Search Results (39)

To address the worsening environmental pollution caused by the large-scale release of tetracycline (TC) into the environment, this study developed an advanced oxidation system utilizing ultraviolet (UV)-activated peroxyacetic acid (PAA) for the removal of TC. The results showed that the UV/PAA system exhibited markedly enhanced performance compared to individual treatments. Under identical conditions (1.0 mM PAA, 400 W UV irradiation), the TC removal rates by PAA alone and UV irradiation alone were 25.80% and 55.05%, respectively. In contrast, the combined UV/PAA system achieved a significantly higher degradation efficiency of 79.77%, which was 3.09 times and 1.45 times higher than that of PAA and UV processes alone. This superior performance is attributed to the generation of highly reactive species within the system. The degradation process followed pseudo-first-order kinetics. An increase in TC concentration led to a decrease in degradation efficiency, whereas elevating the PAA dosage or light intensity increased the concentration of radicals in the system, thereby enhancing removal performance. Overall degradation efficiency was slightly higher under alkaline conditions compared to acidic conditions, while neutral conditions resulted in slower degradation rates. Among coexisting anions, HCO₃⁻ and H₂PO₄⁻ inhibited TC degradation, SO₄²⁻ and Cl⁻ exhibited negligible effects, and NO₃⁻ promoted the degradation of TC. Radical quenching experiments confirmed that hydroxyl radicals (·OH) were the dominant reactive species, working together with superoxide anion radicals (O₂·⁻) and singlet oxygen (¹O₂) to drive TC degradation in the UV-activated PAA system. Experiments conducted in real water matrices demonstrated that the system could effectively degrade TC in ultrapure water, tap water, and campus lake water, highlighting its strong environmental adaptability. These findings provide both technical support and a theoretical foundation for the treatment of antibiotic pollutants. Full article

Hydroponic nutrient solution (HNS) has been established as an ideal conduit for pathogen contamination and proliferation. This study evaluated the efficacy of lactic acid bacteria and their metabolites in mitigating the risk of foodborne pathogens in HNS when compared to conventional chemical treatments. Hoagland’s HNS were prepared according to the manufacturer’s instructions and inoculated with Salmonella Typhimurium, Escherichia coli 0157:H7, and Listeria innocua at 10⁵ CFU/mL cell concentration. These nutrient solutions were subjected to treatment with various concentrations of Lactobacillus rhamnosus live cells, a cell-free extract (CFE) of L. rhamnosus metabolites, sodium hypochlorite and peroxyacetic acid at 22 ± 1 °C for up to 96 h using appropriate controls. The survived cells were enumerated on respective selective media at regular intervals. Additionally, the impact of these treatments on lettuce growth and the physico-chemical properties of HNS, such as pH, electrical conductivity, salinity, total dissolved solids, and % lactic acid content, were determined over 21 days using standard procedures. Both S. Typhimurium and E. coli O157: H7, when in combination with L. rhamnosus, remained stable in HNS over a 96 h period, while L. innocua showed a 3-log reduction. Whereas CFE treatment of HNS showed a significant reduction in Salmonella and E. coli O157: H7 (both undetectable after 96 h; LOD: <1 log CFU/mL). Interestingly, L. innocua levels remained stable after CFE treatment. PAA treatments at 12 mg/L notably reduced Salmonella and L. innocua growth, but not E. coli O157:H7. Lettuce plants in untreated control were significantly taller and heavier compared to those treated with CFE. These findings highlight the potential of biological interventions while emphasizing their limitations in hydroponic systems for pathogen control. Full article

The increasing demand for fresh fruits and vegetables has been accompanied by a rise in foodborne illness outbreaks linked to fresh produce. Traditional antimicrobial washing treatments, such as chlorine and peroxyacetic acid, have limitations in efficacy and pose environmental and worker health concerns. This study evaluated the effectiveness of organic acids (citric, malic, and lactic acid) and power ultrasound, individually and in combination, for the reduction in Salmonella enterica and Listeria monocytogenes on four fresh produce types: romaine lettuce, cucumber, tomato, and strawberry. Produce samples were inoculated with bacterial cocktails at 8–9 log CFU/unit and treated with organic acids at 2 or 5% for 2 or 5 min, with or without power ultrasound (40 kHz). Results showed that pathogen reductions varied based on the produce matrix with smoother surfaces such as tomato, exhibiting greater reductions than rougher surfaces (e.g., romaine lettuce and strawberry). Lactic and malic acids were the most effective treatments, with 5% lactic acid achieving a reduction of >5 log CFU/unit for S. enterica and 4.53 ± 0.71 log CFU/unit for L. monocytogenes on tomatoes. The combination of organic acids and power ultrasound demonstrated synergistic effects, further enhancing pathogen reduction by <1.87 log CFU/unit. For example, S. enterica on cucumbers was reduced by an additional 1.87 log CFU/unit when treated with 2% malic acid and power ultrasound for 2 min compared to malic acid alone. Similarly, L. monocytogenes on strawberries was further reduced by 1.84 log CFU/unit when treated with 5% malic acid and power ultrasound for 2 min. These findings suggest that organic acids, particularly malic and lactic acids, combined with power ultrasound, may serve as an effective hurdle technology for enhancing the microbial safety of fresh produce. Future research can include validating these treatments in an industrial processing environment. Full article

For several decades, recurring outbreaks of human gastrointestinal infections associated with contaminated sprouts have posed an enduring challenge, highlighting the necessity of controlling the etiological agents on contaminated sprout seeds. This study investigated the efficacy of calcium hypochlorite and peroxyacetic acid treatments in inactivating the cells of four enterohemorrhagic Escherichia coli (EHEC) isolates—viz. E. coli O157:H7 K4492, F4546, and H1730, as well as E. coli O104:H4 BAA-2326—on alfalfa seeds and sprouts. The 2–3 log CFU/g of EHEC cells inoculated to sprout seeds became undetectable (≤1.40 log CFU/g) after treatment with the two sanitizers, even with the enrichment steps. Sprouts grown from calcium hypochlorite- and peroxyacetic acid-treated seeds had mean EHEC populations that were 4.54–4.60 log CFU/g and 1.25–1.52 log CFU/g lower, respectively, compared to those on sprouts grown from the untreated control seeds. Significantly (p ≤ 0.05) different from one another, the mean populations of the four EHEC isolates on harvested sprout samples were in the descending order of E. coli O157:H7 K4492, F4546, H1730, and E. coli O104:H4 BAA-2326. The results suggest that both sanitizing treatments effectively suppressed EHEC growth on alfalfa seeds and sprouts, but their effectiveness was bacterial-isolate-dependent. Full article

The persistence of Listeria monocytogenes biofilms on equipment surfaces poses a significant risk of cross-contamination, necessitating effective surface decontamination strategies. This study assessed the effectiveness of hurdle treatments combining peroxyacetic acid (PAA) and saturated steam against 7-day-old L. innocua (a non-pathogenic surrogate for L. monocytogenes) biofilms on stainless steel (SS), polyester (PET), and rubber surfaces. Results demonstrated >6 log₁₀ CFU/coupon L. innocua reductions on SS and PET surfaces after PAA (40 ppm, 1 min) followed by steam treatment (100 °C, 6 s). On rubber surfaces, PAA (80 ppm, 1 min) followed by steam treatment (100 °C, 6 s) resulted in ~5 log₁₀ CFU/coupon L. innocua reduction. The presence of apple juice soil reduced the efficacy of hurdle treatments, with PAA (40 ppm, 1 min) and steam exposure (6 s) resulting in 5.6, 5.8, and 4.2 log₁₀ CFU/coupon reductions of L. innocua on SS, PET, and rubber, respectively. The efficacy of this antimicrobial combination was further reduced by surface defects, especially in the presence of organic matter. Nevertheless, the treatment still achieved >5 log₁₀ CFU/coupon reductions of L. innocua on worn SS and PET soiled with apple juice and ~4.5 log₁₀ CFU/coupon reduction on worn, soiled rubber surfaces. These findings highlight that PAA treatments followed by a brief steam exposure are effective strategies for controlling Listeria on food-contact surfaces. Full article

The increase in vegetable consumption has underlined the importance of minimizing the risks associated with microbiological contamination of fresh produce. The critical stage of the vegetable washing process has proven to be a key point for cross-contamination and the persistence of pathogens. In this context, the agri-food industry has widely adopted the use of disinfectants to reduce the bacterial load in the wash water. Therefore, we conducted laboratory-scale experiments in order to demonstrate the antimicrobial activity of disinfectants used in the wash tank of agro-food industries. Different wash water matrices of shredded lettuce, shredded cabbage, diced onion, and baby spinach were treated with sodium hypochlorite (NaClO), chlorine dioxide (ClO₂), and per-oxyacetic acid (PAA) at recommended concentrations. To simulate the presence of pathogenic bacteria, a cocktail of E. coli O157:H7 was inoculated into the process water samples (PWW) to determine whether concentrations of disinfectants inhibit the pathogen or bring it to a viable non-culturable state (VBNC). Hereby, we used quantitative qPCR combined with different photo-reactive dyes such as ethidium monoazide (EMA) and propidium monoazide (PMA). The results indicated that concentrations superior to 20 ppm NaClO inhibit the pathogen E. coli O157:H7 artificially inoculated in the process water. Concentrations between 10–20 ppm ClO₂ fail to induce the pathogen to the VBNC state. At concentrations of 80 ppm PAA, levels of culturable bacteria and VBNC of E. coli O157:H7 were detected in all PWWs regardless of the matrix. Subsequently, this indicates that the recommended concentrations of ClO₂ and PAA for use in the fresh produce industry wash tank do not inhibit the levels of E. coli O157:H7 present in the wash water. Full article

Fe/Cu bimetallic catalysts have a synergistic effect that can effectively enhance catalytic activity, so Fe/Cu bimetallic catalysts have been extensively studied. However, the efficacy and mechanisms of Fe/Cu bimetallic catalysts’ peroxidation activation have rarely been explored. In this study, Fe/Cu bimetallic materials were fabricated to catalyze different oxidizing agents, including peroxymonosulfate (PMS), peroxydisulfate (PDS), peroxyacetic acid (PAA), and hydrogen peroxide (H₂O₂), for the degradation of sulfamethoxazole (SMX). The Fe/Cu/oxidant systems exhibited an excellent degradation efficiency of sulfamethoxazole (SMX). In the Fe/Cu/PMS, Fe/Cu/PDS, and Fe/Cu/PAA systems, the main reactive oxygen species (ROS) responsible for SMX degradation were hydroxyl radical (^•OH) and singlet oxygen (¹O₂), while the main ROS was only ^•OH in the H₂O₂ system. The differences in the surface structure of the materials before and after oxidation were examined, revealing the presence of a large amount of flocculent material on the surface of the oxidized PMS material. Anion experiments and actual body experiments also revealed that the PMS system had a strong anti-interference ability. Finally, a comprehensive comparison concluded that the PMS system was the optimal system among the four oxidation systems. Overall, this work revealed that the PMS oxidant has a better catalytic degradation of SMX compared to other oxidizers for Fe/Cu, that PMS generates more ROS, and that the PMS system has a stronger resistance to interference. Full article

There is an urgent need to develop efficient and environmentally friendly decontaminants for poultry products. In this study, we aimed to evaluate the practical application of peroxyacetic acid (PAA) as a replacement for sodium hypochlorite (SH) to sterilize fresh chicken carcasses, using microbial, color, and electronic-nose analyses. We evaluated the decontamination effects of different concentrations of PAA and SH on chicken carcasses. The bactericidal effects of PAA at pH 3, 7, and 9, and SH at pH 10, at concentrations ranging from 100 to 500 ppm on coliform bacteria, total bacteria, and Salmonella spp. were evaluated. PAA induced a similar bactericidal effect at lower concentrations than SH. Therefore, at the same concentration and treatment time, PAA showed better bactericidal effects than SH. Although treatment with PAA (pH 3) and SH (pH 10) resulted in considerable discoloration, the degree of discoloration decreased when the pH of PAA was increased to 7 and 9. Therefore, by increasing the pH of PAA, the discoloration effect on chicken carcasses can be reduced without altering the microbial-reduction effect. Electronic-nose analysis showed that the flavor of the chicken was almost unaffected by volatile components at a treatment time < 30 min. Therefore, this study experimentally identified the optimal PAA concentration for the decontamination of chicken carcasses. The study findings provide a theoretical basis for the replacement of traditional bactericides, such as SH, with PAA for the production of poultry products. Full article

This study assessed the extent of L. monocytogenes transfer from onions to the surface of a commercial dicer, from inoculated onions to uninoculated onions, and the efficacy of various sanitizers during the subsequent flume washing of diced onions. Spanish yellow onions (Allium cepa L.) were dip-inoculated in a 3-strain avirulent L. monocytogenes cocktail (5.9 or 4.2 log CFU/50 g) and air-dried. After dicing one 2.2 kg batch of onions inoculated at ~5.9 log CFU/50 g followed by ten uninoculated batches of 2.2 kg each, L. monocytogenes progressively decreased from 4.6 to 2.6 log CFU/50 g in baches 1 through 10, respectively. After onions inoculated at ~4.0 log CFU/g were diced and flume washed for 2 min in tap water, electrolyzed water containing 55 ppm free chlorine, 80 ppm free chlorine from a commercial sanitizer, or 80 ppm peroxyacetic acid and dewatered on a mechanical shaker table, L. monocytogenes populations decreased 0.4, 0.3, 1.4, and 1.0 log, respectively, with populations of ~1.2 log CFU/mL in water for all three sanitizers. These findings should be useful in future risk assessments and aid in the development of improved industry guidelines to better enhance the safety of diced onions. Full article

The tomato brown rugose fruit virus (ToBRFV), a formidable tobamovirus, poses a significant threat to tomato production globally. This comprehensive study is dedicated to establishing an integrated control strategy for ToBRFV, encompassing the entire tomato cultivation process from seed to harvest. Initial investigations revealed a 0.8% seed transmission rate of ToBRFV, with viral presence detected in endosperms but not in seed embryos. Employing a multifaceted approach, infected seeds underwent a meticulous disinfection process. Gradual heating in a rotating thermal machine from 20 °C to 72 °C for 3 days resulted in a remarkable 0.3% contamination rate, rendering the virus non-infectious. Furthermore, ToBRFV-infected seeds underwent UV light treatment at 254 nm for 30 min, resulting in a 50% reduction in contamination rates. Chemical disinfectants, including 1% Tsunami 100 (comprising 30–60% acetic acid, 15.2% peroxyacetic acid, and 11.2% hydrogen peroxide) and 1% Biocon A (a combination of potassium peroxymonosulfate with buffer and organic acid), exhibited notable success. This study not only unravels the intricate dynamics of ToBRFV transmission and inactivation but also underscores the efficacy of integrated control measures. The findings provide valuable insights for the sustainable management of ToBRFV, contributing to the resilience of global tomato cultivation against this viral menace. Full article

Peroxyacetic acid (PAA)-based advanced oxidation processes (AOPs) have attracted much attention in wastewater treatment by reason of high selectivity, long half-life reactive oxygen species (ROS), and wider applicability. In this study, cobalt ferrite (CoFe₂O₄) was applied to activate PAA for the removal of ofloxacin (OFX). The degradation of OFX could reach 83.0% via the CoFe₂O₄/PAA system under neutral conditions. The low concentration of co-existing anions and organic matter displayed negligible influence on OFX removal. The contributions of hydroxyl radicals (·OH), organic radicals (R-O·), and other reactive species to OFX degradation in CoFe₂O₄/PAA were systematically evaluated. Organic radicals (especially CH₃C(O)OO·) and singlet oxygen (¹O₂) were verified to be the main reactive species leading to OFX destruction. The Co(II)/Co(III) redox cycle occurring on the surface of CoFe₂O₄ played a significant role in PAA activation. The catalytic performance of CoFe₂O₄ remained above 80% after five cycles. Furthermore, the ecotoxicity of OFX was reduced after treatment with the CoFe₂O₄/PAA system. This study will facilitate further research and development of the CoFe₂O₄/PAA system as a new strategy for wastewater treatment. Full article

The food industry has recognized a pressing need for highly effective disinfection protocols to decrease the risk of pathogen emergence and proliferation in food products. The integration of antimicrobial treatments in food production has occurred as a potential strategy to attain food items of superior quality with respect to microbiological safety and sensory attributes. This study aims to investigate the individual and synergistic effects of heat and peroxyacetic acid on the inactivation of bacterial cells, considering various contact times and environmental conditions. Four Salmonella serotypes, isolated from industrial meat production surfaces, were employed as model organisms. By systematically assessing the impacts of individual factors and synergistic outcomes, the effectiveness of bacterial cell inactivation and the efficiency of heat and peroxyacetic acid could be predicted. To better approximate real-world food processing conditions, this study also incorporated a bovine albumin-rich condition as a simulation of the presence of organic loads in processing steps. The findings revealed the essential need for a synergistic interplay of investigated parameters with the following optimized values: 1.5% concentration of peroxyacetic acid, temperature range of 60–65 °C, and contact time of 3 min for the complete effect regardless of the degree of contamination. Full article

The paper presents the synthesis and thermal behavior of novel epoxy resins prepared from epoxidized castor oil in the presence of or without trimethylolpropane triglycidyl ether (TMP) crosslinked with 3-hexahydro-4-methylphtalic anhydride (MHHPA) and their comparison with a petroleum-based epoxy resin (MHHPA and TMP). Epoxidized castor oil (ECO) was obtained via in situ epoxidation of castor oil with peroxyacetic acid. The chemical structures of castor oil (CO), ECO, and epoxy matrix were confirmed using FT-IR and ¹H-NMR spectroscopy. The morphological and thermal behavior of the resulting products have been investigated. Compared to petroleum-based resins, castor oil-based ones have a lower T_g. Anyway, the introduction of TMP increases the T_g of the resins containing ECO. The morphological behavior is not significantly influenced by using ECO or by adding TMP in the synthesis of resins. The dielectric properties of epoxy resins have been analyzed as a function of frequency (1 kHz–1 MHz) and temperature (−50 to 200 °C). The water absorption test showed that as T_g increased, the percent mass of water ingress decreased. Full article

Minimally processed produce is frequently contaminated with foodborne bacterial pathogens. Power ultrasound is a non-thermal and cost-effective technology that can be combined with other chemical sanitization methods. This study investigated the reduction of Listeria monocytogenes and Salmonella Newport on grape tomato, romaine lettuce, and spinach washed with water, chlorine, or peroxyacetic acid alone or in combination with 25 or 40 kHz power ultrasound for 1, 2, or 5 min. Produce items were inoculated with either pathogen at 10 log CFU/g, dried for 2 h, and treated. Combined treatment of ultrasound and sanitizers resulted in 1.44–3.99 log CFU/g reduction of L. monocytogenes and 1.35–3.62 log CFU/g reduction of S. Newport, with significantly higher reductions observed on grape tomato. Synergistic effects were achieved with the hurdle treatment of power ultrasound coupled with the chemical sanitizers when compared to the single treatments; an additional 0.48–1.40 log CFU/g reduction of S. Newport was obtained with the addition of power ultrasound on grape tomato. In general, no significant differences were observed in pathogen reductions between the ultrasound frequencies, the sanitizers, or the treatment lengths. Results from this study suggest that incorporation of power ultrasound into the current washing procedure may be beneficial for the reduction, but not elimination, of bacterial pathogens on certain produce items, including tomatoes. Full article

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. Full article