Effects of sodium hypochlorite and peroxyacetic acid on the inactivation of murine norovirus-1 in Chinese cabbage and green onion

A ratiometric fluorescent probe for selective detection of hypochlorite (ClO-) and gallium (III) (Ga3+) ions in environmental and food samples

Hypochlorite (ClO-) and gallium (Ⅲ) ions (Ga3+) have extensive applications in various human industries and daily activities. However, their inherent toxicity poses significant risks to environmental preservation and human well-being. Hence, the development of reliable and handy detection tools for ClO- and Ga3+ in the environment and food is crucial. In this study, a ratiometric fluorescent probe was prepared based on benzothiazolaldehyde and pyridine-2-carboxylic acid hydrazide, which exhibited exceptional performance characteristics for the selective detection of ClO- and Ga3+. These features include high specificity, low detection limits (0.28 μM for ClO-, 0.13 μM for Ga3+), mild pH conditions (pH 4-11 for ClO-, pH 6-11 for Ga3+), fast response time (within 30 s), as well as versatile applicability across different matrices such as water, soil, food, and plant samples. Additionally, this probe can be used with a smartphone color recognition app. The probe offers a convenient and effective tool for the detection of ClO- and Ga3+, demonstrating its potential application value in environmental monitoring and food safety.

Evaluating the Potential of Ozone Microbubbles for Inactivation of Tulane Virus, a Human Norovirus Surrogate

This study investigated the efficacy of low-dose ozone microbubble solution and conventional aqueous ozone as inactivation agents against Tulane virus samples in water over a short period of time. Noroviruses are the primary cause of foodborne illnesses in the US, and the development of effective inactivation agents is crucial. Ozone has a high oxidizing ability and naturally decomposes to oxygen, but it has limitations due to its low dissolution rate, solubility, and stability. Ozone microbubbles have been promising in enhancing inactivation, but little research has been done on their efficacy against noroviruses. The study examined the influence of the dissolved ozone concentration, inactivation duration, and presence of organic matter during inactivation. The results showed that ozone microbubbles had a longer half-life (14 ± 0.81 min) than aqueous ozone (3 ± 0.35 min). After 2, 10, and 20 min postgeneration, the ozone concentration of microbubbles naturally decreased from 4 ppm to 3.2 ± 0.2, 2.26 ± 0.19, and 1.49 ± 0.23 ppm and resulted in 1.43 ± 0.44, 0.88 ± 0.5, and 0.68 ± 0.53 log10 viral reductions, respectively, while the ozone concentration of aqueous ozone decreased from 4 ppm to 2.52 ± 0.07, 0.43 ± 0.05, and 0.09 ± 0.01 ppm and produced 0.8 ± 0.28, 0.29 ± 0.41, and 0.16 ± 0.21 log10 reductions against Tulane virus, respectively (p = 0.0526), suggesting that structuring of ozone in the bubbles over the applied treatment conditions did not have a significant effect, though future study with continuous generation of ozone microbubbles is needed.

Effects of multi-frequency ultrasonic assisted sodium hypochlorite on the cleaning effect and quality of fresh-cut scallion stems

This study aimed to evaluate the feasibility of multi-frequency ultrasound-assisted sodium hypochlorite (NaClO) on fresh-cut scallion stem (FCS) cleaning. Ultrasonic cleaning parameters (frequency mode, frequency amplitude, and the sample to water ratios) were optimized against cleanliness and microbial biomass as evaluation indexes. Under the optimum conditions, the free chlorine residues and quality attributes of FCS were also investigated. The results showed that the cleanliness of FCS improved significantly (p < 0.05) and the total number of microorganisms, especially Escherichia coli, decreased dramatically under the optimized cleaning condition with the simultaneous ultrasound (US) at the sweep frequency (SF) combination of 20 + 28 kHz, the ultrasonic density of 60 W/L, pulse time of 10 s, which indicated that the shelf life of FCS would be extended. Compared to FCS after the 250 ppm NaClO cleaning, the retention of ascorbic acid (AA), color, and texture structure of FCS had no significant difference after ultrasound-assisted NaClO treatment. Meanwhile, the content of allicin increased by 52.5% under ultrasound-assisted cleaning. The integration of US into the cleaning process resulted in a notably reduction of 68% in NaClO concentration, as well as the weight loss and respiration rate (RR) of the scallion stems. Therefore, ultrasound-assisted NaClO cleaning was regarded as a promising and effective approach for cleaning fresh-cut vegetables.

Effects of Peroxyacetic Acid on Postharvest Diseases and Quality of Blueberries

Postharvest diseases are a limiting factor in the storage of fresh blueberries. Gray mold caused by Botrytis cinerea and Alternaria rot caused by Alternaria spp. are important postharvest diseases in blueberries grown in California. Control of these fungal pathogens is generally dependent on preharvest sprays of synthetic fungicides, but in California multiple fungicide resistance has already developed in those pathogens, leading to the failure of disease control. Therefore, alternatives to synthetic fungicides are needed for the control of postharvest diseases. Peroxyacetic acid (PAA) is a disinfectant agent that poses low risk to human health. In this study, we evaluated the effects of postharvest use of PAA at 24 µl liter^-1 and 85 µl liter^-1 on fruit decay caused by fungal pathogens and quality of stored blueberry fruit. PAA treatment was applied to four cultivars over three seasons using two methods, dipping or spraying. Dipping blueberries compared with spraying them with PAA and its application at 85 µl liter^-1 were the most effective treatments. For example, when applied to 'Snowchaser' blueberries, this combination reduced naturally occurring decay after 4 weeks of storage at 0 to 1°C from 14.3% among water-treated controls to 2.7% in 2018, and from 25.7% among water-treated controls to 8.6% in 2020. In general, PAA did not adversely affect fruit quality or sensory quality of blueberries. Postharvest use of PAA appears to be a promising means to reduce postharvest decay of blueberries. To reliably obtain an acceptable level of disease control, the best use of PAA may be in combination with other practices rather than using it alone.

Potential application of novel technology developed for instant decontamination of personal protective equipment before the doffing step

The use of personal protective equipment (PPE) has been considered the most effective way to avoid the contamination of healthcare workers by different microorganisms, including SARS-CoV-2. A spray disinfection technology (chamber) was developed, and its efficacy in instant decontamination of previously contaminated surfaces was evaluated in two exposure times. Seven test microorganisms were prepared and inoculated on the surface of seven types of PPE (respirator mask, face shield, shoe, glove, cap, safety glasses and lab coat). The tests were performed on previously contaminated PPE using a manikin with a motion device for exposure to the chamber with biocidal agent (sodium hypochlorite) for 10 and 30s. In 96.93% of the experimental conditions analyzed, the percentage reduction was >99% (the number of viable cells found on the surface ranged from 4.3x106 to <10 CFU/mL). The samples of E. faecalis collected from the glove showed the lowest percentages reduction, with 86.000 and 86.500% for exposure times of 10 and 30 s, respectively. The log10 reduction values varied between 0.85 log10 (E. faecalis at 30 s in glove surface) and 9.69 log10 (E. coli at 10 and 30 s in lab coat surface). In general, E. coli, S. aureus, C. freundii, P. mirabilis, C. albicans and C. parapsilosis showed susceptibility to the biocidal agent under the tested conditions, with >99% reduction after 10 and 30s, while E. faecalis and P. aeruginosa showed a lower susceptibility. The 30s exposure time was more effective for the inactivation of the tested microorganisms. The results show that the spray disinfection technology has the potential for instant decontamination of PPE, which can contribute to an additional barrier for infection control of healthcare workers in the hospital environment.

Impact of chlorine dioxide and electron-beam irradiation for the reduction of murine norovirus in low-salted "jogaejeotgal", a traditional Korean salted and fermented clam

Clam jeotgal, called "jogaejeotgal," is a Korean fermented seafood product with, generally, a high amount of added salt to inhibit the growth of pathogenic microorganisms. This study aimed to evaluate the efficacy of chlorine dioxide (ClO₂) and sodium hypochlorite (NaOCl) against murine norovirus 1 (MNV-1), a surrogate for human norovirus, in salt-fermented clam, jogaejeotgal. The sequential effect of ClO₂ and electron-beam (e-beam) irradiation on the inactivation of MNV-1 was also investigated. Treatments of up to 300 ppm ClO₂ and 1000 ppm NaOCl were used to determine the disinfectant concentrations at which more than 1 log (90%) MNV-1 inactivation occurred. The sequential treatment of ClO₂ (50-300 ppm) and e-beam (1-5.5 kGy) was performed after storage at 4 °C for 7 days. There was a 1.9-log reduction of the virus in seasoned clams irradiated at 5.5 kGy after ClO₂ treatment at 300 ppm. No significant change (p > 0.05) in physicochemical quality was observed after the combined treatment, suggesting the potential for the use of a combined treatment using ClO₂ (300 ppm) and e-beam (5.5 kGy) in the jeotgal manufacturing industry for the reduction of norovirus.