Effect of Temperature and pH on the Survival of Campylobacter fetus1

1982 ◽  
Vol 45 (3) ◽  
pp. 253-259 ◽  
Author(s):  
F. M. CHRISTOPHER ◽  
G. C. SMITH ◽  
C. VANDERZANT
Keyword(s):  
Ground Beef ◽  
Effect Of Temperature ◽  
Internal Temperature ◽  
Final Temperature ◽  
Brucella Broth ◽  
Viable Cells ◽  
Fetus Subsp

Test strains of C. fetus subsp. jejuni and C. fetus subsp. intestinalis failed to survive heating in skimmilk at 60 C for 1 min. A few strains survived heating in skimmilk at 55 C for 1–3 min. D50C values for C. fetus subsp. jejuni and C. fetus subsp. intestinalis in skimmilk ranged from 1.3–4.5 and from 1.0–3.7, respectively. No survivors of C. fetus subsp. jejuni and C. fetus subsp. intestinalis were detected in beef roasts inoculated at levels of 106–107 viable cells per g when the final temperature in the center was 57 and 55 C, respectively. At an internal temperature of 50–53 C, survivors of C. fetus were detected in beef roasts. Storage of skimmilk, beef and ground beef inoculated with C. fetus at −20, 1, 10, 20, 30 or 40 C resulted in decreases in C. fetus count. Survival of C. fetus was best at 1 and 10 C. Rapid increases in C. fetus counts occurred at 37 C in Brucella broth adjusted to pH 6–8. At pH 5, no survivors were detected after 24 h. At pH 9, counts of C. fetus subsp. jejuni decreased rapidly while those of C. fetus subsp. intestinalis increased slightly.

BEHAVIOR OF CLOSTRIDIUM PERFRINGENS IN PRECOOKED CHILLED GROUND BEEF GRAVY DURING COOLING, HOLDING, AND REHEATING1

1974 ◽  
Vol 37 (10) ◽  
pp. 494-498 ◽  
Author(s):  
S. Tuomi ◽  
M. E. Matthews ◽  
E. H. Marth
Keyword(s):  
Clostridium Perfringens ◽  
Ground Beef ◽  
Final Temperature ◽  
Vegetative Cells ◽  
Viable Cells ◽  
Plate Counts ◽  
Handling Practices

The suitability of handling practices used in school kitchens was evaluated using ground beef gravy that was contaminated with Clostridium perfringens. Cooked gravy was cooled to 110 F (43.5 C) and inoculated with a mixture of vegetative cells and spores of C. perfringens NCTC 8239 to provide approximately 10,000 organisms/g. After inoculation, gravy was packed in bags, refrigerated for 16 h, held for 5 h at 82 F (28 C) or 42 F (5.5 C), and then heated in a compartment steamer for 35 min or until the temperature of the gravy at the center of the pan reached 165 F (74 C). C. perfringens was enumerated at intervals during cooling, holding, and heating of the gravy. The number of viable cells after 16 h of refrigeration at 42 F (5.5 C) was influenced by the first 6 h of cooling when the temperature of the gravy was in the range that permitted growth of C. perfringens (65–122 F; 18.5–50 C). Plate counts of gravy held for 5 h at 82 F (28 C) or 42 F (5.5 C) indicated stablization of the C. perfringens population. When 165 F (74 C) was the final temperature to which the gravy was heated, no viable cells of C. perfringens were found.

scholarly journals Effect of Temperature and Cell Viability on Uranium Biomineralization by the Uranium Mine Isolate Penicillium simplicissimum

2021 ◽  
Vol 12 ◽  
Author(s):  
Sebastian Schaefer ◽  
Robin Steudtner ◽  
René Hübner ◽  
Evelyn Krawczyk-Bärsch ◽  
Mohamed L. Merroun
Keyword(s):  
Heavy Metal ◽  
Cell Viability ◽  
Laser Fluorescence ◽  
Contaminated Sites ◽  
Effect Of Temperature ◽  
Uranium Mine ◽  
Penicillium Simplicissimum ◽  
Removal Capacity ◽  
Viable Cells ◽  
Dry Biomass

The remediation of heavy-metal-contaminated sites represents a serious environmental problem worldwide. Currently, cost- and time-intensive chemical treatments are usually performed. Bioremediation by heavy-metal-tolerant microorganisms is considered a more eco-friendly and comparatively cheap alternative. The fungus Penicillium simplicissimum KS1, isolated from the flooding water of a former uranium (U) mine in Germany, shows promising U bioremediation potential mainly through biomineralization. The adaption of P. simplicissimum KS1 to heavy-metal-contaminated sites is indicated by an increased U removal capacity of up to 550 mg U per g dry biomass, compared to the non-heavy-metal-exposed P. simplicissimum reference strain DSM 62867 (200 mg U per g dry biomass). In addition, the effect of temperature and cell viability of P. simplicissimum KS1 on U biomineralization was investigated. While viable cells at 30°C removed U mainly extracellularly via metabolism-dependent biomineralization, a decrease in temperature to 4°C or use of dead-autoclaved cells at 30°C revealed increased occurrence of passive biosorption and bioaccumulation, as confirmed by scanning transmission electron microscopy. The precipitated U species were assigned to uranyl phosphates with a structure similar to that of autunite, via cryo-time-resolved laser fluorescence spectroscopy. The major involvement of phosphates in U precipitation by P. simplicissimum KS1 was additionally supported by the observation of increased phosphatase activity for viable cells at 30°C. Furthermore, viable cells actively secreted small molecules, most likely phosphorylated amino acids, which interacted with U in the supernatant and were not detected in experiments with dead-autoclaved cells. Our study provides new insights into the influence of temperature and cell viability on U phosphate biomineralization by fungi, and furthermore highlight the potential use of P. simplicissimum KS1 particularly for U bioremediation purposes.Graphical Abstract

Carvacrol and Cinnamaldehyde Facilitate Thermal Destruction of Escherichia coli O157:H7 in Raw Ground Beef†

2008 ◽  
Vol 71 (8) ◽  
pp. 1604-1611 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
MENDEL FRIEDMAN
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Inactivation Kinetics ◽  
Escherichia Coli O157 ◽  
Internal Temperature ◽  
Circulating Water ◽  
Critical Control Points ◽  
Thermal Death ◽  
D Values ◽  
D Value

The heat resistance of a four-strain mixture of Escherichia coli O157:H7 in raw ground beef in both the absence and presence of the antimicrobials carvacrol and cinnamaldehyde was tested at temperatures ranging from 55 to 62.5°C. Inoculated meat packaged in bags was completely immersed in a circulating water bath, cooked for 1 h to an internal temperature of 55, 58, 60, or 62.5°C, and then held for predetermined lengths of time ranging from 210 min at 55°C to 5 min at 62.5°C. The surviving bacteria were enumerated by spiral plating onto tryptic soy agar overlaid with sorbitol MacConkey agar. Inactivation kinetics of the pathogens deviated from first-order kinetics. D-values (time for the bacteria to decrease by 90%) in the control beef ranged from 63.90 min at 55°C to 1.79 min at 62.5°C. D-values determined by a logistic model ranged from 43.18 min (D1, the D-value of a major population of surviving cells) and 89.84 min (D2, the D-value of a minor subpopulation) at 55°C to 1.77 (D1) and 0.78 min (D2) at 62.5°C. The thermal death times suggested that to achieve a 4-D reduction, contaminated processed ground beef should be heated to an internal temperature of 60°C for at least 30.32 min. Significantly increased sensitivity to heat (P < 0.05) was observed with the addition and/or increasing levels of carvacrol or cinnamaldehyde from 0.5 to 1.0%. The observed thermal death times may facilitate the design of acceptance limits at critical control points for ground beef at lower times and temperatures of heating.

Effect of Temperature on Growth and Alpha Toxin Production by Clostridium perfringens1

1979 ◽  
Vol 42 (11) ◽  
pp. 848-851 ◽  
Author(s):  
Y. PARK ◽  
E. M. MIKOLAJCIK
Keyword(s):  
Growth Phase ◽  
Incubation Temperature ◽  
Ground Beef ◽  
Population Level ◽  
Toxin Production ◽  
Stationary Growth Phase ◽  
Effect Of Temperature ◽  
Alpha Toxin ◽  
Stationary Growth ◽  
Incubation Temperatures

Growth and alpha toxin production by a strain of Clostridium perfringens was determined in Thioglycollate medium, beef broth with ground beef, and beef broth with ground beef and soy protein. Incubation temperatures ranged from 15 to 50 C. In Thioglycollate medium, maximum alpha toxin production occurred at 35 C and was 40 times greater than that observed at 45 C. However, generation time and maximum population were approximately the same at 35 and 45 C. At 15 C, a two log cycle reduction in viable counts occurred within 6 h. Irrespective of incubation temperature, alpha toxin levels in Thioglycollate medium declined as the incubation period was extended beyond the stationary growth phase. In the beef broth with ground beef system which was studied at 35 C only, the organism grew slower and produced less toxin than in Thioglycollate medium. The amount of alpha toxin detected was influenced to a greater extent by the incubation time and temperature, the holding time beyond the stationary growth phase, and the growth medium than by the population level of C. perfringens.

Studies of the microaerophilic nature of Campylobacter fetus subsp. jejuni. I. Physiological aspects of enhanced aerotolerance

1979 ◽  
Vol 25 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Paul S. Hoffman ◽  
Noel R. Krieg ◽  
Robert M. Smibert
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Sod Activity ◽  
Aconitate Hydratase ◽  
Cycle Enzyme ◽  
Whole Cells ◽  
Brucella Broth ◽  
Campylobacter Fetus ◽  
Oxygen Sensitive ◽  
Fetus Subsp ◽  
Total Superoxide Dismutase

The aerotolerance of the microaerophilic bacterium Campylobacter fetus subsp. jejuni strain H840 (ATCC 29428) can be enhanced by addition of a combination of ferrous sulfate, sodium bisulfite, and sodium pyruvate (FBP), or of dihydroxyphenyl compounds such as nor-epinephrine (NE), to Brucella broth. Transport of 55Fe3+ was increased by NE, suggesting that ordinary rates of transport, while adequate for growth at 6% O2, might not permit growth at 21% O2. Growth with FBP at 21% O2 did not appreciably affect levels of cytochromes or of various tricarboxylic acid cycle enzyme activities. Activities of certain iron-dependent enzymes (succinate dehydrogenase and aconitate hydratase), and also respiration rates of whole cells, were lower in cells grown at 21% O2 in Brucella broth compared to 6% O2, but FBP did not cause an increase in these activities or rates. FBP caused a decrease in catalase and peroxidase activities. Total superoxide dismutase (SOD) activity increased when cells were grown at 21% O2 with FBP. When grown without FBP, however, the organism possessed SOD activity as high as that in Escherichia coli, and a variant strain of H840 possessed nearly double this activity but was no more aerotolerant than the parent strain. A very oxygen-sensitive strain of C. fetus subsp. intestinalis also possessed high SOD activity. Consequently, total SOD activity in C. fetus does not appear to account for lack of aerotolerance. No evidence that FBPcauses any physiological change in C. fetus that could satisfactorily account for enhancement of aerotolerance could be obtained. It is possible that FBP or NE might not affect some physiological process in the organisms but might instead act on the culture medium.

Examination of Poultry Giblets, Raw Milk and Meat for Campylobacter fetus subsp. jejuni

1982 ◽  
Vol 45 (3) ◽  
pp. 260-262 ◽  
Author(s):  
F. M. CHRISTOPHER ◽  
G. C. SMITH ◽  
C. VANDERZANT
Keyword(s):  
Antimicrobial Agents ◽  
Biceps Femoris ◽  
Raw Milk ◽  
Polymyxin B ◽  
Defibrinated Horse Blood ◽  
Brucella Broth ◽  
Campylobacter Fetus ◽  
Horse Blood ◽  
Fetus Subsp ◽  
Bulk Tank

An MPN procedure was used to determine the presence of Campylobacter fetus subsp. jejuni in poultry giblets. This procedure consists of (a) subculturing a sample in Brucella broth supplemented with 0.15% agar, 0.05% sodium pyruvate and the following antimicrobial agents per liter: vancomycin 10 mg, trimethoprim 5 mg, polymyxin B sulfate 2,500 IU, amphotericin B 2 mg and cephalothin 15 mg and (b) subsequent streaking of a loopful of Brucella broth held at 42 C for 48 h on plates of Brucella agar supplemented with 10% defibrinated horse blood and the concentrations of antimicrobial agents identified above. C. fetus subsp. jejuni was present in 85% of the chicken livers and in 89% of the chicken gizzards obtained immediately after evisceration. The organism was not recovered from samples treated with chlorinated water. C. fetus subsp. jejuni was not recovered from raw milk (bulk tank samples or individual cow samples) or from beef (infraspinatus or biceps femoris muscles).

scholarly journals 84 Cooking loss of ground beef

2019 ◽  
Vol 97 (Supplement_1) ◽  
pp. 28-28
Author(s):  
Robin G Coombs ◽  
C R Richardon
Keyword(s):  
Ground Beef ◽  
Quality Attributes ◽  
Grocery Store ◽  
Cooking Loss ◽  
Internal Temperature ◽  
Solid Portion ◽  
George Foreman

Abstract This study was conducted to measure two quality variables of ground beef: cooking loss and shrinkage. Twenty 454g packages of ground chuck from a commercial grocery store 80:20 lean:fat ratio (calculated per label to be 71:29), and 20 packages of ground beef from a specific breed (SB) (calculated per label to be 75:25) were used. Each package was divided into four hand-formed patties weighing 118-120g (n = 80). Prior to grilling, the patties were weighed, circumference measured (cm), and thickness measured (cm). Patties were grilled on a George Foreman Grill to an internal temperature of 73.9° C. Cooking loss (meat drippings) from grilled patties was collected. After reaching the desired internal temperature, individual patties were removed from the grill, weighed, and circumference and thickness measured. Cooking loss was collected in a grease tray and from the grill surface with a spatula. Cooking loss was weighed (g) and contents poured into a glass jar and stored in a freezer for further evaluation. There was no difference (P > 0.05) in cooking loss between the control and SB treatment, 61.40% and 61.34% respectively. A difference (P < 0.05) was found in cooking shrinkage (circumference and thickness). Circumference between fresh and cooked showed a change of 15.48% (control) and 12.88% (SB) (P < 0.05). Patty thickness between fresh and cooked changed by 9.32% (control) and 5.71 % (SB) (P<0.05). Total cooking loss per 454g package did not differ 13.74% (control) and 14.16% (SB). However, when cooking loss was separated in solid and liquid portions, the solid portion was 19.71% (control) and 28.30% (SB) (P < 0.05). These data indicate that quality attributes of ground beef vary between sources with similar lean:fat ratio.

EFFECT OF TEMPERATURE AND pH ON GROWTH AND ENTEROTOXIN PRODUCTION BY STAPHYLOCOCCUS AUREUS1

1973 ◽  
Vol 36 (5) ◽  
pp. 249-252 ◽  
Author(s):  
D. L. Scheusner ◽  
L. L. Hood ◽  
L. G. Harmon
Keyword(s):  
Brain Heart Infusion ◽  
Effect Of Temperature ◽  
Aureus Strain ◽  
Type B ◽  
Time Intervals ◽  
Sodium Phosphate Buffer ◽  
Type D ◽  
Viable Cells ◽  
Initial Ph ◽  
Type C

Four strains of Staphylococcus aureus producing enterotoxin types A, B, C, and D were inoculated into buffered Brain Heart Infusion (BHI) broth at a concentration of 106 cells/ml and incubated with agitation at temperatures ranging from 7 to 50 C for intervals extending to 4 weeks. At 45 C, strains 265 (type A), 493 (type C), and 315 (type D) grew and produced enterotoxin, but there was a rapid decrease in viable cells and no enterotoxin produced by strain 243 (type B). In the range of 19 to 39 C, all strains grew and produced enterotoxin. At 13 C, strains 265, 243, and 493 grew but only strain 243 produced enterotoxin. Strain 315 did not grow at 13 C and none of the strains grew at 7 or 50 C. The population of S. aureus varied from 1.3 × 107 to 5.5 × 108 cells/ml when enterotoxin was first detected. S. aureus strain 243 was inoculated at a concentration of 108 cells/ml into BHI broth with and without 0.2 M sodium phosphate buffer and incubated at 37 C for time intervals extending to 172 hr. The initial pH of the broth was adjusted to various values from 3.62 to 9.84. Growth occurred when the initial pH of the broth was 4.96 to 9.02 and a slight increase in population was noted at pH 4.76 and 9.40. Production of detectable amounts of enterotoxin was restricted to pH 5.15 to 9.02. Detectable enterotoxin was produced in 4 to 6 hr in non-buffered broth, but a minimum of 9 hr was required in buffered broth.

Thermal Destruction of Microorganisms in Meat by Microwave and Conventional Cooking1

1977 ◽  
Vol 40 (7) ◽  
pp. 442-444 ◽  
Author(s):  
F. LEON CRESPO ◽  
H. W. OCKERMAN
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Thermal Destruction ◽  
Ground Beef ◽  
Internal Temperature ◽  
Temperature Level ◽  
Microwave Cooking ◽  
Microbial Destruction

When heating ground beef to internal temperatures of 34, 61, and 75 C, high temperature (232 ± 6 C) oven cooking was more effective for bacterial destruction than low temperature (149 ± 6 C) oven cooking. Low temperature oven cooking was more effective than microwave cooking. These differences in microbial destruction rates became significant (P&lt;05) when the meat reached the 75-C internal temperature level.

Reversible Heat Block of Electrical Activity in the Goldfish Brain

1958 ◽  
Vol 192 (3) ◽  
pp. 453-456
Author(s):  
Jean A. Cerf ◽  
Leon S. Otis ◽  
Sadayuki F. Takagi
Keyword(s):  
Critical Temperature ◽  
Electrical Activity ◽  
Room Temperature ◽  
Effect Of Temperature ◽  
Temperature Elevation ◽  
Final Temperature ◽  
Slow Potential ◽  
Vagal Lobe ◽  
Heat Application ◽  
The Brain

The effect of temperature elevation on the electrical activity of the vagal lobe was studied in both intact and isolated goldfish brain. The slow potential changes recorded at room temperature ceased above a critical temperature (about 37°C), and reappeared on cooling. The degree of reversibility of the block was inversely proportional to the duration of heat application and the final temperature of the brain immediately preceding cooling.

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