples ◽  
C Value

The thermal resistance of Listeria monocytogenes strain Scott A that had been associated with a recent milkborne outbreak of listeriosis was determined in whole and skim milk, heavy cream, and ice cream mix. L. monocytogenes suspended at concentrations of approximately 1 × 105 cells/ml was heated at temperatures ranging from 52.2 to 79.4°C at various contact times. The D71.7°C values computed for milk samples ranged from 0.9 to 2.7 s. The D7.94°C value in ice cream mix was 0.5 s. The zD value for fluid products ranged from 5.8 to 7.1°C; the zF value for ice cream mix was 7.0°C. The L. monocytogenes suspensions would not survive a proper pasteurization process given to raw dairy products.

57 EFFECT OF CHOLESTANOL OR CHOLESTEROL ON THE MOTILITY OF FROZEN GOAT SPERMATOZOA AFTER A THERMAL RESISTANCE TEST

2014 ◽  
Vol 26 (1) ◽  
pp. 142
Author(s):  
B. G. Silva ◽  
E. A. Moraes ◽  
W. C. G. Matos ◽  
C. S. Oliveira ◽  
W. D. Ferrari Junior ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Liquid Nitrogen ◽  
Semen Analysis ◽  
Egg Yolk ◽  
Water Bath ◽  
Resistance Test ◽  
Computer Assisted ◽  
Progressive Motility ◽  
Working Solution ◽  
Analysis System

The objective of the present study was to determine the concentration of cholesterol or cholestanol-loaded-cyclodextrin that needs to be added to goat sperm before cryopreservation to optimize its survival. The cholesterol or cholestanol loaded methyl-β-cyclodextrin was prepared as described by Moraes et al. (2010 Anim. Reprod. Sci. 118, 148–154). A working solution of the cholesterol or cholestanol-loaded cyclodextrin was prepared by adding 50 mg of each one to 1 mL of TALP at 37°C and mixing the solution briefly using a vortex mixer. Ejaculates (n = 24) from 5 bucks were used for this experiment. Sperm from each ejaculate were diluted 1 : 1 (vol : vol) in Tris diluent (200 mM Tris, 65 mM citric acid, and 55 mM glucose) and centrifuged at 800 × g for 10 min. The pellets were resuspended to a concentration of 120 × 106 sperm mL–1 in Tris and subdivided into 7 aliquots of 5 mL each (600 × 106 total sperm). Sperm were treated in 7 treatment groups that received no additive (0 mg; control) or different levels of cholesterol or cholestanol (0.75, 1.5, or 3.0 mg/120 × 106 sperm). All treatments were incubated for 15 min at room temperature and then cooled to 4°C over 2 h. The samples were diluted with Tris-egg yolk diluent containing 2% glycerol. The sperm were packaged into 0.5-cc straws and frozen in static liquid nitrogen vapor for 20 min and then straws were plunged into liquid nitrogen and stored until analysed for motility and thermal resistance test using a computer-assisted semen analysis system (CASA). Two straws from each treatment were thawed in a 37°C water bath for 30 s and extended in Tris. For the thermal resistance test, after thawing, 0.5 mL of semen from each treatment was placed in 1.5-mL tubes in a water bath at 37°C for 3 h. At 0, 60, 120, and 180 min, subsamples were evaluated for sperm total and progressive motility using a computer-assisted sperm motion analyzer. A total of 200 spermatozoa were counted in at least 5 different fields. Data were analysed using ANOVA and treatment means were separated, using the SNK test at 5% probability. Cholesterol (0.75 mg; 46.7%) and cholestanol (1.5 mg; 40.5%) produced an increase in progressive motility compared with other treatments after 1 h of incubation (P < 0.05). However, cholestanol (0.75 mg; 39.5 and 31%) was higher for total and progressive motility after 3 h of sperm incubation compared with the control (27 and 17.8%; P < 0.05), respectively. The addition of 0.75 mg of cholestanol in fresh sperm before cryopreservation improved the motility of freeze-thawed goat sperm compared with cholesterol. Therefore, adding cholestanol to goat sperm membranes improved cell cryosurvival. Supported by Fundação de Amparo à Ciência e Tecnologia de Pernambuco (FACEPE) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

THERMAL RESISTANCE OF YERSINIA ENTEROCOLITICA AND LISTERIA MONOCYTOGENES IN MEAT AND POTATO SUBSTRATES

1998 ◽  
Vol 18 (2) ◽  
pp. 69-83 ◽  
Author(s):  
ALICE M. DOHERTY ◽  
CAROL. M.M. McMAHON ◽  
J.J. SHERIDAN ◽  
I.S. BLAIR ◽  
D.A. McDOWELL ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Yersinia Enterocolitica

Thermal Destruction of Listeria monocytogenes in Ice Cream Mix

1992 ◽  
Vol 55 (4) ◽  
pp. 234-237 ◽  
Author(s):  
V. H. HOLSINGER ◽  
P. W. SMITH ◽  
J. L. SMITH ◽  
S. A. PALUMBO
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Thermal Destruction ◽  
Variable Viscosity ◽  
Ice Cream ◽  
High Fructose Corn Syrup ◽  
Corn Syrup ◽  
High Fructose ◽  
Solids Content

Thermal destruction of Listeria monocytogenes strain Scott A was studied in refrigerated ice cream mixes to evaluate the relationship of mix composition to heat resistance with differing heat treatments. A central composite response surface design with two independent variables (high fructose corn syrup solids content and milkfat content) and one dependent variable (viscosity of the mix) was developed. High fructose corn syrup solids (HFCSS) content ranged from 1 to 7%, milkfat (MF) content from 4 to 18%, and total solids content from 28 to 44%. Sucrose content (11%) and milk-solids-not-fat content (10%) were kept constant. D140°F values were established in the mixes with a simulated batch pasteurization procedure using closed vials. Survivor data indicated sigmoidal responses with initial shoulders and tailing, but shoulder values were not significantly affected by either HFCSS or MF. D and F (F = 7D + shoulder) values were significantly (p = 0.01, R2 = .88; p = 0.01, R2 = .89, respectively) correlated to HCFSS content with increasing heat resistance conferred at higher concentrations. MF content had little or no effect on thermal death time but had a greater effect on viscosity of the mix than did content of HFCSS. Increased thermal resistance of LM was associated with the common ice cream stabilizer used; stabilizer contained guar gum and carrageenan. Pasteurization guidelines for ice cream mix are adequate to ensure inactivation of LM. Since results suggest that major ingredients in ice cream, ice milk, and shake mixes increase thermal resistance of LM, it is important that every precaution be taken to inactivate the organism.

Sign in / Sign up

Export Citation Format

Share Document