Peracetic Acid Research Articles

Peracetic Acid Emissions and Exposures during Building Disinfection Events

Since the onset of the COVID-19 pandemic, there has been a significant increase in chemical disinfection of high-touch surfaces in buildings. Peracetic acid (PAA) is a commercially available and widely used disinfectant for inactivation of viruses and bacteria. The objective of this study is to evaluate indoor PAA emissions and exposures during full-scale building disinfection events via real-time PAA measurement in a test house. The measurements revealed that PAA-based surface disinfection can lead to a significant increase in PAA concentrations in indoor air (0.1–1 mg/m3). PAA emission factors (EFs) for spray-based products ranged from 0.22–0.59 mg of PAA emitted per mg of PAA sprayed, indicating that a significant fraction of the PAA applied to surfaces is emitted into the indoor atmosphere. Inhalation intake fractions (iFs) ranged from 1,597–3,436 ppm for a one-hour exposure period, demonstrating that around 0.16–0.34% of the PAA emitted into indoor air can be inhaled by an occupant during a disinfection event. iFs were similar between the active disinfection period and the subsequent concentration decay period, suggesting that inhalation intake is important both during and after the disinfectant is applied. Real-time breathing zone (BZ) experiments demonstrated that occupants can be exposed to elevated PAA concentrations beyond those measured in the bulk indoor air due to the source-to-BZ proximity effect inherent in disinfection processes. The PAA EFs enabled modeling of PAA dynamics in different indoor environments. Model results show that PAA concentrations often exceed exposure limits, indicating a need for improved exposure mitigation strategies.

Unraveling the multiple role of UV in PAA/Fe(III) advanced oxidation: Mechanism, efficiency, and toxicity analysis

In recent years, the advanced Fenton-like oxidation technology based on peracetic acid (PAA) has attracted increasing attention, while accelerating the cycle of Fe(III)/Fe(II) remains a limitation for widespread PAA/Fe(III) system application. Herein, in this study, the dual mechanism of UV synchronous acceleration of Fe(III)/Fe(II) cycling and activation of PAA was systematic investigated with the introduction of UV in PAA/Fe(III) systems. Results suggested that the target pollutant Rhodamine B (RhB) could achieve over 95% degradation within 12minutes in the Fe (III)/PAA/UV system. The crucial roles of UV radiation has been determined to activate PAA independently, and synchronously accelerates the transfer of Fe (III) to Fe (II) to generate hydroxyl radicals (·OH), while also enhancing the generation of Fe (IV), ultimately achieving a redox cycle in Fe (III)/PAA/UV system. The ·OH, Fe(IV) and organic free radicals (R-O·) were identified as the mainly active substances via the various analysis methods including characteristic product detection, quenching experiments, electron paramagnetic resonance (EPR), and fluorescence analysis, and the contribution to the RhB degradation followed as ·OH(68.61%) > Fe(IV) (17.52%) > R-O·(11.69%). 12 intermediates and two potential degradation pathways of RhB were identified by combining density functional theory (DFT) calculations and Ultra-Performance Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry (UPLC-QTOF-MS) analyses, and the ecotoxicity was evaluated through Ecological Structure Activity Relationships (ECOSAR) program. Response surface methodology was employed to analyze optimal degradation conditions, considering Fe(III) and PAA dosage, pH, and inhibitory effects of anions. This study systematically revealed the internal mechanism of Fe(III)/PAA/UV system for organic pollutant degradation and verified its efficiency and eco-friendliness.

Attachment and removal of porcine rotavirus (PRV) and Tulane virus (TV) on fresh and artificial phylloplanes of Romaine lettuce and Carmel spinach as affected by ultrasonication in combination with oxidant- or surfactant-based sanitizer(s).

This work examined the attachment of porcine rotavirus (PRV) and Tulane virus (TV), a surrogate for human norovirus, to fresh and artificial phylloplanes of Romaine lettuce and Carmel spinach. The effect of produce type, sanitizer, and ultrasound treatment on removal of PRV and TV from produce and artificial surfaces was also investigated. Sanitization was performed with two oxidant-based sanitizers (chlorine and peroxyacetic acid) and one surfactant-based sanitizer (0.5% malic acid +0.05% thiamine lauryl sulfate) in combination with ultrasound. PRV and TV were spot inoculated to fresh and artificial produce surfaces and treated for 1min with a sanitizing solution with and without ultrasound. No significant differences were observed in the attachment of PRV and TV to fresh and artificial leaf surfaces. The removal of PRV from produce leaves treated by different sanitizers was significantly higher than that of TV. No difference in viral removal between the fresh and artificial produce surfaces was found. The addition of ultrasound significantly increased viral removal from both type of produce surfaces. The removal of virus attached to fresh and artificial phylloplanes was virus-type, sanitizer-type, and produce cultivar dependent. Artificial phylloplanes may provide a novel platform for screening of sanitizers in food safety applications.

Efficacy and mechanism of peracetic acid activation with CuFeS2 to degrade tetracycline: Synergy of copper and iron species

Efficacy and mechanism of peracetic acid activation with CuFeS2 to degrade tetracycline: Synergy of copper and iron species

Efficient degradation of sulfonamides by high-valence cobalt-oxo species in Co(OH)2@chitosan activated peracetic acid advanced oxidation system

Efficient degradation of sulfonamides by high-valence cobalt-oxo species in Co(OH)2@chitosan activated peracetic acid advanced oxidation system

Hydroxylamine hydrochloride enhanced Fe-C nano-microelectrolytic material for efficient peracetic acid activation: Proton/electron synergistic effect

Hydroxylamine hydrochloride enhanced Fe-C nano-microelectrolytic material for efficient peracetic acid activation: Proton/electron synergistic effect

Rapid and selective spectrophotometric determination of peracetic acid in water via oxidative coloration of N,N-diethyl-p-phenylenediamine with the assistance of Co(II)

Rapid and selective spectrophotometric determination of peracetic acid in water via oxidative coloration of N,N-diethyl-p-phenylenediamine with the assistance of Co(II)

P-263. Sodium dichloroisocyanurate: A promising candidate for the disinfection of resilient drain biofilm

Abstract Background Biofilms are complex multicellular communities of microorganisms which can lead to a variety of human diseases and infections. Biofilms consist of microbes which are contained within a protective extra polymeric substance layer, resulting in increased resistance to disinfectants. From an economic perspective, it is estimated that potentially deadly biofilms, which cause 1.7 million hospital acquired infections (HAIs) each year in the US, can result in costs of $11.5 billion in treatment. Biofilms thrive in a variety of diverse environments, including hospital sinks and drains, which can pose a significant threat to patient safety. Sink drains maintain one of the highest burdens of antibiotic resistant bacteria amongst all other surfaces, with Pseudomonas aeruginosa consistently being the most prominent species found within ICU sink drains. Studies have shown that by completely removing sinks from patient rooms, there is a significant reduction in the colonisation of gram-negative bacteria, a leading cause of HAIs. Methods The aim of this study was to determine if three hospital-grade disinfectants were capable of killing biofilm, and as such, if they could be used as potential drain disinfectants. Disinfectants were comprised of Sodium Dichloroisocyanurate (NaDCC), Peracetic acid and bleach-based disinfectants. Pseudomonas aeruginosa biofilms were cultivated using the CDC biofilm reactor, a standardised method for determining biofilm efficacy within the United States. Results The NaDCC product was successful in completely killing the biofilm (using a one-minute contact time), resulting in a total 8.70 log reduction. Peracetic acid reduced biofilm by 3.82 logs, followed by bleach, which had the lowest reduction at 3.78 logs. Conclusion Drain disinfection is critical to ensure patient safety and reduce the instances of HAIs. This experiment can help in predicting the effectiveness of three hospital disinfectants for drain applications. NaDCC could provide a reliable solution for drain applications and subsequent patient safety. Disclosures Abbbie Martin, BsC, Kersia Ireland: Employee Tom O'Mahony, PhD, Kersia Ireland: Employee Natasha Doyle, PhD, Kersia Ireland: Employee

P-284. Effect of Different Disinfection Methods on Hospital Sink Drain Disinfection

Abstract Background A commercially available foaming disinfectant containing hydrogen peroxide, peracetic acid, and octanoic acid is EPA-registered for biofilm disinfection in sink drains, but recolonization occurs quickly. We evaluated the impact of adding physical removal of bioburden to foaming disinfectant use on bacterial colonization in sink drains. Methods We conducted a longitudinal study in a level-IV neonatal intensive care unit (NICU) at an academic medical center in Baltimore, MD. The NICU has 52 single-patient rooms with sinks with removable drain plug covers. We included 20 unique rooms to investigate the effect of foaming disinfectant alone and coupled with physical removal of biofilm through (1) mechanical cleaning with a brush, and (2) replacement of drain cover (Figure 1). In addition, we sampled 10 room sinks as control (no intervention). Samples were collected from 2 inches below the sink drain and underside of the drain cover using a polyester tripped swab (Puritan ESK environmental sampling kit with neutralizing buffer) at baseline (day 0) and days 1, 3, 5, and 7 post-intervention. Samples were serially diluted, plated on MacConkey II agar (Becton Dickinson), and incubated for 24 hours at 35+2°C. Colony-forming units (CFU) of total gram-negative bacilli (GNB) were calculated. The primary outcome was the difference in GNB burden (mean log CFUs) from baseline at each time point, for each intervention strategy, compared using paired t-test. Results Baseline counts for all groups including control were similar. On day 1, we found significant reductions from baseline for each intervention strategy, with differences from baseline becoming smaller over time. There was no significant change in GNB counts for the control group at any time point (Figure 2, Table 1). Strategies with mechanical cleaning (vs without) performed better for sinks, whereas sink cover change (vs without) resulted in greater log reductions in the cover bioburden through day 7 (Figure 2, Table 1). Conclusion Physical bioburden removal improved the effect of a foaming disinfectant on GNB counts in hospital sink drains. The impact of this strategy on hospital-acquired infections needs to be studied. Disclosures J Kristie Johnson, PhD, D (ABMM), biomerieux: has given presentations/speeches for the company listed above

P-255. Evaluation of automated disinfectant dispenser systems in 6 hospitals demonstrates a need for improved monitoring to ensure that correct disinfectant concentrations are delivered

Abstract Background Automated dispensers that dilute concentrated disinfectants with water are commonly used in healthcare facilities. However, most facilities do not perform routine monitoring to ensure that the dispensers are functioning correctly and being used as recommended by the manufacturer.Table 1.Concentrations of disinfectant measured in samples obtained from automated dispensers and from in-use buckets on environmental services carts in 6 hospitalsQA, quaternary ammonium disinfectant; PA, peracetic acid-based disinfectant.a. Expected concentrations, ∼1,300 parts per million (PPM) for PA and ∼800 PPM for QA; higher-than-expected concentration of peracetic acid, >1,800 ppm; b. Lower than expected concentration, 300-900 PPM for PA and 200-400 PPM for QA; cNo disinfectant detected, limit of detection (∼300 PPM for PA and ∼150 PPM for QA); d. Wrong product, the in-use product that was supposed to be PA or QA was a detergent intended for floors. Methods In 6 acute care hospitals in Northeast Ohio, we tested disinfectant concentrations and pH of products obtained from automated dispensers and in-use containers from environmental services (EVS) personnel carts. The disinfectants included quaternary ammonium (800 parts per million [ppm]; pH 8) and peracetic acid-based products (∼1300 ppm; pH 3). Results All 6 hospitals had 1 or more malfunctioning dispensers (Table 1). Of 57 systems assessed, 14 (25%) dispensed products with lower-than-expected concentrations, including 8 (14%) with no detectable disinfectant (i.e., water). Nine of 62 (15%) in-use products had no detectable disinfectant, and 4 (7%) were the wrong product (i.e., a detergent for floors used for high-touch surfaces). Reasons for dispenser malfunction included incorrect connection of the concentrate container, dysfunction of a low-product indicator, and failure to change the concentrate container when indicated. pH measurements identified disinfectants with lower-than-expected concentrations, and an intervention that included monitoring was effective in ensuring that the dispensers were operating correctly. Conclusion Improved monitoring of automated disinfectant dispenser systems in healthcare facilities is needed to ensure patient safety. pH measurements could provide a simple means to ensure that dispensers are functioning correctly. Disclosures Elie Saade, MD, MPH, FIDSA, Janssen Global Services: Advisor/Consultant|Janssen Global Services: Advisor/Consultant|Janssen Research and Development: Advisor/Consultant|Janssen Research and Development: Advisor/Consultant Curtis Donskey, MD, Clorox: Grant/Research Support|Pfizer: Grant/Research Support

Antimicrobial Effectiveness of Clove Oil in Decontamination of Ready-to-Eat Spinach (Spinacia oleracea L.).

Due to an increased demand for natural food additives, clove oil was assessed as a natural alternative to chemical disinfectants in produce washing. This study assessed the antimicrobial activity of 5 and 10% (v/v) clove oil-amended wash liquid (CO) using a zone of inhibition (ZIB) test and determined the time required to completely inactivate pathogenic bacteria using bacterial death curve analysis. A washing experiment was used to evaluate CO's ability to inhibit bacterial growth on inoculated RTE spinach and in the wash water. The findings showed that Shigella flexneri, Salmonella Typhimurium, and Salmonella enterica recovery were completely inhibited within 5 min. Escherichia coli and Staphylococcus aureus recovery were completely inhibited at 10 and 30 min, respectively. The ZIB test showed that 5% CO had the highest inhibitory effect on both Salmonella strains and E. coli with approximately 10 mm ZIB diameter. Additionally, 5% CO completely inactivated all bacterial strains on spinach samples and in the wash water except for S. aureus. A total of 80 mg/L peracetic acid (PAA) resulted in >2log CFU/mL recovery on experimental washed samples. These findings suggest that 5% CO was highly effective in inhibiting microbial growth on RTE spinach, potentially contributing to sustainable food safety and shelf-life extension strategies.

Experimental study of extracellular vesicle-small intestine submucosa novel biological composite for urethral stricture repair and reconstruction

Background Urethral stricture (US) is a common condition that considerably affects patients’ quality of life. Objectives This study aimed to explore the adoption value of the extracellular vesicle (EV)- small intestinal submucosa (SIS) complex in the repair of USs. Methods EVs were extracted from healthy male New Zealand white rabbits, and SIS was prepared using peracetic acid (PAA) oxidation and decellularization. The morphology and particle size of the prepared EV-SIS complex were evaluated using electron microscopy and qNano nanoparticle analyzer, and the labeled proteins of EVs were detected using Western blot method. EV-SIS the complex was implanted in a rabbit model of US, and urodynamic parameters were assessed. Results The EV-SIS complex displayed a full morphology, intact membrane structure, and uniform particle size. The protein concentration of EVs in the complex was approximately 0.351 µg/µL, with a yield of approximately 1.86 µg/106 cells. The complex exhibited remarkable repair effects in the rabbit model of US, with bladder capacity, maximal urethral pressure, and minimal urethral pressure all markedly superior to those in the US group ( P < 0.05). Conclusion The EV-SIS complex demonstrates potential clinical value in the repair of USs, improving urodynamic parameters, and offering a promising therapeutic option for patients with US.

Emerging biofilm formation and disinfectant susceptibility of ESBL-producing Klebsiella pneumoniae

Klebsiella pneumoniae is an opportunistic pathogen responsible for various infections in humans and animals. It is known for its resistance to multiple antibiotics, particularly through the production of Extended-Spectrum Beta-Lactamases (ESBLs), and its ability to form biofilms that further complicate treatment. This study aimed to isolate and identify K. pneumoniae from animal and environmental samples and assess commercial disinfectants’ effectiveness against K. pneumoniae isolates exhibiting ESBL-mediated resistance and biofilm-forming ability in poultry and equine farms in Giza Governorate, Egypt. A total of 320 samples, including nasal swabs from equine (n = 60) and broiler chickens (n = 90), environmental samples (n = 140), and human hand swabs (n = 30), were collected. K. pneumoniae was isolated using lactose broth enrichment and MacConkey agar, with molecular confirmation via PCR targeting the gyrA and magA genes. PCR also identified ESBL genes (blaTEM, blaSHV, blaCTX-M, blaOXA-1) and biofilm genes (luxS, Uge, mrkD). Antimicrobial susceptibility was assessed, and the efficacy of five commercial disinfectants was evaluated by measuring inhibition zones. Klebsiella pneumoniae was isolated from poultry (13.3%), equine (8.3%), wild birds (15%), water (10%), feed (2%), and human hand swabs (6.6%). ESBL and biofilm genes were detected in the majority of the isolates, with significant phenotypic resistance to multiple antibiotics. The disinfectants containing peracetic acid and hydrogen peroxide were the most effective, producing the largest inhibition zones, while disinfectants based on sodium hypochlorite and isopropanol showed lower efficacy. Statistical analysis revealed significant differences in the effectiveness of disinfectants against K. pneumoniae isolates across various sample origins (P < 0.05). The presence of K. pneumoniae in animal and environmental sources, along with the high prevalence of ESBL-mediated resistance and biofilm-associated virulence genes, underscores the zoonotic potential of this pathogen. The study demonstrated that disinfectants containing peracetic acid and hydrogen peroxide are highly effective against ESBL-producing K. pneumoniae. Implementing appropriate biosecurity measures, including the use of effective disinfectants, is essential for controlling the spread of resistant pathogens in farm environments.

New insights into the Fe(III)-activated peroxyacetic acid: Oxidation properties and mechanism.

Iron-activated peroxyacetic acid (PAA) represents an innovative advanced oxidation process (AOP). However, the efficiency of PAA activation by Fe(III) is often underestimated due to the widespread assumption that Fe(III) exhibits much lower ability than Fe(II) to activate PAA. Herein, the oxidative degradation of Rhodamine B (RhB) by Fe(III)-activated PAA process was investigated, and some new insights into the performance and mechanism of the Fe(III)/PAA system were presented. Although the reaction rate of Fe(III) with PAA was slightly slower than that of Fe(II), Fe(III) was still able to activate PAA effectively, and the degradation efficiency of RhB was comparable to that of the Fe(II)/PAA system after 30min of reaction. Notably, the Fe(III)/PAA system demonstrated superior oxidation capacity compared to conventional oxidant systems, including Fe(III)/H2O2, Fe(III)/PDS, Fe(III)/PMS. The degradation efficiency varied significantly across different water substrates. While Cl- exhibited a certain inhibitory effect on the degradation of RhB, H2PO4- exerted a pronounced inhibitory influence, whereas NO3-, SO42- and HCO3- had negligible effects. The increase of humic acid (HA) showed a facilitating effect in the initial stage, followed by an inhibitory effect. Furthermore, mechanistic studies indicated that H2O2 in PAA solution was not effectively activated. The degradation of RhB primarily occurred through a non-radical pathway generated by PAA activation, with the contribution of reactive species (RS) in the order of FeIVO2+>•OH>R-O• (CH3COO• and CH3COOO•). RhB degradation was achieved not only by attacking the chromophore of RhB molecules, but also the effective destruction of the stable structures such as benzene rings. This study enhances the understanding of Fe(III)-activated PAA and broadens its potential for developing and applying PAA-based AOPs.

Assessing the Toxicity of Peracetic Acid to Parr, Smolt, and Post‐Smolt Atlantic Salmon Salmo salar in RAS Water

The risk associated with the presence of bacterial and fungal pathogens in recirculating aquaculture systems (RASs) has resulted in an industry‐wide need for low‐cost, safe, and effective disinfectants. The toxicity of peracetic acid (PAA) to Atlantic salmon (Salmo salar) eggs, fry, and fingerlings (~16.3 g) in freshwater RAS water has been previously assessed; however, its toxicity to later juvenile life‐stages was yet to be investigated. The 24‐h LC50 value of PAA was determined for parr ( = 47 g), smolt ( = 66.5 g), and post‐smolt ( = 176.7 g) Atlantic salmon in RAS water static PAA treatments. The 24‐h LC50 values were calculated using the trimmed Spearman–Karber (TSK) method and toxicity relationship analysis program (TRAP). TRAP LC50 values for parr, smolt, and post‐smolt were 4.26, 4.27, and 4.78 mg/L PAA, respectively, while TSK LC50 values for parr, smolt, and post‐smolt were 4.27, 3.94, and 4.65 mg/L PAA, respectively. These 24‐h LC50 values provide novel guidance for developing safe PAA treatment protocols for Atlantic salmon parr, smolt, and post‐smolt in freshwater RAS, although the influence of varying water quality scenarios needs to be considered.

Dynamic electrode reconfiguration promotes in situ electrochemical peracetic acid synthesis for selective water decontamination.

In situ synthesis and activation of peracetic acid (PAA) for water decontamination is a promising way to overcome the transport and storage problems in PAA applications. Here, an in situ electrochemical PAA synthesis and activation system is constructed using RuO2-Ti "active" electrode and graphite plate as the anode and the cathode, respectively. PAA is efficiently generated at the RuO2-Ti anode with a maximum real-time concentration of ∼1020 μM and a negligible precursor loss of 2.91 % after 180 min, and can be activated at the cathode to destruct a refractory pollutant (i.e., benzoic acid (BA)) with the rate constant of 0.22-0.28 h-1, even under the interference of co-existing anions. Multiple pieces of evidence, including differential electrochemical mass spectrometry, sulfoxide probing test, and electron paramagnetic resonance spectroscopy, indicate that the oxygen-atom-transferring oxidation of CH3COO- by a high-valent ruthenium-oxo intermediate (i.e., RuO3) in situ formed through the electrode reconfiguration between RuO2 and chem-sorbed HO• mainly accounts for PAA synthesis. Acetylperoxyl radical (CH3C(O)OO•) was evidenced as the dominant species for BA degradation. This study proposes an in situ strategy to electrochemically synthesize and activate PAA for selective water decontamination and enriches the understandings of the mechanism of "active" electrode in peroxide synthesis.

Odorant production surges induced by exogenous oxidative stress: An overlooked risk in PAA-based moderate preoxidation for algal-laden water.

Moderate preoxidation is feasible for odor-producing algae treatments, usually requiring trade-offs in algal removal and integrity maintenance. However, dosing oxidants may cause internal oxidative homeostasis imbalances and secondary odorous metabolite responses, adding new trade-offs for moderate treatments. Peracetic acid (PAA)/Fe processes are promising strategies in moderate treatments and thus were applied to examine how to achieve the following three trade-offs: good algal removal, no odorant increases and no releases. For algal removal, the highest removal efficiency was 71.1 %, 87.0 % and 98.1 %, respectively, in PAA/Fe(Ⅲ) separate, PAA/Fe(Ⅱ) separate and PAA/Fe(Ⅱ) simultaneous process. Odorant responses always followed a pattern of "promotion-low dosages, inhibition-high dosages", with the highest production reaching 3.91-fold of the control without PAA addition, well above odorant threshold concentrations (500 ng/L). Instant releases did not occur, yet with delayed releases observed during sludge retention in sedimentation tanks (5, 16 h). It was verified that exogenous oxidative stress stimulated odorant generation with multiple reactive species. Among them, PAA oxidant was crucial in algal removal and odorant promotion; R-O· and ·OH caused odorant generation and degradation, respectively. Overall, PAA/Fe(Ⅱ) processes were more suitable for moderate treatments, simultaneously avoiding odorant increases and allowing sludge retention. This work provides a novel perspective for moderate preoxidation, highlighting instant odorant generation and delayed releases triggered by exogenous PAA stressors.

Efficacy of sodium hypochlorite and peracetic acid in reducing cross-contamination during washing of baby spinach at different water quality levels.

We evaluated the antimicrobial performance of sodium hypochlorite (NaOCl) and peracetic acid (PAA) during washing of baby spinach in water of varying levels of organic load, as measured by its chemical oxygen demand (COD). Escherichia coli TVS353 was spot inoculated onto one unwashed leaf. Sanitizers were added into water with preadjusted COD (300 or 2500ppm) to achieve concentrations from 20 to 80ppm. One inoculated leaf was washed with nine uninoculated leaves in 500mL water (n=6). Bacterial load on inoculated leaves was lowered by sanitizers in a dose-dependent manner (p<0.05) and the lowest bacterial survivor levels were observed at 80ppm with 2.7±1.2 and 5.1±0.5 Log MPN/leaf for PAA and NaOCl, respectively, at low CODs. PAA was more effective in reducing bacterial load from the inoculated leaf than NaOCl at high CODs (p<0.05), with 2.9±2.8 and 5.3±0.8 Log MPN/leaf survivors for PAA and NaOCl, respectively. At 80ppm sanitizer levels, the bacteria was not detected in wash water at any condition but was detected at 20 and 40ppm at high CODs. The lowest levels of bacteria transferred to uninoculated leaves were observed at 80ppm sanitizer, at 0.3±0.2 and 0.2±0.1 Log MPN/leaf for PAA and 1.1±1.0 and 0.3±0.3 Log MPN/leaf for NaOCl at low and high CODs, respectively. The log percentage of bacteria transferred ranged from -1.1 at 0ppm to over -4.5 at 80ppm, highlighting a reduction in cross-contamination by the sanitizers. PRACTICAL APPLICATION: This study provides effective data on sanitizer usage to fresh produce industry for ensuring food safety during washing of produce. It evaluated the sanitizer effect in a broad range of scenarios including various sanitizer concentrations, and wash water with low and high organic load that is common when recirculating wash water. The results also revealed the differences in two common sanitizers (PAA and NaOCl) in terms of their effectiveness.

Determination of an Effective Sanitizing Procedure for Listeria innocua in Personal Protective Equipment Used in Dairy Facilities.

The presence of Listeria monocytogenes in the dairy environment remains a food safety challenge. The source of microbial contamination may include employees and their personal protective equipment (PPE). This study investigated the effectiveness of cleaning protocols (i.e., detergents and mechanical action) and three chemical sanitizers commonly employed at dairy facilities against Listeria innocua contamination on different types of gloves, aprons, and boots. Coupons made of PPE material were inoculated with a two-strain cocktail of L. innocua suspended in either Phosphate Buffered Saline (PBS) or skim milk to determine the potential effect of organic matter. In general, peroxyacetic acid (0.20% (v/v)) was more effective at reducing Listeria counts on aprons and gloves compared to chlorine and quaternary ammonium at 200 ppm. Depending on the type of sanitizer, Listeria reductions ranged from 1.95 - 4.72 and 1.52 - 4.60 log CFU/in2 on aprons and gloves, respectively. In comparison, sanitizers achieved a 0.93 - 2.32 log CFU/in2 reduction on boot soles, with no significant differences observed among sanitizers. PVC (vinyl) gloves achieved lower Listeria log reductions than nitrile and latex gloves. Sanitizers were less effective on boots with wider and deeper lugs than those with shallow lugs. The presence of organic matter significantly reduced the antimicrobial efficacy of all sanitizers (<1 log CFU/in2 reduction). However, the inclusion of cleaning protocols with and without mechanical action achieved a ≥3 log CFU/in2 reduction in the different types of PPE. This study highlights the importance of scrubbing as an essential step to reduce Listeria on PPE.

Microbiological hazards associated with the use of water in the post‐harvest handling and processing operations of fresh and frozen fruits, vegetables and herbs (ffFVHs)

Abstract This tender, developed under a self‐task mandate from the BIOHAZ Panel, analysed the characteristics of the water and the practices followed by the European food business operators (FBOs) to maintain process water quality used during the post‐harvest handling and processing operations for fresh and frozen fruits, vegetables and herbs (ffFVHs) using: information and data obtained from FBOs, experimental data extracted from literature and dynamic mass balance modelling. Quantitative data were obtained from 61 FBO scenarios (29 from the fresh‐whole sector, 19 from the fresh‐cut sector, and 13 from the frozen sector). The impact of no water treatment was evaluated in 17 scenarios, while in 44, the challenges of maintaining the microbiological quality with water disinfection agents were examined, including chlorine, peroxyacetic acid, and hydrogen peroxide. The findings highlighted that when no water disinfection treatment was used Listeria monocytogenes was detected in some scenarios of the fresh‐whole and frozen FVH sectors as well as Salmonella, pathogenic Escherichia coli and norovirus in the fresh‐cut and frozen FVH sector. Additionally, inadequate or improper monitoring systems resulted in either excessively high or insufficient disinfectant concentrations in the water, which, when too low, failed to sufficiently reduce the microbial load. The literature review revealed a tendency to: focus on leafy greens, use chlorine‐based disinfectants, and employ chemical oxygen demand (COD) as the primary physico‐chemical parameter, with total dissolved solids (TDS) and turbidity considered to a lesser extent, as indicators of water quality. Additionally, dynamic mass balance modelling was used to interpret experimental data from literature and FBOs. The model was fundamental to estimate key unknown parameters, predict the microbial contamination and accumulation of organic matter and allowing to simulate “what‐if scenarios.”