Evaluation of physicochemical properties and bactericidal activity of efficient Chemical Germicidal Water (CGW)

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.

Occurrence, effects, and ecological risks of chemicals in sanitizers and disinfectants: A review

In response to the novel coronavirus referred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – a virus that causes COVID-19 disease has led to wide use of sanitizers and disinfectants. This, in turn, triggered concerns on their potential deleterious effects to human health and the environment due to numerous chemicals incorporated in both product categories. Here, the current state of science regarding the occurrence and ecological effects of different classes of chemicals in these products (e.g., ultraviolent filters, fragrances, etc.) are summarized in different natural (e.g., rivers) and engineered (e.g., wastewater treatment plants) systems. Data collected in the literature suggests chemicals incorporated in sanitizers and disinfectants are present in the environment, and a large portion are toxic to fish, algae, and daphnia. Using the risk quotient approach based on occurrence data, we found eight chemicals that posed the highest risk to aquatic organisms in freshwater systems were benzalkonium chloride, 4-chloro-m-cresol, sodium ortho phenyl phenate, hydrogen peroxide, 1, 2-propanediol, 4-Methyl-benzilidine-camphor, ethylhexyl methoxy cinnamate, and octocrylene. Considering limited occurrence and effects information for most chemicals, further studies on environmental monitoring and potential consequences of long-term exposure in aquatic ecosystems are recommended.

Unexpected Enhancement in Antibacterial Activity of N-Halamine Polymers from Spheres to Fibers

Preventing bacterial infections is a main focus of medical care. Antibacterial agents with broad and excellent disinfection capability against pathogenic bacteria are in fact urgently required. Herein, a novel strategy for the development of N-halamine polymers from spheres to fibers using a combined copolymerization-electrospinning-chlorination technique was reported, allowing fight against bacterial pathogen. Optimizing the process conditions, e.g., comonomer molar ratio, concentration of electrospinning solution, chlorination order, and chlorination period, resulted in the formation of N-halamine fibers with controllable morphology. N-Halamine polymers were tested against two common bacterial pathogens, Escherichia coli and Staphylococcus aureus, and were found to be extremely potent against both bacteria, suggesting that they possess powerful sterilizing properties. Remarkably, compared with those with sphere morphology, N-halamine fibers show unexpected enhancement toward both pathogens possibly because of their shape (fiber morphology), surface state (rough surfaces), and surface charge (positive zeta potentials). It is believed that this approach has great potential to be utilized in various fields where antifouling and antibacterial properties are highly required.