Ppm Chlorine Research Articles

Evaluation of Commercially Available Sanitizers Efficacy to Control Salmonella (Sessile and Biofilm Forms) on Harvesting Bins and Picking Bags

This study evaluated the efficacy of five commercially available sanitizers to reduce Salmonella (sessile and biofilm forms) count on experimentally inoculated materials representative of harvesting bins and picking bags in the fresh produce industry. Sessile Salmonella cells were grown onto tryptic soy agar to create a bacterial lawn, while multistrain Salmonella biofilms were grown in a Centers for Disease Control and Prevention (CDC) reactor at 22 ± 2 °C for 96 h. Samples were exposed to 500 ppm free chlorine, 500 ppm peroxyacetic acid (PAA), 75 psi steam, and 5% silver dihydrogen citrate (SDC) for 30 sec, 1, or 2 min or 100 ppm chlorine dioxide gas for 24 h. Sanitizer, surface type, and application time significantly affected the viability of Salmonella in both sessile and biofilm forms (P < 0.05). All treatments resulted in a significant reduction of Salmonella when compared to the control (P < 0.05). Chlorine dioxide gas was the most effective treatment in both sessile and biofilm forms regardless of the type of surface, and it achieved a 5-log reduction. PAA at 500 ppm applied for 2 min was the only liquid sanitizer that resulted in a greater than 3-log reduction in all surfaces. Scanning electronic microscopy demonstrated the porous surface nature of nylon and wood, compared to HDPE, impacted sanitizer antimicrobial activity. Understanding the efficacy of sanitizers to control Salmonella on harvesting bins and picking bags may improve the safety of fresh produce by increasing available sanitizing treatment.

Occurrence of chlorine-resistant Pseudomonas aeruginosa in hospital water systems: threat of waterborne infections for patients

BackgroundSeveral healthcare-associated infection outbreaks have been caused by waterborne Pseudomonas aeruginosa exhibiting its ability to colonize water systems and resist conventional chlorine treatment. This study aims to investigate the occurrence of Pseudomonas aeruginosa in hospital drinking water systems and the antimicrobial resistance profiles (antibiotic and chlorine resistance) of isolated strains.MethodsWe investigated the presence of Pseudomonas aeruginosa in water and biofilms developed in nine hospital water systems (n = 192) using culture-based and molecular methods. We further assessed the survival of isolated strains after exposure to 0.5 and 1.5 ppm concentrations of chlorine. The profile of antibiotic resistance and presence of antibiotic resistance genes in isolated strains were also investigated.ResultsUsing direct PCR method, Pseudomonas aeruginosa was detected in 22% (21/96) of water and 28% (27/96) of biofilm samples. However, culturable Pseudomonas aeruginosa was isolated from 14 samples. Most of P. aeruginosa isolates (86%) were resistant to at least one antibiotic (mainly β-lactams), with 50% demonstrating multidrug resistance. Moreover, three isolates harbored intI1 gene and two isolates contained blaOXA−24,blaOXA−48, and blaOXA−58‌ genes. Experiments with chlorine disinfection revealed that all tested Pseudomonas aeruginosa strains were resistant to a 0.5 ppm concentration. However, when exposed to a 1.5 ppm concentration of chlorine for 30 min, 60% of the strains were eliminated. Interestingly, all chlorine-resistant bacteria that survived at 30-minute exposure to 1.5 ppm chlorine were found to harbor the intI1 gene.ConclusionsThe detection of antimicrobial resistant Pseudomonas aeruginosa in hospital water systems raises concerns about the potential for infections among hospitalized patients. The implementation of advanced mitigation measures and targeted disinfection methods should be considered to tackle the evolving challenges within hospital water systems.

Effect of ozone, hydrogen peroxide, and chlorine solution in reduction of chlorpyrifos and cypermethrin residues from cauliflower

The extensive utilization of chlorpyrifos and cypermethrin in agriculture raises concerns regarding the accumulation of pesticide residues in human food, posing a threat to human health. This study aimed to investigate the effect of ozonation on cauliflower to decrease the level of pesticides. Cypermethrin and organophosphate chlorpyrifos were applied to cauliflower at specific doses. High-performance liquid chromatographic techniques were employed to detect pesticide residues in cauliflower. The effects of common oxidizers (hydrogen peroxide, chlorine, and ozone) on the reduction of pesticide residues were investigated. Solutions of hydrogen peroxide (10 and 100 ppm), chlorine (10 and 100 ppm), and ozone (10 and 100 ppm) were prepared, and the cauliflower sample was immersed for 20 min. The immersion in 10 ppm hydrogen peroxide solution reduced chlorpyrifos and cypermethrin by 68 and 65%, respectively. Meanwhile, at 100 ppm hydrogen peroxide solution, the reduction rates of chlorpyrifos and cypermethrin residues were 72 and 75%, respectively. Immersion in ozone solution at 10 ppm concentration reduced chlorpyrifos and cypermethrin by 58 and 57%, respectively. At 100 ppm ozone, chlorpyrifos was reduced up to 64%, and cypermethrin reduction was 74%. Chlorine immersion at 10 ppm reduced chlorpyrifos residues by 68% and cypermethrin residues by 81%, while a 100 ppm chlorine solution reduced chlorpyrifos residues by 100% and cypermethrin residues by 84%. From these results, it was concluded that chlorine was the most effective of all the cleaning solutions to remove pesticides from vegetables.

Magma recharge in persistently active basaltic–andesite systems and its geohazards implications: the case of Villarrica volcano, Chile

We report whole-rock chemistry, mineral chemistry, and volatile content from Villarrica volcano’s major recent paroxysms and background activity. Composition of the volcanic products are basalt to basaltic andesite with whole-rock SiO2 content between 50 and 56 wt%, and a mineralogy dominated by olivine (Fo71-80), clinopyroxene (Mg# ~ 50) and plagioclase (An60–80). Volatile contents in melt inclusions are up to 1.5 wt% H2O, 500 ppm CO2, 1230 ppm sulfur and 580 ppm chlorine. Regardless of the type of activity, there are no substantial variations in whole-rock composition or the volatile content when the activity switches from background activity to a major paroxysm, strongly suggesting that this shift does not just depend on the arrival of new magma in the shallow magmatic system. Geothermobarometry constrains crystallization of the major mineral phases at various depths between 3 and 12.7 km, suggesting that degassing of a volatile-rich recharge magma occurs deeper than 12 km, producing efficient mixing throughout the whole system, and sustaining the lava lake activity in Villarrica’s summit crater. The occurrence of a permanent lava lake also suggests that the magma recharge must be close to continuous and therefore sudden changes between background and paroxysmal volcanic activity are likely controlled by relatively small changes in the rate of recharge and/or the volatile release rate in the magmatic system. This has important implications for the understanding of eruption triggers and the forecasting of volcanic eruptions.Graphical abstract

Evaluation of combined disinfection methods of infectious myonecrosis virus (IMNV) in seawater using Pacific white shrimp (Penaeus vannamei)

The global spread of infectious myonecrosis virus (IMNV) poses a serious threat to the shrimp aquaculture industry and urgent actions are needed to control its transmission and prevalence. Aquaculture water serves as an important route of IMN transmission, and disinfection of aquaculture water is crucial to ensure the health and stable production of shrimp. In this study, we introduced the purified IMNV into seawater and then subjected the seawater to different disinfection treatments (PMS, PMS + PVP-I and ClO2 + PVP-I) before culturing shrimp. By performing RT-qPCR tests on both the seawater and Pacific white shrimp (Penaeus vannamei) samples, we evaluated the effectiveness of the different disinfection methods in eradicating IMNV from the seawater. The results showed that peroxymonosulfate (PMS) could effectively reduce the viral load of IMNV in seawater samples. The combined disinfection approach (10 ppm) of PMS disinfection (combined with povidone‑iodine) followed by a standing time of at least 2 days, or 10 ppm chlorine dioxide disinfection (combined with povidone‑iodine) followed by a standing time of at least 4 days, were found to be successful in the efficient disinfection of IMNV. This research provides a method to effectively remove IMNV from marine aquaculture water, thereby contributing to reducing the risk of IMN disease transmission and providing a sound basis for the sustainable and healthy development of the shrimp aquaculture industry.

Assessing the stability and sporicidal efficacy of oxidizing disinfectants

The role of the healthcare environment in the transmission of clinical pathogens is well established. EN 17126:2018 was developed to address the need for regulated sporicidal product testing and includes a realistic medical soil to enable validation of products that claim combined cleaning and disinfection efficacy. To investigate the chemical stability and sporicidal efficacy of oxidizing disinfectant products in the presence of simulated clean and medical dirty conditions. Disinfectant stability and sporicidal efficacy were evaluated in like-for-like ratios of soil:product. Disinfectants were exposed to simulated test soils and free chlorine, chlorine dioxide or peracetic acid concentrations were measured using standard colorimetric methods. Efficacy of disinfectants against C. difficile R027 endospores was assessed as per EN 17126:2018. Comparisons of performance between clean and medical dirty conditions were performed using one-way analysis of variance. Correlation analysis was performed using Pearson product-moment correlation. Performance of chlorine-releasing agents (sodium dichloroisocyanurate, chlorine dioxide and hypochlorous acid) was concentration dependent, with 1000 ppm chlorine showing reduced stability and efficacy in dirty conditions. By contrast, peracetic acid product demonstrated stability and consistently achieved efficacy in dirty conditions. These results have implications for clinical practice, as ineffective environmental decontamination may increase the risk of transmission of pathogens that can cause healthcare-associated infections.

Biomarker profiling in plants to distinguish between exposure to chlorine gas and bleach using LC-HRMS/MS and chemometrics

Since its first employment in World War I, chlorine gas has often been used as chemical warfare agent. Unfortunately, after suspected release, it is difficult to prove the use of chlorine as a chemical weapon and unambiguous verification is still challenging. Furthermore, similar evidence can be found for exposure to chlorine gas and other, less harmful chlorinating agents. Therefore, the current study aims to use untargeted high resolution mass spectrometric analysis of chlorinated biomarkers together with machine learning techniques to be able to differentiate between exposure of plants to various chlorinating agents. Green spire (Euonymus japonicus), stinging nettle (Urtica dioica), and feathergrass (Stipa tenuifolia) were exposed to 1000 and 7500 ppm chlorine gas and household bleach, pool bleach, and concentrated sodium hypochlorite. After sample preparation and digestion, the samples were analyzed by liquid chromatography high resolution tandem mass spectrometry (LC-HRMS/MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS). More than 150 chlorinated compounds including plant fatty acids, proteins, and DNA adducts were tentatively identified. Principal component analysis (PCA) and linear discriminant analysis (LDA) showed clear discrimination between chlorine gas and bleach exposure and grouping of the samples according to chlorine concentration and type of bleach. The identity of a set of novel biomarkers was confirmed using commercially available or synthetic reference standards. Chlorodopamine, dichlorodopamine, and trichlorodopamine were identified as specific markers for chlorine gas exposure. Fenclonine (Cl-Phe), 3-chlorotyrosine (Cl-Tyr), 3,5-dichlorotyrosine (di-Cl-Tyr), and 5-chlorocytosine (Cl-Cyt) were more abundantly present in plants after chlorine contact. In contrast, the DNA adduct 2-amino-6-chloropurine (Cl-Ade) was identified in both types of samples at a similar level. None of these chlorinated biomarkers were observed in untreated samples. The DNA adducts Cl-Cyt and Cl-Ade could clearly be identified even three months after the actual exposure. This study demonstrates the feasibility of forensic biomarker profiling in plants to distinguish between exposure to chlorine gas and bleach.

Effect of TRPV4 Antagonist GSK2798745 on Chlorine Gas-Induced Acute Lung Injury in a Swine Model.

As a regulator of alveolo-capillary barrier integrity, Transient Receptor Potential Vanilloid 4 (TRPV4) antagonism represents a promising strategy for reducing pulmonary edema secondary to chemical inhalation. In an experimental model of acute lung injury induced by exposure of anesthetized swine to chlorine gas by mechanical ventilation, the dose-dependent effects of TRPV4 inhibitor GSK2798745 were evaluated. Pulmonary function and oxygenation were measured hourly; airway responsiveness, wet-to-dry lung weight ratios, airway inflammation, and histopathology were assessed 24 h post-exposure. Exposure to 240 parts per million (ppm) chlorine gas for ≥50 min resulted in acute lung injury characterized by sustained changes in the ratio of partial pressure of oxygen in arterial blood to the fraction of inspiratory oxygen concentration (PaO2/FiO2), oxygenation index, peak inspiratory pressure, dynamic lung compliance, and respiratory system resistance over 24 h. Chlorine exposure also heightened airway response to methacholine and increased wet-to-dry lung weight ratios at 24 h. Following 55-min chlorine gas exposure, GSK2798745 marginally improved PaO2/FiO2, but did not impact lung function, airway responsiveness, wet-to-dry lung weight ratios, airway inflammation, or histopathology. In summary, in this swine model of chlorine gas-induced acute lung injury, GSK2798745 did not demonstrate a clinically relevant improvement of key disease endpoints.

Microbial profile of broiler carcasses processed at a university scale mobile poultry processing unit

Chicken and chicken products have been associated with foodborne pathogens such as Salmonella, Campylobacter, and Escherichia coli (E. coli). Poultry comprises an important segment of the agricultural economy (75 million birds processed as of 2019) in West Virginia (WV). The risk of pathogens on processed chickens has risen with the increased popularity of mobile poultry processing units (MPPUs). This study evaluated the microbial safety of broilers processed in a MPPU in WV. This study assessed aerobic plate counts (APCs), E. coli counts and the presence/absence of Salmonella and Campylobacter on 96 broiler carcasses following each MPPU step of scalding, eviscerating, and chilling. Samples were either chilled in ice water only (W) or ice water with 5 ppm chlorine (CW). The highest number of bacteria recovered from carcasses were APCs (4.21 log10CFU/mL) and E. coli (3.77 log10CFU/mL; P = 0.02). A total reduction of 0.30 (P = 0.10) and 0.63 (P = 0.01) log10CFU/mL for APCs and E. coli, respectively, occurred from chilling carcasses in CW. Overall, results show that E. coli, Salmonella, and Campylobacter were significantly (P < 0.05) reduced from the initial scalding to the chilling step. However, Salmonella frequency doubled (15.63-34.38%) after the evisceration step, indicating that washing carcasses after evisceration may be a critical control point in preventing cross-contamination by Salmonella. Proper chilling is also an important microbial mitigation step in MPPU processing. Results indicate that Campylobacter was more resistant to chilling than Salmonella. Campylobacter was not completely inactivated until carcasses were chilled in CW, whereas W was sufficient to reduce Salmonella on carcasses. The results led to the conclusion that although 5 ppm chlorine (Cl2) achieved more bacterial reductions than water alone, the reductions were not always significant (P > 0.05). Further MPPU studies are needed to verify more effective chilling and processing strategies.

Gas ultrafine bubbles improve the efficacy of antimicrobials against eliminating fresh and aged Bacillus subtilis biofilms on various dairy processing surfaces

The objective of this research was to study the impact of incorporating gas ultrafine bubbles (UFB) on the efficacy of chlorine and peracetic acid antimicrobial (AM) solutions against Bacillus subtilis biofilms on polypropylene, silicone, and stainless-steel surfaces. B. subtilis biofilms were grown on coupons of various surfaces at 25 °C (for 3 and 30 days for fresh and aged biofilms, respectively) by immersing in B. subtilis inoculated brain heart infusion broth. The AM solutions (50, 100, and 200 ppm chlorine, and 20, 40, and 80 ppm peracetic acid) were prepared from the water incorporated with air, CO2, or N2 UFB. Coupons with biofilms were treated by submerging in AM solutions with or without UFB for 1 min. The AM solutions with CO2 UFB resulted in significantly higher log reductions (2.2–3.7 log CFU cm−2) of fresh and aged B. subtilis biofilms on all surfaces compared to AM solutions without UFB (1.2–2.5 log CFU cm−2).

Unlocking the Hidden Threat: Impacts of Surface Defects on the Efficacy of Sanitizers Against Listeria monocytogenes Biofilms on Food-contact Surfaces in Tree Fruit Packing Facilities

Food-contact surfaces showing signs of wear pose a substantial risk of Listeria monocytogenes contamination and may serve as persistent sources of cross-contamination in fresh produce packinghouses. This study offers a comprehensive exploration into the influence of surface defects on the efficacies of commonly used sanitizers against L. monocytogenes biofilms on major food-contact surfaces. The 7-day-old L. monocytogenes biofilms were cultivated on food-contact surfaces, including stainless steel, polyvinyl chloride, polyester, low-density polyethylene, and rubber, with and without defects and organic matter. Biofilms on those surfaces were subjected to treatments of 200 ppm chlorine, 400 ppm quaternary ammonium compound (QAC), or 160 ppm peroxyacetic acid (PAA). Results showed that surface defects significantly (P < 0.05) increased the population of L. monocytogenes in biofilms on non-stainless steel surfaces and compromised the efficacies of sanitizers against L. monocytogenes biofilms across various surface types. A 5-min treatment of 200 ppm chlorine caused 1.84–3.39 log10 CFU/coupon reductions of L. monocytogenes on worn surfaces, compared to 2.79–3.93 log10 CFU/coupon reduction observed on new surfaces. Similarly, a 5-min treatment with 400 ppm QAC caused 2.05–2.88 log10 CFU/coupon reductions on worn surfaces, compared to 2.51–3.66 log10 CFU/coupon reductions on new surfaces. Interestingly, PAA sanitization (160 ppm, 1 min) exhibited less susceptibility to surface defects, leading to 3.41–4.35 log10 CFU/coupon reductions on worn surfaces, in contrast to 3.68–4.64 log10 CFU/coupon reductions on new surfaces. Furthermore, apple juice soiling diminished the efficacy of sanitizers against L. monocytogenes biofilms on worn surfaces (P < 0.05). These findings underscore the critical importance of diligent equipment maintenance and thorough cleaning processes to effectively eliminate L. monocytogenes contamination on food-contact surfaces.

Exploring Washing Procedures for Produce Brush Washer

Previous environmental monitoring projects in food production facilities have revealed inconsistencies in how produce brush washer machines are cleaned after use; thus, the study of effective sanitation procedures for these machines is needed. Four chlorine solution treatments (ranging from 25 to 200 ppm), as well as a water-only treatment, were tested for efficacy in reducing bacterial loads for a selected small brush washer machine. Results indicate that rinsing with the machine’s power and water alone, a frequent practice among some produce processors, yielded a reduction of 0.91–1.96 log CFU per brush roller in bacterial counts, which was not statistically significant (p > 0.05). However, the chlorine treatments were found to be effective in reducing bacterial loads significantly, with higher concentrations being the most effective. The 200 ppm and 100 ppm chlorine treatments yielded bacterial reductions of 4.08 and 3.95 log CFU per brush roller, respectively, leaving bacterial levels statistically similar to the levels at postprocess decontamination, meaning these are the most effective at killing bacteria of all the chlorine concentrations tested. These data suggest the use of at least 100 ppm chlorine sanitizer solution is a good method to sanitize hard-to-clean produce washing machines, yielding an approximate 4 log CFU reduction of the inoculated bacteria.

Microbiological and physicochemical quality of tilapia fillets treated with ozone and chlorine solution and stored under refrigeration

Fish are foods of high nutritional value for the human diet. However, they deteriorate easily due to microbial activity. The combined action of sanitizing solutions on fillets, the antimicrobial and physicochemical effects of aqueous ozone and chlorine used to wash fillets were investigated immediately after application and during storage. The fillets were treated with demineralized water (control), 5 ppm chlorine solution (Cl), 5 ppm ozone solution (Oz) or 5 ppm chlorine solution with 5 ppm ozone (Cl+Oz). The proximate composition and pH of the fillets were not altered immediately after treatment. The mesophilic count decreased by 0.49 log CFU/g at Cl and 0.56 log CFU/g at Cl+Oz. The Cl treatment showed lower values of lipid oxidation, and the control and Cl treatments showed lower values for total volatile base nitrogen (TVB-N). The treatments did not differ from each other during storage; increases in lipids, TVB-N, lipid oxidation and mesophilic and psychrotrophic counts, as well as a reduction in proteins, were observed. These results were expected due to microbial degradation during storage. The results indicated that the combined action of the sanitizers regulated microbial activity better than the control but was not able to promote the shelf life of the product.

Use of Essential Oil Emulsions to Control Escherichia coli O157:H7 in the Postharvest Washing of Lettuce.

Essential oils (EOs) have strong antibacterial properties and can be potential sanitizers to reduce pathogen load and prevent cross-contamination during postharvest washing. The objective of this study was to investigate the efficacy of emulsions containing oregano (OR; Origanum vulgare) and winter savory (WS; Satureja montana) EOs at different concentrations (0.94 and 1.88 µL/mL) and storage times (0 h, 24 h, and 7 days), in reducing Escherichia coli O157:H7 on the surface of three types of lettuce (romaine, crisphead, and butterhead). The EO emulsions were compared with one no-rinse treatment and three rinse treatments using water, 200 ppm chlorine, and 80 ppm peroxyacetic acid (PAA), respectively, in a simulated washing system. The results showed that while the EO emulsions significantly reduced E. coli O157:H7 on crisphead lettuce over time, not all treatments were effective for romaine and butterhead lettuce. The mixture of OR and WS at concentrations of 0.94 and 1.88 µL/mL was found to be the most effective in reducing E. coli O157:H7 on inoculated lettuce, resulting in reductions of 3.52 and 3.41 log CFU/g, respectively. Furthermore, the PAA and the mixture of OR and WS at 1.88 µL/mL effectively limited bacterial cross-contamination close to the detection limit for all lettuce types during all storage times. These results suggest that OR and WS EOs could serve as potential alternatives to chemical sanitizers for postharvest lettuce washing.

Erratum: Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs.

Erratum: Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs.

Differential Expression of Antioxidant Enzymes in Chlorine-Resistant Acinetobacter and Serratia spp. Isolated from Water Distribution Sites in Mumbai: A Study on Mechanisms of Chlorine Resistance for Sustainable Water Treatment Strategies

Chlorination is a widely used process for disinfecting drinking water, but the emergence of chlorine-resistant bacteria has become a significant concern. While previous research has focused on identifying chlorine-resistant organisms, there has been limited investigation into the mechanisms behind chlorine resistance. Some bacterial isolates that display resistance to chlorine treatment may protect themselves using various mechanisms, including biofilm production, antibiotic resistance, horizontal transfer of antibiotic resistance genes, or producing antioxidant enzymes. Given that chlorination employs hypochlorous acid (HOCl), which is an extremely potent oxidizing agent, the most critical mechanism to investigate is antioxidant enzymes. This study investigated the antioxidant profile of eight chlorine-resistant isolates (three of the Serratia sp. and five of the Acinetobacter) after chlorine exposure. The profiles, both between and within species, were noticeably different. Among the isolates, Acinetobacter junii NA 3-2 showed a significant increase in the specific activity of superoxide dismutase, catalase, and ascorbate peroxidase after exposure to 20 ppm chlorine. In the guaiacol peroxidase (GPX) assay, only isolates belonging to Serratia marcescens showed GPX activity, and Serratia marcescens 3929-1 showed significant increase after exposure to 20 ppm of chlorine. None of the isolates belonging to Acinetobacter spp. showed GPX activity. Additionally, almost all control samples exhibited some enzyme activity, which may explain their survival against chlorine treatment in reservoirs. Principal component analysis revealed no strain-dependent similarities, while the balance of scavenging enzymes changed, as demonstrated in the heat map. Thus, this study suggests that antioxidant enzymes may be one mechanism of protection for some bacterial species against oxidative stress from chlorination, resulting in chlorine resistance. Understanding the mechanism of chlorine resistance is critical to identifying potential solutions. This study highlights the need to consider more modern approaches to disinfecting drinking water.

Seed Disinfestation Practices to Control Seed-Borne Fungi and Bacteria in Home Production of Sprouts.

Concern over microbial contamination limits the adoption of home production of sprouts as a nutritious and sustainable food. Simple, accessible approaches to seed disinfection could support safe home seed sprouting. Here, we quantify bacterial and fungal contamination of seeds of 14 plant cultivars sold for home sprout production and test a range of chemical and physical methods for seed disinfestation appropriate for home use. Most seeds are contaminated with a variety of bacteria and fungi, and those microbes are usually limited to the seed surface. Heat treatments are not effective for seed disinfection because the high temperatures needed to effectively reduce microbial contamination also reduce seed germination. Two chlorine-based chemical disinfectants-dilute household bleach (0.6% sodium hypochlorite) and freshly generated hypochlorous acid (800 ppm chlorine)-were the most effective disinfection agents tested (up to a 5-log reduction in bacteria) that also did not harm seed germination.

Application of Chitosan as Chlorine Substitution in Tilapia Fillet (Oreochromis sp.)

Chitosan has gained high interest in recent times to extend the shelf-life of fish product due to its nontoxicity, biodegradability, biocompatible and antibacterial activity. This research was aimed to determine the antibacterial effect of chitosan on the shelf-life of tilapia fillets at room temperature storage (25-27 oC). This study used a actorial randomized design (RAF) with two factors, namely antibacterial treatment consisting of 3 levels (positive control with distilled water immersion on tilapia fillets, immersion of tilapia fillets with 0.8% chitosan and negative control with 10 ppm chlorine immersion in tilapia fillet) and observation time consisted of 3 levels (0 hours, 6 hours and 12 hours observations). Antibacterial treatment consisted of 3 levels, namely. Each treatment was carried out in three replications. The data were analyzed using analysis of variance (ANOVA) and the duncan multiple range test (DMRT) at a 95% confidence level. The results of the research showed that chitosan was able to suppress bacterial growth and suppress the increase in TVB values at room temperature storage for 12 hours, indicated by the significant difference in the total number of bacteria and TVB values with chlorine and controls (p&lt;0.05). These indicated that chitosan has a function as a natural antibacterial to replace chlorine in the shelf-life extension of tilapia fillets.

Chlorine and ozone applications used for fruit and vegetable disinfection in tourism accommodation facilities

Samples of vegetable and fruit were taken from the kitchens of tourism accommodation facilities and microbiological analyses were made. The samples were analysed after being disinfected with 100 ppm chlorine for 2-10 minutes and with 2 ppm ozone for 2-10 minutes. In the examined vegetables and fruit samples, Escherichia coli, E. coli O157, Salmonella spp., Listeria monocytogenes were examined in terms of microorganisms. Before disinfection, E. coli was detected in all 30 samples: E. coli O157 in 8 samples, Salmonella spp. in 4 samples, and L. monocytogenes in 3 samples. As a result of disinfection applications with 100 ppm chlorine for 2 minutes, E. coli decreased by more than 45%. Salmonella spp. was detected in 1 sample and E. coli O157 was detected in 2 samples. After disinfection applications with 2 ppm ozone for 2 minutes, E. coli decreased by more than 60%. A decrease of more than 70% was observed in E. coli. after disinfection applications with 100 ppm chlorine for 5 minutes. As a result of disinfection applications with 2 ppm ozone for 5 minutes, E. coli decreased by more than 85%. No bacteria were found in the samples after disinfection with 100 ppm chlorine and 2 ppm ozone for 10 minutes. It was observed that there was a decrease in the microorganism loads as a result of the chlorination and ozonation processes of the vegetable and fruit samples.

Essential Oil Microemulsions Inactivate Antibiotic-Resistant Bacteria on Iceberg Lettuce during 28-Day Storage at 4 °C.

The objective of this study was to investigate the antimicrobial activities of essential oil-based microemulsions in the wash water against Escherichia coli O157:H7 and Pseudomonas fluorescens on Iceberg lettuce. Evaluated wash microemulsions included oregano oil, lemongrass oil, and cinnamon oil, along with a plant-based emulsifier for improved solubility. Iceberg lettuce was inoculated for 2 min with E. coli O157:H7 (6.0 log CFU/g) or P. fluorescens (6.0 log CFU/g) and then dip-treated in a phosphate buffered saline (PBS) control, 50 ppm chlorine, 3% hydrogen peroxide treatment or a 0.1%, 0.3%, or 0.5% microemulsion solution. Treated leaves were stored at 4 °C, and analyzed for surviving bacteria on days 0, 3, 7, 10, 14, 21, and 28. Efficacies of the antimicrobials were concentration and storage-time dependent. There was a 1.26–4.86 log CFU/g reduction in E. coli O157:H7 and significant reductions (0.32–2.35 log CFU/g) in P. fluorescens during storage at days 0–28 (p < 0.05). The 0.1% oregano oil microemulsion resulted in the best visual appeal in Iceberg leaves inoculated with E. coli O157:H7 and showed better improvement in the quality of the Iceberg leaves inoculated with spoilage bacteria P. fluorescens. The results suggest that 0.5% cinnamon and 0.3% oregano oil treatments have the potential to provide natural, eco-friendly, and effective alternatives to chemicals for the decontamination of leafy greens, eliminating E. coli O157:H7 and P. fluorescens.