Hae In Yong

Flexible thin-layer dielectric barrier discharge plasma treatment of pork butt and beef loin: Effects on pathogen inactivation and meat-quality attributes

The effects of a flexible thin-layer dielectric barrier discharge (DBD) plasma system using a sealed package on microbial inactivation and quality attributes of fresh pork and beef were tested. Following a 10-min treatment, the microbial-load reductions of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium were 2.04, 2.54, and 2.68 Log CFU/g in pork-butt samples and 1.90, 2.57, and 2.58 Log CFU/g in beef-loin samples, respectively. Colorimetric analysis showed that DBD-plasma treatment did not significantly affect L* values (lightness) of pork and beef samples, but lowered a* values (redness) significantly after 5- and 7.5-min exposures. The plasma treatment significantly influenced lipid oxidation only after a 10-min exposure. The texture of both types of meat was unaffected by plasma treatment. All sensory parameters of treated and non-treated samples were comparable except for taste, which was negatively influenced by the plasma treatment (P < 0.05). This thin-layer DBD-plasma system can be applied to inactivate foodborne pathogens. The observed minor deterioration of meat quality might be prevented by the use of hurdle technology.

Evaluation of pathogen inactivation on sliced cheese induced by encapsulated atmospheric pressure dielectric barrier discharge plasma

Pathogen inactivation induced by atmospheric pressure dielectric barrier discharge (DBD) (250 W, 15 kHz, air discharge) produced in a rectangular plastic container and the effect of post-treatment storage time on inactivation were evaluated using agar plates and cheese slices. When agar plates were treated with plasma, populations of Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes showed 3.57, 6.69, and 6.53 decimal reductions at 60 s, 45 s, and 7 min, respectively. When the pathogens tested were inoculated on cheese slices, 2.67, 3.10, and 1.65 decimal reductions were achieved at the same respective treatment times. The post-treatment storage duration following plasma treatment potently affected further reduction in pathogen populations. Therefore, the newly developed encapsulated DBD-plasma system for use in a container can be applied to improve the safety of sliced cheese, and increasing post-treatment storage time can greatly enhance the systems pathogen-inactivation efficiency.

The use of atmospheric pressure plasma-treated water as a source of nitrite for emulsion-type sausage.

We investigated the possible use of atmospheric pressure plasma-treated water (PTW) as a nitrite source in curing process. Emulsion-type sausages were manufactured with PTW, celery powder containing nitrite, and synthetic sodium nitrite at a concentration of nitrite ion 70mgkg(-1). In terms of sausage quality, there were no noticeable effects of PTW on the total aerobic bacterial counts, color, and peroxide values of sausages compared with those of celery powder and sodium nitrite throughout 28days of storage at 4°C. Sausage with added PTW had lower concentrations of residual nitrite compared to those of added celery powder and sodium nitrite during the storage period (P<0.05). The sensory properties of PTW-treated and sodium nitrite-treated sausages were not different, whereas the sausage with added celery powder received the lowest scores in taste and acceptability. From the results, it is concluded that PTW can be used as a nitrite source equivalent to a natural curing agent.

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.

Effect of atmospheric pressure dielectric barrier discharge plasma on the biological activity of naringin

The biological activity of naringin treated with atmospheric pressure plasma was evaluated to investigate whether exposure to plasma can be used as a method to improve the biological activity of natural materials. Naringin was dissolved in methanol (at 500 ppm) and transferred to a container. A dielectric barrier discharge (DBD) (250 W, 15 kHz, ambient air) was then generated. Treatment with the plasma for 20 min increased the radical-scavenging activity, FRAP value, and the total phenolic compound content of naringin from 1.45% to 38.20%, from 27.78 to 207.78 μM/g, and from 172.50 to 225.83 ppm, respectively. Moreover, the tyrosinase-inhibition effect of naringin increased from 6.12% to 83.30% upon plasma treatment. Naringin treated with plasma exhibited antimicrobial activity against foodborne pathogens, especially Salmonella Typhimurium; an activity that was absent before plasma treatment. Structural modifications induced in the naringin molecule by plasma might be responsible for improving the biological activity of naringin.

Evaluation of the Treatment of Both Sides of Raw Chicken Breasts with an Atmospheric Pressure Plasma Jet for the Inactivation of Escherichia coli

Atmospheric pressure plasma (APP) is an emerging nonthermal microbial inactivation technique. In this study, agar and raw chicken breast were inoculated with Escherichia coli and treated with an APP jet based on cold arc plasma. The aim of this study was to investigate the optimum conditions for the plasma treatment of an APP jet in order to maximize the efficiency of E. coli inactivation. The combination of N2+O2 (10 standard cubic centimeters per minute) and a longer treatment time (10 min) resulted in the highest inactivation of E. coli on agar plates with an optimum treatment distance of 20 mm. The samples in dry and wet conditions showed similar reductions in E. coli count when one side of the samples was treated at a given treatment time. Treating both sides-2.5 min on each side-resulted in a higher growth inhibition of E. coli than treatment of a single side only for 5 min. However, there was no significant difference between one-side treated samples (10 min) and both-sides treated samples (5+5 min). When the concentration of E. coli in the chicken breast sample was 10(4) colony-forming units (CFU)/g, the reduction rate of the E. coli was the highest, followed by 10(5), 10(6), and 10(7) CFU/g; however, no difference was found between 10(3) and 10(4) CFU/g. In conclusion, various treatment conditions may affect the inactivation efficiency of E. coli. In the present study, the optimum condition was determined as the treatment distance of 20 mm and longer treatment time (10 min) with the addition of oxygen to the nitrogen gas flow. Furthermore, the cell concentration of sample was an important parameter for the efficacy of the inactivation process.

Effect of Inactivating Salmonella Typhimurium in Raw Chicken Breast and Pork Loin Using an Atmospheric Pressure Plasma Jet

The optimal conditions for applications of an atmospheric pressure plasma (APP) jet for the inactivation of Salmonella Typhimurium in chicken breast and pork loins were investigated. APP jet treatment for 10 min (versus 5 minutes) showed a higher inactivation of S. Typhimurium in an agar plate, with the best effect at a distance of 20 mm. A treatment on both sides (both-side treatment) for 2.5 + 2.5 min showed a greater inhibition on S. Typhimurium growth compared to single-side treatment for 5 min, with reduction levels of 0.66 log CFU/g in chicken breast and 1.33 log CFU/g in pork loin, respectively. However, there was no significant difference between single-side treatment for 10 min and both-side treatment for 5 + 5 min in chicken breasts and pork loin samples. In conclusion, APP jet treatment conditions, including distance, time, and direction, may affect the inactivation efficiency of S. Typhimurium. In this experiment, distance of 20 mm and both-side treatment were the best conditions. Therefore, the optimal APP jet treatment conditions were evaluated to maximize its practical efficiency.

Effects of Combined Treatments of Electron-Beam Irradiation and Addition of Leek (Allium tuberosum) Extract on Reduction of Pathogens in Pork Jerky

This study investigated the combined effect of electron-beam irradiation and addition of leek (Allium tuberosum R.) extract on pork jerky inoculated with selected foodborne pathogens. Prepared pork jerky samples (control and samples with 1.0% leek extract) were inoculated with pathogens and subsequently irradiated at 0, 0.5, 1, 2, 3, and 4 kGy doses. In comparison with the control, samples with 1.0% leek extract showed significant reduction in the numbers of Escherichia coli, Listeria monocytogenes, and Salmonella Typhimurium. No viable counts were detected for Salmonella Typhimurium in both control and leek-extract samples, and for E. coli and L. monocytogenes in the leek-extract sample exposed to 3 kGy irradiation dose. The D(10) values for E. coli, L. monocytogenes, and Salmonella Typhimurium observed in the irradiated samples with leek extract were 0.39, 0.34, and 0.32 kGy, while the D(10) values in those without leek extract were 0.65, 0.65, and 0.39 kGy, respectively. Therefore, our results clearly showed that irradiation combined with leek extract was effective in reducing pathogens, suggesting that a low dose of irradiation combined with the addition of a natural antimicrobial agent can enhance the microbial safety and shelf-life of pork jerky.

Evaluation of the microbiological safety, quality changes, and genotoxicity of chicken breast treated with flexible thin-layer dielectric barrier discharge plasma

The microbiological safety, quality changes, and genotoxicity of chicken breasts treated with flexible thin-layer dielectric barrier discharge (FTDBD) plasma inside a sealed package were investigated. Following 10 min plasma treatment, the numbers of total aerobic bacteria, Listeria monocytogenes, Escherichia coli, and Salmonella Typhimurium were reduced by 3.36, 2.14, 2.73, and 2.71 Log CFU/g, respectively. Color L* and b* values increased whereas a* value decreased following plasma treatment with increasing exposure duration. Lipid oxidation was unaffected by plasma treatment. In sensory evaluation, flavor decreased and off-flavor increased with extended plasma exposure time, however, these changes had no effect on acceptability. Increased cohesiveness was the only texture profile analysis parameter that changed following plasma treatment. No genotoxicity was detected in plasma-treated chicken breast using the Salmonella mutagenicity assay. Therefore, FTDBD plasma is applicable since it is able to improve microbiological safety with minimal changes in sensory properties of the chicken breast.

Mutagenicity and Immune Toxicity of Emulsion-type Sausage Cured with Plasma-treated Water.

Cold plasma has been developed to reduce microbial contamination and to improve safety of food and medical products. In addition, the technology can be used in the manufacture of sausages without addition of nitrite. To be applied in food industry commercially, the new technology should be safe and efficient. However, toxicological test of plasma-treated food is limited. Therefore, the purpose of this study was to determine the mutagenicity and immune toxicity of the meat products cured with plasma-treated water (PTW) as a nitrite source. Emulsion sausages were prepared with no nitrite (control), sodium nitrite (SCS), and PTW (SCP). For a mutagenicity test, the Ames test was performed with the sausage samples. For immune toxicity test, 8-wk-old female Balb/c mice were given free access to the sausages in order to evaluate the tumor necrosis factor (TNF)-α level. As a result, no mutagenicity was detected in the sausages by the Ames test. The serum TNF-α values were less than 10 pg/mL in mice after feeding control and treated samples for 32 d, indicating that no inflammatory response was occurred by feeding the sausages made by PTW. Therefore, the present study opens the possibility of using plasma-treated water as a nitrite source without any toxicity.