In-package Cold Plasma Treatment Research Articles

Effects of in-package cold plasma treatment on poultry breast meat packaged in high CO2 atmosphere

High CO2 in packages significantly extends microbiological shelf life of poultry meat. Cold plasma is an emerging antimicrobial treatment, which generates various reactive gas species and inactivates microbials effectively. The objective of this study was to explore the potential effects of combining high CO2 package and in-package cold plasma (IPCP) treatments on the quality and safety of raw chicken breast meat. Non-inoculated samples and samples inoculated with Campylobacter jejuni and Salmonella Typhimurium were packaged in 0, 30, 70, or 100% CO2 (with make-up gas N2) and treated with IPCP at 70 kV for 3 min. Ozone formation, microbial counts, drip loss, pH, and color were measured. There was no interaction effect between high CO2 package and IPCP on microbial counts, drip loss, and color measurements. IPCP reduced spoilage microbial growth by 0.43 log (from 7.00 log to 6.57 log, P = 0.033) and C. jejuni populations by 0.67 log (from 4.82 log to 4.15 log, P < 0.001) on meat surface but did not affect S. Typhimurium (P = 0.206). Increased CO2 in packages had more effect on spoilage microbial growth (more than 1.5 log from 8.08 log to 6.35 log, P < 0.001) and S. Typhimurium populations (more than 0.5 log from 4.94 log to 4.39 log, P = 0.004) than IPCP but did not affect C. jejuni (P = 0.163). IPCP resulted in increases in changes in L* by 1.67 units (0.70 versus 2.37, P = 0.016) and a* values by 0.56 units (0.73 versus 1.29, P < 0.001) and decreases in b* values by 0.91 units (0.46 versus -0.45, P = 0.015). High CO2 levels caused increases in changes in L* values by 4.35 units (-0.82 versus 3.53, P < 0.001) with no effects on a* and b* values (P > 0.05). Data demonstrate that there are no combined effects by high CO2 package and IPCP on meat quality and safety of raw chicken breast meat under our experimental conditions. Either high CO2 package or IPCP can retain microbial quality and safety, even though they may cause changes in appearance of stored chicken breast meat.

Effects of Gas Composition on the Lipid Oxidation and Fatty Acid Concentration of Tilapia Fillets Treated with In-Package Atmospheric Cold Plasma.

Cold plasma (CP) is a non-thermal preservation technology that has been successfully used to decontaminate and extend the shelf life of aquatic products. However, the preservation effect of CP treatment is determined by several factors, including voltage, time, and gas compositions. Therefore, this study aimed to investigate the effects of gas composition (GasA: 10% O2, 50% N2, 40% CO2; GasB: air; GasC: 30% O2, 30% N2, 40% CO2) on the lipid oxidation of tilapia fillets treated after CP treatment. Changes in the lipid oxidation values, the percentages of fatty acids, and sensory scores were studied during 8 d of refrigerator storage. The results showed that the CP treatment significantly increased all the primary and secondary lipid oxidation values measured in this study, as well as the percentages of saturated fatty acids, but decreased the percentages of unsaturated fatty acids, especially polyunsaturated fatty acids. The lipid oxidation values were significantly increased in the GasC-CP group. After 8 d, clearly increased percentages of saturated fatty acids, a low level of major polyunsaturated fatty acids (especially linoleic (C18:2n-6)), and a decrease in the percentages of eicosapentaenoic acid (C20:5n-3) and docosahexaenoic acid (C22:6n-3) were found in GasC-CP; that is, the serious oxidation of lipids was found in the high O2 concentration group. In addition, the sensory score was also lower than that of the hypoxia CP group. Therefore, high O2 concentrations can enhance lipid oxidation and the changes in the fatty acid concentration. Controlling the O2 concentration is reasonable to limit the degree to which lipids are oxidized in tilapia after the in-package CP treatment.

Effects of in-package cold plasma treatment on the physicochemical and oral toxicological properties of raw grape tomatoes and the probability of salmonellosis from consumption of the tomatoes

Effects of in-package cold plasma treatment on the physicochemical and oral toxicological properties of raw grape tomatoes and the probability of salmonellosis from consumption of the tomatoes

Effects of in-package atmospheric dielectric barrier discharge cold plasma treatment on the antimicrobial efficacy of whey protein isolate-based edible films that incorporate malic acid against Salmonella in chicken breast processed meat

Effects of in-package atmospheric dielectric barrier discharge cold plasma (CP) treatment on the antimicrobial efficacy of malic acid-incorporated whey protein isolate (MA–WPI) coating and MA diffusion in MA–WPI-coated skinless chicken breast processed meat (CBPM) were evaluated. MA–WPI coating followed by CP treatment (MA–WPI + CP) inactivated Salmonella (5.6 log CFU/g) in CBPM by 1.8 log CFU/g. CP treatment increased Salmonella reduction rates in MA–WPI-coated samples during storage at 4 and 10 °C and the diffusion coefficients of MA in the coating, which was confirmed by comparing results of MA–WPI + CP-treated and MA–WPI-coated samples. CP treatment facilitates MA diffusion in the coating, thereby increasing the Salmonella inhibition efficacy of the coating. MA–WPI + CP treatment did not influence the color and lipid oxidation of CBPM during storage at 4 °C and the water vapor permeability, elongation, and elastic modulus of MA–WPI films. Industrial relevanceThrough the technological development of in-package cold plasma treatment for decontamination of food in the industrial production line, the microbiological safety of ready-to-eat foods coated with antimicrobials can be effectively increased by exposing the coated foods to cold plasma to accelerate the diffusion of the antimicrobials in the coating to the site of microbial contamination at the surface. The effect of cold plasma treatment on the antimicrobial efficacy of the antimicrobial coating is useful, especially during the initial stages when the coating is expected to exhibit highly efficacious antimicrobial function.

Impact of in-package cold plasma treatment on the physicochemical properties and shelf life of button mushrooms (Agaricus bisporus)

Button mushrooms are perishable due to microbial spoilage and browning. The effect of in-package cold plasma CP treatment on the quality and shelf life of button mushrooms is presented. Samples were sealed inside a package with different gas combinations [80% O2 + 10% CO2 + 10% N2, 10% O2 + 10% CO2 + 80% N2, and 10% O2 + 80% CO2 + 10% N2], treated with CP for 15 min at 28 kV and stored at 4 °C for 7 days. Microbiological and physicochemical properties of button mushrooms (control, samples treated with direct cold plasma (DCP), and those packed in three different modified atmospheric packing (MAP) compositions) were analyzed on days 1, 4, and 7 after treatment. Following DCP and in-package CP treatment, the total bacterial count was reduced by 0.93 and 1.14 log CFU/g, while the yeast and mold count was reduced by 1.07 and 1.24 log CFU/g, respectively. In-package CP reduced PPO activity by 29%. Changes in physicochemical properties of button mushrooms were insignificant on day 1. MAP with high oxygen showed larger microbial reductions than the other two gas combinations. At the end of storage, all in-package CP treated button mushrooms maintained significantly (p < 0.05) better quality characteristics than control and DCP-treated mushrooms. The samples treated with CP and kept in a high O2 gas concentration exhibited better quality characteristics. Therefore, in-package CP technology with high O2 concentration can be used as a potential tool for the decontamination and shelf-life extension of button mushrooms.

In-package cold plasma treatment for microbial inactivation in plastic-pouch packaged steamed rice cakes

In-package atmospheric cold plasma (ICP) treatment was investigated as a method to inactivate microorganisms in Korean steamed rice cakes (SRCs) packaged in plastic pouches. The effect against Escherichia coli O157:H7 increased with increasing ICP treatment power and time and using nylon-containing pouches. Moreover, E. coli O157:H7 growth was effectively inhibited at 4 and 25 °C when SRCs were in a pouch filled with an O2-CO2 (70 % and 30 %) gas. Under optimal treatment power (30 W), treatment time (4 min), and headspace-to-SRC volume ratio (7:1) conditions, ICP effectively inactivated E. coli O157:H7, Bacillus cereus spores, Penicillium chrysogenum, and indigenous aerobic bacteria, as well as yeast and molds in SRCs packaged with air in the nylon/low density polyethylene pouch by 2.2 ± 0.2 log CFU/g, 1.4 ± 0.2 log spores/g, 2.2 ± 0.3 log spores/g, 1.1 ± 0.2 log CFU/g, and 1.0 ± 0.1 log CFU/g, respectively. Furthermore, post-treatment storage was effective in preventing the growth of E. coli O157:H7 in SRCs at 4 °C and 25 °C when the pouch was filled with N2–CO2 (50 % and 50 %) or O2–CO2 (70 % and 30 %). Collectively, these findings indicate that ICP treatment effectively decontaminates SRCs and represents a potential non-thermal microbial decontamination technology for SRCs in pouch packaging.

In-package cold plasma treatment enhances the antimicrobial efficacy of malic acid-incorporated whey protein edible coating against Salmonella and Listeria monocytogenes in steamed fish paste

An in-package atmospheric dielectric barrier discharge cold plasma (CP) treatment integrated with malic acid (MA)-incorporated whey protein isolate coating treatment (MA-WPI + CP treatment) was developed to inactivate Salmonella and Listeria monocytogenes in steamed fish paste packaged in a plastic container. MA-WPI + CP treatment inactivated Salmonella and L. monocytogenes more effectively than either one of the treatments. MA-WPI + CP treatment more effectively inhibited the growth of Salmonella and L. monocytogenes in fish paste than MA-WPI coating during storage at 4 °C. The diffusion coefficients of MA in WPI films increased by CP treatment from 2.11 × 10−14 and 3.27 × 10−14 to 2.79 × 10−14 and 4.83 × 10−14 m2/s at 4 and 10 °C, respectively. The accelerated diffusion of MA by CP could increase the microbial inhibition in steamed fish paste coated with MA-WPI during storage. MA-WPI + CP treatment showed potential to increase microbial safety of steamed fish paste.

In-package cold plasma treatment of braised chicken: voltage effect

This study investigated the effect of different dielectric barrier discharge cold plasma (DBD-CP) treatment voltages on the microbiological growth and quality characteristics of braised chicken during storage at (4 ± 1) °C. Argon-packed samples were subjected to DBD-CP treatment for 3min at voltages of 50, 60 and 70kV. As a result, there was no significant (P > 0.05) difference in L⁎, a⁎, b⁎ and pH of braised chicken between control and treatment groups at the same storage time. However, the development of lipid oxidation in DBD-CP treatment samples was slower than that in air-packed samples. Compared to air-packed samples, the reduction of total viable count, yeasts and molds, lactic acid bacteria and Pseudomonads spp. in 70kV treated samples on day 15 were 3.21, 2.41, 2.44 and 1.96 lg (CFU/g), respectively. The results indicate that DBD-CP treatment could extend the shelf life of braised chicken without negative impacts on quality characteristics.

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

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.

Optimization of in-package cold plasma treatment conditions for raw chicken breast meat with response surface methodology

Response surface methodology (RSM) was used to optimize in-package cold plasma (IPCP) treatment for raw chicken breast meat. Non-inoculated and inoculated samples with Campylobacter (5.06 log10 CFU/mL) and Salmonella (5.40 log10 CFU/mL) were packaged in 35% O2/60% CO2, 65% O2/30% CO2, or 95% O2/0% CO2 and treated at 60, 70, or 80 kV for 60, 180, or 300 s. Microbial counts, color, pH, and drip loss were measured. There were no differences in Campylobacter, Salmonella, drip loss, or pH between treatments. IPCP could reduce psychrophiles by >1.0 log, depending on O2 and voltage interaction. Treatment effects on meat color varied by CIE L*a*b*. RSM analysis suggested that packaging atmosphere with 35% O2 and 60% CO2 and IPCP at 60 kV for 60 s were the optimal condition for maximizing microbiological shelf-life and minimizing appearance changes in raw chicken meat packaged in a barrier film and stored at 4 °C for 5 days. Industrial relevanceThe current study used response surface methodology to determine the optimal condition in the combination of voltage and time of an in-package cold plasma (IPCP) treatment and modified atmosphere (MA) packaging for extending shelf life and reducing food safety risk of pre-packaged raw chicken breast meat during refrigerated storage. Our data provided evidence that the optimal IPCP-treatment parameters and packaging atmosphere varied with targeted microorganisms and CIEL*a*b* color indicators. In MA packaging, changes in IPCP treatment voltage and time did not affect populations of Campylobacter and Salmonella, drip loss and pH; however, low IPCP treatment voltage (60 kV) for short exposure time (60 s) was as effective as the high voltage (80 kV) for longer treatment time (300 s) against psychrophiles and could reduce the changes in raw meat appearance (indicated with CIEL* measurements) due to IPCP treatment. Reducing O2 in packages from 95 to 35% resulted in better inhibition of psychrophilic growth on raw meat and changes in raw meat appearance or meat color lightness. It is recommended to use MA of 35% O2 and 60% CO2 and IPCP treatment at 60 kV for 60 s to extend microbiological shelf life, improve food safety, and retain quality of raw chicken breast meat packaged with a barrier film and stored at refrigerated temperature.

Inactivation of Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Tulane virus in processed chicken breast via atmospheric in-package cold plasma treatment

This study investigated the efficacy of atmospheric dielectric barrier discharge in-package cold plasma treatment (ADCPT) in inactivating Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Tulane virus (TV) in whey protein-coated boiled chicken breast (BCB) cubes. The optimal ADCPT conditions for Salmonella inactivation were determined, and the effects of ADCPT on lipid oxidation and color were also evaluated. The optimal ADCPT voltage and time for Salmonella inactivation were found to be 39 kV and 3.5 min, respectively, resulting in a reduction of 3.7 log CFU/cube. Further, these conditions effectively inactivated E. coli O157:H7 (3.9 log CFU/cube), L. monocytogenes (3.5 log CFU/cube), and TV (2.2 PFU/cube). A second-order polynomial model can be used to explain the inactivation of Salmonella. ADCPT did not significantly affect the values of thiobarbituric acid reactive substance or color of BCB. Thus, these results suggest that ADCPT is an effective method for enhancing the microbiological safety of ready-to-eat packaged BCB by inactivating major foodborne pathogens and human norovirus without affecting the lipid oxidation and color of BCB.

Influence of in-package cold plasma treatment on microbiological shelf life and appearance of fresh chicken breast fillets

The effect of in-package cold plasmas (CP) was studied on microbiological shelf life and surface lightness of fresh chicken fillets (pectoralis major). Chicken fillets were packaged in food trays in air or modified atmosphere (MA) gas (O2:CO2:N2 = 65:30:5) and stored at 4 °C after exposed to an in-package cold plasma (80 kV for 180 s) treatment. Populations of mesophiles, psychrophiles, and pseudomonas spp. were measured as indicators for microbiological shelf life and CIELAB L∗ values as an indicator for raw meat appearance. Results show that regardless of microbial type, there were no significant differences in microbial counts between the control and CP treated chicken fillets packed in air. However, in the MA packages, microbial counts were consistently lower than the non-treated control during refrigerated storage. Regardless of CP treatment, the microbial counts on the samples packed in air were much higher than in MA. They were more than 6 logs cfu/g in air compared to fewer than 4 logs cfu/g in MA after 7 d storage and fewer than 6 logs cfu/g after 14 d storage. Regardless of CP treatment and gas composition in package, there were no significant differences in the surface L∗ value between the fillets pre-treatment and those after storage at 4 °C. These results demonstrate that the effects of in-package CP treatments on microbiological shelf life of fresh chicken fillets depend upon headspace composition in packages. When fresh chicken fillets are packed in air, CP treatment has no effect on microbiological shelf life. MA packages with high O2 and CO2 significantly extend shelf life and CP treatment with MA can at least double shelf life of fresh chicken meat (more than 14 days). Regardless of headspace composition, in-package CP does not have negative effects on chicken meat appearance.

Characterization of a Novel Atmospheric Air Cold Plasma System for Treatment of Packaged Biomaterials

<abstract><title><italic>Abstract.</italic></title> The technology of atmospheric plasma (ionized gas), widely used in material processing, offers one of the most significant breakthroughs in food and agri-material processing. This technology allows for the generation of bactericidal molecules very efficiently with low power requirements. Non-thermal atmospheric plasma has been used to effectively decontaminate surfaces, but it has received limited investigation for in-package decontamination. This study demonstrates the potential for in-package plasma treatment of model liquids within sealed packages. The advantage of in-package cold plasma treatment is that the bactericidal molecules are generated and contained in the package, allowing extended exposure to bacteria while reverting back to the original package gas within 24 h storage. This study treated liquid food surrogates containing bacteria and oxidation sensitive dye (methylene blue) inside sealed packages. The surrogates were placed in 96-well plates and were packaged in air and exposed directly and indirectly to the plasma field in a 2.2 cm high × 23 cm × 31 cm sealed polypropylene container for up to 5 min. Treatments were carried out using a prototype dielectric barrier discharge (DBD) operating at a voltage of 40 kV and frequency of 50 Hz. The UV-Vis emission spectra of the plasma revealed emission bands for nitrogen and oxygen species, including strong emission lines for excited states of the atomic species O, O⁺, N, and N⁺. The results from the evaluation of methylene blue suggest that direct exposure to the plasma ionization field produced a greater oxidative effect compared to indirect exposure. For 5 min treatment, direct exposure of methylene blue resulted in a 90% reduction in absorbance, and indirect exposure of methylene blue resulted in a 75% reduction in absorbance. These reductions may result from conversion of ozone into hydroxyl radicals, which reduces the methylene blue from dark blue color to clear. This process is irreversible. Additionally, bacterial studies examining treatment of E. coli ATCC 25922 suspended in maximum recovery diluent in 96-well plates found a 7 log₁₀ reduction after 50 s treatment and 24 h storage for both direct and indirect plasma exposure. Ozone concentrations measured immediately after 5 min of ionization were approximately 1600 ppm. The goal of this research is to maximize bacterial reductions and minimize quality (oxidative) loss for biomaterials inside a sealed package.