Note: Ultra High Hydrostatic Pressure Inactivation of Escherichia Coli in Milk, and Orange and Peach Juices

2003 ◽  
Vol 9 (6) ◽  
pp. 403-407 ◽  
Author(s):  
C. Dogan ◽  
O. Erkmen
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
Cell Growth ◽  
Orange Juice ◽  
High Hydrostatic Pressure ◽  
Raw Milk ◽  
Aerobic Bacteria ◽  
Bacterial Cells ◽  
E Coli ◽  
Peach Juice

Inactivation of Escherichia coli by high hydrostatic pressure (UHHP) was determined in broth, milk and orange and peach juices inoculated with the bacteria. HHP ranged from 200 to 700 MPa at 25 C and different treatment times. No cell growth occurred in broth after 60, 25, 15, 10 and 7 min at 300, 400, 500, 600 and 700 MPa, respectively. Reduction of aerobic bacteria in milk and peach juice were 3.08 and 6.07 log units after 15 min at 400 MPa, respectively, while all bacterial cells were inactivated in orange juice. Sterilisation of raw milk contaminated with E. coli occurred at 600 MPa for 30 min, while peach and orange juices needed 12 and 10 min, respectively. The injury of cells in broth at 300 MPa ranged from 8.8 to 100% depending on magnitude of pressure and treated time. In general, inactivation of aerobic bacteria and E. coli was enhanced significantly (P<0.01) by increasing the pressure.

Inactivation of Escherichia coli O157:H7 on Orange Fruit Surfaces and in Juice Using Photocatalysis and High Hydrostatic Pressure

2015 ◽  
Vol 78 (6) ◽  
pp. 1098-1105 ◽  
Author(s):  
SUNGYUL YOO ◽  
KASHIF GHAFOOR ◽  
JEONG UN KIM ◽  
SANGHUN KIM ◽  
BORA JUNG ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
Orange Juice ◽  
High Hydrostatic Pressure ◽  
Tap Water ◽  
Microbial Inactivation ◽  
Inactivation Kinetics ◽  
Escherichia Coli O157 ◽  
Biphasic Model ◽  
E Coli

Nonpasteurized orange juice is manufactured by squeezing juice from fruit without peel removal. Fruit surfaces may carry pathogenic microorganisms that can contaminate squeezed juice. Titanium dioxide–UVC photocatalysis (TUVP), a nonthermal technique capable of microbial inactivation via generation of hydroxyl radicals, was used to decontaminate orange surfaces. Levels of spot-inoculated Escherichia coli O157:H7 (initial level of 7.0 log CFU/cm2) on oranges (12 cm2) were reduced by 4.3 log CFU/ml when treated with TUVP (17.2 mW/cm2). Reductions of 1.5, 3.9, and 3.6 log CFU/ml were achieved using tap water, chlorine (200 ppm), and UVC alone (23.7 mW/cm2), respectively. E. coli O157:H7 in juice from TUVP (17.2 mW/cm2)–treated oranges was reduced by 1.7 log CFU/ml. After orange juice was treated with high hydrostatic pressure (HHP) at 400 MPa for 1 min without any prior fruit surface disinfection, the level of E. coli O157:H7 was reduced by 2.4 log CFU/ml. However, the E. coli O157:H7 level in juice was reduced by 4.7 log CFU/ml (to lower than the detection limit) when TUVP treatment of oranges was followed by HHP treatment of juice, indicating a synergistic inactivation effect. The inactivation kinetics of E. coli O157:H7 on orange surfaces followed a biphasic model. HHP treatment did not affect the pH, °Brix, or color of juice. However, the ascorbic acid concentration and pectinmethylesterase activity were reduced by 35.1 and 34.7%, respectively.

Inactivation by Ultrahigh-Pressure Homogenization of Escherichia coli Strains Inoculated into Orange Juice

2006 ◽  
Vol 69 (5) ◽  
pp. 984-989 ◽  
Author(s):  
WILFIDO JOSÉ BRIÑEZ ◽  
ARTUR X. ROIG-SAGUÉS ◽  
M. MANUELA HERNÁNDEZ HERRERO ◽  
BUENAVENTURA GUAMIS LÓPEZ
Keyword(s):  
Escherichia Coli ◽  
Orange Juice ◽  
Ultrahigh Pressure ◽  
Inlet Temperature ◽  
Bacterial Cells ◽  
Refrigerated Storage ◽  
E Coli ◽  
Sublethal Injury ◽  
Strain Type ◽  
And Control

The aim of this work was to evaluate the efficacy of ultrahigh-pressure homogenization (UHPH) for inactivation and/or sublethal injury of two strains of Escherichia coli (O58:H21 ATCC 10536 and O157:H7 CCUG 44857) inoculated into orange juice (pH 3.6). The effects of orange juice inlet temperature (6 and 20°C) on the lethality values and the capacity of these strains for survival, repair, and growth during refrigerated storage after UHPH treatment also was evaluated. Samples of orange juice that had been treated with ultrahigh temperatures were inoculated with E. coli in the stationary phase of growth until a final concentration of approximately 7.0 log CFU/ml was reached. These samples were then treated for one cycle with a double-valve UHPH machine, with 300 MPa at the primary homogenizing valve and 30 MPa at the secondary valve. Counts of viable and injured bacterial cells were obtained for samples taken 2 h after UHPH treatment and after 3, 6, 9, 12, 15, 18, 21, 27, and 33 days of storage at 4°C. The inlet temperature and the strain type both influenced significantly (P &lt; 0.05) the lethality effect on E. coli, which was higher when the inlet temperature was 20°C. No sublethal injuries were detected after any treatment. The changes in viable counts over time for both strains in pressurized and control samples were similar. The viable counts remained high from day 0 to day 18 and then tended to decrease. After 27 days of storage at 4°C, E. coli O157: H7 was more resistant in orange juice samples pressurized at inlet temperatures of 6 and 20°C, with viable counts of 3.41 and 3.20 log CFU/ml, respectively.

scholarly journals Heat Shock Protein-Mediated Resistance to High Hydrostatic Pressure in Escherichia coli

2004 ◽  
Vol 70 (5) ◽  
pp. 2660-2666 ◽  
Author(s):  
Abram Aertsen ◽  
Kristof Vanoirbeek ◽  
Philipp De Spiegeleer ◽  
Jan Sermon ◽  
Kristel Hauben ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Hydrostatic Pressure ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
High Hydrostatic Pressure ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
E Coli ◽  
Shock Proteins

ABSTRACT A random library of Escherichia coli MG1655 genomic fragments fused to a promoterless green fluorescent protein (GFP) gene was constructed and screened by differential fluorescence induction for promoters that are induced after exposure to a sublethal high hydrostatic pressure stress. This screening yielded three promoters of genes belonging to the heat shock regulon (dnaK, lon, clpPX), suggesting a role for heat shock proteins in protection against, and/or repair of, damage caused by high pressure. Several further observations provide additional support for this hypothesis: (i) the expression of rpoH, encoding the heat shock-specific sigma factor σ32, was also induced by high pressure; (ii) heat shock rendered E. coli significantly more resistant to subsequent high-pressure inactivation, and this heat shock-induced pressure resistance followed the same time course as the induction of heat shock genes; (iii) basal expression levels of GFP from heat shock promoters, and expression of several heat shock proteins as determined by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins extracted from pulse-labeled cells, was increased in three previously isolated pressure-resistant mutants of E. coli compared to wild-type levels.

Combined Effect of High Hydrostatic Pressure and Nisin on Loss of Viability, Membrane Damage and Release of Intracellular Contents of Bacillus subtilis and Escherichia coli

2010 ◽  
Vol 6 (5) ◽  
Author(s):  
Wei-Min Qi ◽  
Ping Qian ◽  
Jian-Yong Yu ◽  
Chi-Yu Zhang ◽  
Xiao Chen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Hydrostatic Pressure ◽  
Synergistic Effect ◽  
High Hydrostatic Pressure ◽  
Cell Envelope ◽  
Membrane Damage ◽  
Combined Effect ◽  
Gram Negative Bacteria ◽  
E Coli

Bacillus subtilis and Escherichia coli were chosen to investigate the combined effect of high hydrostatic pressure (HHP) and Nisin on loss of viability, membrane damage and release of intracellular contents of microorganisms. The results showed that the combination of 200 IU/mL Nisin and HHP exhibited a synergistic effect over 2 log on the inactivation of B. subtilis at pressure 300 MPa. The similar synergistic effect was observed on the membrane damage and release of intracellular contents of B. subtilis. The Nisin alone had no effect against E. coli, which belongs to gram negative bacteria. However, at pressure 300 MPa, Nisin caused the membrane damage from 55% to 80%. The synergistic effect of Nisin and HHP on loss of viability, membrane damage and release of intracellular contents of E. coli were also illustrated when the HHP pressure exceeded 300 MPa as the consequence of the serious changes produced by HHP at higher pressure in the cell envelope. It allows the entry of Nisin molecules to cell membrane.

scholarly journals Inactivation of Escherichia coli andListeria innocua in Milk by Combined Treatment with High Hydrostatic Pressure and the Lactoperoxidase System

2000 ◽  
Vol 66 (10) ◽  
pp. 4173-4179 ◽  
Author(s):  
Cristina García-Graells ◽  
Caroline Valckx ◽  
Chris W. Michiels
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Combined Treatment ◽  
Food Preservation ◽  
Pressure Treatment ◽  
E Coli ◽  
Preservation Method ◽  
Lactoperoxidase System

ABSTRACT We have studied inactivation of four strains each ofEscherichia coli and Listeria innocua in milk by the combined use of high hydrostatic pressure and the lactoperoxidase-thiocyanate-hydrogen peroxide system as a potential mild food preservation method. The lactoperoxidase system alone exerted a bacteriostatic effect on both species for at least 24 h at room temperature, but none of the strains was inactivated. Upon high-pressure treatment in the presence of the lactoperoxidase system, different results were obtained for E. coli and L. innocua. For none of the E. coli strains did the lactoperoxidase system increase the inactivation compared to a treatment with high pressure alone. However, a strong synergistic interaction of both treatments was observed for L. innocua. Inactivation exceeding 7 decades was achieved for all strains with a mild treatment (400 MPa, 15 min, 20°C), which in the absence of the lactoperoxidase system caused only 2 to 5 decades of inactivation depending on the strain. Milk as a substrate was found to have a considerable effect protecting E. coli and L. innocua against pressure inactivation and reducing the effectiveness of the lactoperoxidase system under pressure on L. innocua. Time course experiments showed that L. innocua counts continued to decrease in the first hours after pressure treatment in the presence of the lactoperoxidase system.E. coli counts remained constant for at least 24 h, except after treatment at the highest pressure level (600 MPa, 15 min, 20°C), in which case, in the presence of the lactoperoxidase system, a transient decrease was observed, indicating sublethal injury rather than true inactivation.

Pasteurization of Fruit Juices of Different pH Values by Combined High Hydrostatic Pressure and Carbon Dioxide

2012 ◽  
Vol 75 (10) ◽  
pp. 1873-1877 ◽  
Author(s):  
LI WANG ◽  
JIAN PAN ◽  
HUIMING XIE ◽  
YI YANG ◽  
DIANFEI ZHOU ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Orange Juice ◽  
High Hydrostatic Pressure ◽  
Combined Treatment ◽  
Physiological Saline ◽  
Fruit Juices ◽  
E Coli ◽  
Sublethal Injury ◽  
Pressure Resistance ◽  
Low Pressures

The inactivation of the selected vegetative bacteria Escherichia coli, Listeria innocua, and Lactobacillus plantarum by high hydrostatic pressure (HHP) in physiological saline (PS) and in four fruit juices with pHs ranging from 3.4 to 6.3, with or without dissolved CO2, was investigated. The inactivation effect of HHP on the bacteria was greatly enhanced by dissolved CO2. Effective inactivation (&gt;7 log) was achieved at 250 MPa for E. coli and 350 MPa for L. innocua and L. plantarum in the presence of 0.2 M CO2 at room temperature for 15 min in PS, with additional inactivation of more than 4 log for all three bacteria species compared with the results with HHP treatment alone. The combined inactivation by HHP and CO2 in tomato juice of pH 4.2 and carrot juice of pH 6.3 showed minor differences compared with that in PS. By comparison, the combined effect in orange juice of pH 3.8 was considerably promoted, while the HHP inactivation was enhanced only to a limited extent. In another orange juice with a pH of 3.4, all three strains lost their pressure resistance. HHP alone completely inactivated E. coli at relatively mild pressures of 200 MPa and L. innocua and L. plantarum at 300 MPa. Observations of the survival of the bacteria in treated juices also showed that the combined treatment caused more sublethal injury, which increased further inactivation at a relatively mild pH of 4.2 during storage. The results indicated that the combined treatment of HHP with dissolved CO2 may provide an effective method for the preservation of low- or medium-acid fruit and vegetable juices at relatively low pressures. HHP alone inactivated bacteria effectively in high-acid fruit juice.

Fate of Escherichia coli Strains Inoculated in Model Cheese Elaborated with or without Starter and Treated by High Hydrostatic Pressure

2006 ◽  
Vol 69 (12) ◽  
pp. 2856-2864 ◽  
Author(s):  
SÍLVIA DE LAMO-CASTELLVÍ ◽  
MARTA CAPELLAS ◽  
ARTUR X. ROIG-SAGUÉS ◽  
TOMÁS LÓPEZ-PEDEMONTE ◽  
M. MANUELA HERNÁNDEZ-HERRERO ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Culture Medium ◽  
Storage Period ◽  
E Coli ◽  
Ph Values ◽  
Cell Counts ◽  
Agar Layer ◽  
Selective Culture Medium

The aim of this research was to study high hydrostatic pressure inactivation of two strains of Escherichia coli (E. coli O59:H21 [CECT 405] and E. coli O157:H7 [CECT 5947]) inoculated in washed-curd model cheese elaborated with and without starter and the ability of these strains for survival, recovery, and growth. Samples were treated at 300, 400, and 500 MPa for 10 min at 20°C and analyzed after the treatment and after 1, 7, and 15 days of storage at 8°C to study the behavior of Escherichia populations. Cheeses elaborated with starter showed the maximum lethality at 400 and 500 MPa, and no significant differences in the baroresistant behavior of either strains were detected, except for E. coli O157:H7 at 400 MPa in cell counts obtained with thin agar layer method medium, where the decrease value was significantly lower. In cheese elaborated without starter, the highest decrease value was observed at 500 MPa, except for E. coli O59:H21 in cell counts obtained with selective culture medium, where the highest decrease value was also found at 400 MPa. The ability to repair and grow was not observed in model cheese elaborated with starter, as cell counts of treated samples decreased after 15 days of storage at 8°C. By contrast, in cheese elaborated without starter, all pressurized samples showed the trend to repair and grow during the storage period in both strains. These results suggest that the presence of starter and low pH values are the main factors that control the ability of Escherichia strains inoculated in this type of cheese and treated by high hydrostatic pressure to recover and grow.

scholarly journals Variation in Resistance to High Hydrostatic Pressure andrpoS Heterogeneity in Natural Isolates ofEscherichia coli O157:H7

2001 ◽  
Vol 67 (10) ◽  
pp. 4901-4907 ◽  
Author(s):  
Marianne Robey ◽  
Amparo Benito ◽  
Roger H. Hutson ◽  
Cristina Pascual ◽  
Simon F. Park ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
Stationary Phase ◽  
Sigma Factor ◽  
High Hydrostatic Pressure ◽  
E Coli ◽  
Commensal Strain ◽  
Natural Isolates ◽  
Pressure Resistance ◽  
Sigma Factor Rpos

ABSTRACT Several natural isolates of Escherichia coliO157:H7 have previously been shown to exhibit stationary-phase-dependent variation in their resistance to inactivation by high hydrostatic pressure. In this report we demonstrate that loss of the stationary-phase-inducible sigma factor RpoS resulted in decreased resistance to pressure inE. coli O157:H7 and in a commensal strain. Furthermore, variation in the RpoS activity of the natural isolates of O157:H7 correlated with the pressure resistance of those strains. Heterogeneity was noted in the rpoS alleles of the natural isolates that may explain the differences in RpoS activity. These results are consistent with a role for rpoS in mediating resistance to high hydrostatic pressure in E. coliO157:H7.

scholarly journals Stress-Induced Evolution of Heat Resistance and Resuscitation Speed in Escherichia coli O157:H7 ATCC 43888

2016 ◽  
Vol 82 (22) ◽  
pp. 6656-6663 ◽  
Author(s):  
Elisa Gayán ◽  
Alexander Cambré ◽  
Chris W. Michiels ◽  
Abram Aertsen
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Hydrostatic Pressure ◽  
Foodborne Pathogens ◽  
High Hydrostatic Pressure ◽  
Cross Resistance ◽  
Content Type ◽  
E Coli ◽  
Mild Heat ◽  
Mutant Strains

ABSTRACTThe development of resistance in foodborne pathogens to food preservation techniques is an issue of increasing concern, especially in minimally processed foods where safety relies on hurdle technology. In this context, mild heat can be used in combination with so-called nonthermal processes, such as high hydrostatic pressure (HHP), at lower individual intensities to better retain the quality of the food. However, mild stresses may increase the risk of (cross-)resistance development in the surviving population, which in turn might compromise food safety. In this investigation, we examined the evolution ofEscherichia coliO157:H7 strain ATCC 43888 after recurrent exposure to progressively intensifying mild heat shocks (from 54.0°C to 60.0°C in 0.5°C increments) with intermittent resuscitation and growth of survivors. As such, mutant strains were obtained after 10 cycles of selection with ca. 106-fold higher heat resistance than that for the parental strain at 58.0°C, although this resistance did not extend to temperatures exceeding 60.0°C. Moreover, these mutant strains typically displayed cross-resistance against HHP shock and displayed signs of enhanced RpoS and RpoH activity. Interestingly, additional cycles of selection maintaining the intensity of the heat shock constant (58.5°C) selected for mutant strains in which resuscitation speed, rather than resistance, appeared to be increased. Therefore, it seems that resistance and resuscitation speed are rapidly evolvable traits inE. coliATCC 43888 that can compromise food safety.IMPORTANCEIn this investigation, we demonstrated thatEscherichia coliO157:H7 ATCC 43888 rapidly acquires resistance to mild heat exposure, with this resistance yielding cross-protection to high hydrostatic pressure treatment. In addition, mutants ofE. coliATCC 43888 in which resuscitation speed, rather than resistance, appeared to be improved were selected. As such, both resistance and resuscitation speed seem to be rapidly evolvable traits that can compromise the control of foodborne pathogens in minimal processing strategies, which rely on the efficacy of combined mild preservation stresses for food safety.

scholarly journals Inactivation of Escherichia coli O157:H7 by High Hydrostatic Pressure Combined with Gas Packaging

2019 ◽  
Vol 7 (6) ◽  
pp. 154 ◽  
Author(s):  
Bing Zhou ◽  
Luyao Zhang ◽  
Xiao Wang ◽  
Peng Dong ◽  
Xiaosong Hu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Cellular Structure ◽  
Combined Treatment ◽  
Physiological Saline ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Significant Difference

The inactivation of Escherichia coli O157:H7 (E. coli) in physiological saline and lotus roots by high hydrostatic pressure (HHP) in combination with CO2 or N2 was studied. Changes in the morphology, cellular structure, and membrane permeability of the cells in physiological saline after treatments were investigated using scanning electron microscopy, transmission electron microscopy, and flow cytometry, respectively. It was shown that after HHP treatments at 150–550 MPa, CO2-packed E. coli cells had higher inactivation than the N2-packed and vacuum-packed cells, and no significant difference was observed in the latter two groups. Further, both the morphology and intracellular structure of CO2-packed E.coli cells were strongly destroyed by high hydrostatic pressure. However, serious damage to the intracellular structures occurred in only the N2-packed E. coli cells. During HHP treatments, the presence of CO2 caused more disruptions in the membrane of E. coli cells than in the N2-packed and vacuum-packed cells. These results indicate that the combined treatment of HHP and CO2 had a strong synergistic bactericidal effect, whereas N2 did not have synergistic effects with HHP. Although these two combined treatments had different effects on the inactivation of E. coli cells, the inactivation mechanisms might be similar. During both treatments, E. coli cells were inactivated by cell damage induced to the cellular structure through the membrane components and the extracellular morphology, unlike the independent HHP treatment.

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