Jooyoung Park

Flexible thin-layer plasma inactivation of bacteria and mold survival in beef jerky packaging and its effects on the meat's physicochemical properties

The aims of the present study were to examine the use of a flexible thin-layer plasma system in inactivating bacteria and mold on beef jerky in a commercial package and to evaluate the physicochemical changes of the jerky. After plasma treatment for 10min, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, and Aspergillus flavus populations on the beef jerky were reduced by approximately 2 to 3Log CFU/g. No significant changes in metmyoglobin content, shear force, and myofibrillar fragmentation index were found in the plasma-treated beef jerky. On the other hand, the peroxide content and L⁎ value were decreased whereas the a⁎ and ΔE value were increased in the plasma-treated sample. Sensory evaluation indicated negative effects of plasma treatment on flavor, off-odor, and overall acceptability of the beef jerky. In conclusion, the flexible thin-layer plasma system could be employed as a means for decontamination of beef jerky, with slight changes to the physicochemical quality of the product.

The Monte-Carlo method without sorting for uncertainty propagation analysis in PRA

Abstract The Monte-Carlo method has been widely used for the analysis of an uncertainty propagation in fault tree analysis. The conventional Monte-Carlo method is time-consuming because of the sorting process. In this study, the Monte-Carlo method without sorting is developed by using the segmentation between the sufficient upper bound and the sufficient lower bound of the evaluated top event frequencies into meshes and interpolation within the mesh. It is shown that the results obtained from the new method are almost equivalent to those from the conventional method, and that the new method reduces greatly the computational running time.

Analytical and numerical unavailability analysis of redundant systems with dependent human error

This paper discusses a theoretical and numerical investigation of dependent human error on the failure probability of the redundant system tested periodically. Two methodologies of calculating the failure probability are developed. One is developed using the modified Karnaugh map and it can analytically compute the failure probability of the simple system. The other is developed using the minimal cut set and it gives the conservative solution. However, this method can be easily applied to the complicated system without making significant errors.

Plasma-Functionalized Solution: A Potent Antimicrobial Agent for Biomedical Applications from Antibacterial Therapeutics to Biomaterial Surface Engineering

Deadly diseases caused by pathogenic bacteria and viruses have increasingly victimized humans; thus, the importance of disinfection has increased in medical settings as well as in food and agricultural industries. Plasma contains multiple bactericidal agents, including reactive species, charged particles, and photons, which can have synergistic effects. In particular, the chemicals formed in aqueous solution during plasma exposure have the potential for high antibacterial activity against various bacterial infections. Here, we report the antibiotic potency of plasma-treated water (PTW). To illustrate the applicability of PTW for disinfecting biological substances, an Escherichia coli biofilm was used. We sought to identify the chemical species in PTW and investigate their separate effects on biofilm removal. Dielectric barrier discharge in ambient air was used to prepare the PTW and treat the biofilm directly. Hydrogen peroxide, ozone, and nitrites were identified as the long-lived reactive species in the PTW, whereas hydroxyl radicals and superoxide anions were identified as the short-lived reactive species in the PTW; all these species showed an ability to disinfect in biofilm removal.