Advanced wound dressings that can deliver potent antibacterial action are still much in need, especially for treating wound infections caused by drug-resistant bacteria. In this research, we utilized electron beam (EB) irradiation to develop antibacterial hydrogel sheet dressings from poly(vinyl alcohol) (PVA) and silver nanoparticles (AgNPs) in a two-step processing and evaluated their bactericidal efficacy, as well as the AgNP release. The effect of the irradiation dose on the swelling, gel fraction, network parameters, and mechanical properties of the hydrogels was first determined to establish the optimal doses for the two-step processing. The prototypic hydrogel sheets were then formed in the first EB irradiation and served as a matrix for the AgNP synthesis by the reduction of the silver nitrate precursors during the second EB irradiation. The diffusion assay showed that the minimal inhibition concentration (MIC) of the AgNP-load hydrogels was 0.25 and 0.5 mg/cm² against Escherichia coli and Staphylococcus aureus, respectively. At these MIC levels, the released AgNPs increased sharply before reaching the maximum, ~950 and 1800 ppb, at 24 h as analyzed by atomic absorption. Therefore, we successfully demonstrated that this two-step processing by EB irradiation provides a convenient platform to fabricate AgNP-loaded hydrogel dressings that can be further developed for wound healing.

The aim of this study was to compare the effects of gamma ray and x-ray irradiation at different dose levels 95, 10, 15 and 20 kGy) on in mangosteen peel. The antioxidant activities were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP), while total phenolic contents and antibacterial activities against Staphylococcus aureus and Escherichia coli of 60 % ethanolic mangosteen powder extracts were analyzed. The results indicated that both types of ionizing radiations showed a non-significant decrease in measured parameters with increasing doses. The minimum inhibitory concentration (MIC) values of irradiated mangosteen peel extracted against S. aureus and E. coli ranged from 0.125 to 2.0 mg/mL. The quantity of bioactive compound mangostin determined via high-performance liquid chromatography (HPLC), did not show significant decrease with different irradiation sources and doses. In microbiological aspect, total yeast and mold from both irradiation sources were reduced by 1 log cycle after irradiation at 5 kGy. The irradiation induced color changes corresponding to Hunter color L a b value. X-ray irradiation caused slight color alteration compared to gamma rays. The advantage of x-ray irradiation was that it revealed non-significant changes in b values, whereas gamma irradiation showed the significant change in L, and b values with increasing dosage. The x-ray irradiation at the dose 5 kGy effectively decreased microbial contamination while causing minimal changes to phytochemical qualities and color. HIGHLIGHTS Irradiation at 5 kGy was sufficient to control microbial contamination There were no significant changes in antioxidant activities (DPPH, FRAP), a-mangostin contents, total phenolic contents (TPC) and antibacterial activities: after irradiation up to 20 kGy X-ray irradiation was an excellent alternative to gamma irradiation for decontamination with a non-significant alteration in b values. GRAPHICAL ABSTRACT

Num-Tub is a traditional Northeastern Thai pork sausage, often consumed fresh or fermented. The ingredients were naturally rich in protein, fat and moisture content. These conditions are conducive to the growth of beneficial and harmful microbes. Its perishable nature poses microbial safety challenges. Irradiation effectively extends the shelf life of Num-tub by reducing microbial contamination and inactivating spoilage microorganisms. This study investigated the effects of gamma irradiation at doses of 0, 5, and 10 kGy on the microbiological, chemical, and color attributes of vacuum-packed Num-Tub during 24 days at 28 ± 2 °C. Irradiation at 5 kGy reduced total viable counts (TVC) and lactic acid bacteria (LAB) to undetectable levels, though microbial regrowth occurred over time and eliminated key pathogens including Salmonella spp, E. coli, C. perfringens, S. aureus. However, this dose could not prevent microbial regrowth. In contrast, irradiation at 10 kGy improved microbial control and color (higher oxymyoglobin and redness) up to day 9 but significantly increased lipid oxidation. Correlation analysis indicated positive associations between microbial growth, acidity, lipid oxidation, and metmyoglobin formation, while pH, myoglobin, oxymyoglobin, and redness were negatively correlated. Gamma irradiation at 10 kGy is a non-thermal method that improves microbial safety by eliminating pathogens, suppressing lactic acid. It also increases oxymyoglobin levels, which enhances product redness. However, it may also lead to increased lipid oxidation during the 9-day storage period at ambient temperature. Further research should focus on integrating gamma irradiation with natural antioxidants or modified atmosphere packaging to mitigate lipid oxidation and pigment degradation. Additionally, sensory evaluation and consumer acceptance studies are essential to establish optimal irradiation protocols that balance safety, quality, and market viability. HIGHLIGHTS Gamma irradiation improved microbial safety and extended shelf life of Num-Tub sausage. Irradiation at 5 kGy eliminated the pathogen and delayed acid production. Irradiation at 10 kGy effectively suppressed microbial regrowth but accelerated lipid oxidation. Irradiation induced oxymyoglobin formation until day 9, preserving redness and color quality. Microbial growth, acidity, and oxidation were closely correlated. GRAPHICAL ABSTRACT