Inactivation and sublethal injury ofEscherichia coliandListeria innocuaby high hydrostatic pressure in model suspensions and beetroot juice

Food business operators search for new, mild technologies, which extend the shelf life of product without changing the sensory and nutritional properties. High hydrostatic pressure (HHP) meets these requirements; however it also triggers sublethal injury of bacterial cells. Sublethal injuries could spoil the product during storage and potentially pose major public health concerns. This study aims to examine the changes of sublethally injured pathogens cells in two vegetable juices: carrot juice (pH 6.0-6.7) and beetroot juice (pH 4.0-4.2) that are induced by HHP (300-500 MPa). The possibilities of recovery of bacterial cells during 28 days of juices storage at two different temperatures (5°C and 25°C) were determined using plate count methods. During the entire period of storage of carrot juice at refrigerated temperature, the propagation and regeneration ofL. innocuastrains were observed. Storage at 25°C showed that the number of these bacteria drastically decreased between 14 and 21 days. The above phenomenon was not detected inE. colicase. There was no cells recovery during long-term refrigerated storage for all strains in beetroot juice. However, in some cases spoiling of this product intermittently occurred at 25°C storage temperature. This work demonstrates that carrot juice supports growth and regeneration of HHP-sublethally injuredL. innocua, while beetroot juice can be classified as a safe product.

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Relationship between Sublethal Injury and Microbial Inactivation by the Combination of High Hydrostatic Pressure and Citral or tert-Butyl Hydroquinone

Applied and Environmental Microbiology ◽

10.1128/aem.00936-08 ◽

2008 ◽

Vol 74 (24) ◽

pp. 7570-7577 ◽

Cited By ~ 63

Author(s):

Maria Somolinos ◽

Diego García ◽

Rafael Pagán ◽

Bernard Mackey

Keyword(s):

Hydrostatic Pressure ◽

High Hydrostatic Pressure ◽

Antimicrobial Effect ◽

Microbial Inactivation ◽

Medium Ph ◽

E Coli ◽

Treatment Conditions ◽

Sublethal Injury ◽

The Relationship ◽

Treatment Medium

ABSTRACT The aim was to investigate (i) the occurrence of sublethal injury in Listeria monocytogenes, Escherichia coli, and Saccharomyces cerevisiae after high hydrostatic pressure (HHP) treatment as a function of the treatment medium pH and composition and (ii) the relationship between the occurrence of sublethal injury and the inactivating effect of a combination of HHP and two antimicrobial compounds, tert-butyl hydroquinone (TBHQ) and citral. The three microorganisms showed a high proportion of sublethally injured cells (up to 99.99% of the surviving population) after HHP. In E. coli and L. monocytogenes, the extent of inactivation and sublethal injury depended on the pH and the composition of the treatment medium, whereas in S. cerevisiae, inactivation and sublethal injury were independent of medium pH or composition under the conditions tested. TBHQ alone was not lethal to E. coli or L. monocytogenes but acted synergistically with HHP and 24-h refrigeration, resulting in a viability decrease of >5 log10 cycles of both organisms. The antimicrobial effect of citral depended on the microorganism and the treatment medium pH. Acting alone for 24 h under refrigeration, 1,000 ppm of citral caused a reduction of 5 log10 cycles of E. coli at pH 7.0 and almost 3 log10 cycles of L. monocytogenes at pH 4.0. The combination of citral and HHP also showed a synergistic effect. Our results have confirmed that the detection of sublethal injury after HHP may contribute to the identification of those treatment conditions under which HHP may act synergistically with other preserving processes.

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High hydrostatic pressure processing of beetroot juice: effects on nutritional, sensory and microbiological quality

High Pressure Research ◽

10.1080/08957959.2019.1666842 ◽

2019 ◽

Vol 39 (4) ◽

pp. 691-706 ◽

Cited By ~ 2

Author(s):

Marta Ubeira-Iglesias ◽

Diego Wilches-Pérez ◽

M. Mar Cavia ◽

Sara Alonso-Torre ◽

Celia Carrillo

Keyword(s):

Hydrostatic Pressure ◽

High Hydrostatic Pressure ◽

Microbiological Quality ◽

Beetroot Juice ◽

High Hydrostatic Pressure Processing

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

Journal of Food Protection ◽

10.4315/0362-028x.jfp-12-127 ◽

2012 ◽

Vol 75 (10) ◽

pp. 1873-1877 ◽

Cited By ~ 8

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 (>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.

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Comparison of Sublethal Injury Induced in Salmonella enterica Serovar Typhimurium by Heat and by Different Nonthermal Treatments

Journal of Food Protection ◽

10.4315/0362-028x-66.1.31 ◽

2003 ◽

Vol 66 (1) ◽

pp. 31-37 ◽

Cited By ~ 132

Author(s):

ELKE Y. WUYTACK ◽

L. DUONG THI PHUONG ◽

A. AERTSEN ◽

K. M. F. REYNS ◽

D. MARQUENIE ◽

...

Keyword(s):

High Pressure ◽

Hydrostatic Pressure ◽

High Hydrostatic Pressure ◽

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Mechanistic Model ◽

Food Preservation ◽

Sublethal Injury ◽

Serovar Typhimurium ◽

Selective Plating

We have studied sublethal injury in Salmonella enterica serovar Typhimurium caused by mild heat and by different emerging nonthermal food preservation treatments, i.e., high-pressure homogenization, high hydrostatic pressure, pulsed white light, and pulsed electric field. Sublethal injury was determined by plating on different selective media, i.e., tryptic soy agar (TSA) plus 3% NaCl, TSA adjusted to pH 5.5, and violet red bile glucose agar. For each inactivation technique, at least five treatments using different doses were applied in order to cover an inactivation range of 0 to 5 log units. For all of the treatments performed with a technique, the logarithm of the viability reductions measured on each of the selective plating media was plotted against the logarithm of the viability reduction on TSA as a nonselective medium, and these points were fitted by a straight line. Sublethal injury between different techniques was then compared by the slope and the y intercept of these regression lines. The highest levels of sublethal injury were observed for the heat and high hydrostatic pressure treatments. Sublethal injury after those treatments was observed on all selective plating media. For the heat treatment, but not for the high-pressure treatment, sublethal injury occurred at low doses, which were not yet lethal. The other nonthermal techniques resulted in sublethal injury on only some of the selective plating media, and the levels of injury were much lower. The different manifestations of sublethal injury were attributed to different inactivation mechanisms by each of the techniques, and a mechanistic model is proposed to explain these differences.

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The effect of high hydrostatic pressure on the survival ofSaccharomyces cerevisiaein model suspensions and beetroot juice

High Pressure Research ◽

10.1080/08957959.2013.769047 ◽

2013 ◽

Vol 33 (1) ◽

pp. 165-171 ◽

Cited By ~ 16

Author(s):

B. Sokołowska ◽

S. Skąpska ◽

M. Fonberg-Broczek ◽

J. Niezgoda ◽

M. Rutkowska ◽

...

Keyword(s):

Hydrostatic Pressure ◽

High Hydrostatic Pressure ◽

Beetroot Juice

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Survival of mouse blastocysts after low-temperature preservation under high pressure

Acta Veterinaria Hungarica ◽

10.1556/avet.52.2004.4.10 ◽

2004 ◽

Vol 52 (4) ◽

pp. 479-487 ◽

Cited By ~ 7

Author(s):

Cs. Pribenszky ◽

M. Molnár ◽

S. Cseh ◽

L. Solti

Keyword(s):

Phase Transition ◽

Hydrostatic Pressure ◽

Low Temperature ◽

High Hydrostatic Pressure ◽

Room Temperature ◽

Freezing Point ◽

Significant Loss ◽

Embryo Cryopreservation ◽

Subzero Temperatures ◽

Survival Capacity

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21°C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0°C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

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