Life Sciences Commons^™

Atmospheric Cold Plasma Inactivation Of Escherichia Coli, Salmonella Enterica Serovar Typhimurium And Listeria Monocytogenes Inoculated On Fresh Produce, Dana Ziuzina, Sonal Patil, Patrick Cullen, Kevin Keener, Paula Bourke

Articles

Atmospheric cold plasma (ACP) represents a potential alternative to traditional methods for non-thermal decontamination of foods. In this study, the antimicrobial efficacy of a novel dielectric barrier discharge ACP device against Escherichia coli, Salmonella enterica Typhimurium and Listeria monocytogenes inoculated on cherry tomatoes and strawberries, was examined. Bacteria were spot inoculated on the produce surface, air dried and sealed inside a rigid polypropylene container. Samples were indirectly exposed (i.e. placed outside plasma discharge) to a high voltage (70kVRMS) air ACP and subsequently stored at room temperature for 24 h. ACP treatment for 10, 60 and 120 s resulted in reduction …

Atmospheric Cold Plasma Inactivation Of Escherichia Coli In Liquid Media Inside A Sealed Package, Dana Ziuzina, Sonal Patil, Paula Bourke, Kevin Keener, Patrick Cullen

Articles

Abstract Aims: The main objective of this study was to determine the inactivation efficacy of dielectric barrier discharge atmospheric cold plasma (DBD-ACP) generated inside a sealed package for Escherichia coli ATCC 25922. Methods and Results: A plasma discharge was generated between two circular aluminium electrodes at 40 kV. E. coli suspensions (10^7 CFU/ml) in either maximum recovery diluent (MRD) or phosphate buffered saline (PBS) were treated in a 96-well microtitre plate inside a sealed package. The effects of treatment time, post-treatment storage time, either direct or indirect samples exposure to the plasma discharge and suspension media were studied. Regardless of …

Quantitative Assessment Of The Shelf-Life Of Ozonated Apple Juice, Sonal Patil, Vasilis Valdramidis, Brijesh Tiwari, Patrick Cullen, Paula Bourke

Articles

Sterile apple juice inoculated with S. cerevisiae ATCC 9763 (10³ CFU/mL) was processed in a bubble column with gaseous ozone of flow rate of 0.12 L/min and concentration of 33-40 µg/mL for 8 min. The growth kinetics of S. cerevisiae as an indicator of juice spoilage was monitored at 4, 8, 12 and 16 ºC for up to 30 days. The kinetics were quantitatively described by the primary model of Baranyi and Robert’s and the maximum specific growth rate was further modeled as a function of temperature by the Ratkowsky type model. The developed model was successfully validated for …

Assessing The Microbial Oxidative Stress Of Ozone: Significant Role Of The Oxidative Stress Proteins In The Survival Of E. Coli In Ozone Treatment, Sonal Patil, Vasilis Valdramidis, A. Katratzas, Patrick Cullen, Paula Bourke

Articles

Aims: To investigate the effect of the oxidative stress of ozone on microbial inactivation, cell membrane integrity, membrane permeability and morphology changes of Escherichia coli during ozone treatment.

Methods and Results: E. coli BW 25113 and its isogenic mutants in soxR, soxS, oxyR, rpoS, dnaK genes were treated with ozone at a concentration of 6 µg mL^-1 for a period up to 4 min. A significant effect of ozone exposure on microbial inactivation was observed. After ozonation, minor effects on the cell membrane integrity and permeability were observed. Scanning Electron Microscopy (SEM) analysis showed slightly altered cell …

Ozone Inactivation Of Acid Stressed Listeria Monocytogenes And Listeria Innocua In Orange Juice Using A Bubble Column, Sonal Patil, Vasilis Valdramidis, Jesus Maria Frias, Patrick Cullen, Paula Bourke

Articles

Orange juice inoculated with Listeria monocytogenes strains ATCC 7644, NCTC 11994 and Listeria innocua NCTC 11288 (10⁶ CFU/ml) as challenge microorganisms was treated with direct ozone at 0.098mg/min/ml for different time periods (0-8 min) using an ozone bubble column. Ozone treatment of mild acid stressed and mild acid stress-habituated (pH 5.5) cells of L. monocytogenes resulted in higher inactivation times compared to control non-acid stressed cells. Additionally acid stressed cells habituated in orange juice (ATCC 7644 & NCTC 11288), showed higher inactivation times during ozonation by comparison with the control as well as the mild-acid stressed cells. Overall the …

Quality And Safety Assessment During The Ozonation Of Cloudy Apple Juice, Sonal Patil, B. Torres, Brijesh Tiwari, Hilda Wingaard, Paula Bourke, Patrick Cullen, C. O'Donnell, Vasilis Valdramidis

Articles

Traditionally, ozone processing within the food industry has focused on solid foods by either gaseous treatment or washing with ozonated water. However, with the FDA’s approval of ozone as a direct additive to food, the potential for liquid applications has emerged. This study investigates the effect of ozone processing on microbial inactivation (E. coli ATCC 25922 and NCTC 12900), and quality parameters (colour, phenolic content) of apple juice. Apple juice samples were ozonated at room temperature (20±1.5^oC) with an ozone concentration of 0.048 mg O₃ min^-1 ml^-1 and treatment time of 0 to 10 …

Efficacy Of Ozone And Ultrasound For Microbial Reduction In Fruit Juice, Sonal Patil

Doctoral

Concerns have arisen regarding the microbiological safety of fruit juices due to a number of outbreaks associated with pathogens. Non-thermal technologies for the inactivation of microorganisms are of increasing interest to the food industry for the control of spoilage as well as safety concerns. The objective of this thesis was to investigate the efficacy of ultrasound and ozone treatments for control of microbial issues associated with fruit juices. Inactivation of Escherichia coli (ATCC 25922, NCTC 12900) using power ultrasound was found to be influenced by strain, prior acid adaptation and suspension liquid, but the effect was negated at the higher …

Inactivation Of Escherichia Coli By Ozone Treatment Of Apple Juice At Different Ph Levels, Sonal Patil, Vasilis Valdramidis, Patrick Cullen, Jesus Maria Frias, Paula Bourke

Articles

This research investigated the efficacy of gaseous ozone for the inactivation of Escherichia coli ATCC 25922 and NCTC 12900 strains in orange juice. Orange juice inoculated with E. coli (10⁶ CFU mL^-1) as a challenge microorganism was treated with ozone at 75-78µg mL^-1 for different time periods (0-18 min). The efficacy of ozone for inactivation of both strains of E. coli was evaluated as a function of different juice types: model orange juice, fresh unfiltered juice, juice without pulp, and juice filtered through 500mm or 1mm sieves. Fast inactivation rates for total reduction of E. coli …

Extrinsic Control Parameters For Ozone Inactivation Of Escherichia Coli Using A Bubble Column, Sonal Patil, Patrick Cullen, Bridget Cullen, Jesus Maria Frias, Paula Bourke

Articles

Aims: To investigate the effect of extrinsic control parameters for ozone inactivation of E. coli in a bubble column. Methods and Results: Ozone inactivation of Escherichia coli ATCC 25922 in Tryptic Soya Broth was examined. The parameters studied included temperature (ambient, 20, 25 and 30°C), exposure time (up to 30 min), gas flow rate (0·03, 0·06, 0·12, 0·25, 0·5 and 0·75 l min−1) and concentration level (five different levels). The efficacy of ozone treatment was a function of the parameters investigated and optimum control parameters of flow rate (0·12 l min−1), temperature (ambient) and ozone concentration (75 μg ml−1) resulted …

Inactivation Of Escherichia Coli In Orange Juice Using Ozone, Sonal Patil, Paula Bourke, Jesus Maria Frias, Brijesh Tiwari, Patrick Cullen

Articles

This research investigated the efficacy of gaseous ozone for the inactivation of Escherichia coli ATCC 25922 and NCTC 12900 strains in orange juice. Orange juice inoculated with E. coli (10⁶ CFU mL^-1) as a challenge microorganism was treated with ozone at 75-78µg mL^-1 for different time periods (0-18 min). The efficacy of ozone for inactivation of both strains of E. coli was evaluated as a function of different juice types: model orange juice, fresh unfiltered juice, juice without pulp, and juice filtered through 500mm or 1mm sieves. Fast inactivation rates for total reduction of E. coli …

Effect Of Ozone And Calcium Lactate Treaments On Browning And Textured Properties Of Fresh-Cut Lettuce, Daniel Rico, Ana Belen Martin-Diana, Gary Henehan, Jesus Maria Frias, Catherine Barry-Ryan

Articles

The effects of three treatments, 1 mg L⁻¹ ozone at 18–20 °C, 15 g L⁻¹ calcium lactate (CLac) at 50 °C and a combination thereof, were compared on fresh-cut lettuce over 10 days of refrigerated storage. Respiration rate, browning and texture were examined as main quality indicators. The use of ozone produced a significantly (P < 0.05) higher oxygen decline than the use of CLac (from day 3 to day 10). At the end of storage, CLac (alone or combined with ozone) samples had higher oxygen content (∼9%) than ozone samples (∼6%). Enzymatic activity decreased significantly (P < 0.05) in ozone samples. Polyphenol oxidase activity in fresh-cut lettuce treated with ozone (alone or combined with CLac) showed lower values on day 1 (−1) and at the end of storage (g⁻¹) than CLac samples (4000–4800 units g⁻¹). Ozone also reduced peroxidase activity to ∼300 units g⁻¹ after treatment. Finally, pectin methylesterase activity was also reduced with ozone, showing a negative effect on textural properties. Data suggested that …