Effect of Using Milk as a Heating Menstruum on the Apparent Heat Resistance of Bacillus stearothermophilus Spores1

1977 ◽  
Vol 40 (4) ◽  
pp. 228-231 ◽  
Author(s):  
J. L. MAYOU ◽  
J. J. JEZESKI
Keyword(s):  
Heat Resistance ◽  
Bacillus Stearothermophilus ◽  
Survival Curves ◽  
Ph Range ◽  
D Values ◽  
D Value

Heat resistance at 121.1 C (250 F) of Bacillus stearothermophilus spores was studied using two heating menstrua. D values of 3.8 and 3.5 min were obtained when spores were heated in 0.01 M PO4 buffer, pH 6.5, and in skimmilk, pH 6.5, respectively. With buffer as a heating menstruum. increasing the pH from 6.5 to 7.2 resulted in an increase in the D value from 3.8 to 4.1 min. When the pH of skimmilk was increased from 6.5 to 7.2, D values increased from 3.5 to 5.2 min. Skimmilk as a component of the enumeration medium inhibited germination and/or outgrowth of B. stearothermophilus spores; however, this inhibition was not influenced over the pH range of 6.0 to 7.2. Addition of 10% skimmilk, pH 6.5, to the medium for enumeration of spores heated in buffer at pH 6.5 or 7.2, in each instance reduced the number of spores that could be recovered but did not change the slopes of survival curves.

Increased Heat Resistance of Salmonellae in Beef with Added Soy Proteins

1983 ◽  
Vol 46 (5) ◽  
pp. 380-384 ◽  
Author(s):  
S. E. CRAVEN ◽  
L. C. BLANKENSHIP
Keyword(s):  
Heat Resistance ◽  
Soy Protein ◽  
Soy Proteins ◽  
Plate Count ◽  
Maximum Heat ◽  
Plate Count Agar ◽  
Isolated Soy Protein ◽  
Soy Isolate ◽  
Ph Range ◽  
D Values

Raw beef inoculated with cells of a composite of five Salmonella strains was heated at 54 or 60°C. Survivors were enumerated by plating samples in plate count agar (PCA), XL agar or PCA followed by an XL agar overlay. Best differential recoveries of salmonellae were effected by incubation of PCA plates for 4 h at 37°C followed by overlay with XL agar and incubation for an additional 44 h. D-values of salmonellae at 54 and 60°C were increased significantly when ground beef was supplemented with 30% textured soy protein, soy protein concentrate or isolated soy protein. Increased heat resistance appeared to be caused by an increase in the pH of beef from 5.8–5.9 to 6.1 upon addition of the soy proteins. After adjusting the pH of mixtures of beef and soy proteins with hydrochloric or lactic acid to 5.8 to 5.9, survival of salmonellae to heat was reduced to the level of survival in beef alone. The pH of beef with added structured soy isolate was the same as beef, and heat resistance of salmonellae was not increased in this product. In the pH range 5.9 to 7.1, the maximum heat resistance of salmonellae in beef containing textured soy protein occurred at pH values of 6.5 to 6.8.

Thermotolerance of Escherichia coli O157:H7 ATCC 43894, Escherichia coli B, and an rpoS-Deficient Mutant of Escherichia coliO157:H7 ATCC 43895 Following Exposure to 1.5% Acetic Acid

1998 ◽  
Vol 61 (9) ◽  
pp. 1184-1186 ◽  
Author(s):  
NICOLE C. WILLIAMS ◽  
STEVEN C. INGHAM
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Heat Resistance ◽  
Acid Stress ◽  
Deficient Mutant ◽  
E Coli ◽  
Significant Difference ◽  
Stressed Cells ◽  
D Values ◽  
D Value

On a beef carcass, Escherichia coli may sequentially encounter acid- and heat-intervention steps. This study tested whether acid stress (1.5% [vol/vol] acetic acid, pH 4.0, 37°C, 15 min) would enhance subsequent heat resistance of E. coli. Initially, cells (E. coli O157:H7 ATCC 43894, nonpathogenic E. coli B [strain FRIK-124], and rpoS-deficient mutant 813-6 [derived from E. coli O157:H7 ATCC 43895]) were acid stressed and transferred to 54°C tiypticase soy broth (TSB), and survivors were immediately enumerated after at least three intervals of 12, 2, and 6 min, respectively, by plating. The ATCC 43894 and 813-6 strains survived the acid stress but strain FRIK-124 did not. Acid-stressed ATCC 43894 had significantly lower D values than the non-acid-stressed controls. Strain 813-6 had significantly lower D values than strain ATCC 43894, with no significant difference between acid-stressed and non-acid-stressed cells. In a second experiment, cooling of cells prior to plating resulted in an increased D value for acid-stressed ATCC 43894 cells, such that it was not significantly different from the D value for non-acid-stressed Controls. Using this protocol, there was no significant difference in D values between acid-stressed and non-acid-stressed ATCC 43894 cells in prewarmed TSB (54, 58, and 62°C), in prewarmed ground beef slurry (GBS; 58°C), or in TSB and GBS inoculated at 5°C and heated to 58°C. The acid stress tested does not enhance subsequent heat resistance of E. coli.

Effect of Sporulation Media on the Heat Resistance of Bacillus stearothermophilus Spores1

1977 ◽  
Vol 40 (4) ◽  
pp. 232-233 ◽  
Author(s):  
J. L. MAYOU ◽  
J. J. JEZESKI
Keyword(s):  
Heat Resistance ◽  
Bacillus Stearothermophilus ◽  
Nutrient Broth ◽  
Nutrient Agar ◽  
Heat Inactivation ◽  
Vegetative Cells ◽  
Temperature Range ◽  
Heat Treated ◽  
D Values

Based on D values obtained over the temperature range of 121.1 C (250 F) to 126.7 C (260 F), Bacillus stearothermophilus vegetative cells sporulated in the presence of milk were more resistant to heat inactivation than spores grown on nutrient agar fortified with MnSo4. Spores grown in the presence of milk and heat-treated at 121.1 and 126.7 C had D values of 4.7 and 0.8 min, respectively. Spores grown on fortified nutrient agar and beat-treated at 121.1 and 126.7 C had D values of 3. 7 and 0.55 min, respectively. No difference in heat resistance was observed between spores derived from vegetative cells grown in milk or nutrient broth when tested at 121.1 C.

Thermal Resistance of Bacillus stearothermophilus Spores Heated in Acidified Mushroom Extract

1994 ◽  
Vol 57 (1) ◽  
pp. 37-41 ◽  
Author(s):  
PABLO S. FERNANDEZ ◽  
MARIA J. OCIO ◽  
TOMAS SANCHEZ ◽  
ANTONIO MARTINEZ
Keyword(s):  
Citric Acid ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Bacillus Stearothermophilus ◽  
Ph Effect ◽  
Bidistilled Water ◽  
Mushroom Extract ◽  
Reference Medium ◽  
D Values

The thermal resistance of Bacillus stearothermophilus spores was studied in bidistilled water as the reference medium, mushroom extract and acidified mushroom extract. Citric acid and glucono-δ-lactone were used as acidulants. Results indicated that mushroom extract affects the heat resistance of spores; D values were lower than for those in bidistilled water. The pH effect was lower with higher treatment temperatures. Acidification reduced the thermal resistance of spores, the reduction being similar for both types of acidulants, and in general it also had the effect of increasing the z values. It has been confirmed that acidification of the canned mushrooms could actually help to control the thermophilic spoilage. This acidification could also be obtained by the use of glucono-δ-lactone, which has been shown to be as effective as citric acid in reducing the heat resistance of spores.

scholarly journals Influence of Heating and Sodium Acidic Polyphosphate on Inhibition of Salmonella Enteritidis and Lactobacillus Rhamnosus in Pomelo Juice

2021 ◽  
Vol 947 (1) ◽  
pp. 012046
Author(s):  
Nhu Khue Doan ◽  
Quoc Dat Lai ◽  
Thi Kim Phung Le ◽  
Tran Diem Ai Chau
Keyword(s):  
Heat Treatment ◽  
Heat Resistance ◽  
Salmonella Enteritidis ◽  
Lactobacillus Rhamnosus ◽  
Heating Treatment ◽  
D Values ◽  
D Value

Abstract The research focused on the heat resistance of Salmonella Enteritidis (S. Enteritidis) and Lactobacillus rhamnosus (L. rhamnosus) in pomelo juice. Sodium acidic polyphosphate was used to enhance the inhibition of these bacteria in heat treatment of pomelo juice. Temperature increased from 52 to 58°C, D-values of S. Enteritidis decreased from 1.94 to 0.15 min. With L. rhamnosus, D value reduced from 0.15 to 0.72 min when the temperature increased from 60 to 75°C. Z values of L. rhamnosus and S. Enteritidis were 16.31 and 5.37°C, respectively. It means that heat resistance of L. rhamnosus is more than that of S. Enteritidis. Adding 0.1% of sodium acidic polyphosphate significantly enhanced the inhibition of S. Enteritidis and L. rhamnosus in the heating treatment of pomelo juice. The result can be applied for pasteurization of pomelo juice.

Thermal Inactivation of Shiga Toxin–Producing Escherichia coli in Ground Beef with Varying Fat Content

2018 ◽  
Vol 81 (6) ◽  
pp. 986-992 ◽  
Author(s):  
JAGPINDER S. BRAR ◽  
JOLENA N. WADDELL ◽  
MATTHEW BAILEY ◽  
SYDNEY CORKRAN ◽  
CARMEN VELASQUEZ ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Thermal Inactivation ◽  
Ground Beef ◽  
Fat Content ◽  
Water Bath ◽  
Survival Curves ◽  
Laboratory Medium ◽  
D Values ◽  
D Value

ABSTRACT Decimal reduction time (D-value) was calculated for six non-O157 Shiga toxin–producing Escherichia coli (STEC) in a laboratory medium and ground beef. For the laboratory medium, an overnight culture of each strain of STEC was divided into 10-mL sample bags and heated in a water bath for a specific time on the basis of the temperatures. Survival curves were generated by plotting the surviving bacterial population against time, and a linear-log primary model was used to estimate the D-values from survival curves. The z-values (the temperature raised to reduce the D-value by one-tenth) were calculated by plotting the log D-values against temperature. Similarly, for ground beef, six fat contents, 5, 10, 15, 20, 25, and 30% of ground beef were formulated for this study. Inoculated meat was divided into 5-g pouches and submerged in a water bath set at specific temperatures (55, 60, 65, 68, and 71.1°C). The average D-value for these strains in a laboratory medium was 17.96 min at 55°C, which reduced significantly (P < 0.05) to 1.58 min at 60°C, and then further reduced (P < 0.05) to 0.46 min at 65°C. In ground beef, a negative correlation (P < 0.05) between fat content of ground beef and D-values was observed at 55°C. However, at temperatures greater than 60°C, there was no impact (P > 0.05) of fat content of ground beef on the thermal resistance of non-O157 STECs. Irrespective of the fat content of ground beef, the D-values ranged from 15.93 to 11.69, 1.15 to 1.12, and 0.14 to 0.09 min and 0.05 at 55, 60, 65, and 68°C, respectively. The data generated from this study can be helpful for the meat industry to develop predictive models for thermal inactivation of non-O157 STECs in ground beef with varying fat content.

Simple Technique to Determine Heat Resistance of Bacillus stearothermophilus Spores in Fluid Systems1

1980 ◽  
Vol 43 (10) ◽  
pp. 799-804 ◽  
Author(s):  
E. M. MIKOLAJCIK ◽  
KATHLEEN T. RAJKOWSKI
Keyword(s):  
Heat Resistance ◽  
Soy Protein ◽  
Milk Protein ◽  
Bacillus Stearothermophilus ◽  
Capillary Tube ◽  
Serum Bottle ◽  
Maximum Heat ◽  
Heat Activation ◽  
The Difference ◽  
D Values

A simple, rapid, highly reproducible procedure was developed to determine heat resistance of Bacillus stearothermophilus spores in milk and soy protein-based formulas at temperatures > 100 C. Plating efficiencies on different media and heat activation temperatures were also studied. The procedure involved use of a serum bottle to which was added formula. The bottle was closed with a rubber septum and sealed air-tight with a crimped aluminum cap. The formula was agitated during heating in a thermostatically controlled oil bath, using a wrist action shaker. When the formula attained the desired temperature, a spore suspension was injected through the rubber septum, using a high-pressure GLC syringe. At selected time intervals, a portion was withdrawn from the bottle, using a sterile GLC syringe. The number of surviving spores was determined by plating on Trypticase Soy agar, which yielded significantly higher spore recovery count than did Trypticase Soy broth fortified with 1.5% agar with and without starch, or Dextrose Tryptone agar. The serum bottle procedure yielded higher D values than did the capillary tube procedure. The difference was significant where p = 0.05 but not where p = 0.01. With the serum bottle procedure, D values for spores in the milk protein base formula were 18.46, 3.56 and 1.13 min at 115, 121 and 125 C, respectively. In the soy protein base formula, D values were 26.1, 3.64 and 1.26 min, respectively. The z values were 7.7 and 7.6 Centigrade degrees (13.86 and 13.68 Fahrenheit degrees). Maximum heat activation of the spore was at 95 C for 10 min in milk protein base formula and at 100 C for 5 min in the soy product.

Modeling the Effects of Temperature, Sodium Chloride, and Green Tea and Their Interactions on the Thermal Inactivation of Listeria monocytogenes in Turkey†

2014 ◽  
Vol 77 (10) ◽  
pp. 1696-1702 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
JIMENA GARCIA-DÁVILA ◽  
JULIO CESAR LOPEZ-ROMERO ◽  
ETNA AIDA PENA-RAMOS ◽  
JUAN PEDRO CAMOU ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Sodium Chloride ◽  
Protective Effect ◽  
Heat Resistance ◽  
Green Tea ◽  
Thermal Inactivation ◽  
Heating Temperature ◽  
Lethal Effect ◽  
Interactive Effects ◽  
D Values

The interactive effects of heating temperature (55 to 65°C), sodium chloride (NaCl; 0 to 2%), and green tea 60% polyphenol extract (GTPE; 0 to 3%) on the heat resistance of a five-strain mixture of Listeria monocytogenes in ground turkey were determined. Thermal death times were quantified in bags that were submerged in a circulating water bath set at 55, 57, 60, 63, and 65°C. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. D-values were analyzed by second-order response surface regression for temperature, NaCl, and GTPE. The data indicated that all three factors interacted to affect the inactivation of the pathogen. The D-values for turkey with no NaCl or GTPE at 55, 57, 60, 63, and 65°C were 36.3, 20.8, 13.2, 4.1, and 2.9 min, respectively. Although NaCl exhibited a concentration-dependent protective effect against heat lethality on L. monocytogenes in turkey, addition of GTPE rendered the pathogen more sensitive to the lethal effect of heat. GTPE levels up to 1.5% interacted with NaCl and reduced the protective effect of NaCl on heat resistance of the pathogen. Food processors can use the predictive model to design an appropriate heat treatment that would inactivate L. monocytogenes in cooked turkey products without adversely affecting the quality of the product.

Modeling Penicillium expansum Resistance to Thermal and Chlorine Treatments

2009 ◽  
Vol 72 (12) ◽  
pp. 2618-2622 ◽  
Author(s):  
BEATRIZ C. M. SALOMÃO ◽  
JOHN J. CHUREY ◽  
GLÁUCIA M. F. ARAGÃO ◽  
RANDY W. WOROBO
Keyword(s):  
Apple Juice ◽  
Weibull Model ◽  
Superior Performance ◽  
Penicillium Expansum ◽  
Heat Inactivation ◽  
Survival Curves ◽  
Biphasic Model ◽  
Log Reduction ◽  
Weibull Models ◽  
D Values

Apples and apple products are excellent substrates for Penicillium expansum to produce patulin. In an attempt to avoid excessive levels of patulin, limiting or reducing P. expansum contamination levels on apples designated for storage in packinghouses and/or during apple juice processing is critical. The aim of this work was (i) to determine the thermal resistance of P. expansum spores in apple juice, comparing the abilities of the Bigelow and Weibull models to describe the survival curves and (ii) to determine the inactivation of P. expansum spores in aqueous chlorine solutions at varying concentrations of chlorine solutions, comparing the abilities of the biphasic and Weibull models to fit the survival curves. The results showed that the Bigelow and Weibull models were similar for describing the heat inactivation data, because the survival curves were almost linear. In this case, the concept of D- and z-values could be used, and the D-values obtained were 10.68, 6.64, 3.32, 1.14, and 0.61 min at 50, 52, 54, 56, and 60°C, respectively, while the z-value was determined to be 7.57°C. For the chlorine treatments, although the biphasic model gave a slightly superior performance, the Weibull model was selected, considering the parsimony principle, because it has fewer parameters than the biphasic model has. In conclusion, the typical pasteurization regimen used for refrigerated apple juice (71°C for 6 s) is capable of achieving a 6-log reduction of P. expansum spores.

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.

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