Inhibition of fruit softening by cold plasma treatments: affecting factors and applications

Integrated in-package treatment of hydrogen peroxide and cold plasma for microbial inactivation of cabbage slices

The efficacy of an in-package microbial inactivation method, combining H2O2 and atmospheric dielectric barrier discharge cold plasma (ADCP) treatments (H2O2-ADCP), in reducing contamination of Brassica oleracea (cabbage) slices was investigated. Cabbage slices were placed in a polyethylene terephthalate container with a H2O2-soaked polypropylene pad attached to the inside of the lid, followed by subjecting the closed container to ADCP treatment. The H2O2-ADCP treatment inactivated Escherichia coli O157:H7 and Listeria monocytogenes, resulting in reductions of 1.8 and 2.0 log CFU/g, respectively, which were greater than the sum of the inactivation effects observed with each individual treatment. The combined treatment decreased the count of Bacillus cereus spores and indigenous bacteria by 1.0 log spores/g and 1.3 log CFU/g, respectively. Moreover, the in-package method did not alter the moisture content or texture of cabbage slices. These results demonstrate the potential of H2O2-ADCP as a microbial decontamination method for packaged cabbage slices.

In vivo biological analysis of cold plasma on allergenicity reduction of tropomyosin in shrimp

In vivo biological regulations of the allergenicity of tropomyosin (TM) treated by cold plasma (CP) were investigated by in vivo mouse model. The sensitization models of Balb/c mice were successfully established. CP treatment reduced the allergic symptoms of mice and regulated the Th1/Th2 balance to prevent allergy by activating Treg cells, which was deduced by serum and cytokines analysis. For intestinal flora analysis, allergy occurrence was accompanied by the decreased species abundance and the increased species diversity of intestinal flora. The significant species composition difference between the TM group and the PBS group showed a possible connection between bacterial diversity and allergy. Furthermore, Firmicutes, Bacteroidetes, Parabacteroides, Alloprevotella, Bacteroides, and Lachnospiraceae could relate to allergy occurrence. Intestinal section analysis suggested that allergy occurrence was accompanied by the damaged intestinal structure, and CP treatment could relieve the damage caused by an allergy.

Intervention mechanisms of cold plasma pretreatment on the quality, antioxidants and reactive oxygen metabolism of fresh wolfberries during storage

Fresh wolfberries, a nutritious "super fruit", face limited marketing potential due to storage difficulties. This study aimed to enhance their storage stability using dielectric barrier discharge plasma (DBD) pretreatment and investigate the intervention mechanism. The results indicated that the optimal condition of DBD pretreatment for fresh wolfberries was 13.64 kV, 70 s and 2.7 kHz, which extended their shelf from 2 to 5 d at room temperature. This pretreatment reduced decay, weight loss, and firmness reduction by inactivating microorganisms and inhibiting respiration. Additionally, the decline of phenols, flavonoids, ascorbic acid, and antioxidant activity was inhibited, while maintaining high content of polysaccharides, titratable acid, and carotenoids. Interestingly, moderate DBD treatment produced reactive oxygen species (ROS) that triggered the defense response of wolfberries' ROS metabolism system and promoted the biosynthesis of flavonoids, thereby enhancing resistance to decay. The findings offer new insight into plasma effects on fruits and vegetables.

Enhanced properties of non-starch polysaccharide and protein hydrocolloids through plasma treatment: A review

Hydrocolloids are important ingredients in food formulations and their modification can lead to novel ingredients with unique functionalities beyond their nutritional value. Cold plasma is a promising technology for the modification of food biopolymers due to its non-toxic and eco-friendly nature. This review discusses the recent published studies on the effects of cold plasma treatment on non-starch hydrocolloids and their derivatives. It covers the common phenomena that occur during plasma treatment, including ionization, etching effect, surface modification, and ashing effect, and how they contribute to various changes in food biopolymers. The effects of plasma treatment on important properties such as color, crystallinity, chemical structure, rheological behavior, and thermal properties of non-starch hydrocolloids and their derivatives are also discussed. In addition, this review highlights the potential of cold plasma treatment to enhance the functionality of food biopolymers and improve the quality of food products. The mechanisms underlying the effects of plasma treatment on food biopolymers, which can be useful for future research in this area, are also discussed. Overall, this review paper presents a comprehensive overview of the current knowledge in the field of cold plasma treatment of non-starch hydrocolloids and their derivatives and highlights the areas that require further investigation.

Inhibition of cell wall pectin metabolism by plasma activated water (PAW) to maintain firmness and quality of postharvest blueberry

Blueberry is a class of berries with high nutritional and economic value but has short shelf life due to its rapid softening at room temperature. This study investigated the effects of plasma-activated water (PAW) treatment on the softening quality and cell wall pectin metabolism of blueberries stored for 10 d at 25 °C after being immersed in PAW for 10 min. PAW was generated by plasma with different times (1 and 2 min), fixed frequency (10 kHz) and fixed voltage (50 kV). The analysis showed that the firmness of PAW-treated fruit significantly increased (P < 0.05) by 36.4% after 10 d storage. PAW treatment controlled the solubilization of pectin from water-insoluble to water-soluble. The activities of cell wall pectin-degrading enzymes like polygalacturonase (PG), β-galactosidase (β-Gal) and pectin methylesterase (PME) in PAW-treated blueberries decreased by 15.7%, 18.3%, and 27.9%, respectively, on day 10. After PAW treatment, blueberries also maintained better postharvest quality (firmness, colour, soluble solid content and anthocyanin content) and intact epidermal waxy and cell wall structure. These results suggested that PAW showed great potential for postharvest fresh-keeping of blueberry.

The combined effects of ultrasound and plasma-activated water on microbial inactivation and quality attributes of crayfish during refrigerated storage

In this study, a decontamination technology combining ultrasound (US) and plasma-activated water (PAW) was developed to better preserve crayfish. First, the decontamination efficacy of US, PAW and their combinations (UP) on crayfish was quantified after 0, 20, 40, or 60 min of treatments. The total viable count (TVC) was reduced by 0.27-0.77 Log CFU/g after individual US or PAW treatments, while a TVC reduction of 1.17 Log CFU/g was achieved after 40 min of UP treatment. Besides, the changes in psychrotrophic bacteria, lactic acid bacteria, yeasts and molds followed a similar trend to TVC. UP treatments normally resulted in more significant reductions in the natural microbiota of crayfish than US or PAW treatments. Furthermore, the microbial quality, physicochemical properties and sensory properties of crayfish after different treatments were assessed during storage at 4 °C for 12 days. According to TVC and total volatile basic nitrogen (TVB-N) values, the control group became unacceptable from 4 days, US or PAW groups became unacceptable from 6 days, while UP group extended the storage time to 8-10 days. During storage, thiobarbituric acid reactive substances (TBARS) values of all the groups were maintained below 0.5 mg/kg, among which the control group exhibited the highest value (0.39 mg/kg). Moreover, UP treatment effectively retarded the deterioration in color and texture properties of crayfish. Fourier transform infrared (FTIR) spectroscopy analysis indicated that UP treatment decreased the α-helix contents and increased the β-sheet contents of crayfish proteins, while the structural changes were not evident at the end of storage. Low-field nuclear magnetic resonance (LF-NMR) analysis revealed that UP treatment reduced the water migration and enhanced the stability of bond water in crayfish. In addition, E-nose analysis revealed the protection of UP treatment on the sensory properties of crayfish during storage. This study demonstrated that the combinations of US and PAW treatments effectively accelerated the decontamination of crayfish and contributed to better storage quality.

Current and Potential Applications of Atmospheric Cold Plasma in the Food Industry

The cost-effectiveness and high efficiency of atmospheric cold plasma (ACP) incentivise researchers to explore its potentials within the food industry. Presently, the destructive nature of this nonthermal technology can be utilised to inactivate foodborne pathogens, enzymatic ripening, food allergens, and pesticides. However, by adjusting its parameters, ACP can also be employed in other novel applications including food modification, drying pre-treatment, nutrient extraction, active packaging, and food waste processing. Relevant studies were conducted to investigate the impacts of ACP and posit that reactive oxygen and nitrogen species (RONS) play the principal roles in achieving the set objectives. In this review article, operations of ACP to achieve desired results are discussed. Moreover, the recent progress of ACP in food processing and safety within the past decade is summarised while current challenges as well as its future outlook are proposed.

Toxic reactive oxygen species stresses for reconfiguring central carbon metabolic fluxes in foodborne bacteria: Sources, mechanisms and pathways

The toxic reactive oxygen species (toxROS) is the reactive oxygen species (ROS) beyond the normal concentration of cells, which has inactivation and disinfection effects on foodborne bacteria. However, foodborne bacteria can adapt and survive by physicochemical regulation of antioxidant systems, especially through central carbon metabolism (CCM), which is a significant concern for food safety. It is thus necessary to study the antioxidant regulation mechanisms of CCM in foodborne bacteria under toxROS stresses. Therefore, the purpose of this review is to provide an update and comprehensive overview of the reconfiguration of CCM fluxes in foodborne bacteria that respond to different toxROS stresses. In this review, two key types of toxROS including exogenous toxROS (exo-toxROS) and endogenous toxROS (endo-toxROS) are introduced. Exo-toxROS are produced by disinfectants, such as H₂O₂ and HOCl, or during food non-thermal processing such as ultraviolet (UV/UVA), cold plasma (CP), ozone (O₃), electrolyzed water (EW), pulsed electric field (PEF), pulsed light (PL), and electron beam (EB) processing. Endo-toxROS are generated by bioreagents such as antibiotics (aminoglycosides, quinolones, and β-lactams). Three main pathways for CCM in foodborne bacteria under the toxROS stress are also highlighted, which are glycolysis (EMP), pentose phosphate pathway (PPP), and tricarboxylic acid cycle (TCA). In addition, energy metabolisms throughout these pathways are discussed. Finally, challenges and future work in this area are suggested. It is hoped that this review should be beneficial in providing insights for future research on bacterial antioxidant CCM defence under both exo-toxROS stresses and endo-toxROS stresses.

Enhancement of Wheat Seed Germination, Seedling Growth and Nutritional Properties of Wheat Plantlet Juice by Plasma Activated Water

Previous studies have shown the great potential of using plasma-activated water (PAW) on improving agriculture seed germination, however, information on the influence of PAW on crop plantlet juice remains scanty. In this research, the effect of PAW generated by atmosphere pressure Ar-O₂ plasma jet for 1-5 min on wheat seed germination, seedling growth and nutritional properties of wheat plantlet juice was investigated. Results revealed that all PAWs could enhance wheat seed germination and seedling growth in 7 days by improving the germination rate, germination index, fresh weight, dry weight and vigour index, and especially that PAW activated for 3 min (PAW-3) showed the best overall performance. In addition, the application of PAWs enhanced the nutritional properties of wheat plantlet juice from those grown for 14 days by improving total soluble solids, protein content, photosynthetic pigments, total phenolic content, antioxidant activity, enzyme activity, free amino acids and minerals content, and the best enhancement was also observed in PAW-3. It was concluded that PAWs would be an effective technique to enhance the growth and nutritional properties of crop sprouts, which could be served as functional foods in many forms.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s00344-022-10677-3.

Storage Quality Variation of Mushrooms (Flammulina velutipes) after Cold Plasma Treatment

Flammulina velutipes is susceptible to mechanical damage, water loss, microbial growth, and other factors that lead to postharvest deterioration, thereby shortening the storage period. The purpose of this study was to analyze the effects of cold plasma treatment on the physicochemical properties and antioxidant capacity of F. velutipes during storage at 4 °C for 21 days. Compared to the control group, cold plasma cold sterilization (CPCS) treatment (150 Hz, 95 kV for 150 s) effectively inhibited the growth and multiplication of microorganisms on the surface of F. velutipes, with no significant effect on the fresh weight change and the superoxide anion generation rate, but with a higher postharvest 1,1-dephenyl-2-picrylhydrzyl (DPPH) clearance rate. Moreover, CPCS increased antioxidant enzyme activities, delayed both malondialdehyde (MDA) accumulation and vitamin C loss, inhibited the browning reaction and polyphenol oxidases (PPO) activity and protected F. velutipes cell membrane from disruption. In general, CPCS not only achieved bacteriostatic effects on F. velutipes during storage, but also reduced cell damage from free radical oxidation, resulting in better postharvest quality and longer shelf life.

Oxidative lesions and post-treatment viability attenuation of listeria monocytogenes triggered by atmospheric non-thermal plasma

AIMS

The aim of the current study was to investigate the effect of plasma-mediated oxidative stress on the post-treatment viability of Listeria monocytogenes at the physiological and molecular levels.

METHODS AND RESULTS

10⁷  CFU/ml L. monocytogenes in 10 ml phosphate-buffered saline (PBS) was treated with atmospheric non-thermal plasma for 0, 30, 60, 90 and 120 s respectively. Optical diagnostics using optical emission spectroscopy (OES) confirmed that dielectric barrier discharge (DBD) plasma was a significant source of ample exogenous reactive oxygen and nitrogen species (RONS). The development of extracellular main long-lived species was associated with plasma exposure time, accompanied by a massive accumulation of intracellular ROS in L. monocytogenes (p < 0.01). With the exception of virulence genes (hly), most oxidation resistance genes (e.g. sigB, perR, lmo2344, lmo2770 and trxA) and DNA repair gene (recA) were upregulated significantly (p < 0.05). A visible fragmentation in genomic DNA and a decline in the secretion of extracellular proteins and haemolytic activity (p < 0.01) were noticed. The quantitate oxygen consumption rates (OCRs) and extracellular acidification rates (ECARs) confirmed the viability attenuation from the aspect of energy metabolism. Survival assay in a real food system (raw milk) further suggested not only the viability attenuation, but also the resuscitation potential and safety risk of mild plasma-treated cells during post-treatment storage.

CONCLUSION

DBD plasma had the potential to inactivate and attenuate the virulence of L. monocytogenes, and it was recommended that plasma exposure time longer than 120 s was more suitable for attenuating viability and avoiding the recovery possibility of L. monocytogenes in raw milk within 7 days.

SIGNIFICANCE AND IMPACT OF THE STUDY

The current results presented a strategy to inactivate and attenuate the viability of L. monocytogenes, which could serve as a theoretical basis for better application of non-thermal plasma in food in an effort to effectively combat foodborne pathogens.

Impact of vanillin on postharvest disease control of apple

Apple fruits are susceptible to infection by postharvest fungal pathogens, which may cause fruit decay and severe economic losses. This study investigated the antifungal spectrum of vanillin against common decay pathogens of apple and explored the antifungal mechanisms of vanillin in vitro. In vivo experiments were carried out to evaluate the effects of vanillin on apple postharvest disease control and fruit quality. Moreover, the induced resistance mechanism of vanillin on apple fruit was preliminarily explored. The results showed that vanillin has broad-spectrum antifungal effects, especially on Alternaria alternata. Vanillin could significantly inhibit the growth rate, mycelium biomass, and spore germination of pathogenic fungi by increasing the cell membrane permeability and lipid peroxidation. Importantly, vanillin treatment reduced the incidence of apple decay caused by A. alternata and Penicillium expansum, and contributed to improve fruit quality. Further studies indicated that vanillin could induce elevation in the activities of defense-related enzymes in apple fruit, such as phenylalanine ammonia-lyase (PAL), chitinase (CHI) and β-1,3-glucanase (β-1,3-GA), and increase total phenols and flavonoids contents. Generally, these results suggest that vanillin may contribute to the induced resistance of apple fruits to pathogenic fungi. To conclude, the results of this research provide theoretical foundations for the application of vanillin in the control of apple postharvest decay caused by fungal pathogens.

Hybridising plasma functionalized water and ultrasound pretreatment for enzymatic protein hydrolysis of Larimichthys polyactis: Parametric screening and optimization

Hybridising plasma functionalized water and ultrasound pretreatment for the enzymatic hydrolysis (HPUEH) of Larimichthys polyactis was evaluated by adopting Plackett-Burman design for parametric screening of six key variables, and Box-Behnken design for optimizing three most significant variables including plasma generating voltage (P_V), ultrasound treatment time (U_T), and enzyme concentration (E_C). The models developed for predicting the degree of hydrolysis (DoH), protein recovery (PVY), and soluble protein content (SPC) were sufficiently fitted to the experimental data (R² ≥ 0.966) with non-significant lack of fit and used for determining the optimum conditions as P_V of 70 V, U_T of 15 min, and E_C of 1.787%, with predictive values of 27.74%, 85.62%, and 3.28 mg/mL for DoH, PVY, and SPC, respectively. HPUEH presented hydrolysates with smaller peptide sizes and molecular weights, enhanced DoH, PVY, SPC, amino acids and antioxidant activity, but reduced emulsifying and foaming properties when compared with conventional enzymatic hydrolysis.

Modelling of inactivation kinetics of Escherichia coli and Listeria monocytogenes on grass carp treated by combining ultrasound with plasma functionalized buffer

Linear (first-order) and non-linear (Weibull, biphasic, and log-logistic) models were evaluated for predicting the inactivation kinetics of Escherichia coli and Listeria monocytogenes on grass carp treated by a novel technique (UPFB) combining ultrasound (US) with plasma functionalized buffer (PFB). Results showed that UPFB was more effective for inactivating bacteria when compared with individual applications of US or PFB with reductions of 3.92 and 3.70 log CFU/g for Escherichia coli and Listeria monocytogenes, respectively. Compared with the linear model, the three non-linear models presented comparable performances and were more suitable for describing the inactivation kinetics with superior adj-R² (0.962-0.999), accuracies (0.970-1.006) and bias factors (0.995-1.031), and by assessing the strengths of evidence, weights of evidence and evidence ratios for the models, the biphasic model was identified as the best fit model. The current study provided new insights into the effective evaluation of decontamination methods.

Subcellular damages of Colletotrichum asianum and inhibition of mango anthracnose by dielectric barrier discharge plasma

Colletotrichum asianum (C. asianum) is a new pathogenic fungus that causes mango anthracnose. Cold plasma is a novel non-thermal decontamination technology, which has been proven to be effective in controlling postharvest fungus. Herein, dielectric barrier discharge (DBD) plasma was used to treat C. asianum spores in sterile phosphate-buffered saline, the damages in subcellular structures of C. asianum and inhibition of mango anthracnose were evaluated. Results showed that after 9 min treatment, the spore germination rate and spore viability were decreased by 95.48% and 98.82%, respectively, and the subcellular structures were damaged (P < 0.05), leading to spores death. Besides, DBD plasma treatments could control mango anthracnose and maintain mango quality, and the disease incidence and lesion diameter of mango treated for 9 min were decreased by 48.00% and 62.95%, respectively. Therefore DBD plasma inactivated C. asianum spore, providing an alternative technique for preventing and controlling mango anthracnose.

Cold plasma: a promising technology for improving the rheological characteristics of food

At the beginning of the 21st century, many consumers show interest in purchasing safe, healthy, and nutritious foods. The intent requirement of end-users and many food product manufacturers are trying to feature a new processing technique for the healthy food supply. The non-thermal nature of cold plasma treatment is one of the leading breakthrough technologies for several food processing applications. The beneficial response of cold plasma processing on food quality characteristics is widely accepted as a substitution technique for new food manufacturing practices. This review aims to elaborate and offer crispy innovative ideas on cold plasma application in various food processing channels. It highlights the scientific approaches on the principle of generation and mechanism of cold plasma treatment on rheological properties of foods. It provides an overview of the behavior of cold plasma in terms of viscosity, crystallization, gelatinization, shear stress, and shear rate. Research reports highlighted that the cold plasma treated samples demonstrated a pseudoplastic behavior. The published literatures indicated that the cold plasma is a potential technology for modification of native starch to obtain desirable rheological properties. The adaptability and environmentally friendly nature of non-thermal cold plasma processing provide exclusive advantages compared to the traditional processing technique.

Functional and bioactive properties of Larimichthys polyactis protein hydrolysates as influenced by plasma functionalized water-ultrasound hybrid treatments and enzyme types

The effects of plasma functionalized water (PFW) and its combination with ultrasound (UPFW) on the functional and bioactive properties of small yellow croaker protein hydrolysates (SYPHs) produced from three enzymes were investigated. Fluorescence and UV-Vis spectroscopy indicated that SYPHs tended to unfold with increasing intensity and shift in wavelengths to more flexible conformations under PFW and UPFW treatments. Particle size distribution and microstructure analysis revealed that treatments could disrupt aggregation of protein molecules to increase the roughness, specific surface area, and decrease the particle size of peptides during hydrolysis. The partially denatured structure of SYPHs induced by treatments increased the susceptibility of the fish proteins to exogenous enzymes, thereby accelerating the hydrolytic process to yield peptides with improved solubility, decreased emulsifying and foaming properties, and improved enzyme-specific antioxidant properties. The results revealed that the functionality of SYPHs was influenced by the treatment method and the enzyme type employed.

Effects of combined treatment of plasma activated liquid and ultrasound for degradation of chlorothalonil fungicide residues in tomato

The effects of combined treatment (PAL-U) of plasma-activated liquid (PAL) including plasma-activated water (PAW) and plasma-activated buffer solution (PABS) and ultrasound (U) for the degradation of chlorothalonil fungicide on tomato fruit was investigated. Distilled water and buffer solution were activated by radiofrequency plasma jet for durations of 1, 3, 5, and 10 min to obtain PAL₁ to PAL₁₀. Fruits were immersed in PAL for 15 min and also in distilled water with sonication for 15 min for individual treatments, and in PAL with sonication for 15 min for combined treatments. The maximum chlorothalonil fungicide residues were reduced by 89.28 and 80.23% for PAW₁₀-U and PABS₁₀-U, respectively. HPLC-MS characterization revealed chlorothalonil degradation pathway and formation of 2,4,5-trichloroisophthalonitrile, 2,4-dichloroisophthalonitrile, 4-chloroisophthalonitrile, isophthalonitrile and phenylacetonitrile as degradation products. Treatments also showed no negative effects on tomato quality. Therefore, PAL and PAL-U treatments could serve as effective methods for degrading pesticides on tomatoes.

An overview of tropomyosin as an important seafood allergen: Structure, cross-reactivity, epitopes, allergenicity, and processing modifications

Tropomyosin (TM) is a major allergen in crustaceans, which often causes allergy and is fatal to some consumers. Currently, the most effective treatment is to avoid ingesting TM, although most adverse events occur in accidental ingestion. In this review, the molecular characterization, epitopes, cross-reactivity, and pathogenesis of TM are introduced and elucidated. Modification of TM by traditional processing methods such as heat treatment and enzymatic hydrolysis, and innovative processing technologies including high-pressure treatment, cold plasma (CP), ultrasound, pulsed electric field (PEF), pulsed ultraviolet, microwave and irradiation are discussed in detail. Particularly, enzymolysis, PEF, and CP technologies show great potential for modifying TM and more studies are needed to verify their effectiveness for the seafood industry. Possible mechanisms and the advantages/disadvantages of these technologies for the mitigation of TM allergenicity are also highlighted. Further work should be conducted to investigate the allergenicity caused by protein segments such as epitopes, examine the interaction sites between the allergen and the processing techniques and reveal the reduction mechanism of allergenicity.

Modification of cellulose from sugarcane (Saccharum officinarum) bagasse pulp by cold plasma: Dissolution, structure and surface chemistry analysis

Cellulose is a most abundant natural biopolymer, however, the strong hydrogen bonding system makes cellulose hard to dissolve, limiting its further applications. In this study, an innovative cold plasma (CP) technology was used to modify cellulose from sugarcane (Saccharum officinarum) bagasse pulp. Dissolution, structure, and surface chemistry of cellulose before and after CP treatment were investigated. Results showed that the dissolution rate of cellulose after different CP treatment time (3-12 min) and operating voltage (40-70 kV) was significantly improved. Roughness, even holes (CP treatment 9 min with 50 kV) and breakage (CP treatment 9 min with 70 kV) were observed on the surface. The crystallinity index decreased from 62.31% (control) to 60.88% (CP treatment 3 min with 50 kV). The hydrogen bonding force was weakened and the peak intensity of CO and CO stretching vibration groups were enhanced. Therefore, CP-modified cellulose may be applied more in future, such as biological films for food future packaging.

Metabolomic analyses on microbial primary and secondary oxidative stress responses

Food safety is veryimportant in our daily life. In food processing or disinfection, microorganisms are commonly exposed to oxidative stress perturbations. However, microorganisms can adapt and respond to physicochemical interventions, leading to difficulty and complexity for food safety assurance. Therefore, understanding the response mechanisms of microbes and providing an overview of the responses under oxidative stress conditions are beneficial for ensuring food safety for the industry. The current review takes the metabolomics approach to reveal small metabolite signatures and key pathway alterations during oxidative stress at the molecular and technical levels. These alterations are involved in primary oxidative stress responses due to inactivation treatments such as using hypochlorite (HOCl), hydrogen peroxide (H₂ O₂ ), electrolyzed water (EW), irradiation, pulsed light (PL), electron beam (EB), and secondary oxidative stress responses due to exposures to excessive conditions such as heat, pressure, acid, and alkaline. Details on the putative origin of exogenous or endogenous reactive oxygen species (ROS) are discussed, with particular attention paid to their effects on lipid, amino acid, nucleotide, and carbohydrate metabolism. In addition, mechanisms on counteracting oxidative stresses, stabilization of cell osmolality as well as energy provision for microbes to survive are also discussed.

Helium Atmospheric Pressure Plasma Jet Source Treatment of White Grapes Juice for Winemaking

In the last few years, new emerging technologies to develop novel winemaking methods were reported. Most of them pointed out the need to assess the barrel aging on the wine product, fermentation process, green technologies for wine treatment for long term storage. Among these, plasma technologies at atmospheric pressure are on the way of replacing old and expensive methods for must, wine and yeast treatment, the goal being the long-term storage, aging and even decontamination of such products, and seems to meet the requirements of the winemakers. Using the principles of dielectric barrier discharge, we power up an atmospheric pressure plasma jet in helium. This plasma is used for treatment of fresh must obtained from white grapes. Our research manuscript is focused on the correlation of plasma parameters (applied voltage, plasma power, reactive species, gas temperature) with the physico-chemical properties of white must and wine (1 and 2 years old), via ultraviolet–visible and infrared spectroscopy, and colorimetry. Two types of white must were plasma treated and studied over time. The 10 W plasma source did not exceed 40 °C during treatment, the must did not suffer during thermal treatment. A higher quantity of RONS was observed during plasma-must exposure, supporting further oxidation processes. The UV-Vis and FTIR spectroscopy revealed the presence of phenols, flavones and sugar in the wine samples. Simultaneous visualization of CIE L*a*b* and RGB in color space charts allows easier understanding of wine changing in color parameters. These experimental results supporting the possible usability of atmospheric pressure plasma for winemaking.

Novel technique for treating grass carp (Ctenopharyngodon idella) by combining plasma functionalized liquids and Ultrasound: Effects on bacterial inactivation and quality attributes

A novel technique for treating grass carp by combining plasma functionalized liquids and ultrasound to inactivate bacteria was developed. The effects of the plasma functionalized liquids (PFL) including plasma functionalized water (PFW) and buffer (PFB) and their respective combination with ultrasound treatment (USPFW and USPFB) on the oxidative and physical qualities of grass carp were also investigated. Individual applications of PFW and PFB significantly reduced the populations of Escherichia coli and Shewanella putrefaciens in the range of 0.31-1.18 log CFU/g, compared with the control with a reduction of 0.18 log CFU/g, while combined treatments of USPFW and USPFB presented additional reductions of 0.05-0.65 log CFU/g, with potential synergy demonstrated for PFW and ultrasound. The treatment resulted in improved biomedical index and nutritional value of fatty acids and lipids, protein structural unfolding, increased lipid oxidation and protein degradation with values within the acceptable limits, and the combined treatment was more effective for retarding the hardness reduction in grass carp, while the colour change was also significantly affected, resulting in increased whiteness. The results indicated that the combined treatments may be a promising approach to improving the quality of seafood products.

Optimisation of treatment conditions for reducing Shewanella putrefaciens and Salmonella Typhimurium on grass carp treated by thermoultrasound-assisted plasma functionalized buffer

A novel method of thermoultrasound-assisted plasma functionalized buffer (PFB) for decontaminating grass carp was evaluated using the Box-Behnken design (BBD) with processing variables including PFB generating voltage (P_V), ultrasound treatment time (U_T) and temperature (T_P). The predicted models were found to be significant (p < 0.05) and displayed sufficient fitness with experimental data as indicated by non-significant (p > 0.05) lack of fit and high coefficient of determination (R²≥0.97) values. The optimum decontamination conditions for the responses of S. putrefaciens and S. Typhimurium were P_V of 66 V, U_T of 14.90 min and T_P of 60 ℃, achieving reductions of 4.40 and 3.97 log CFU/g, respectively, with a desirability of 0.998. Among the variables, temperature presented higher significance for inactivating bacteria and the production of volatile basic nitrogen and lipid peroxidation under the optimized conditions were within the limits of freshness for grass carp. Additionally, the effects of PFB and the optimized thermoultrasound-assisted PFB decontamination were mild on the microstructure of grass carp with slight ruptures and loose myofibril structures, indicating the potential of thermoultrasound-assisted PFB for seafood products decontamination with reduced processing time.