Inactivation of Indigenous Microorganisms and Salmonella in Korean Rice Cakes by In-Package Cold Plasma Treatment

Abstract

The antimicrobial effects of in-package cold plasma (CP) treatment on Korean rice cakes (KRC) were evaluated. The CP treatment (25 kV) inactivated indigenous mesophilic aerobic bacteria by 0.8–1.0 log CFU/g, irrespective of the position of KRC in the package. The addition of a shaking step during CP treatment increased the reduction in microbes by ~1 log CFU/g. The microbial inactivation efficiency increased significantly when the treatment time increased from 1 to 3 min. Microbial inactivation activity was highest for packages containing eight rice cakes. The optimized CP treatment achieved a 2.0 ± 0.1 log CFU/g reduction in indigenous bacteria. In addition, the optimum CP treatment inactivated indigenous yeast and molds and Salmonella in KRC by 1.7 ± 0.1 log CFU/g and 3.9 ± 0.3 log CFU/g, respectively. No significant changes in color and firmness were observed, and the surface temperature of KRC did not exceed 22 °C after CP treatment. Moreover, CP treatment damaged the cellular membrane of Salmonella, mainly by inducing lipid peroxidation. This study demonstrates the potential use of in-package CP treatment for the non-thermal microbial inactivation of KRC.

Effective control of antibiotic resistance using a sonication-based combinational treatment and its application to fresh food

“…Food color was measured using a colorimeter (CR-400, Minolta, Co., Tokyo, Japan) at room temperature (25 ± 1 °C) as described previously, with slight modifications [12] , [31] . The colorimeter was calibrated using white standard tiles, and the results were expressed as L* (whiteness/darkness), a* (redness/greenness), and b* (yellowness/blueness).…”

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“…In contrast, Gram-positive bacteria do not contain an outer membrane and are enveloped by a thicker layer of peptidoglycan, which is less susceptible to oxidative damage. Therefore, the cell wall of Gram-positive bacteria is not easily damaged by CAP directly, but the active molecules generated can enter the cell through the interstitial spaces into the cell interior, causing oxidative damage to intracellular molecules (Huang et al 2020 ; Kang et al 2021 ). In summary, CAP causes bacterial damage to Gram-negative bacteria mainly by damaging the cell membrane and inducing leakage of intracellular material, while for Gram-positive bacteria, CAP enters the cell interior directly and causes oxidative damage to intracellular material resulting in bacterial death.…”

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“…Kang et al [ 52 ] have conducted research on Korean packaged rice cakes (KRC), inoculated with Salmonella and treated with 25 kV DBD plasma for 1 and 3 min. Subsequently, the effectiveness in eradicating both Salmonella and spoilage flora was studied.…”