scholarly journals Survival of Escherichia coli O157:H7 during Moderate Temperature Dehydration of Plant-Based Foods

Foods ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2162
Author(s):  
Yadwinder Singh Rana ◽  
Philip M. Eberly ◽  
Quincy J. Suehr ◽  
Ian M. Hildebrandt ◽  
Bradley P. Marks ◽  
...  
Keyword(s):  
Pilot Scale ◽  
Microbial Inactivation ◽  
Moderate Temperature ◽  
Isothermal Treatment ◽  
Pathogen Inactivation ◽  
Decimal Reduction Time ◽  
E Coli ◽  
Log Reduction ◽  
D Values ◽  
Time Required

The effect of moderate-temperature (≤60 °C) dehydration of plant-based foods on pathogen inactivation is unknown. Here, we model the reduction of E. coli O157:H7 as a function of product-matrix, aw, and temperature under isothermal conditions. Apple, kale, and tofu were each adjusted to aw 0.90, 0.95, or 0.99 and inoculated with an E. coli O157:H7 cocktail, followed by isothermal treatment at 49, 54.5, or 60.0 °C. The decimal reduction time, or D-value, is the time required at a given temperature to achieve a 1 log reduction in the target microorganism. Modified Bigelow-type models were developed to determine D-values which varied by product type and aw level, ranging from 3.0–6.7, 19.3–55.3, and 45.9–257.4 min. The relative impact of aw was product dependent and appeared to have a non-linear impact on D-values. The root mean squared errors of the isothermal-based models ranged from 0.75 to 1.54 log CFU/g. Second, we performed dynamic drying experiments. While the isothermal results suggested significant microbial inactivation might be achieved, the dehydrator studies showed that the combination of low product temperature and decreasing aw in the pilot-scale system provided minimal inactivation. Pilot-scale drying at 60 °C only achieved reductions of 3.1 ± 0.8 log in kale and 0.67 ± 0.66 log in apple after 8 h, and 0.69 ± 0.67 log in tofu after 24 h. This illustrates the potential limitations of dehydration at ≤60 °C as a microbial kill step.

scholarly journals Choice of sterilizing/disinfecting agent: determination of the Decimal ReductionTime (D-Value)

2009 ◽  
Vol 45 (4) ◽  
pp. 701-708 ◽  
Author(s):  
Priscila Gava Mazzola ◽  
Angela Faustino Jozala ◽  
Letícia Célia de Lencastre Novaes ◽  
Patricia Moriel ◽  
Thereza Christina Vessoni Penna
Keyword(s):  
Medical Devices ◽  
Cross Contamination ◽  
Decimal Reduction Time ◽  
E Coli ◽  
Health Care Unit ◽  
Sodium Dichloroisocyanurate ◽  
D Values ◽  
Spread Of Infection ◽  
Disinfectant Efficacy

Efforts to diminish the transmission of infections include programs in which disinfectants play a crucial role. Hospital surfaces and medical devices are potential sources of cross contamination, and each instrument, surface or area in a health care unit can be responsible for spread of infection. The decimal reduction time was used to study and compare the behavior of selected strains of microorganisms. The highest D-values for various bacteria were obtained for the following solutions: (i) 0.1% sodium dichloroisocyanurate (pH 7.0) - E. coli and A. calcoaceticus (D = 5.9 min); (ii) sodium hypochlorite (pH 7.0) at 0.025% for B. stearothermophilus (D = 24 min), E. coli and E. cloacae (D = 7.5 min); at 0.05% for B. stearothermophilus (D = 9.4 min) and E. coli (D = 6.1 min). The suspension studies were an indication of the disinfectant efficacy on a surface. The data in this study reflect the formulations used and may vary from product to product. The expected effectiveness from the studied formulations shows that the tested agents can be recommended for surface disinfection as stated in present guidelines and emphasize the importance and need to develop routine and novel programs to evaluate product utility.

Monochloramine Versus Sodium Hypochlorite as Antimicrobial Agents for Reducing Populations of Bacteria on Broiler Chicken Carcasses

2005 ◽  
Vol 68 (4) ◽  
pp. 758-763 ◽  
Author(s):  
SCOTT M. RUSSELL ◽  
STEPHEN P. AXTELL
Keyword(s):  
Nalidixic Acid ◽  
Sodium Hypochlorite ◽  
Broiler Chicken ◽  
Antimicrobial Agents ◽  
Tap Water ◽  
Pilot Scale ◽  
Bacterial Populations ◽  
E Coli ◽  
Log Reduction ◽  
Salmonella Serovars

Studies were conducted to compare the effect of sodium hypochlorite (SH) versus monochloramine (MON) on bacterial populations associated with broiler chicken carcasses. In study 1, nominal populations (6.5 to 7.5 log CFU) of Escherichia coli, Listeria monocytogenes, Pseudomonas fluorescens, Salmonella serovars, Shewanella putrefaciens, and Staphylococcus aureus were exposed to sterilized chiller water (controls) or sterilized chiller water containing 50 ppm SH or MON. SH at 50 ppm eliminated all (6.5 to 7.5 log CFU) viable E. coli, L. monocytogenes, and Salmonella serovars; 1.2 log CFU of P. fluorescens; and 5.5 log CFU of S. putrefaciens. MON eliminated all (6.5 to 7.5 log CFU) viable E. coli, L. monocytogenes, S. putrefaciens, and Salmonella serovars and 4.2 log CFU of P. fluorescens. In study 2, chicken carcasses were inoculated with P. fluorescens or nalidixic acid–resistant Salmonella serovars or were temperature abused at 25°C for 2 h to increase the populations of naturally occurring E. coli. The groups of Salmonella serovar–inoculated or temperature-abused E. coli carcasses were immersed separately in pilot-scale poultry chillers and exposed to tap water (controls) or tap water containing 20 ppm SH or 20 ppm MON for 1 h. The P. fluorescens–inoculated group was immersed in pilot-scale poultry chillers and exposed to tap water (controls) or tap water containing 50 ppm SH or 50 ppm MON for 1 h. Carcasses exposed to the SH treatment had nominal increases (0.22 log CFU) in E. coli counts compared with controls, whereas exposure to MON resulted in a 0.89-log reduction. Similarly, average nalidixic acid–resistant Salmonella serovar counts increased nominally by 34% (41 to 55 CFU/ml) compared with controls on carcasses exposed to SH, whereas exposure to MON resulted in an average nominal decrease of 80% (41 to 8 CFU/ml). P. fluorescens decreased by 0.64 log CFU on carcasses exposed to SH and decreased by 0.87 log CFU on carcasses exposed to MON. In study 3, SH or MON was applied to the chiller in a commercial poultry processing facility. E. coli counts (for carcass halves emerging from both saddle and front-half chillers) and Salmonella prevalence were evaluated. Data from carcasses exposed to SH during an 84-day historical (Hist) and a 9-day prepilot (Pre) period were evaluated. Other carcasses were exposed to MON and tested during a 27-day period (Test). E. coli counts for samples collected from the saddle chiller were 25.7, 25.2, and 8.6 CFU/ml for Hist, Pre, and Test, respectively. E. coli counts for samples collected from the front-half chiller were 6.7, 6.9, and 2.5 CFU/ml for Hist, Pre, and Test, respectively. Salmonella prevalence was reduced from 8.7% (Hist + Pre) to 4% (Test). These studies indicate that MON is superior to SH in reducing microbial populations in poultry chiller water.

Modeling of pathogen inactivation in thermal septic tanks

2013 ◽  
Vol 4 (1) ◽  
pp. 81-88 ◽  
Author(s):  
T. Koottatep ◽  
S. Phuphisith ◽  
T. Pussayanavin ◽  
A. Panuvatvanich ◽  
C. Polprasert
Keyword(s):  
Oxygen Demand ◽  
Weibull Model ◽  
Septic Tank ◽  
Most Probable Number ◽  
Pathogen Inactivation ◽  
Probable Number ◽  
E Coli ◽  
Septic Tanks ◽  
Log Reduction ◽  
Safe Level

Thermal application has been widely used for pathogen inactivation in various fields. The purpose of this research was to develop a model of pathogen inactivation in septic tanks operating at various temperatures. Four laboratory-scale septic tanks fed with septage were operated at temperatures of 30, 40, 50 and 60 °C and Escherichia coli (E. coli) was selected as the pathogenic indicator. The efficiencies of E. coli inactivation were found to increase with increasing temperatures, while the opposites were observed for chemical oxygen demand (COD) reduction. At 60 °C, the E. coli concentrations were reduced from 9.6 × 106 to about 10 most probable number (MPN)/100 mL or 6 log reduction. The kinetics of E. coli reduction followed a modified Weibull model which could be applied to septic tank design and operation. The percentage COD removal was found to be 93, 94, 89 and 84 at temperatures of 32, 40, 50 and 60 °C, respectively. The results of this study suggested that pathogenic microorganisms in septic tanks could be inactivated to be at a safe level with thermal application.

Virus removal in a pilot-scale ‘advanced’ pond system as indicated by somatic and F-RNA bacteriophages

2005 ◽  
Vol 51 (12) ◽  
pp. 107-110 ◽  
Author(s):  
R.J. Davies-Colley ◽  
R.J. Craggs ◽  
J. Park ◽  
J.P.S. Sukias ◽  
J.W. Nagels ◽  
...  
Keyword(s):  
Pilot Scale ◽  
High Rate ◽  
Virus Removal ◽  
E Coli ◽  
Waste Stabilisation Ponds ◽  
Log Reduction ◽  
Effective Removal ◽  
Solar Uv ◽  
Settling Ponds ◽  
Rna Phage

Advanced pond systems (APS), incorporating high-rate ponds, algal settling ponds, and maturation ponds, typically achieve better and more consistent disinfection as indicated by Escherichia coli than conventional waste stabilisation ponds. To see whether this superior disinfection extends also to enteric viruses, we studied the removal of somatic phages (‘model’ viruses) in a pilot-scale APS treating sewage. Measurements through the three aerobic stages of the APS showed fairly good removal of somatic phage in the summer months (2.2 log reduction), but much less effective removal in winter (0.45 log reduction), whereas E. coli was removed efficiently (>4 logs) in both seasons. A very steep depth-gradient of sunlight inactivation of somatic phage in APS pond waters (confined in silica test tubes) is consistent with inactivation mainly by solar UVB wavelengths. Data for F-RNA phage suggests involvement of longer UV wavelengths. These findings imply that efficiency of virus removal in APS will vary seasonally with variation in solar UV radiation.

Thermal and Pressure-Assisted Thermal Destruction Kinetics for Spores of Type A Clostridium botulinum and Clostridium sporogenes PA3679

2016 ◽  
Vol 79 (2) ◽  
pp. 253-262 ◽  
Author(s):  
N. RUKMA REDDY ◽  
EDUARDO PATAZCA ◽  
TRAVIS R. MORRISSEY ◽  
GUY E. SKINNER ◽  
VIVIANA LOEZA ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
High Temperatures ◽  
Clostridium Botulinum ◽  
Pilot Scale ◽  
Inactivation Kinetics ◽  
Clostridium Sporogenes ◽  
Log Reduction ◽  
Pressure Test ◽  
D Values

ABSTRACT The purpose of this study was to determine the inactivation kinetics of the spores of the most resistant proteolytic Clostridium botulinum strains (Giorgio-A and 69-A, as determined from an earlier screening study) and of Clostridium sporogenes PA3679 and to compare the thermal and pressure-assisted thermal resistance of these spores. Spores of these strains were prepared using a biphasic medium method. C. sporogenes PA3679 spores were heat treated before spore preparation. Using laboratory-scale and pilot-scale pressure test systems, spores of Giorgio-A, 69-A, and PA3679 suspended in ACES [N-(2-acetamido)-2-aminoethanesulfonic acid] buffer (pH 7.0) were exposed to various combinations of temperature (93 to 121°C) and pressure (0.1 to 750 MPa) to determine their resistance. More than a 5-log reduction occurred after 3 min at 113°C for spores of Giorgio-A and 69-A and after 5 min at 117°C for spores of PA3679. A combination of high temperatures (93 to 121°C) and pressures yielded greater log reductions of spores of Giorgio-A, 69-A, and PA3679 compared with reduction obtained with high temperatures alone. No survivors from initial levels (>5.0 log CFU) of Giorgio-A and 69-A were detected when processed at a combination of high temperature (117 and 121°C) and high pressure (600 and 750 MPa) for <1 min in a pilot-scale pressure test system. Increasing pressure from 600 to 750 MPa at 117°C decreased the time from 2.7 to 1 min for a >4.5-log reduction of PA3679 spores. Thermal D-values of Giorgio-A, 69-A, and PA3679 spores decreased (i.e., 29.1 to 0.33 min for Giorgio-A, 40.5 to 0.27 min for 69-A, and 335.2 to 2.16 min for PA3679) as the temperature increased from 97 to 117°C. Pressure-assisted thermal D-values of Giorgio-A, 69-A, and PA3679 also decreased as temperature increased from 97 to 121°C at both pressures (600 and 750 MPa) (i.e., 17.19 to 0.15 min for Giorgio-A, 9.58 to 0.15 min for 69-A, and 12.93 to 0.33 min for PA3679 at 600 MPa). At higher temperatures (117 or 121°C), increasing pressure from 600 to 750 MPa had an effect on pressure-assisted thermal D-values of PA3679 (i.e., at 117°C, pressure-assisted thermal D-value decreased from 0.55 to 0.28 min as pressure increased from 600 to 750 MPa), but pressure had no effect on pressure-assisted thermal D-values of Giorgio-A and 69-A. When compared with Giorgio-A and 69-A, PA3679 had higher thermal and pressure-assisted thermal D-values. C. sporogenes PA3679 spores were generally more resistant to combinations of high pressure and high temperature than were the spores of the C. botulinum strains tested in this study.

Combined High Pressure and Subzero Temperature Phase Transition on the Inactivation of Escherichia coli ATCC 10536

2008 ◽  
Vol 4 (4) ◽  
Author(s):  
Sung Hee Park ◽  
Geun Pyo Hong ◽  
Sang Gi Min ◽  
Mi Jung Choi
Keyword(s):  
Escherichia Coli ◽  
Phase Transition ◽  
High Pressure ◽  
Atmospheric Pressure ◽  
Microbial Inactivation ◽  
Subzero Temperature ◽  
Temperature Phase ◽  
E Coli ◽  
Log Reduction ◽  
Temperature Phase Transition

Combined high pressure and subzero temperature phase transition was performed to inactivate Escherichia coli ATCC 10536 at 200 MPa. Inactivation was compared among atmospheric pressure inactivation (APFI), pressure assisted freezing inactivation (PAFI), pressure assisted thawing inactivation (PATI), and pressure shift freezing inactivation (PSFI). Phase transition characteristics of microbial suspension were concurrently analyzed to investigate its influence on microbial inactivation. Phase transition temperature of E. coli ATCC 10536 suspension decreased to -23.8°C at 200 MPa, which is observed from the phase transition plateau. Supercooling was observed from nucleation temperature (-25°C) of PAFI. PATI resulted in the most inactivation of 4.37 log reduction, followed by PAFI and PSFI in decreasing order. APFI showed no efficacy of inactivation for E. coli ATCC 10536. Synergistic effect of high pressure, subzero temperature, and phase transition was expected for microbial inactivation.

Ozonation of a secondary effluent both for fresh water protection and re-use

2006 ◽  
Vol 1 (2) ◽  
Author(s):  
M. Antonelli ◽  
V. Mezzanotte ◽  
C. Nurizzo
Keyword(s):  
Contact Time ◽  
Pilot Scale ◽  
Secondary Effluent ◽  
Water Protection ◽  
Faecal Coliforms ◽  
Colour Removal ◽  
E Coli ◽  
Log Reduction ◽  
Ionic Compounds ◽  
Higher Doses

49 trials were carried out at pilot scale to evaluate ozonation for polishing a nitrified and filtered effluent discharged in a brook, lying in a recreational protected area whose low and irregular flow provides a negligible dilution. Four ozone doses (3, 5, 7.5 and 10 mg O3/L) were tested and contact time was set at 10 minutes for each of the three contact columns. In most cases, at 3 mg O3/L, residual ozone concentration was below detection limit after 10 minutes contact time. For faecal coliforms and E. coli, log reduction increased from 3 mg O3/L to higher ozone doses, among which no appreciable difference was observed. No improvement in disinfection efficiency was seen for contact times over 10 minutes. Complete disinfection was obtained only in few cases, but final counts complying with the limits for discharge were always met. COD removal was low, while colour removal was significant and clearly increasing from 3 mg O3/L to higher doses. The removal of surfactants slightly increased with increasing dose for non ionic compounds, but not for anionic ones. Data confirmed that slight increases in ozone dose involve the release of bacterial organic matter which partially counterbalance the removal of COD.

Inactivation Kinetics of Pathogens during Thermal Processing in Acidified Broth and Tomato Purée (pH 4.5)

2017 ◽  
Vol 80 (12) ◽  
pp. 2014-2021 ◽  
Author(s):  
Evann L. Dufort ◽  
Jonathan Sogin ◽  
Mark R. Etzel ◽  
Barbara H. Ingham
Keyword(s):  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
E Coli ◽  
Log Reduction ◽  
Tomato Puree ◽  
Weibull Models ◽  
Canned Foods ◽  
D Values ◽  
Log Linear

ABSTRACT Thermal inactivation kinetics for single strains of Shiga toxin–producing Escherichia coli (STEC), Listeria monocytogenes, and Salmonella enterica were measured in acidified tryptic soy broth (TSB; pH 4.5) heated at 54°C. Inactivation curves also were measured for single-pathogen five-strain cocktails of E. coli O157:H7, L. monocytogenes, and S. enterica heated in tomato purée (pH 4.5) at 52, 54, 56, and 58°C. Inactivation curves were fit using log-linear and nonlinear (Weibull) models. The Weibull model yields the time for a 5-log reduction (t*) and a curve shape parameter (β). Decimal reduction times (D-values) and thermal resistance constants (z-values) from the two models were compared by defining t* = 5D* for the Weibull model. When the log-linear and Weibull models match at the 5-log reduction time, then t* = 5D* = 5D and D = D*. In 18 of 20 strains heated in acidified TSB, D and D* for the two models were not significantly different, although nonlinearity was observed in 35 of 60 trials. Similarly, in 51 of 52 trials for pathogen cocktails heated in tomato purée, D and D* were not significantly different, although nonlinearity was observed in 31% of trials. At a given temperature, D-values for S. enterica << L. monocytogenes < E. coli O157:H7 in tomato purée (pH 4.5). When using the two models, z-values calculated from the D-values were not significantly different for a given pathogen. Across all pathogens, z-values for E. coli O157:H7 and S. enterica were not different but were significantly lower than the z-values for L. monocytogenes. These results are useful for supporting process filings for tomato-based acidified food products with pH 4.5 and below and are relevant to small processors of tomato-based acidified canned foods who do not have the resources to conduct research on and validate pathogen lethality.

scholarly journals Organic Matter, Solid and Pathogen Removals from Black Water in A Pilot-Scale Solar Septic Tank

2020 ◽  
pp. 74-83
Author(s):  
Tatchai Pussayanavina ◽  
Thammarat Koottatep ◽  
Le My Dinh ◽  
Sopida Khamyai ◽  
Wattanapong Sangchun ◽  
...  
Keyword(s):  
Nutrient Loading ◽  
Oxygen Demand ◽  
Total Solid ◽  
Pilot Scale ◽  
Septic Tank ◽  
Operational Conditions ◽  
E Coli ◽  
Log Reduction ◽  
Black Water ◽  
Solar Powered

Demonstrating the operational feasibility of a solar-powered septic tank as an alternative and sustainable sanitation option for communities was presented in this study. The efficiency and technical feasibility of a solar septic tank (SST) were tested and evaluated in pilot scale for treatment of black water from communal toilets. The system consisted of a modified septic tank equipped with a disinfection chamber inside the tank. Solar radiation was collected as a heat source for heating and disinfection. The system could achieve high removal efficiencies of total chemical oxygen demand (TCOD), 5-day biological oxygen demand (BOD5), total solid (TS), and total volatile solid (TVS) of 97%, 94%, 91% and 96%, respectively. The inactivation efficiencies of E. coli and total coliforms in the SST were about 2.2 log reduction. The increased temperature inside the septic tank could help to inactivate pathogens and reduce the environmental issues related to conventional fecal sludge management. In turn, this improved the water quality of groundwater and surface water and minimize health risks. Influence of operational conditions including organic/nutrient loading rate and ratio between TCOD and TKN in the black water on the performance of the SST were discussed.

Ultraviolet inactivation of bacteria and model viruses in coconut water using a collimated beam system

2019 ◽  
Vol 25 (7) ◽  
pp. 562-572 ◽  
Author(s):  
Manreet S Bhullar ◽  
Ankit Patras ◽  
Agnes Kilonzo-Nthenge ◽  
Bharat Pokharel ◽  
Michael Sasges
Keyword(s):  
Pathogenic Bacteria ◽  
Microbial Inactivation ◽  
Coconut Water ◽  
Inactivation Kinetics ◽  
E Coli ◽  
Log Reduction ◽  
Ultraviolet C ◽  
Log Linear ◽  
Kinetics Of ◽  
Collimated Beam

This study investigated the effect of ultraviolet-C irradiation on the inactivation of microorganisms in coconut water, a highly opaque liquid food (1.01 ± 0.018 absorption coefficient). Ultraviolet-C inactivation kinetics of two bacteriophages (MS2, T1UV) and three surrogate bacteria ( Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes) in 0.1% (w/v) peptone and coconut water were investigated. Ultraviolet-C irradiation at 254 nm was applied to stirred samples, using a collimated beam device. A series of known ultraviolet-C doses (0–40 mJ cm−2) were applied for ultraviolet-C treatment except for MS2 where higher doses were delivered (100 mJ cm−2). Inactivation levels of all organisms were proportional to ultraviolet-C dose. At the highest dose of 40 mJ cm−2, three surrogates of pathogenic bacteria were inactivated by more than 5-log10 (p < 0.05) in 0.1% (w/v) peptone and coconut water. Results showed that ultraviolet-C irradiation effectively inactivated bacteriophage and surrogate bacteria in highly opaque coconut water. The log reduction kinetics of microorganisms followed log-linear and exponential models with higher R2 (>0.95) and low root mean square error values. The D10 values of 3, 5.48, and 4.58 mJ cm−2 were obtained from the inactivation of E. coli, S. Typhimurium, and L. monocytogenes, respectively. Models for predicting log reduction as a function of ultraviolet-C irradiation dose were found to be significant (p < 0.05). Fluid optics were the key controlling parameters for efficient microbial inactivation. Therefore, the ultraviolet-C dose must be calculated not only from the incident ultraviolet-C intensity but must also consider the attenuation in the samples. The results from this study imply that adequate log reduction of vegetative cells and model viruses is achievable in coconut water and suggested significant potential for ultraviolet-C treatment of other liquid foods.

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