E.coli O157:H7 Reduction with Ozone
When we hear of food safety issues and recalls regarding “E.Coli” (Escherichia coli) the specific strain of E.coli that is typically referred to is the O157:H7 strain. Ozone is effective at inactivating all strains of E.Coli including the dangerous O157:H7 strain.
Escherichia coli (E.coli) is a Gram negative bacterium commonly found in the intestines of animals and humans. There are a wide variety of specific E.coli strains, many of which are not hazardous to human health or only hazardous at extremely high levels. However, the specific strain, E.coli O157:H7 is a common cause of food borne illness. So much so, that the generic term “E.coli” is used when referring to the source of a food borne illness. This strain of E.coli results in an estimated 2,100 hospitalizations annually in the United States, and can be life threatening.
This strain of E.coli can be found on many vegetables, meats, and even the water supply. Most infections from E.coli O157:57 are caused from food borne illness, mainly undercooked ground beef. However some have been waterborne, in May, 2000 in the Canadian town of Walkerton, Ontario the municipal water supply was contaminated with this pathogen and has been blamed for over 2,000 illnesses and 7 deaths.
Antimicrobial interventions to reduce food-borne pathogens are getting harder to find. For example, historically Chlorine has been a low cost and relatively easy to use oxidizer that is effective against a wide variety of pathogens. However, the use of chlorine is becoming more difficult to integrate as the potentially harmful side effects of chlorine are becoming more and more apparent. This is also happening with other antimicrobial interventions such as methyl bromide, chlorine dioxide, and sodium hypochlorite.
A fairly new and effective antimicrobial intervention that is both effective and safe is ozone. The use of ozone has been popular drinking water and bottled water for many years. In recent years ozone is gaining popularity in food processing, and surface sanitation. While ozone is effective on a wide variety of pathogens, studies were needed to prove that ozone is effective against the specific deadly strain of E.coli O157:H7. Research has been performed and ozone has proven to be a successful antimicrobial agent in reduction of E.coli O157:H7. We have assembled a few research papers that used ozone on various food products to successfully reduce or eliminate Ecoli O157:H7.
Implementation of Ozone
The most common method of using ozone for pathogen reduction is dissolving ozone into water. Aqueous ozone is very stable, safe, and easy to manage. Typically ozone is dissolved into water using an ozone injection system and then sprayed onto the surface requiring disinfection. This surface may be a hard equipment surface, or the surface of a food product.
Ozone levels of 2.0 ppm are commonly used for E.coli O157:H7 reduction. Only a few seconds of contact time of the aqueous ozone with the pathogen is necessary for inactivation. See chart below for details.
Using this data a determination of spray nozzles, spray bars, or even conveyers can be established. It is clearly shown that 2.0 ppm of aqueous ozone is very effective in only a short period of time, while higher ozone levels show only marginal improvement.
Ozone can also be used in drinking water to inactivate Ecoli O157:H7. This has been confirmed by the EPA and recognized as a suitable disinfectant for water.
The use of gaseous ozone for the elimination of pathogens is less common. There is also less research showing the effects of gaseous ozone on bacteria. The application of gaseous ozone is dependent upon the temperature, humidity, contact time, and ozone levels. Research has been conducted to determine that gaseous ozone will reduce and inactivate Ecoli O157:H7, however more research is necessary to determine the effectiveness of ozone within different variables.
The use of ozone in either gaseous or aqueous forms is effective at inactivating E.Coli O157:H7 and should be considered a viable option in many food processing applications. However, proper care on the engineering and installation should be taken.
View the papers below for examples of ozone use. To learn how ozone can be implemented in your applications please contact our office, we would be glad to help.
Ozone Regulations in Food Processing
Ozone regulations in Organic food production
Resolution Concerning the Use of Ozone in Food Processing from original EPRI documents
Original EPRI Direct Food Additive Petition used to gain GRAS approval for ozone
Listeria Inactivation with Ozone
Papers on the use of ozone elimination of E.Coli O157:H7
Antimicrobial Effects of Ozonated Water Against Generic E.coli on Swine Intestines Varying Ozone Concentrations and Exposure Times
Authors: George Kraft, Kraft Science Consulting, 821 Main Street, Boyden, IA 51234
Swine intestines harvested then turned inside-out and washed with cold water to remove all visible contaminants were tested to have a generic E.coli load of 6 to 7.5 logs per gram of tissue. Samples of these tissues were treated with ozonated water at various concentrations for various lengths of time up to a total of 30 seconds. It was determined that concentrations below 1 ppm had no significant anti-E.coli effects at any of the exposure times tested. At 1 ppm and above significant kills were achieved with a 1 second exposure time. At 1 ppm and up to 2.5 ppm a 15 second exposure time was needed to achieve the greatest E.coli kill, and at 3 ppm and above a 1 second exposure time was all that was needed to achieve the greatest E-coli kill.
Utilization of Ozone for the Decontamination of Small Fruits
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Paper number 056147, 2005 ASAE Annual Meeting . (doi: 10.13031/2013.19588) @2005
Authors: Katherine L. Bialka, Ali Demirci
Keywords: E. coli O157:H7, Salmonella, strawberry, gaseous ozone
Each year there are approximately 76 million foodborne illnesses and fresh produce is the second most common vehicle for such illnesses. Small fruits have been implicated in several outbreaks although none have been bacterial. Prior to market small fruits are not washed or treated in any manner so as to extend their shelf life. Washing alone is not a viable option and the use of novel technologies needs to be investigated. One such technology is ozone which has been used to treat drinking water since the late nineteenth century. The efficacy of gaseous ozone to decontaminate pathogens on strawberries, which were used as a model for small fruits, was investigated in this study. Strawberries were artificially contaminated with 5 strains of E. coli O157:H7 and Salmonella. Fruits were treated with 4 ozone treatments; i) continuous ozone flow for 2, 4, 8, 16, 32, and 64 min, ii) pressurized ozone (83 kPa) for 2, 4, 8, 16, 32, and 64 min, iii) continuous ozone (64 min) followed by pressurized ozone (64 min). Maximum reductions of 1.81, 2.32, and 2.96 log10 CFU/g of E. coli O157:H7 were achieved for continuous, pressurized, and continuous followed by pressurized ozone, respectively. For Salmonella reductions of 0.97, 2.18, and 2.60 log10 CFU/g were achieved for continuous, pressurized, and continuous followed by pressurized ozone, respectively. It was concluded that continuous ozone was the least effective treatment, and that there was no significant difference between pressurized ozone treatment and continuous followed by pressurized ozone treatment. These results demonstrate that gaseous ozone has the potential to be used a decontamination method for small fruits.
Mitigation strategies for Salmonella, E. coli O157:H7, and antimicrobial resistance throughout the beef production chain
Author: Casas Murillo, Diego Eduardo 0000-0002-7897-9904
According to the World Bank, foodborne illness costs over $110 billion per year in low- and middle-income countries. In the United States, Salmonella and big 7 Shiga toxin-producing E. coli (STEC) account for 26% of economic burden of foodborne illness. Meat and poultry are attributed approximately 38% and 27% of Salmonella and E. coli O157:H7 foodborne illnesses respectively. Consequently, the beef industry has diligently developed and researched different antimicrobial mitigation strategies that will reduce the concentration and prevalence of Salmonella and E. coli O157:H7, as well as antibiotic resistance development throughout the beef production chain. In our first study, the objective was to determine the effect of dietary L28 and tylosin on Salmonella, Enterococci, generic E. coli, and E. coli O157 presence in fecal grabs, perineal and hide swabs, and subiliac lymph node samples and their antimicrobial susceptibility profile. Generic E. coli and Enterococci presence were high throughout the feeding trial, 98.3% and 96.1% respectively. Salmonella presence was substantially high (62.7%) within pens and similar among treatments. No effects (P > 0.152) among treatment on microbial presence were observed in any of the four microorganisms studied within the pen and perineal samples. However, Salmonella presence within lymph nodes was affected by the treatments (P < 0.001). The MONPRO treatment (34.8%, 26/46) had a greater presence of Salmonella than the MONTY (8.7%, 4/46) and the PRO treatment (0.0%, 0/42). The presence of Salmonella, Enterococci, generic E. coli, and O157 did not increase with supplementation of L28 compared to the control. All Salmonella isolated was susceptible to every antibiotic class evaluated except one isolated with ample resistance to β-lactams. No significant difference (P > 0.05) between treatments was observed in the overall phenotypic resistance of Salmonella, E. coli, and Enterococci. Moreover, a tendency in the increase of overall resistance was observed across treatments as the days of feed increased. The absence of Salmonella in L28 treatment lymph nodes suggests supplementation of L28 may contribute to mitigating Salmonella’s capacity to invade the lymphatic system. This poses a significant contribution to the beef industry as lymph nodes can be a substantial source of Salmonella in ground beef. In the second study the objective was to conduct a longitudinal field study to probe the impact of the soil properties and weather on Salmonella survival and persistence in the feedlot ecosystem. Subsequently leading to the identification of factors that can be used as pre-harvest mitigation strategies. Salmonella prevalence varied throughout the seasons (P < 0.01), where the highest prevalence was observed in summer and fall seasons. A difference in prevalence between feedlots was observed (P <0.01), Feedlot 4 had the highest prevalence with an average of 57.2% (151/264) in all the year. In comparison, Feedlot 3 had a 17.4% (46/264) average prevalence in the year. Surface pen samples had a higher presence of Salmonella than deeper soil stratum sampled. Soil nutrient profile exploratory analysis showed a significant predictor effect in Salmonella presence, suggesting potassium, phosphorus, and calcium concentration in soil were positively correlated with Salmonella presence, whereas copper and magnesium were negatively correlated with Salmonella presence. Further research will elucidate the effect specific nutrients in the soil have on Salmonella presence and persistence. Moreover, seasonal variation of Salmonella presence can lead to tailored interventions at different stages of the year based on the possible risk of Salmonella entrance into the beef processing environment and have a risk-based approach to Salmonella mitigation to further ensure food safety. In the third study, the objective was to evaluate the antimicrobial efficacy of an aqueous ozone (Bio-Safe) treatment and lactic acid solutions on natural microbiota and E. coli O157:H7 and Salmonella surrogates on beef carcasses and trim in a commercial beef processing plant. Ozone and lactic acid interventions significantly reduced (p < 0.003) bacterial counts in carcasses and trim samples. Moreover, lactic acid further reduced APC and coliforms in trim samples compared to ozone intervention (p < 0.009). In the surrogate trials, ozone significantly reduced (p < 0.001) surrogate concentration. Historical data from the plant revealed a reduction (p < 0.001) of presumptive E. coli O157:H7 in trim after a full year of ozone intervention implementation. The novel technology for ozone generation and application as an antimicrobial can become an alternative option that may also act synergistically with existing interventions, minimizing the risk of pathogens such as Salmonella and E. coli O157:H7. In the fourth study, the objective was to determine the impact of spray and dry chilling combined with hot water carcass treatments on the levels of microbial indicator organisms during the long-term refrigerated storage of beef cuts. Not enough evidence (p > 0.05) was found indicating the hot water wash intervention reduced bacterial concentration on the carcass surface. E. coli was below detection limits (< 0.25 CFU/cm2) in most of the samples taken. No significant difference (p > 0.05) was found between coliform counts throughout the sampling dates. Feed type did not seem to influence the (P > 0.25) microbial load of the treatments. Even though no immediate effect was seen when comparing spray or dry chilling of the samples at day 0, as the product aged, a significantly lower (p < 0.05) concentration of aerobic and psychrotrophic organisms in dry-chilled samples could be observed when compared to their spray-chilled counterparts. Data collected can be used to select alternative chilling systems to maximize shelf life in vacuum packaged beef kept over prolonged storage periods.
Effectiveness of ozone for inactivation of Escherichia coli and Bacillus cereus in pistachios
First published: 28 February 200
The effectiveness of ozone for the decontamination of Escherichia coli and Bacillus cereus in kernels, shelled and ground pistachios was investigated. Pistachios were inoculated with known concentrations of E. coli and B. cereus. Pistachio samples were exposed to gaseous ozone in a chamber at three different concentrations (0.1, 0.5 and 1.0 ppm) for various times (0–360 min) at 20 °C and 70% relative humidity. The effectiveness of ozone against E. coli and B. cereus increased with increasing exposure time and ozone concentration. The physico-chemical properties including: pH, free fatty acids and peroxide values, colour and fatty acid composition of pistachios did not change significantly after the ozonation treatments, except for the peroxide value of ground pistachios ozonized at 1.0 ppm for 360 min. Ozone concentration of 1.0 ppm was effective in reducing E. coli and B. cereus counts in kernels and shelled pistachios, while ozone concentrations <1.0 ppm were found to be appropriate in reducing the number of both bacteria in ground pistachios without having any change in their physico-chemical properties.
Application of Ozone for Inactivation of Escherichia Coli O157:H7 on Inoculated Alfalfa Sprouts
Journal Of Food Processing And Preservation Research, 27 (2003) 51-64
Authors: Sharma, Demirci, Beuhat, Fett
Alfalfa sprouts contaminated with the bacterial pathogens Salmonella and Escherichia coli O157:H7 have been the source of several foodborne outbreaks in the US and other countries. New, more effective antibacterial treatments are required to ensure the microbial safety of sprouts for the consuming public. In this study, we tested the ability of ozone in water to eliminate E. coli O157:H7 from inoculated alfalfa sprouts. Treatments (from 2 to 64 minutes in durations) with ozone in water (up to 21 ppm) were tested. In some experiments the ozone was continuously fed into the water solution during treatment with or without pressurization. Immersion of sprouts into ozone in water reduced bacterial populations by less than 90%. With continuous feeding of ozone, reductions increased to 99%. The use of pressure during ozone treatments did not increase efficacy. The use of ozone alone will not ensure the microbial safety of sprouts, but ozone in combination with other antibacterial treatments may be able to achieve that goal.
Chemical treatments to eliminate pathogens on inoculated sprouts have shown little success. This study investigated the antimicrobial potential of ozone on alfalfa sprouts. Alfalfa sprouts inoculated with a five strain cocktail of Escherichia coli O157:H7 were immersed in water containing 21 ppm ozone for 2, 4, 8, 16, 32, 64 min at 4 C. To increase accessibility of ozone into sprout crevices alternative treatments with continuous ozone sparging with and without pressurization were evaluated. Immersion of inoculated alfalfa sprouts in water containing 21-ppm ozone reduced the population of E. coli O157:H7 by 85.8% at 64 min. There was no significant difference (P > 0.05) between treatment and control and also between different time intervals. Continuous ozone sparging resulted in 85.0 to 99.4% reduction, which was significantly higher (P 0.05) than reduction by sparging with air. Application of low hydrostatic pressure of 12 psi for 5 min subsequent to continuous ozone sparging for 2 - 64 min reduced E. coli O157:H7 populations by 99.0%. Pressurized ozone treatments did not differ significantly from un-pressurized ozone treatments except at 32 min. Ozone treatment did not have any visible detrimental effect on sprouts quality. Further investigation is required to develop methods for ozone introduction for decontaminating sprouts to reduce health risk. However ozone has the potential to replace chemical treatments being used
Efficacy of Ozone Against Escherichia coli O157:H7 on Apples
Authors: M. Achen and 1 A.E. Yousef 1
Authors are with the Department of Food Science and Technology, The Ohio State University, Parker Hall, 2015Fyffe Rd., Columbus, Ohio 43210. Direct inquiries to author Yousef
This research was supported by a grant from the Ohio Agricultural Research and Development Center. The authors to thank J.G. Kim for his valuable advice and technical support.
Copyright 2001 by the Institute of Food Technologists
Apples were inoculated with Escherichia coli O157:H7 and treated with ozone. Sanitization treatments were more effective when ozone was bubbled during apple washing than by dipping apples in pre-ozonated water. The corresponding decreases in counts of E. coli O157:H7 during 3-min treatments were 3.7 and 2.6 log10 CFU on apple surface, respectively, compared to < 1 log10 CFU decrease in the stem-calyx region in both delivery methods. Optimum conditions for decontamination of whole apples with ozone included a pretreatment with a wetting agent, followed by bubbling ozone for 3 min in the wash water, which decreased the count of E. coli O157:H7 by 3.3 log10CFU/g.
Efficacy of aqueous ozone for the decontamination of Escherichia coli O157:H7 and Salmonella on raspberries and strawberries.
Authors: Bialka KL, Demirci A.
Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
J Food Prot. 2007 May;70(5):1088-92.
The efficacy of ozone as a water additive for washing raspberries and strawberries was investigated. Pathogen-inoculated fruits were treated with aqueous ozone concentrations of 1.7 to 8.9 mg/liter at 20 degrees C for 2 to 64 min, with an aqueous ozone concentration of 21 mg/liter at 4 degrees C for 64 min, or with water as a control. Maximum pathogen reductions on raspberries were 5.6 and 4.5 log CFU/g for Escherichia coli O157:H7 and Salmonella, respectively, at 4 degrees C, whereas reductions on strawberries were 2.9 and 3.3 log CFU/g for E. coli O157:H7 and Salmonella, respectively, at 20 degrees C after 64 min. Washing with water (sparging with air as control) resulted in reductions of approximately 1 log CFU/g. The results presented here indicate that aqueous ozone may be useful as a decontaminant for small fruits.
Survival of Escherichia coli O157:H7 and Salmonella in apple cider and orange juice as affected by ozone and treatment temperature
- PMID: 15553616
- DOI: 10.4315/0362-028x-67.11.2381
Inactivation of Escherichia coli O157:H7 and Salmonella in apple cider and orange juice treated with ozone was evaluated. A five-strain mixture of E. coli O157:H7 or a five-serovar mixture of Salmonella was inoculated (7 log CFU/ml) into apple cider and orange juice. Ozone (0.9 g/h) was pumped into juices maintained at 4 degrees C, ambient temperature (approximately 20 degrees C), and 50 degrees C for up to 240 min, depending on organism, juice, and treatment temperature. Samples were withdrawn, diluted in 0.1% peptone water, and surface plated onto recovery media. Recovery of E. coli O157:H7 was compared on tryptic soy agar (TSA), sorbitol MacConkey agar, hemorrhagic coli agar, and modified eosin methylene blue agar; recovery of Salmonella was compared on TSA, bismuth sulfite agar, and xylose lysine tergitol 4 (XLT4) agar. After treatment at 50 degrees C, E. coli O157:H7 populations were undetectable (limit of 1.0 log CFU/ml; a minimum 6.0-log CFU/ml reduction) after 45 min in apple cider and 75 min in orange juice. At 50 degrees C, Salmonella was reduced by 4.8 log CFU/ml (apple cider) and was undetectable in orange juice after 15 min. E. coli O157:H7 at 4 degrees C was reduced by 4.8 log CFU/ml in apple cider and by 5.4 log CFU/ml in orange juice. Salmonella was reduced by 4.5 log CFU/ml (apple cider) and 4.2 log CFU/ml (orange juice) at 4 degrees C. Treatment at ambient temperature resulted in population reductions of less than 5.0 log CFU/ml. Recovery of E. coli O157:H7 and Salmonella on selective media was substantially lower than recovery on TSA, indicating development of sublethal injury. Ozone treatment of apple cider and orange juice at 4 degrees C or in combination with mild heating (50 degrees C) may provide an alternative to thermal pasteurization for reduction of E. coli O157:H7 and Salmonella in apple cider and orange juice.
Link to full paper access HERE
Inactivation of E. coli O157:H7 in apple cider by ozone at various temperatures and concentrations
Authors: STEENSTRUP Lotte Dock ; FLOROS John D.
Authors Affiliations: BioCentrum-DTU, Technical University of Denmark, Søltofts Plods Bldg. 221, 2800 Lyngby, DANEMARK
Department of Food Science, 111 Borland Laboratory, Penn State University, University Park, PA 16802, ETATS-UNIS
Journal Title: Journal of food processing and preservation ISSN 0145-8892 CODEN JFPPDL
Source: 2004, vol. 28, no2, pp. 103-116 [14 page(s) (article)] (1 p.3/4)
The effect of temperature (5-20C) at 860 ppm (v/v) ozone and different gaseous ozone concentrations above 1,000 ppm on inactivation of E. coli O157:H7 in apple cider was studied. Lag times ranged from 3.5 min at 20C to 6.7 min at 10C before the on-set of E. coli O157:H7 inactivation. D-values ranged from 0.6 to 1.5 min at 20C and 5C, respectively. After ozone treatment of cider for 14 min, dissipation of ozone from cider was slow, decreasing to about 5 mg/L after 2 h at 5C. At high gaseous ozone concentration, lag time was shortest and D-value lowest. There was a critical concentration of dissolved ozone of about 5-6 mg/L at 20C, before the on-set of E. coli O157:H7 inactivation in the cider. Total processing times, based on lag time plus 5D, ranged from about 4 to 14 min depending on temperature and ozone concentration. Overall, inactivation of E. coli O157:H7 by ozone was fast enough to allow practical applications in cider production, and it should be considered as an alternative to thermal pasteurization.
Link to full paper access HERE
Inactivation of Escherichia coli O157:H7 and Natural Microbiota on Spinach Leaves Using Gaseous Ozone during Vacuum Cooling and Simulated Transportation
Authors: Vurma, Mustafa1; Pandit, Ram B.2; Sastry, Sudhir K.2; Yousef, Ahmed E.1
Source: Journal of Food Protection®, Volume 72, Number 7, July 2009 , pp. 1538-1546(9)
Publisher: International Association for Food Protection
The aim of this study was to integrate an ozone-based sanitization step into existing processing practices for fresh produce and to evaluate the efficacy of this step against Escherichia coli O157:H7. Baby spinach inoculated with E. coli O157:H7 (∼107 CFU/g) was treated in a pilot-scale system with combinations of vacuum cooling and sanitizing levels of ozone gas (SanVac). The contribution of process variables (ozone concentration, pressure, and treatment time) to lethality was investigated using response-surface methodology. SanVac processes decreased E. coli O157:H7 populations by up to 2.4 log CFU/g. An optimized SanVac process that inactivated 1.8 log CFU/g with no apparent damage to the quality of the spinach had the following parameters: O3 at 1.5 g/kg gas-mix (935 ppm, vol/vol), 10 psig of holding pressure, and 30 min of holding time. In a separate set of experiments, refrigerated spinach was treated with low ozone levels (8 to 16 mg/kg; 5 to 10 ppm, vol/vol) for up to 3 days in a system that simulated sanitization during transportation (SanTrans). The treatment decreased E. coli populations by up to 1.4 log CFU/g, and the optimum process resulted in a 1.0-log inactivation with minimal effect on product quality. In a third group of experiments, freshly harvested unprocessed spinach was inoculated with E. coli O157:H7 and sequentially subjected to optimized SanVac and SanTrans processes. This double treatment inactivated 4.1 to ≥5.0 log CFU/g, depending on the treatment time. These novel sanitization approaches were effective in considerably reducing the E. coli O157:H7 populations on spinach and should be relatively easy to integrate into existing fresh produce processes and practices.
Decontamination of Escherichia coli O157:H7 and Salmonella enterica on blueberries using ozone and pulsed UV-light.
Authors: K L Bialka; A Demirci
Publication Detail: Type: Evaluation Studies; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.
Title: Journal of food science Volume: 72 ISSN: 1750-3841 ISO Abbreviation: J. Food Sci. Publication Date: 2007 Nov
Created Date: 2007-11-23 Completed Date: 2008-03-24
Efficacy of gaseous ozone, aqueous ozone, and pulsed UV-light was evaluated for the purpose of decontaminating blueberries artificially contaminated with either Escherichia coli O157:H7 or Salmonella. Blueberries were exposed to 4 different gaseous ozone treatments: continuous ozone exposure, pressurized ozone exposure, and 2 combined treatments. Maximum reductions of Salmonella and E. coli O157:H7 after 64-min pressurized or 64-min continuous exposure were 3.0 and 2.2 log(10) CFU/g, respectively. Aqueous ozone experiments were conducted at 20 degrees C and 4 degrees C and zero plate counts were observed for E. coli O157:H7 and Salmonella after 64 min of ozone exposure at 20 degrees C. Finally, pulsed UV-light was evaluated at 3 different distances from the light. Maximum reductions of 4.3 and 2.9 log(10) CFU/g were observed at 8 cm from the light after 60 s of treatment for Salmonella and E. coli O157:H7, respectively. A sensory analysis as well as color analysis was performed on blueberries from each treatment agent; neither analysis detected a difference between treated and untreated blueberries. The results presented in this study indicate that ozone and pulsed UV-light are good candidates for decontamination of blueberries.
Efficacy of Chlorine Dioxide, Ozone, and Thyme Essential Oil or a Sequential Washing in Killing Escherichia coli O157:H7 on Lettuce and Baby Carrots
Publication Detail: University, of Georgia, Department of Food Science & Technology, Food Science Building, Athens, GA, 30602-7610, U.S.A., Purdue University, Department of Food Science, West Lafayette, IN, 47907-1160, U.S.A., Purdue University, Department of Agricultural and Biological Engineering, West Lafayette, IN, 47907-1160, U.S.A.,
Received 23 July 2002, Accepted 6 August 2002, Available online 3 December 2002.
Chlorine dioxide (ClO2), ozone, and thyme essential oil has been found to be effective in reducing pathogens, including Escherichia coli O157:H7, on selected produce. The efficacy of these sanitizers was evaluated, alone or through their sequential washing to achieve a 3 or more log reduction of mixed strains of E. coli O157:H7 on shredded lettuce and baby carrots. Samples sprinkle inoculated with mixed strains of E. coli O157:H7 were air-dried for 1 h at 22±2°C in a biosafety cabinet, stored at 4°C for 24 h, and then treated with different concentrations of disinfectants and exposure time. Sterile deionized water washing resulted in approximately 1log reduction ofE. coli O157:H7 after 10 min washing of lettuce and baby carrots. Gaseous treatments resulted in higher log reductions in comparison to aqueous washing. However, decolorization of lettuce leaves was observed during long exposure time. A logarithmic reduction of 1.48–1.97log10 cfu/g was obtained using aqueous ClO2 (10.0 mg/L for 10 min) ozonated water (9.7 mg/L for 10 min) or thyme oil suspension (1.0 mL/L for 5 min) on lettuce and baby carrots. Of the three sequential washing treatments used in this study, thyme oil followed by aqueous ClO2/ozonated water, or ozonated water/aqueous ClO2 were significantly (P<0.05) more effective in reducing E. coli O157:H7 (3.75 and 3.99log, and 3.83 and 4.34 log reduction) on lettuce and baby carrots, respectively. The results obtained from this study indicate that sequential washing treatments could achieve 3–4log reduction of E. coli O157:H7 on shredded lettuce and baby carrots.
Effect of Combined Ozone and Organic Acid Treatment for Control of Escherichia coli O157:H7 and Listeria Monocytogenes on Lettuce
Authors: Hyun-Gyun Yuk, Mee-Young Yoo, Jae-Won Yoon, Kwang-Deog Moon, Douglas L. Marshall, Deog-Hwan Oh
First published: 30 June 2006
This research was supported by the MAF-SGRP (Ministry of Agriculture and Forestry Special Grants Research Program) in Korea.
This study was conducted to determine the effects of ozonated water (1, 3, and 5 ppm) alone with different exposure times (0.5,1,3, or5min), and combinations of 3 ppm ozone with 1% organic acids (acetic, citric, or lactic acids) during 1-min exposure for inactivating Escherichia coli O157:H7 and Listeria monocytogenes on lettuce and to observe the regrowth of these pathogenic bacteria on treated lettuce during storage for 10 d at 15°C. Results showed that 5 ppm ozone treatment for 5 min gave 1.09-log and 0.94-log reductions of E. coli O157:H7 and L. monocytogenes, respectively, indicating insignificant reductions compared with 3 ppm ozone treatment for 5 min. Treatment with 3 ppm ozone combined with 1 % citric acid for 1 min immersing resulted in 2.31 - and 1.84-log reductions (P < 0.05), respectively. During storage at 15°C for 10 d after combined treatment and packaging, populations of E. coli O157:H7 and L. monocytogenes increased to approximately 9.0-log colony forming unit (CFU) /g, indicating that this treatment did not have a residual antimicrobial effect during storage. Although the storage study did not show control of these pathogens, the combined ozone-organic acid treatment was more effective in reducing population levels of these pathogens on lettuce than individual treatments.
Inactivation of Escherichia coli O157:H7 by ozone in different substrates
Food Microbiology - Research Paper Published: 03 December 2018
Authors: Stefania Marcia de Oliveira Souza, Ernandes Rodrigues de Alencar, Jaqueline Lamounier Ribeiro & Marcia de Aguiar Ferreira
Brazilian Journal of Microbiology volume 50, pages 247–253 (2019)
Ozone has a broad antimicrobial spectrum and each microorganism species has inherent sensitivity to the gas. The objective of this study was to evaluate the effect of ozone gas on Escherichia coli O157:H7 inoculated on an organic substrate, and the efficacy of ozonated water in controlling the pathogen. For the first experiment, E. coli O157:H7 (ATCC® 43890™) was inoculated in milk with different compositions and in water, which was ozonated at concentrations of 35 and 45 mg L−1 for 0, 5, 15, and 25 min. In the second experiment, water was ozonated at 45 mg L−1 for 15 min. E. coli O157:H7 was exposed for 5 min to the ozonated water immediately after ozonation, and after storage for 0.5, 1.0, 1.5, 3.0, and 24 h at 8 °C. The results showed that the composition of the organic substrate interfered with the action of ozone on E. coli O157:H7. In lactose-free homogenized skim milk, reductions of 1.5 log cycles were obtained for ozonation periods of 25 min at the concentrations tested. Ozonated water was effective in inactivating of E. coli O157:H7 in all treatments. The efficiency of ozone on E. coli O157:H7 is influenced by the composition of the organic substrates, reinforcing the need for adequate removal of organic matter before sanitization. Furthermore, refrigerated ozonated water stored for up to 24 h is effective in the control of E. coli O157:H7.
Response Surface Modeling of the INactivation of Escherichia coli O157:H7 on Green Peppers (Capsicum annuum) by Ozone Gas Treatment
Authors: Y. Han, J. D. Floros, R. H. Linton, S. S. Nielsen, P. E. Nelson
First published: 20 July 2006
This research was supported by the U.S. Dept. of Agriculture /CSREES grant (Special Research Grants Program, Food Safety Research) nr 98-34382-6914. The authors thank Banu Ozen for her technical assistance and LaTisha White for her preparation of media.
The effects of ozone gas concentration (2 to 8 mg/l), relative humidity (RH) (60 to 90%), and treatment time (10 to 40 min) on inactivation of E. coli O157:H7 on green peppers were studied using response surface methodology. A 3-factor Box-Behnken experimental plan was designed and microbial log reduction was measured as a response. The statistical analysis of developed predictive model suggested that ozone gas concentration, RH, and treatment time all significantly (P < 0.01) increased the rate of log reduction of E. coli O157:H7. Among the 3 factors, the effect of ozone gas concentration on bacterial inactivation was the greatest, while the effect of RH was the least. The interaction between ozone gas concentration and RH exhibited a significant and synergistic effect (P < 0.05).
Inactivation of Escherichia coli O157:H7 and Natural Microbiota on Spinach Leaves Using Gaseous Ozone during Vacuum Cooling and Simulated Transportation
Authors: MUSTAFA VURMA; RAM B. PANDIT; SUDHIR K. SASTRY; AHMED E. YOUSEF
J Food Prot (2009) 72 (7): 1538–1546.
The aim of this study was to integrate an ozone-based sanitization step into existing processing practices for fresh produce and to evaluate the efficacy of this step against Escherichia coli O157:H7. Baby spinach inoculated with E. coli O157:H7 (∼107 CFU/g) was treated in a pilot-scale system with combinations of vacuum cooling and sanitizing levels of ozone gas (SanVac). The contribution of process variables (ozone concentration, pressure, and treatment time) to lethality was investigated using response-surface methodology. SanVac processes decreased E. coli O157:H7 populations by up to 2.4 log CFU/g. An optimized SanVac process that inactivated 1.8 log CFU/g with no apparent damage to the quality of the spinach had the following parameters: O3 at 1.5 g/kg gas-mix (935 ppm, vol/vol), 10 psig of holding pressure, and 30 min of holding time. In a separate set of experiments, refrigerated spinach was treated with low ozone levels (8 to 16 mg/kg; 5 to 10 ppm, vol/vol) for up to 3 days in a system that simulated sanitization during transportation (SanTrans). The treatment decreased E. coli populations by up to 1.4 log CFU/g, and the optimum process resulted in a 1.0-log inactivation with minimal effect on product quality. In a third group of experiments, freshly harvested unprocessed spinach was inoculated with E. coli O157:H7 and sequentially subjected to optimized SanVac and SanTrans processes. This double treatment inactivated 4.1 to ≥5.0 log CFU/g, depending on the treatment time. These novel sanitization approaches were effective in considerably reducing the E. coli O157: H7 populations on spinach and should be relatively easy to integrate into existing fresh produce processes and practices.
A Novel Aqueous Ozone Treatment as a Spray Chill Intervention against Escherichia coli O157:H7 on Surfaces of Fresh Beef
Authors: NORASAK KALCHAYANAND; DREW WORLIE; TOMMY WHEELER
J Food Prot (2019) 82 (11): 1874–1878.
This experiment determined the efficacy of using a novel aqueous ozone treatment as a spray chill intervention to reduce Escherichia coli O157:H7 on surfaces of fresh beef compared with traditional water spray chill. Cutaneous trunci muscles were obtained from a local beef cattle processing plant. Muscles were divided into sixteen 25-cm2 sections, and each section was individually inoculated with E. coli O157:H7 to the final concentration of approximately 105 CFU/cm2. Muscle sections were collected and tested before and after simulated spray chill treatments of water or the novel aqueous ozone solution. Enumeration of survivors of each treatment was compared with that of the untreated muscle sections. Water spray chill reduced (P ≤ 0.05) E. coli O157:H7 0.60 log, whereas the aqueous ozone spray chill reduction (P ≤ 0.05) was 1.46 log on surfaces of fresh beef. Aqueous ozone spray chill reduced (P ≤ 0.05) aerobic bacteria 0.99 log, but water spray chill did not significantly (P > 0.05) reduce aerobic bacteria on surfaces of fresh beef. The findings indicate that aqueous ozone can be used as a spray chill intervention to enhance the safety of beef.
Aqueous ozone spray chill could be an effective antimicrobial intervention.
Nanobubble technology may enhance the efficacy of ozone application.
These results need to be validated under commercial conditions.
The present study was carried out to determine the effect of ozonated water (2 mg L−1) at different temperatures (4 °C and 15 °C) on the microbiological, color and sensory properties of lettuce. Cold ozone treatment (4 °C) significantly reduced the natural background microflora of lettuce. Salmonella Typhimurium and Escherichia coli inoculated on lettuce samples were insignificantly influenced by the temperature of water. During storage period at +4 °C for 14 days, the highest quality was observed from the samples treated with cold ozonated water. Ozone treatments did not affect the color properties and sensory quality of lettuce samples.
Ozone is an effective alternative for the postharvest treatment of fruits and vegetables. The purpose of this study was to evaluate the ozone application in gaseous or aqueous phases for postharvest disinfection of tomatoes (Lycopersicon esculentum Mill) cultivar FA-180. Fruits harvested at the breaker stage were exposed to ozone concentrations of 25 and 45 mg m−3 for 2 h per day during 16 days, at non-controlled temperature and relative humidity. Exposure to ozone during storage extends the shelf-life of tomatoes, besides preserving its sensory attributes. Mature tomatoes, inoculated with Escherichia coli ATCC 25922, were washed with ozonated water containing 0.5 to 1.0 mg L−1 during 15 to 30 min. To achieve an adequate disinfection, 1 mg L−1 and 15 min are recommended. The disinfection with ozonated water was effective.