Saccharomyces cerevisiae Thermal Inactivation Kinetics Combined with Ultrasound

1999 ◽  
Vol 62 (10) ◽  
pp. 1215-1217 ◽  
Author(s):  
A. LÓPEZ-MALO ◽  
S. GUERRERO ◽  
S. M. ALZAMORA
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Thermal Inactivation ◽  
Order Reaction ◽  
Heat Inactivation ◽  
Inactivation Kinetics ◽  
Thermal Treatments ◽  
Combined Treatments ◽  
First Order ◽  
D Values ◽  
Kinetics Of

Inactivation kinetics of Saccharomyces cerevisiae during thermal treatments at moderate temperatures (45.0, 47.5, 50.0, 52.5, or 55.0°C) combined with application of 20 kHz of ultrasound were evaluated. S. cerevisiae inactivation under the combined effects of heat and ultrasound followed first-order reaction kinetics, with decimal reduction times (D) that varied from 22.3 to 0.8 min. D values in treatments that combined heat and ultrasound were significantly smaller (P < 0.05) than D values obtained for thermal treatments and were more noticeable at temperatures below 50°C. The dependence of the D value on temperature had a significantly (P < 0.05) greater z value for combined treatments. Yeast heat inactivation kinetics revealed decreased thermal resistance caused by ultrasound.

Thermal Inactivation Kinetics of Sporolactobacillus nakayamae Spores, a Spoilage Bacterium Isolated from a Model Mashed Potato–Scallion Mixture

2016 ◽  
Vol 79 (9) ◽  
pp. 1482-1489
Author(s):  
HAYRIYE BOZKURT ◽  
JAIRUS R. D. DAVID ◽  
RYAN J. TALLEY ◽  
D. SCOTT LINEBACK ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Heat Resistance ◽  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Order Model ◽  
First Order ◽  
Different Temperatures ◽  
Spoilage Bacterium ◽  
D Values ◽  
Kinetics Of

ABSTRACT Sporolactobacillus species have been occasionally isolated from spoiled foods and environmental sources. Thus, food processors should be aware of their potential presence and characteristics. In this study, the heat resistance and influence of the growth and recovery media on apparent heat resistance of Sporolactobacillus nakayamae spores were studied and described mathematically. For each medium, survivor curves and thermal death curves were generated for different treatment times (0 to 25 min) at different temperatures (70, 75, and 80°C) and Weibull and first-order models were compared. Thermal inactivation data for S. nakayamae spores varied widely depending on the media formulations used, with glucose yeast peptone consistently yielding the highest D-values for the three temperatures tested. For this same medium, the D-values ranged from 25.24 ± 1.57 to 3.45 ± 0.27 min for the first-order model and from 24.18 ± 0.62 to 3.50 ± 0.24 min for the Weibull model at 70 and 80°C, respectively. The z-values determined for S. nakayamae spores were 11.91 ± 0.29°C for the Weibull model and 11.58 ± 0.43°C for the first-order model. The calculated activation energy was 200.5 ± 7.3 kJ/mol for the first-order model and 192.8 ± 22.1 kJ/mol for the Weibull model. The Weibull model consistently produced the best fit for all the survival curves. This study provides novel and precise information on thermal inactivation kinetics of S. nakayamae spores that will enable reliable thermal process calculations for eliminating this spoilage bacterium.

Determination of the Thermal Inactivation Kinetics of the Human Norovirus Surrogates, Murine Norovirus and Feline Calicivirus

2013 ◽  
Vol 76 (1) ◽  
pp. 79-84 ◽  
Author(s):  
HAYRIYE BOZKURT ◽  
DORIS H. D'SOUZA ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Feline Calicivirus ◽  
Murine Norovirus ◽  
Order Model ◽  
Human Norovirus ◽  
First Order ◽  
D Values ◽  
Kinetics Of

Studies are needed to bridge existing data gaps and determine appropriate parameters for thermal inactivation methods for human noroviruses. Cultivable surrogates, such as feline calicivirus (FCV-F9) and murine norovirus (MNV-1), have been used in the absence of human norovirus infectivity assays. This study aimed to characterize the thermal inactivation kinetics of MNV-1 and FCV-F9 at 50, 56, 60, 65, and 72°C for different treatment times (0 to 60 min). Thermal inactivation was performed using the capillary tube method with titers of 4.0 × 107 (MNV-1) and 5.8 × 108 (FCV-F9) PFU/ml in triplicate experiments, followed by standard plaque assays in duplicate for each experiment. Weibull and first-order models were compared to describe survival curve kinetics. Model fitness was investigated by comparing the regression coefficients (R2) and the chi-square (χ2) and root mean square error (RMSE) values. The D-values calculated from the first-order model (50 to 72°C) were 0.15 to 34.49 min for MNV-1 and 0.11 to 20.23 min for FCV-9. Using the Weibull model, the tD values needed to destroy 1 log PFU of MNV-1 and FCV-F9 at the same temperatures were 0.11 to 28.26 and 0.06 to 13.86 min, respectively. In terms of thermal resistance, MNV-1 was more sensitive than FCV-F9 up to 65°C. At 72°C, FCV-F9 was slightly more susceptible to heat inactivation. Results revealed that the Weibull model was more appropriate to represent the thermal inactivation behavior of both tested surrogates. The z-values were calculated using D-values for the first-order model and the tD values for the Weibull model. The z-values were 9.31 and 9.19°C for MNV-1 and 9.36 and 9.31°C for FCV-F9 for the first-order and Weibull models, respectively. This study provides more precise information than previous reports on the thermal inactivation kinetics of two norovirus surrogates for use in thermal process calculations.

Determination of the Thermal Inactivation Kinetics of Listeria monocytogenes, Salmonella enterica, and Escherichia coli O157:H7 and non-O157 in Buffer and a Spinach Homogenate

2015 ◽  
Vol 78 (8) ◽  
pp. 1467-1471 ◽  
Author(s):  
EMEFA ANGELICA MONU ◽  
MALCOND VALLADARES ◽  
DORIS H. D'SOUZA ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Thermal Inactivation ◽  
Inactivation Kinetics ◽  
Mild Heat ◽  
Log Reduction ◽  
D Values ◽  
Heat Processes ◽  
Kinetics Of

Produce has been associated with a rising number of foodborne illness outbreaks. While much produce is consumed raw, some is treated with mild heat, such as blanching or cooking. The objectives of this research were to compare the thermal inactivation kinetics of Listeria monocytogenes, Salmonella enterica, Shiga toxin–producing Escherichia coli (STEC) O157:H7, and non-O157 STEC in phosphate-buffered saline (PBS; pH 7.2) and a spinach homogenate and to provide an estimate of the safety of mild heat processes for spinach. Five individual strains of S. enterica, L. monocytogenes, STEC O157:H7, and non-O157 STEC were tested in PBS in 2-ml glass vials, and cocktails of the organisms were tested in blended spinach in vacuum-sealed bags. For Listeria and Salmonella at 56 to 60°C, D-values in PBS ranged from 4.42 ± 0.94 to 0.35 ± 0.03 min and 2.11 ± 0.14 to 0.16 ± 0.03 min, respectively. D-values at 54 to 58°C were 5.18 ± 0.21 to 0.53 ± 0.04 min for STEC O157:H7 and 5.01 ± 0.60 to 0.60 ± 0.13 min for non-O157 STEC. In spinach at 56 to 60°C, Listeria D-values were 11.77 ± 2.18 to 1.22 ± 0.12 min and Salmonella D-values were 3.51 ± 0.06 to 0.47 ± 0.06 min. D-values for STEC O157:H7 and non-O157 STEC were 7.21 ± 0.17 to 1.07 ± 0.11 min and 5.57 ± 0.38 to 0.99 ± 0.07 min, respectively, at 56 to 60°C. In spinach, z-values were 4.07 ± 0.16, 4.59 ± 0.26, 4.80 ± 0.92, and 5.22 ± 0.20°C for Listeria, Salmonella, STEC O157:H7, and non-O157 STEC, respectively. Results indicated that a mild thermal treatment of blended spinach at 70°C for less than 1 min would result in a 6-log reduction of all pathogens tested. These findings may assist the food industry in the design of suitable mild thermal processes to ensure food safety.

Thermal Inactivation of Human Norovirus Surrogates in Spinach and Measurement of Its Uncertainty

2014 ◽  
Vol 77 (2) ◽  
pp. 276-283 ◽  
Author(s):  
HAYRIYE BOZKURT ◽  
DORIS H. D'SOUZA ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Murine Norovirus ◽  
Order Model ◽  
Human Norovirus ◽  
Test Volume ◽  
Total Uncertainty ◽  
First Order ◽  
D Values

Leafy greens, including spinach, have potential for human norovirus transmission through improper handling and/or contact with contaminated water. Inactivation of norovirus prior to consumption is essential to protect public health. Because of the inability to propagate human noroviruses in vitro, murine norovirus (MNV-1) and feline calicivirus (FCV-F9) have been used as surrogates to model human norovirus behavior under laboratory conditions. The objectives of this study were to determine thermal inactivation kinetics of MNV-1 and FCV-F9 in spinach, compare first-order and Weibull models, and measure the uncertainty associated with the process. D-values were determined for viruses at 50, 56, 60, 65, and 72°C in 2-ml vials. The D-values calculated from the first-order model (50 to 72°C) ranged from 0.16 to 14.57 min for MNV-1 and 0.15 to 17.39 min for FCV-9. Using the Weibull model, the tD for MNV-1 and FCV-F9 to destroy 1 log (D = 1) at the same temperatures ranged from 0.22 to 15.26 and 0.27 to 20.71 min, respectively. The z-values determined for MNV-1 were 11.66 ± 0.42°C using the Weibull model and 10.98 ± 0.58°C for the first-order model and for FCV-F9 were 10.85 ± 0.67°C and 9.89 ± 0.79°C, respectively. There was no difference in D- or z-value using the two models (P >0.05). Relative uncertainty for dilution factor, personal counting, and test volume were 0.005, 0.0004, and ca. 0.84%, respectively. The major contribution to total uncertainty was from the model selected. Total uncertainties for FCV-F9 for the Weibull and first-order models were 3.53 to 7.56% and 11.99 to 21.01%, respectively, and for MNV-1, 3.10 to 7.01% and 13.14 to 16.94%, respectively. Novel and precise information on thermal inactivation of human norovirus surrogates in spinach was generated, enabling more reliable thermal process calculations to control noroviruses. The results of this study may be useful to the frozen food industry in designing blanching processes for spinach to inactivate or control noroviruses.

scholarly journals Thermal Inactivation Kinetics of Human Norovirus Surrogates and Hepatitis A Virus in Turkey Deli Meat

2015 ◽  
Vol 81 (14) ◽  
pp. 4850-4859 ◽  
Author(s):  
Hayriye Bozkurt ◽  
Doris H. D'Souza ◽  
P. Michael Davidson
Keyword(s):  
Hepatitis A ◽  
Thermal Inactivation ◽  
Hepatitis A Virus ◽  
Weibull Model ◽  
Activation Energies ◽  
Inactivation Kinetics ◽  
Order Model ◽  
Decimal Reduction Time ◽  
First Order ◽  
Kinetics Of

ABSTRACTHuman noroviruses (HNoV) and hepatitis A virus (HAV) have been implicated in outbreaks linked to the consumption of presliced ready-to-eat deli meats. The objectives of this research were to determine the thermal inactivation kinetics of HNoV surrogates (murine norovirus 1 [MNV-1] and feline calicivirus strain F9 [FCV-F9]) and HAV in turkey deli meat, compare first-order and Weibull models to describe the data, and calculate Arrhenius activation energy values for each model. TheD(decimal reduction time) values in the temperature range of 50 to 72°C calculated from the first-order model were 0.1 ± 0.0 to 9.9 ± 3.9 min for FCV-F9, 0.2 ± 0.0 to 21.0 ± 0.8 min for MNV-1, and 1.0 ± 0.1 to 42.0 ± 5.6 min for HAV. Using the Weibull model, thetD = 1(time to destroy 1 log) values for FCV-F9, MNV-1, and HAV at the same temperatures ranged from 0.1 ± 0.0 to 11.9 ± 5.1 min, from 0.3 ± 0.1 to 17.8 ± 1.8 min, and from 0.6 ± 0.3 to 25.9 ± 3.7 min, respectively. Thez(thermal resistance) values for FCV-F9, MNV-1, and HAV were 11.3 ± 2.1°C, 11.0 ± 1.6°C, and 13.4 ± 2.6°C, respectively, using the Weibull model. Thezvalues using the first-order model were 11.9 ± 1.0°C, 10.9 ± 1.3°C, and 12.8 ± 1.7°C for FCV-F9, MNV-1, and HAV, respectively. For the Weibull model, estimated activation energies for FCV-F9, MNV-1, and HAV were 214 ± 28, 242 ± 36, and 154 ± 19 kJ/mole, respectively, while the calculated activation energies for the first-order model were 181 ± 16, 196 ± 5, and 167 ± 9 kJ/mole, respectively. Precise information on the thermal inactivation of HNoV surrogates and HAV in turkey deli meat was generated. This provided calculations of parameters for more-reliable thermal processes to inactivate viruses in contaminated presliced ready-to-eat deli meats and thus to reduce the risk of foodborne illness outbreaks.

Dry-heat inactivation of Bacillus subtilis var. niger spores with special reference to spore density

1976 ◽  
Vol 22 (3) ◽  
pp. 359-363 ◽  
Author(s):  
G. Molin ◽  
K. Östlund
Keyword(s):  
Bacillus Subtilis ◽  
Spore Density ◽  
Heat Inactivation ◽  
Inactivation Kinetics ◽  
Temperature Range ◽  
Dry Heat ◽  
Z Value ◽  
D Values ◽  
Kinetics Of ◽  
Spore Densities

The dry-heat inactivation kinetics of Bacillus subtilis var. niger (ATCC 9372) spores has been studied in the temperature range of 120–190 °C. The spores were applied to glass plates of a standardized area (3.24 cm2).Spore preparations of five different spore densities were used (8.3 × 104, 7.4 × 105, 7.8 × 106, 6.3 × 107, and 6.6 × 108 spores per sample, respectively). The heat resistance of the spore was dependent on the number of spores per surface unit. Maximum resistance was observed when the concentration was 7.4 × 105 spores per sample. The D-values obtained at 160 °C from these samples were about twice as high as the D-values obtained from samples with a concentration of 6.3 × 107 or 6.6 × 108 spores per sample. The z value was found to be independent of spore density. Thus, for the two concentrations 7.4 × 105 and 6.3 × 107 spores per sample, the z-value was found to be 22 °C and constant over the temperature range investigated.

Inactivation Kinetics of Avirulent Bacillus anthracis Spores in Milk with a Combination of Heat and Hydrogen Peroxide

2008 ◽  
Vol 71 (2) ◽  
pp. 333-338 ◽  
Author(s):  
SA XU ◽  
THEODORE P. LABUZA ◽  
FRANCISCO DIEZ-GONZALEZ
Keyword(s):  
Hydrogen Peroxide ◽  
Bacillus Anthracis ◽  
Capillary Tube ◽  
Inactivation Kinetics ◽  
First Order ◽  
Freeze Dried ◽  
Bacillus Anthracis Spores ◽  
The Mean ◽  
D Values ◽  
Kinetics Of

The combined effect of heat and hydrogen peroxide (HP) on the inactivation of avirulent Bacillus anthracis spores (Sterne strain 7702; strain ANR-1, an avirulent Ames derivative lacking the pXO2 plasmid; and strain 9131, a plasmid-less Sterne strain) was evaluated in milk. The study temperature ranged from 90 to 95°C, and the concentration of added HP varied from 0.05 to 0.5%. Decimal reduction times (D-values) were determined using a sealed capillary tube technique. The mean D- and z-values of hydrated freeze-dried spores of all three strains in milk ranged from 550 s at 90C to180s at 94°C and from 8.6 to 9.0°C, respectively. When 0.05% HP was added to the milk, the D-values were decreased at least threefold, and at 0.5% HP the D-values ranged from 1 to 10 s. At 90°C, all three strains had similar D-values when 0.05% HP was added. Increasing the concentration of HP to 0.5% had a greater reducing effect on the D-value for strain 7702 than on the values for strains ANR-1 and 9131. The rate of inactivation of each strain followed first-order reaction kinetics at each temperature-peroxide combination. Equations in the form of D = Constant × (HP concentration)n had R2 values greater than 0.97 for strains ANR-1 and 7702 and of at least 0.7 for strain 9131. This study suggests that a combination of high temperature (from 90 to 95°C) and HP could be used for inactivation of B. anthracis spores in the event of deliberate contamination of milk such that the contaminated milk could be disposed of safely.

Thermal Inactivation at High Temperatures and Regeneration of Green Asparagus Peroxidase

1996 ◽  
Vol 59 (10) ◽  
pp. 1065-1071 ◽  
Author(s):  
CARMEN RODRIGO ◽  
MIGUEL RODRIGO ◽  
ANDRÉS ALVARRUIZ ◽  
ANA FRÍGOLA
Keyword(s):  
Enzyme Activity ◽  
Peroxidase Activity ◽  
Thermal Inactivation ◽  
Maximum Activity ◽  
Small Samples ◽  
Inactivation Kinetics ◽  
Optimum Conditions ◽  
First Order ◽  
Kinetics Of ◽  
Green Asparagus

A spectrophotometric method was developed for determining the peroxidase activity of green asparagus in small samples. The optimum conditions for the analysis in the cuvette were 45 mM of H2O2 36 mM of guaiacol, and pH 7. The method can be used to determine enzyme activity at up to two decimal reductions. A study was performed of the regeneration and inactivation kinetics of the enzyme when heated between 90 and 125°C. Regenerated asparagus peroxidase reached its maximum activity after being stored 6 days at 25°C. The regenerated enzyme followed first-order inactivation kinetics, showing an Ea = 13.62 kcal/mol and k100°C = 2.07 min−1.

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).

scholarly journals Peroxidase isoenzymes from seedlings of VIGNA sp (V) landrace Vn: distribution and thermal stability

2021 ◽  
Author(s):  
Yves Mann Elate Lea Mbassi ◽  
Marie Solange Evehe Bebandoue ◽  
Wilfred Fon Mbacham
Keyword(s):  
Thermal Stability ◽  
Heat Inactivation ◽  
Inactivation Kinetics ◽  
Potential Candidate ◽  
Order Model ◽  
Peroxidase Isoenzymes ◽  
First Order ◽  
The North ◽  
Soluble Peroxidase ◽  
Kinetics Of

Abstract Several soluble peroxidase isoenzymes are expressed in a landrace of Vigna sp cultivated in the north of Cameroon (landrace called Vn in previous study) during seed germination. There are at least two cathodic peroxidases and eight major anodic peroxidases as shown by their electrophoretic migration at pH 7.4 under native conditions. These isoperoxidases are more expressed in radicles than in shoots. They have different thermal stability, so that heat inactivation kinetics of crude peroxidase extracts from radicles does not fit the first-order model. One major anodic isoperoxidase of the slow migrating group and at least two others anodic isoperoxidases of the The slow and intermediate migrating groups of anodic isoperoxidasesanodic isoperoxidases are stable for ten minutes of incubation at 80°C and 85°C. The major anodic isoperoxidase of the The less anodic slow migrating groupisoperoxidase (named A6 in this study) shows in addition to this great thermal stability, a high activity during germination and is expressed both in radicles and shoots in large amounts. The combination of those characteristics makes thisthat isoperoxidase a a potential candidate for biotechnological applications.

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