scholarly journals Photolysis and TiO2 Photocatalytic Treatment under UVC/VUV Irradiation for Simultaneous Degradation of Pesticides and Microorganisms

2020 ◽  
Vol 10 (13) ◽  
pp. 4493
Author(s):  
Sung Won Choi ◽  
Hafiz Muhammad Shahbaz ◽  
Jeong Un Kim ◽  
Da-Hyun Kim ◽  
Sohee Yoon ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Aqueous Solutions ◽  
Ultraviolet Light ◽  
E Coli ◽  
Log Reduction ◽  
Titanium Dioxide Photocatalysis ◽  
Combined Use ◽  
Significant Difference ◽  
Fresh Cut ◽  
Simultaneous Degradation

Efficiencies of various treatments for UVC photolysis (ultraviolet light-C at 254 nm), VUV photolysis (vacuum ultraviolet light at 254 nm and 185 nm), UVC-assisted titanium dioxide photocatalysis (UVC-TiO2), and VUV-assisted titanium dioxide photocatalysis (VUV-TiO2) were investigated for the degradation of pesticides including pyraclostrobin, boscalid, fludioxonil, and azoxystrobin and inactivation of microorganisms Escherichia coli K12 as a surrogate for E. coli O157:H7 and Saccharomyces cerevisiae in aqueous solutions and on the surface of fresh cut carrots. The degradation efficiencies of VUV were higher than for UVC on pesticides in aqueous solutions. However, there was no significant difference between degradation efficiencies for UVC and UVC-TiO2 treatments, and between VUV and VUV-TiO2 treatments. UVC, VUV, UVC-TiO2, and VUV-TiO2 showed similar inactivation effects against E. coli K12 and S. cerevisiae in aqueous solutions. The combined use of UVC and VUV treatments (combined UV) and combined use of UVC-TiO2 and VUV-TiO2 treatments (combined UV-TiO2) showed higher efficiencies (72–94% removal) for the removal of residual pesticides on fresh cut carrots than bubble water washing (53–73% removal). However, there was no significant difference in removal efficiency between combined UV and combined UV-TiO2 treatments. For E. coli K12 and S. cerevisiae on fresh cut carrots, the combined UV-TiO2 treatment (1.5 log and 1.6 log reduction, respectively) showed slightly higher inactivation effects than combined UV (1.3 log and 1.2 log reduction, respectively). Photolysis and TiO2 photocatalytic treatments under UV irradiation, including VUV as a light source, showed potential for the simultaneous degradation of pesticides and microorganisms as a non-chemical and residue-free technique for surface disinfection of fresh produce.

Quantifying Bacterial Cross-Contamination Rates between Fresh-Cut Produce and Hands

2017 ◽  
Vol 80 (2) ◽  
pp. 213-219 ◽  
Author(s):  
Dane A. Jensen ◽  
Michelle D. Danyluk ◽  
Linda J. Harris ◽  
Donald W. Schaffner
Keyword(s):  
Bacterial Species ◽  
Enterobacter Aerogenes ◽  
Escherichia Coli O157 ◽  
Cross Contamination ◽  
Transfer Rates ◽  
E Coli ◽  
Significant Difference ◽  
Fresh Cut ◽  
Food Safety Risk ◽  
Risk Assessment And Management

ABSTRACT This study quantifies the cross-contamination rates between fresh-cut produce and hands using a nalidixic acid–resistant nonpathogenic Enterobacter aerogenes and cocktails of rifampin-resistant Salmonella or Escherichia coli O157:H7 strains. Volunteers performed the E. aerogenes experiments (n = 20), and one of the authors performed the Salmonella and E. coli O157:H7 experiments multiple times (n =15 and n =10, respectively). Each participant handled 25 g of fresh-cut carrots, celery, or cantaloupe in two different scenarios. In the first scenario, gloved hands were inoculated with 6 log CFU per hand of the bacteria, and in the second scenario, five 25-g pieces of fresh produce were inoculated to a concentration of 6 log CFU/25 g. The glove juice method was used to quantify the bacterial concentration on the gloved hands. About 30% of E. aerogenes on gloved hands was transferred to the carrots and celery, and 18% of E. aerogenes on gloved hands was transferred to the cantaloupe. When carrots or cantaloupe was inoculated with E. aerogenes, 1% was transferred to gloved hands; from inoculated celery, about 0.3% of E. aerogenes was transferred to gloved hands. There was not a significant difference between E. aerogenes and Salmonella cross-contamination rates (P > 0.05). When gloved hands were contaminated with E. coli O157:H7, about 30% was transferred to carrots, about 10% to celery, and about 3% to cantaloupe. When carrots and celery were inoculated with E. coli O157:H7, about 1% was transferred to gloved hands, but from inoculated cantaloupe only about 0.3% was transferred. Direction of transfer (to versus from produce), difference in type of produce, and differences among the bacterial species all had significant effects on the transfer rate. Understanding transfer rates to and from fresh-cut produce will allow for better risk assessment and management of microbial food safety risk related to fresh-cut produce.

scholarly journals Meta-analysis of the reduction of antibiotic-sensitive and antibiotic-resistant Escherichia coli as a result of low- and medium-pressure UV lamps

2018 ◽  
Vol 2017 (2) ◽  
pp. 612-620 ◽  
Author(s):  
Eithne O'Flaherty ◽  
Jeanne-Marie Membré ◽  
Enda Cummins
Keyword(s):  
Escherichia Coli ◽  
Meta Analysis ◽  
Mixed Effect ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Log Reduction ◽  
Medium Pressure ◽  
Operation Conditions ◽  
Significant Difference ◽  
Uv Lamps

Abstract It is vital that harmful bacteria are removed from water and wastewater treatment plants to prevent human/environmental exposure. This paper examines the log reduction of antibiotic-sensitive (AS) and antibiotic-resistant (AR) Escherichia coli (E. coli) as a result of low-pressure (LP) and medium-pressure (MP) UV lamps. A meta-analysis was performed and a mixed-effect model was created in which 303 data points on the log reduction of E. coli from UV treatment were collected. The results show that in order to achieve a 6 log reduction using an MP lamp, on average a UV level of 7.3 mJ/cm2 for AS E. coli and 7.5 mJ/cm2 for AR E. coli were required. Using an LP lamp, a UV level of 8.1 mJ/cm2 for AS E. coli and 8.4 mJ/cm2 for AR E. coli were required. The results show there is no significant difference between the inactivation of AR and AS E. coli at different UV levels. The model predicts that AR or AS E. coli will be inactivated at UV levels lower than the recommended UV operation conditions (40 mJ/cm2), but it is important to use this UV level to inactivate other harmful microorganisms.

Inactivation of Escherichia Coli on Titanium Dioxide Photocatalysis Nanoparticles

2010 ◽  
Vol 96 ◽  
pp. 99-104 ◽  
Author(s):  
Jing Wang ◽  
Zhi Jiang Ji ◽  
Zhong He Shui ◽  
Xiao Yan Wang ◽  
Nan Ding ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Titanium Dioxide ◽  
Cell Membrane ◽  
Particle Diameter ◽  
Average Diameter ◽  
Nano Tio2 ◽  
E Coli ◽  
Tio2 Particles ◽  
Titanium Dioxide Photocatalysis ◽  
The Difference

The effects of P25 TiO2 made by DEGUSSA and one kind nano-titanium dioxide made by a certain company in China (Expressed by Tc) on Escherichia coli were tested by the minimal inhibitory concentration (MIC) method, and the status dispersed of two kinds nano-TiO2 and the micro-phenomenon of the effect on Escherichia coli were observed by scanning electron microscope (SEM). The hydroxyl radical (•OH) signal intensity in liquid produced by nano-TiO2 was tested by electron spinning resonance (ESR). It was found that the MIC of the P25 and Tc were 500 mg/L and 5 g/L, respectively. The cells of E. coli which were attached by the nano-TiO2 particles were damaged strongly, and the membrane was dissolved and dispersed under SEM. The intensity of •OH signal produced by P25 was stronger than that of Tc tested by ESR. The size of E. coli was 0.4~0.7×1~3 µm, and the average diameter of nano-TiO2 was 20 nm. When the nano-TiO2 particles touch the E. coli, it would stick to the surface of the cell wall and destroy the cell membrane, lead to the canker of cell membrane and the outflow of cytoplasm. The difference of the MIC between the two kinds of nano-powders may be due to their dispersion degree and the particle diameter which influence the •OH production.

Inactivation of Escherichia coli Inoculated onto Fresh-Cut Chopped Cabbage Using Electron-Beam Processing

2011 ◽  
Vol 74 (1) ◽  
pp. 115-118 ◽  
Author(s):  
ELIZABETH M. GRASSO ◽  
ROBERTO M. URIBE-RENDON ◽  
KEN LEE
Keyword(s):  
Escherichia Coli ◽  
Electron Beam ◽  
Foodborne Pathogens ◽  
Optimal Dosage ◽  
Beam Irradiation ◽  
E Coli ◽  
Log Reduction ◽  
Fresh Cut ◽  
K 12 ◽  
Indigenous Microflora

During the past decade there were more than 50 reported outbreaks involving leafy green vegetables contaminated with foodborne pathogens. Leafy greens, including cabbage, are fresh foods rarely heated before consumption, which enables foodborne illness. The need for improved safety of fresh food drives the demand for nonthermal food processes to decrease the risk of pathogens while maintaining fresh quality. This study examines the efficacy of electron-beam (e-beam) irradiation in decreasing indigenous microflora on fresh-cut cabbage and determines the optimal dosage to pasteurize fresh-cut cabbage inoculated with Escherichia coli K-12. Fresh-cut cabbage (100 g) was inoculated with ~8 log E. coli K-12 and e-beam irradiated at doses of 0, 1.0, 2.3, or 4.0 kGy. At 2.3 kGy there was <1.0 log indigenous microflora remaining, indicating greater than a 4.0-log reduction by e-beam. At a 4.0-kGy dose there was >7-log reduction of E. coli K-12 in the fresh-cut cabbage. The D10-value for E. coli K-12 in fresh-cut cabbage was 0.564 kGy. E-beam irradiation is thus a viable nonthermal treatment that extends the shelf life and increases the safety of fresh cabbage by reducing or eliminating indigenous microflora and unwanted pathogens.

scholarly journals PSIII-33 Stability and function of encapsulated Lactobacillus zeae for pig gut health

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 367-368
Author(s):  
Linyan Li ◽  
Xiaoyin Wang ◽  
Hai Yu ◽  
Qi Wang ◽  
Luca Lo Verso ◽  
...  
Keyword(s):  
Probiotic Bacterium ◽  
Feed Additives ◽  
Gut Health ◽  
E Coli ◽  
Log Reduction ◽  
Significant Difference ◽  
Pig Performance ◽  
And Function ◽  
Dietary Treatments

Abstract Lactobacilli have been used in livestock production to improve animal gut health; however, they are heat sensitive, which limits their use as feed additives. We have developed a novel spray-drying encapsulation technology that resulted in an approximately 0.5-log reduction of Lactobacillus zeae LB1, a probiotic bacterium known for its potential to reduce the infections caused by Salmonella and enterotoxigenic E. coli in vivo. In this study, encapsulated LB1 was evaluated for its stability during storage and feed pelleting and for its potential to modulate piglet performance. After 14-month storage at 4℃ and 22℃ in a sealed container, the survival rate of encapsulated LB1 represented 17.1% and 85.6% reduction of the original concentration, respectively. In the feed pelleting test, the survived non-encapsulated LB1 in pelleted or mash feed was 1-log lower in the concentration than encapsulated LB1 on the 7th and 30th day after pelleting. To examine the influence of LB1 alone or in combination with colostrum on pig performance, 80 newly-weaned piglets were equally allocated to five groups: 1) basal diets (control-CTL); 2) basal diets supplemented with non-encapsulated LB1 (NEP); 3) basal diets supplemented with encapsulated LB1 (EP); 4) basal diets supplemented with bovine colostrum (BC); 5) basal diets supplemented with EP and BC (EP-BC, same dose as in Group 3 or 4). No significant difference in growth performance was observed between the CTL group and other dietary treatments after five days’ treatment. Supplementation of LB1 or colostrum individually did not affect the population size of Lactobacillus in the ileum and colon of pigs. However, the EP-BC group had a significantly increased population of Lactobacillus in both the ileum and colon (94.57-fold and 23.51-fold, respectively) compared with the CTL group. In conclusion, our encapsulation technology can increase survival and delivery of Lactobacillus zeae potentially beneficial to piglet performance.

Survival of Salmonella and Escherichia coli O157:H7 on Strawberries, Basil, and Other Leafy Greens during Storage

2015 ◽  
Vol 78 (4) ◽  
pp. 652-660 ◽  
Author(s):  
STEFANIE DELBEKE ◽  
SIELE CEUPPENS ◽  
LIESBETH JACXSENS ◽  
MIEKE UYTTENDAELE
Keyword(s):  
Escherichia Coli ◽  
Limit Of Detection ◽  
Escherichia Coli O157 ◽  
Similar Reduction ◽  
Initial Inoculum ◽  
E Coli ◽  
Log Reduction ◽  
Leafy Greens ◽  
Fresh Cut ◽  
Butterhead Lettuce

The survival of Salmonella and Escherichia coli O157:H7 on strawberries, basil leaves, and other leafy greens (spinach leaves, lamb and butterhead lettuce leaves, baby leaves, and fresh-cut iceberg lettuce) was assessed at cold (<7°C) and ambient temperatures. All commodities were spot inoculated with E. coli O157:H7 or Salmonella to obtain an initial inoculum of 5 to 6 log and 4 to 5 log CFU/g for strawberries and leafy greens, respectively. Samples were air packed. Strawberries were stored at 4, 10, 15, and 22°C and basil leaves and other leafy greens at 7, 15, and 22°C for up to 7 days (or less if spoiled before). Both Salmonella and E. coli O157:H7 showed a gradual decrease in numbers if inoculated on strawberries, with a similar reduction observed at 4, 10, and 15°C (2 to 3 log after 5 days). However, at 15°C (and 10°C for E. coli O157:H7), the survival experiment stopped before day 7, as die-off of both pathogens below the lower limit of detection was achieved or spoilage occurred. At 22°C, strawberries were moldy after 2 or 4 days. At that time, a 1- to 2-log reduction of both pathogens had occurred. A restricted die-off (on average 1.0 log) and increase (on average <0.5 log) of both pathogens on basil leaves occurred after 7 days of storage at 7 and 22°C, respectively. On leafy greens, a comparable decrease as on basil was observed after 3 days at 7°C. At 22°C, both pathogens increased to higher numbers on fresh-cut iceberg and butterhead lettuce leaves (on average 1.0 log), probably due to the presence of exudates. However, by using spot inoculation, the increase was rather limited, probably due to minimized contact between the inoculum and cell exudates. Avoiding contamination, in particular, at cultivation (and harvest or postharvest) is important, as both pathogens survive during storage, and strawberries, basil, and other leafy green leaves are consumed without inactivation treatment.

Effect of Hydrogen Peroxide in Combination with Minimal Thermal Treatment for Reducing Bacterial Populations on Cantaloupe Rind Surfaces and Transfer to Fresh-Cut Pieces

2016 ◽  
Vol 79 (8) ◽  
pp. 1316-1324 ◽  
Author(s):  
DIKE O. UKUKU ◽  
SUDARSAN MUKHOPADHYAY ◽  
DAVID GEVEKE ◽  
MODESTO OLANYA ◽  
BRENDAN NIEMIRA
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Combination Treatment ◽  
Bacterial Pathogens ◽  
Escherichia Coli O157 ◽  
Bacterial Populations ◽  
E Coli ◽  
Log Reduction ◽  
Fresh Cut ◽  
Bacterial Cell Morphology

ABSTRACT Surface structure and biochemical characteristics of bacteria and produce play a major role in how and where bacteria attach, complicating decontamination treatments. Whole cantaloupe rind surfaces were inoculated with Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes at 107 CFU/ml. Average population size of Salmonella, Escherichia coli O157:H7, and L. monocytogenes recovered after surface inoculation was 4.8 ± 0.12, 5.1 ± 0.14, and 3.6 ± 0.13 log CFU/cm2, respectively. Inoculated melons were stored at 5 and 22°C for 7 days before washing treatment interventions. Intervention treatments used were (i) water (H2O) at 22°C, (ii) H2O at 80°C, (iii) 3% hydrogen peroxide (H2O2) at 22°C, and (iv) a combination of 3% H2O2 and H2O at 80°C for 300 s. The strength of pathogen attachment (SR value) at days 0, 3, and 7 of storage was determined, and then the efficacy of the intervention treatments to detach, kill, and reduce transfer of bacteria to fresh-cut pieces during fresh-cut preparation was investigated. Populations of E. coli O157:H7 attached to the rind surface at significantly higher levels (P < 0.05) than Salmonella and L. monocytogenes, but Salmonella exhibited the strongest attachment (SR value) at all days tested. Washing with 3% H2O2 alone led to significant reduction (P < 0.05) of bacteria and caused some changes in bacterial cell morphology. A combination treatment with H2O and 3% H2O2 at 80°C led to an average 4-log reduction of bacterial pathogens, and no bacterial pathogens were detected in fresh-cut pieces prepared from this combination treatment, including enriched fresh-cut samples. The results of this study indicate that the microbial safety of fresh-cut pieces from treated cantaloupes was improved at day 6 of storage at 5°C and day 3 of storage at 10°C.

scholarly journals Application of ultraviolet light assisted titanium dioxide photocatalysis for food safety: A review

2016 ◽  
Vol 38 ◽  
pp. 105-115 ◽  
Author(s):  
Tamanna Ramesh ◽  
Balunkeswar Nayak ◽  
Aria Amirbahman ◽  
Carl P. Tripp ◽  
Sudarsan Mukhopadhyay
Keyword(s):  
Titanium Dioxide ◽  
Food Safety ◽  
Ultraviolet Light ◽  
Titanium Dioxide Photocatalysis

Determination of 5-Log Pathogen Reduction Times for Heat-Processed, Acidified Vegetable Brines†‡

2005 ◽  
Vol 68 (2) ◽  
pp. 305-310 ◽  
Author(s):  
F. BREIDT ◽  
J. S. HAYES ◽  
J. A. OSBORNE ◽  
R. F. McFEETERS
Keyword(s):  
Ph Value ◽  
Heat Inactivation ◽  
Weibull Function ◽  
Apple Cider ◽  
E Coli ◽  
Log Reduction ◽  
Vegetable Products ◽  
Significant Difference ◽  
Margin Of Safety

Recent outbreaks of acid-resistant food pathogens in acid foods, including apple cider and orange juice, have raised concerns about the safety of acidified vegetable products. We determined pasteurization times and temperatures needed to assure a 5-log reduction in the numbers of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella strains in acidified cucumber pickle brines. Cocktails of five strains of each pathogen were (separately) used for heat-inactivation studies between 50 and 60°C in brines that had an equilibrated pH value of 4.1. Salmonella strains were found to be less heat resistant than E. coli O157:H7 or L. monocytogenes strains. The nonlinear killing curves generated during these studies were modeled using a Weibull function. We found no significant difference in the heat-killing data for E. coli O157:H7 and L. monocytogenes (P = 0.9709). The predicted 5-log reduction times for E. coli O157:H7 and L. monocytogenes were found to fit an exponential decay function. These data were used to estimate minimum pasteurization times and temperatures needed to ensure safe processing of acidified pickle products and show that current industry pasteurization practices offer a significant margin of safety.

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