Effects of packaging parameters on the inactivation of Salmonella contaminating mixed vegetables in plastic packages using atmospheric dielectric barrier discharge cold plasma treatment

The challenges and prospects of using cold plasma to prevent bacterial contamination and biofilm formation in the meat industry

The risk of foodborne disease outbreaks increases when the pathogenic bacteria are able to form biofilms, and this presents a major threat to public health. An emerging non-thermal cold plasma (CP) technology has proven a highly effective method for decontaminating meats and their products and extended their shelf life. CP treatments have ability to reduce microbial load and, biofilm formation with minimal change of color, pH value, and lipid oxidation of various meat and meat products. The CP technique offers many advantages over conventional processing techniques due to its layout flexibility, nonthermal behavior, affordability, and ecological sustainability. The technology is still in its infancy, and continuous research efforts are needed to realize its full potential in the meat industry. This review addresses the basic principles and the impact of CP technology on biofilm formation, meat quality (including microbiological, color, pH value, texture, and lipid oxidation), and microbial inactivation pathways and also the prospects of this technology.

In-package cold plasma treatment to extend the shelf life of food

Conventional food preservation methods such as heat treatment, irradiation, chemical treatment, refrigeration, and coating have various disadvantages, like loss of food quality, nutrition, and cost-effectiveness. Accordingly, cold plasma is one of the new technologies for food processing and has played an important role in preventing food spoilage. Specifically, in-package cold plasma has become a modern trend to decontaminate, process, and package food simultaneously. This strategy has proven successful in processing various fresh food ingredients, including spinach, fruits, vegetables, and meat. In particular, cold plasma treatment within the package reduces the risk of post-processing contamination. Cryoplasm decontamination within packaging has been reported to reduce significantly the microbial load of many foods' spoilage-causing pathogens. However, studies are needed to focus more on the effects of in-package treatments on endogenous enzyme activity, pest control, and removal of toxic pesticide residues. In this review, we comprehensively evaluated the efficacy of in-package low-temperature plasma treatment to extend the shelf life of various foods. The mechanisms by which cold plasma interacts with food were investigated, emphasizing its effects on pathogen reduction, spoilage mitigation, and surface modification. The review also critically assessed the effects of the treatments on food quality, regulatory considerations, and their potential as viable technologies to improve food safety and packaging life. In-package cold plasma treatment could revolutionize food storage when combined with other sophisticated technologies such as nanotechnology.

SARS-CoV-2 transmission via maritime cold chains: A statistical analysis of nucleic acid detection results of cold chain food imported from Fuzhou ports

Numerous epidemic outbreaks related to cold chains have occurred since the coronavirus disease 2019 (COVID-19) outbreak, suggesting the potential danger of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission through cold chain foods (CCFs). By analyzing SARS-CoV-2 RNA contamination of CCFs imported from Fuzhou ports, this study evaluated the contamination and transmission of SARS-CoV-2 RNA via maritime cold chains, with the aim of provide suggestions for CCFs supervision and public health management. The statistical analysis included 131,385 samples. The majority of the CCFs imported into Fuzhou ports was aquatic raw food that originated in Southeast Asia (57.08 %), South America (19.87 %), and South Asia (11.22 %). South Asia had the highest positivity rate of 0.37 %, followed by Southeast Asia (0.21 %) and South America (0.08 %). The positivity rate showed that the outer packaging of CCFs was the most easily contaminated, accounting for 81.33 % of all positive samples. This suggested that CCFs storage and loading processes were the weak links vulnerable to SARS-CoV-2 contamination. The positivity rates in outer packaging, inner packaging, and content of raw food were 0.48 %, 0.08 %, and 0.05 %, respectively, which were obviously higher than those of processed and refined food. This indicated that increasing the mechanization of factories and implementing sensible worker management practices may decrease viral contamination. The monthly positivity rates varied widely from 0 % (March 2021) to 0.40 % (January 2021), with an average of 0.19 %. The positivity rates in outer packaging, inner packaging and content of crustaceans from Southeast Asia were 2.47 %, 0.41 %, and 0.69 %, which were approximately 5-14 times higher than those of fish and cephalopods. Meanwhile, the monthly detection number show that SARS-CoV-2 epidemic prevention strategies affected the trade of imported CCFs.

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.

Effects of packaging parameters on the microbial decontamination of Korean steamed rice cakes using in-package atmospheric cold plasma treatment

The effects of packaging materials, package shape, and secondary packaging on the inactivation of indigenous mesophilic aerobic bacteria in Korean steamed rice cakes using in-package atmospheric dielectric barrier discharge cold plasma (ADCP) treatment were investigated. Inactivation of indigenous mesophilic aerobic bacteria by ADCP treatment (21 kV, 3 min) was significantly increased by 0.6 and 0.8 log CFU/g (p < 0.05) from 0.7 ± 0.1 and 0.5 ± 0.1 CFU/g, respectively, when polypropylene (PP) and low-density polyethylene (LDPE) were laminated with nylon, respectively. Secondary packaging lowered the inactivation level by 0.7-0.8 log CFU/g from 1.1 to 1.3 log CFU/g. In-package ADCP treatment did not alter the water vapor permeability, oxygen transmission rate, and tensile properties of PP, LDPE, nylon/PP, and nylon/LDPE. Thus, the results demonstrated that lamination of PP or LDPE with nylon and treatment before secondary packaging may be effective strategies for microbial inactivation by in-package ADCP treatment.

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.

Evaluation of In-Package Atmospheric Dielectric Barrier Discharge Cold Plasma Treatment as an Intervention Technology for Decontaminating Bulk Ready-To-Eat Chicken Breast Cubes in Plastic Containers

This article evaluates the effects of in-package atmospheric dielectric barrier discharge cold plasma (ADCP) treatment on microbial inactivation, nitrate and nitrite contents, oral toxicity, and storage quality of protein-coated boiled chicken breast cubes (CBCs). ADCP treatment at 24 kV for 3 min inactivated natural mesophilic aerobic bacteria, Salmonella, and Tulane virus in CBCs by 0.7 ± 0.2, 1.4 ± 0.1 log CFU/cube, and 1.1 ± 0.2 log PFU/cube, respectively. ADCP treatment did not affect the nitrite content of CBCs (p > 0.05). Furthermore, the hematological and blood biochemical parameters from toxicity tests indicated the toxicological safety of ADCP-treated CBCs. Microbial counts of natural bacteria and Salmonella in ADCP-treated CBCs were lower than the ADCP-untreated CBCs by 0.7–0.9 and 1.4–1.7 log CFU/cube, respectively, throughout post-treatment storage at 4 °C for 21 d. ADCP treatment did not alter the pH, color, total volatile basic nitrogen, lipid oxidation, and tenderness of CBCs during storage at 4 and 24 °C, and did not change the sensory properties of CBCs following a 3 d storage period at 4 °C (p > 0.05). Thus, ADCP treatment has the potential to be applied as a method to increase the microbiological safety of packaged ready-to-eat chicken products, leading to overall toxicological safety.