scholarly journals Death kinetics of Escherichia coli in goat milk and Bacillus licheniformis in cloudberry jam treated by ohmic heating

2007 ◽  
Vol 61 (2) ◽  
Author(s):  
R. Pereira ◽  
J. Martins ◽  
C. Mateus ◽  
J. Teixeira ◽  
A. Vicente
Keyword(s):  
Escherichia Coli ◽  
Bacillus Licheniformis ◽  
Ohmic Heating ◽  
Goat Milk ◽  
Conventional Heating ◽  
Decimal Reduction Time ◽  
Fold Reduction ◽  
Death Kinetics ◽  
D Values ◽  
Kinetics Of

AbstractThe influence of ohmic heating on the death kinetic parameters of Escherichia coli ATCC® 25922 in goat milk and spores of Bacillus licheniformis ATCC® 14580 in cloudberry jam was investigated and compared with that of conventional heating. Ohmic treatment of goat milk shortened the decimal reduction time D in comparison with the D values obtained at conventional treatment. Similarly, the z value, increase of temperature required for a ten-fold reduction of D, was also lower at ohmic treatment. The death kinetics of Bacillus licheniformis ATCC® 14580 spores in cloudberry jam was also studied employing both types of heat treatment. Similar conclusions were obtained for the D values as in the case of goat milk. However, the differences between the z values obtained for ohmic and conventional heating were not significant.

Survival of Microorganisms in Stored Pasta

1979 ◽  
Vol 42 (4) ◽  
pp. 330-334 ◽  
Author(s):  
M. K. RAYMAN ◽  
J.-Y. D'AOUST ◽  
B. ARIS ◽  
C. MAISHMENT ◽  
R. WASIK
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Room Temperature ◽  
Penicillium Expansum ◽  
Prolonged Storage ◽  
E Coli ◽  
Death Kinetics ◽  
D Values ◽  
Aspergillus Repens ◽  
Kinetics Of

Numbers of Staphylococcus aureus, Saccharomyces cerevisiae and Penicillium expansum in artificially contaminated pasta declined exponentially during storage at room temperature; corresponding D values ranged from 18–21 days, 40–45 days and 130–160 days. In contrast to the rapid death kinetics of Aspergillus repens and Escherichia coli, Streptococcus faecium survived after 180 days of storage. These results suggest that streptococci are more reliable than E. coli as indicators of fecal contamination in pasta. Detection of Salmonella infantis and Salmonella typhimurium after 360 days indicates that prolonged storage of pasta is not effective for decontamination of infected products.

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.

scholarly journals Effect of Electropermeabilization by Ohmic Heating for Inactivation of Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes in Buffered Peptone Water and Apple Juice

2013 ◽  
Vol 79 (23) ◽  
pp. 7122-7129 ◽  
Author(s):  
Il-Kyu Park ◽  
Dong-Hyun Kang
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Electric Field ◽  
Salmonella Enterica ◽  
Apple Juice ◽  
Ohmic Heating ◽  
Conventional Heating ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Peptone Water

ABSTRACTThe effect of electric field-induced ohmic heating for inactivation ofEscherichia coliO157:H7,Salmonella entericaserovar Typhimurium, andListeria monocytogenesin buffered peptone water (BPW) (pH 7.2) and apple juice (pH 3.5; 11.8 °Brix) was investigated in this study. BPW and apple juice were treated at different temperatures (55°C, 58°C, and 60°C) and for different times (0, 10, 20, 25, and 30 s) by ohmic heating compared with conventional heating. The electric field strength was fixed at 30 V/cm and 60 V/cm for BPW and apple juice, respectively. Bacterial reduction resulting from ohmic heating was significantly different (P< 0.05) from that resulting from conventional heating at 58°C and 60°C in BPW and at 55°C, 58°C, and 60°C in apple juice for intervals of 0, 10, 20, 25, and 30 s. These results show that electric field-induced ohmic heating led to additional bacterial inactivation at sublethal temperatures. Transmission electron microscopy (TEM) observations and the propidium iodide (PI) uptake test were conducted after treatment at 60°C for 0, 10, 20, 25 and 30 s in BPW to observe the effects on cell permeability due to electroporation-caused cell damage. PI values when ohmic and conventional heating were compared were significantly different (P< 0.05), and these differences increased with increasing levels of inactivation of three food-borne pathogens. These results demonstrate that ohmic heating can more effectively reduce bacterial populations at reduced temperatures and shorter time intervals, especially in acidic fruit juices such as apple juice. Therefore, loss of quality can be minimized in a pasteurization process incorporating ohmic heating.

The Effect of Nisin on Growth Kinetics from Activated Bacillus cereus Spores in Cooked Rice and in Milk

2002 ◽  
Vol 65 (2) ◽  
pp. 419-422 ◽  
Author(s):  
THEREZA CHRISTINA VESSONI PENNA ◽  
DANTE AUGUSTO MORAES ◽  
DALETE NOGUEIRA FAJARDO
Keyword(s):  
Bacillus Cereus ◽  
Growth Kinetics ◽  
Lag Phase ◽  
White Rice ◽  
Decimal Reduction Time ◽  
Cooked Rice ◽  
Generation Times ◽  
Different Temperatures ◽  
D Values ◽  
Kinetics Of

The growth kinetics of germinated cells from activated spores of Bacillus cereus in cooked white rice and in milk were evaluated at different temperatures for control samples and for samples with 25 μg of nisin per ml added. Nisin was applied in the form of Nisaplin (106 IU/g), which contained 25,000 μg of nisin per g. The length of the lag phase for cooked white rice controls was 120 h at 10°C, 8 h at 25°C, and 2.5 h at 33°C. The generation times for cooked rice were 327.7 min at 10°C, 59.0 min at 25°C, and 42.3 min at 33°C; those for milk without nisin were 297.0 min at 20°C, 31.2 min at 30°C, 28.6 min at 35°C, and 33.7 min at 40°C; and those for milk with nisin added were 277.2 min at 20°C, 66.9 min at 30°C, and 66.4 min at 35°C. No development of B. cereus was observed for milk with nisin added at 40°C for 12 h, in which germinated cells decreased by a decimal reduction time (D) of 4.7 h. A temperature of 45°C was shown to be harmful to B. cereus, decreasing the germinated cells in both formulations with D-values of 4.3 to 4.6 h. Similar inhibition of cell growth at 40°C was not observed with lower nisin concentrations.

Comparative Radiation Death Kinetics of Clostridium botulinum Spores at Low-Temperature Gamma Irradiation

1977 ◽  
Vol 40 (5) ◽  
pp. 313-316 ◽  
Author(s):  
ABE ANELLIS ◽  
D. BERKOWITZ ◽  
D. KEMPER
Keyword(s):  
Clostridium Botulinum ◽  
Model System ◽  
Radiation Temperature ◽  
60Co Gamma Rays ◽  
Death Kinetics ◽  
D Values ◽  
Increasing Temperature ◽  
Relationship Of ◽  
Kinetics Of ◽  
D Value

Spores of Clostridium botulinum 33A were irradiated with 60Co gamma rays in 0.067 M Sorensen phosphate buffer (pH 7.0) at −196, −140, −80, −30, or 5 C and incubated in recovery broth for 30 days at 30 C, thus simulating an inoculated pack and eliciting “partial spoilage” data. Resistance of the spores decreased linearly with increasing temperature. A simple empirical equation was derived to predict D values for any desired temperature. An Arrhenius plot of the D value—radiation temperature profile indicated that the death kinetics is not first order. Comparison of the data in this model system with those previously observed in beef indicates a similar radiation death pattern, except that resistance of the spores was somewhat more (1.6-fold) temperature dependent, although significantly more resistant, in the beef. A comparison of the D value-temperature relationship of Streptoccus faecium a21, obtained earlier, with strain 33A in the same model system indicated that the spores were considerably less resistant below −20 C and much more resistant above this radiation temperature.

scholarly journals Accelerated Death Kinetics of Aspergillus niger Spores under High-Pressure Carbonation

2002 ◽  
Vol 68 (8) ◽  
pp. 4162-4167 ◽  
Author(s):  
M. Shimoda ◽  
H. Kago ◽  
N. Kojima ◽  
M. Miyake ◽  
Y. Osajima ◽  
...  
Keyword(s):  
High Pressure ◽  
Aspergillus Niger ◽  
Significant Interaction ◽  
Microbial Population ◽  
Treatment Temperature ◽  
Decimal Reduction Time ◽  
First Order ◽  
Death Kinetics ◽  
Time Required ◽  
Kinetics Of

ABSTRACT The death kinetics of Aspergillus niger spores under high-pressure carbonation were investigated with respect to the concentration of dissolved CO2 (dCO2) and treatment temperature. All of the inactivation followed first-order death kinetics. The D value (decimal reduction time, or the time required for a 1-log-cycle reduction in the microbial population) in the saline carbonated at 10 MPa was 0.16 min at 52°C. The log D values were linearly related to the treatment temperature and the concentration of dCO2, but a significant interaction was observed between them.

Apple snack enriched with L-arginine using vacuum impregnation/ohmic heating technology

2017 ◽  
Vol 23 (5) ◽  
pp. 448-456 ◽  
Author(s):  
Jorge Moreno ◽  
Julian Echeverria ◽  
Andrea Silva ◽  
Andrea Escudero ◽  
Guillermo Petzold ◽  
...  
Keyword(s):  
Functional Foods ◽  
Ohmic Heating ◽  
Conventional Heating ◽  
Vacuum Impregnation ◽  
High Demand ◽  
Modern Life ◽  
Generate Functional ◽  
Heating Treatment ◽  
Kinetics Of ◽  
Heating Technology

Modern life has created a high demand for functional food, and in this context, emerging technologies such as vacuum impregnation and ohmic heating have been applied to generate functional foods. The aim of this research was to enrich the content of the semi-essential amino acid L-arginine in apple cubes using vacuum impregnation, conventional heating, and ohmic heating. Additionally, combined vacuum impregnation/conventional heating and vacuum impregnation/ohmic heating treatments were evaluated. The above treatments were applied at 30, 40 and 50  ℃ and combined with air-drying at 40 ℃ in order to obtain an apple snack rich in L-arginine. Both the impregnation kinetics of L-arginine and sample color were evaluated. The impregnated samples created using vacuum impregnation/ohmic heating at 50 ℃ presented a high content of L-arginine, an effect attributed primarily to electropermeabilization. Overall, vacuum impregnation/ohmic heating treatment at 50 ℃, followed by drying at 40 ℃, was the best process for obtaining an apple snack rich in L-arginine.

Evaluation of nonthermal effects of electricity on inactivation kinetics of Staphylococcus aureus and Escherichia coli during ohmic heating of infant formula

2017 ◽  
Vol 38 (1) ◽  
Author(s):  
Rochele de Quadros Rodrigues ◽  
Michelle Dalmás ◽  
Diego Chemello Muller ◽  
Daniela Dambróz Escobar ◽  
Alessandra Campani Pizzato ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Infant Formula ◽  
Ohmic Heating ◽  
Inactivation Kinetics ◽  
Kinetics Of

scholarly journals Long-Term Survival and Thermal Death Kinetics of EnterohemorrhagicEscherichia coliSerogroups O26, O103, O111, and O157 in Wheat Flour

2018 ◽  
Vol 84 (13) ◽  
pp. e00283-18 ◽  
Author(s):  
Fereidoun Forghani ◽  
Meghan den Bakker ◽  
Alexandra N. Futral ◽  
Francisco Diez-Gonzalez
Keyword(s):  
Wheat Flour ◽  
Thermal Inactivation ◽  
Term Survival ◽  
Content Type ◽  
Decimal Reduction Time ◽  
Thermal Death ◽  
Death Kinetics ◽  
Kinetics Of ◽  
Thermal Death Kinetics

ABSTRACTWheat flour has been associated with outbreaks of enterohemorrhagicEscherichia coli(EHEC), but little is known on EHEC's survival during storage and thermal processing. The objective of this study was to determine long-term viability and thermal inactivation kinetics of EHEC serogroups O26, O103, O111, and O157. Wheat flour samples were inoculated with a cocktail of five strains of a single serogroup and stored at 23 and 35°C. Inoculated samples were heated at 55, 60, 65, and 70°C. Viability was determined by plate counting. Decimal reduction time (D) and first decimal reduction time (δ) values were calculated with log-linear and Weibull models, respectively. At 23°C, EHEC counts declined gradually for 84 days and samples tested positive from 84 to 280 days. The thermal resistance (Dand δ) values ranged from 7.5 to 8.2 and 3.1 to 5.3 days, respectively, but there were no significant differences among serogroups (P≤ 0.05). At 35°C, no EHEC was quantifiable by day 7 and no positive samples were detected after 49 days. Heating at 55 and 65°C resulted in δ-value ranges of 15.6 to 39.7 min and 3.0 to 3.9 min, respectively, with no significant difference among serogroups either. Z values were 12.6, 6.7, 10.2, and 13.4°C for O26, O103, O111, and O157, respectively. Thermal death kinetics of EHEC in flour were better described using the Weibull model. Survival and inactivation rates of four serogroups were remarkably similar. These findings indicated that all EHEC serovars tested remained viable for at least 9 months at room temperature and survived for up to 60 min at 70°C in wheat flour.IMPORTANCEEnterohemorrhagicEscherichia coli(EHEC) andSalmonellahave recently caused several gastroenteritis outbreaks and recalls of wheat flour. Because EHEC can cause illness with very low doses and there is very scarce information regarding their ability to survive storage and heating in flour, the present study was undertaken to assess the long-term survival of EHEC serogroups O26, O103, O111, and O157 in flour. These findings are relevant, as we report that EHEC can survive for more than 9 months in wheat flour during storage. In addition, results obtained suggest that thermal inactivation at 65°C for 30 min or 2 months of storage at 35°C may be feasible strategies to mitigate the risk of most EHEC serovars in wheat flour.

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