Progress 10/01/12 to 10/30/12
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Project completed
Publications
|
Progress 11/01/07 to 10/30/12
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Project completed
Publications
|
Progress 01/01/12 to 09/30/12
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Project completed
Publications
|
Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Acidic electrolyzed (AEO) water is gaining popularity as a novel sanitizer to inactivate or eliminate bacteria on foods and food processing equipment surfaces. Near neutral to neutral EO (NEO) water (pH 6-8) can be produced like AEO water, using a two-chamber system with some mixing of AEO and alkaline EO water during production or using a single chamber system. These systems produce EO water with increased stability and less chlorine smell due to low levels of chlorine gas at near neutral pH. Another way to produce EO water is by electrolysis of hydrochloric acid solution (3-6%; v/v) in an electrolytic cell without a diaphragm separation. Because no NaCl is used for the electrolysis hence no Na ion is present in the SAEO water. Due to the absence of Na ion in the solution, this type of SAEO may not cause corrosion to metal compared to AEO water. This study was designed to determine the efficacy of SAEO water produced from HCl in killing or reducing E. coli O157:H7 on the surfaces of iceberg lettuce and tomatoes under simulated food service operation conditions compared to AEO water. In phase I, the inoculated whole lettuce leaves were washed with running SAEO water (ca. 2.8 L/min) or with running AEO water (ca 2.0 L/min) for 15 or 30 s. In phase II, the inoculated lettuce leaves were washed with running SAEO water or with running AEO water for 15 s, cut into 2-3 cm pieces, then placed in a 1.5-liter round-bottom Whirl-Pak bag, and chilled with respective SAEO or AEO water. Chilling was performed by adding 175 mL of chilled (4 C) SAEO or AEO water to each leaf and storing at 4 C for 15 min. Inoculated tomatoes were individually washed with running SAEO water or with running AEO water for 8 or 15 s. Tomatoes were washed by rubbing the samples evenly with gloved hands under running wash water. PARTICIPANTS: Dr. Yen-Con Hung, Department of Food Science and Technology, University of Georgia. yhung@uga.edu TARGET AUDIENCES: Food Processors, produce packing houses, and consumers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Washing lettuce leaves with running SAEO water generated or with running AEO water for 15 s reduced the number of E. coli O157:H7 on lettuce by ca. 1.5 log CFU/leaf. Washing lettuce with running SAEO water produced for 30 s achieved the highest reduction (2.3 log CFU/leaf) of E. coli O157:H7. Sequential washing treatment of lettuce with running SAEO water or with running AEO water for 15 s and followed by chilling in respective water for 15 min increased the reduction of E. coli O157:H7 for 1.9 to 2.4 log CFU/leaf. However, SAEO water and AEO water completely inactivated the pathogen in chilling solutions and hence could prevent cross-contamination during preparation of foods. There was no survival cell detected in chilling solutions even though complete inactivation of the pathogen did not occur on lettuce. Washing tomatoes with running SAEO water for 8 s reduced the pathogen by 5.4 to 6.3 log CFU/tomato which were not significantly different from the reduction achieved by washing with running AEO water for 8 and 15 s. Increasing washing time to 15 s with running SAEO water significantly increased the reduction of the pathogen to 6.6-7.6 log CFU/tomato. In addition to physical rubbing of tomatoes during washing that could help removing the pathogen, the surface of tomato fruits might not have as many stomata as the lettuce leaves where cells could get caught up and prevented the pathogen from EO water.
Publications
- Pangloli, P. and Y.-C. Hung. 2011. Efficacy of slightly acidic electrolyzed water in killing or reducing Escherichia coli O157:H7 on iceberg lettuce and tomatoes under simulated food service operation conditions. J. Food Sci. 76(6):M361-M366.
|
Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: The increase of interest in blueberries due to their nutritional and health benefits has led to an increase of consumption. However, blueberries are consumed mostly raw or minimally processed and are susceptible to microbial contamination like other type of fresh produce. This study was therefore undertaken to evaluate the efficacy of electrostatic spray of electrolyzed oxidizing (EO) water, UV illumination, ozone and a combination of ozone and UV illumination in killing Escherichia coli O157:H7 on blueberries. A five-strain mixture of E. coli O157:H7 were inoculated on the calyx and skin of blueberries and then subjected to the treatments. A five-strain mixture of Escherichia coli O157:H7 isolated from outbreaks associated with raw fruits and vegetables were used. Blueberries were inoculated by applying 6 to 10 small droplets onto the surface of each blueberry and then air dried in a laminar flow hood for 1 h to allow bacteria attachment. Spray treatment was conducted at a distance of 54 cm between blueberry samples and an electrostatic sprayer at 138 kPa with EO water. Ultraviolet (UV) treatment was conducted at the frequencies between 200 and 280 nm for various lengths of time. Blueberries were exposed to ozone for a total of 8 minutes (2 minutes for getting treatment chamber reaches a set concentration of 4,000 mg/L, 1 minute of treatment time at 4,000 mg/L, and another 5 minutes of air flushing to remove ozone from the treatment chamber) before blueberries were taken out for microbial enumeration. Blueberries were also subjected to a combination of UV treatment with the intensity of 7.95 mW/cm2 for 2 min and ozone for 1 min. After treatment, blueberries (6) from each treatment were subjected for microbiological analysis to determine microbial reduction. PARTICIPANTS: Dr. Yen-Con Hung, Department of Food Science and Technology, University of Georgia. yhung@uga.edu TARGET AUDIENCES: Food Processors, produce packing houses, and consumers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Spraying with EO water reduced E. coli O157:H7 by approximately 0.13 to 0.24 log CFU/g on calyx and 0.88 to 1.10 log CFU/g on skin, respectively and there was no significant (P > 0.05) effect of EO water spray on the reduction of bacterial populations. UV illumination with intensity of 20 mW/cm2 at a distance of 0.9 cm from the UV lamp to the calyx of blueberries reduced the populations of E. coli O157:H7 to 4.30 and 4.01 log CFU/g for 1 and 5 min treatment, respectively. Moreover, UV treatment for 1 and 5 min significantly reduced the population of the microorganism on skin of blueberries to 2.42 and 1.83 log CFU/g, respectively and no microorganisms (greater than the reduction of 5.53 log CFU/g) were detected on blueberries skin after 10 min treatment. Ozone treatment with 4,000 mg/L reduced E. coli O157:H7 by only 0.66 and 0.72 log CFU/g on calyx and skin of blueberries, respectively. The combination treatment of 1 min ozone and followed by a 2 min UV achieved more than 1 and 2 log additional reductions on blueberry calyx than UV or ozone alone treatment, respectively.
Publications
- Hung, Y.-C., P. Tilly, and C. Kim. 2010. Efficacy of electrolyzed oxidizing (EO) water and chlorinated water for inactivation of Escherichia coli O157:H7 on strawberries and broccoli. J. Food Quality 33:559-577.
- Hung, Y.-C., D. Bailly, C. Kim, Y. Zhao and X Wang. 2010. Effect of electrolyzed oxidizing (EO) water and chlorinated water treatment on strawberries and broccoli quality. J. Food Quality 33:578-598.
|
Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: In nature, most bacteria typically do not exist as pure cultures but rather as complex sessile communities, usually referred to as biofilms. The objectives of this research were to determine the effectiveness of acidic electrolyzed water for inactivation of L. monocytogenes in mixed biofilms with a food processing isolate of Pseudomonas putida on stainless steel and Teflon surfaces. New stainless steel sheets and Teflon were cut into 2 by 5 cm coupons and cleaned and allowed to dry at room temperature and then autoclaved at 121C for 15 min before use. To prepare biofilms containing both Pseudomonas and L. monocytogenes, ten ml of the P. putida culture was added to 1 L of sterile 1:10 dilution of TSB to produce an initial inoculum of 6 logCFU/ml for the preparation of biofilms. The inoculated dTSB was then dispensed (30 ml) into sterile test tubes holding sterile stainless steel or Teflon coupons and incubated at 25C for 4 h and then rinsed gently in a circular motion for 10 s with peptone water to remove unattached cells and re-immersed in sterile dTSB contained in sterile test tubes and incubated at 25C for 48 h to allow biofilm formation. After the 48 h incubation period, the coupons containing P. putida biofilms were removed from the spent medium, gently rinsed in sterile peptone water and placed in sterile test tubes. Ten ml of L. monocytogenes inoculum was dispensed into the tubes containing the coupons with P. putida biofilms and follow the same procedure as described above to allow the incorporation of Listeria into the Pseudomonas biofilm. Before subjecting the coupons to treatment, coupons were removed from the medium and rinsed in sterile peptone water to remove unattached cells. Electrolyzed oxidizing (EO) water was produced from a ROX-20TA generator at a current setting of 14 A. Coupons containing biofilms were immersed in 250 ml of deionized water, acidic EO water, and alkaline EO water followed by acidic EO water (sequential treatment) for 30 s at room temperature. For the sequential treatment, the coupons were immersed in alkaline EO water for 30 s, removed and then rinsed for 10 s in 0.1% peptone water to remove any excess alkaline EO water before being immersed in the acidic EO water for 30 s. Immediately after the exposure time the coupons were placed in 100 ml neutralizing buffer solution for 30 s to neutralize the active component of the acidic EO water left on the coupon. After neutralization, the coupons were subjected to microbiological analysis. PARTICIPANTS: Dr. Yen-Con Hung, Department of Food Science and Technology, University of Georgia. yhung@uga.edu TARGET AUDIENCES: Food Processors, produce packing houses, and consumers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Treatment of coupons with acidic EO water for 30 s resulted in significant inactivation of L. monocytogenes on both stainless steel and Teflon when compared to the controls. The population of L. monocytogenes recovered after acidic EO water treatment of biofilms on Teflon coupons were however, significantly higher than the population recovered from stainless steel coupons. The sequential treatment which involved the exposure of biofilm containing coupons to alkaline EO water followed by acidic EO water resulted in significantly higher inactivation of L. monocytogenes than the treatment of biofilms with acidic EO water alone. On both stainless steel and Teflon, 7-day biofilms seemed to be less resistant to acidic EO water than the 2-day biofilms. Generally, higher log reductions were achieved after the treatment of 7-day biofilms with acidic EO water and the sequential treatment than after the treatment of 2-day biofilms, however the differences were not significant , except for the acidic EO water treatment of L. monocytogenes biofilms in monospecies and duospecies on stainless steel and Teflon, respectively. The behavior of L. monocytogenes in monospecies and duospecies biofilms were compared to determine the effect of the presence of P. putida on L. monocytogenes, during treatment with EO water. When the biofilms were formed on stainless steel, L. monocytogenes were more susceptible to acidic EO water in duospecies with P. putida than in monospecies. The log reductions (5.25 and 6.58 log CFU per coupon) in L. monocytogenes achieved after treatment of 2- and 7- day duospecies biofilms with acidic EO water were significantly higher than the reductions achieved (4.03 and 4.96 log CFU per coupon) after treatment of the 2- and 7- day monospecies biofilms, respectively. On the other hand, with biofilms formed on Teflon, significantly higher log reductions in L. monocytogenes were obtained after treatment of 2 day monospecies biofilms with acidic EO water as compared to duospecies biofilms. On Teflon, both 2- and 7- day biofilms of L. monocytogenes seemed to be more susceptible to inactivation in duospecies than monospecies when the sequential treatment was applied, however the differences observed between the two were not statistically significant.
Publications
- Hung, Y.-C., P. Tilly, and C. Kim. 2010. Efficacy of electrolyzed oxidizing (EO) water and chlorinated water for inactivation of Escherichia coli O157:H7 on strawberries and broccoli. J. Food Quality (Accepted)
- Hung, Y.-C., D. Bailly, C. Kim, Y. Zhao and X Wang. 2010. Effect of electrolyzed oxidizing (EO) water and chlorinated water treatment on strawberries and broccoli quality. J. Food Quality (Accepted)
|
Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Outbreaks of human illnesses associated with the consumption of raw vegetables and fruits have also increased worldwide in the past decade. Changes in agronomic, harvesting, distribution, processing, and consumption patterns and practices have contributed to this increase. The use of chlorine and chlorine-containing compounds [hypochlorite ions, chlorine and hypochlorous acid] has been the most common disinfecting method since the nineteenth century. However, many chemical sanitizers have either minimal effect on inactivating pathogens on fresh produce or they may production of carcinogenic byproducts when reacts with organic matter. Therefore, safer and more effective methods to inactivate pathogens on fresh produce are needed. Acidic electrolyzed oxidizing (EO) water produced through electrolysis of dilute salt solution has strong microbicidal effect. This study investigates the efficacy of EO and chlorinated water treatments at various temperatures and for various lengths of time in inactivating E. coli O157:H7 on strawberries and broccoli. Additional application of ultrasonication to enhance the effectiveness of the sanitizer treatment was also investigated. Inoculated strawberries were treated with deionized water (control), electrolyzed oxidizing (EO) water (23 and 55 mg/l of residual chlorine) and chlorinated water (55 mg/l of residual chlorine), either with or without ultrasonication. Inoculated broccoli was treated with EO water containing 55 and 100 mg/l of residual chlorine and chlorinated water with 100 mg/l of residual chlorine. Treatments were conducted for 1 and 5 minutes at temperatures of 4 and 24C, respectively. Research findings have been submitted for publication. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Food Processors, produce packing houses, and consumers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Dipping strawberries and broccoli into EO water or chlorinated water significantly reduced the E. coli O157:H7 counts compared with inoculated controls. Dipping inoculated strawberries with chlorinated water or EO water with ultrasonication for 1 or 5 min reduced E. coli O157:H7 cells by 0.7 to 1.9 log CFU/g. Dipping inoculated broccoli into chlorinated water or EO water with ultrasonication for 1 or 5 min reduced the bacterial population by 1.2 to 2.2 log CFU/g. Significant reductions in populations of the pathogen were observed when produce was treated with EO water in conjunction with ultrasonication. Results revealed that EO water was either more than or as effective as chlorinated water in killing E. coli O157:H7 cells on strawberries and broccoli. EO water is also a simple and non-thermal process and can be used effectively to ensure safety of fresh produce. On going research has demonstrated EO water can be easily adapted by processors to inactivate foodborne pathogens during washing with EO water and hence provide additional safety measure for fresh produce.
Publications
- No publications reported this period
|
|