Microbial decontamination of dried laver using corona discharge plasma jet (CDPJ)

Comparison of the pretreatment methods for enhancing hydration of water-soaked adzuki beans (Vigna angularis)

Five pretreatments methods, cold plasma, pressure drop, heating, and bath-type and probe-type sonications were compared to shorten the rehydration process of adzuki bean (Vigna angularis) soaked before the cooking in terms of the hydration and softening efficacies. Moisture content and water activity of the probe-type sonicated beans were most dramatically increased as 11-45% and 0.59-0.97 after soaking for only 2 h, respectively (non-treated: 11-12% and 0.59-0.66). Accordingly, the probe-type sonicated beans were most rapidly softened as 27-5 N in the 2 h-soaking and exhibited the lowest hardness after soaking/cooking as ~ 0.97 N (non-treated: 27-21 N and ~ 5.5 N, respectively). According to scanning electron micrographs, these results can be attributed to formation of prominent fissures or scars in the hilum of the probe-type sonicated beans. Consequently, this study will be provide valuable information for developing a rational process in food industry to shorten the rehydration of the adzuki beans.

Mild processing of seafood-A review

Recent years have shown a tremendous increase in consumer demands for healthy, natural, high-quality convenience foods, especially within the fish and seafood sector. Traditional processing technologies such as drying or extensive heating can cause deterioration of nutrients and sensory quality uncompilable with these demands. This has led to development of many novel processing technologies, which include several mild technologies. The present review highlights the potential of mild thermal, and nonthermal physical, and chemical technologies, either used alone or in combination, to obtain safe seafood products with good shelf life and preference among consumers. Moreover, applications and limitations are discussed to provide a clear view of the potential for future development and applications. Some of the reviewed technologies, or combinations thereof, have shown great potential for non-seafood products, yet data are missing for fish and seafood in general. The present paper visualizes these knowledge gaps and the potential for new technology developments in the seafood sector. Among identified gaps, the combination of mild heating (e.g., sous vide or microwave) with more novel technologies such as pulsed electric field, pulsed light, soluble gas stabilization, cold plasma, or Ohmic heat must be highlighted. However, before industrial applications are available, more research is needed.

Plasma-activated water production and its application in agriculture

The use of plasma-activated water (PAW) treatment is a promising technology that has many advantages, such as high efficiency, flexibility, environmental safety, and no residue. Thus, PAW has been applied in the agriculture industry to increase agricultural production. The application of PAW technology in agricultural production should emphasize its systematic nature, controllability, and operability, making it practical. This review systematically illustrates the production of PAW and the factors influencing it. The application of PAW in agriculture and its mechanism are discussed, including the effect on seed germination, the promotion of plant growth, and the control of plant diseases and pests. The implications of PAW for agriculture production and some of the related challenges are discussed. This review provides a deeper understanding of the viability of PAW technology in agriculture production. © 2021 Society of Chemical Industry.

Decontamination of chokeberries (Aronia melanocarpa L.) by cold plasma treatment and its effects on biochemical composition and storage quality of their corresponding juices

To improve the microbiological quality of chokeberries, corona discharge plasma jet (CDPJ) was employed as a decontaminating agent. The mean levels of aerobic bacteria and yeast and molds contaminants in chokeberries were 4.78 and 4.87 log CFU/g, respectively; the viable counts were decreased by 2.09 and 1.83 log units following CDPJ treatment for 3 min, respectively. A first-order kinetic model was well-suited for explaining the inactivations. The concentration of total polyphenols of chokeberries was unaffected (up to 3 min treatment), whereas DPPH radical scavenging activity was significantly decreased by CDPJ treatment (2 min and more). CDPJ treatment (all tested times) of chokeberries led to a significant decrease of monomeric anthocyanin content of their corresponding juices, whereas soluble solids content (Brix) and pH were unaffected. After storage at 4 °C for 72 h, juices obtained from CDPJ-treated berries possessed relatively low levels of contaminants with no significant alterations in pH and soluble solids content when compared with controls. In conclusion, CDPJ treatment for 2 min was optimal to improve the microbiological quality of the berries without negatively affecting biochemical qualities of their corresponding juices.

Effects of plasma treatment on the oxidative stability of vegetable oil containing antioxidants

Plasma, the fourth stage of matter, is a partially or wholly ionized state of gas. Degree of lipid oxidation and effects of antioxidants were evaluated in bulk oils at plasma treatment. Significant changes in the conjugated dienoic acid were induced after 10 min of plasma treatment, which corresponded to treatment for 2.5 h at 100 °C and 48 h at 60 °C. Tocopherol stability in the stripped corn oil was significantly higher than that in medium-chain triacylglycerol after the plasma treatment. The antioxidant capacities of 10 μM of α-tocopherol and sesamol were higher than that of β-carotene, and synergistic effects among α-tocopherol, sesamol, and β-carotene were not observed. Added α-tocopherol and sesamol decreased CDA formation by 33 and 30% compared to control samples after plasma treatment. Moisture content in oils decreased significantly about 20% moisture after 6 min plasma treatment. Lipid oxidation could be an important issue in plasma-treated lipid-rich products.

Decontamination of collards (Brassica oleracea var. acephala L.) using electrolyzed water and corona discharge plasma jet

Acidic electrolyzed water (AEW) was used for collards sanitization. In the AEW (pH of 3.6; 230 mg/L chlorine) generator, the rates of brine inflow and catholyte outflow were 2.73 and 442 mL/min, respectively. Following treatment of the collards with the AEW alone (5 min), the counts of aerobic bacterial contaminants were reduced by 1.91 log CFU/g, whereas 2.22 log CFU/g reduction was noted by the AEW soaking (5 min) followed by a corona discharge plasma jet treatment (1 min). In a similar manner, the counts of yeasts and mold contaminants were reduced (1.48 and 1.75 log CFU/g, respectively). The combination treatment exhibited an additive effect on the microbial inactivation. The combined treatment did not affect significantly the DPPH-radical scavenging activity and sensory properties (appearance, color and flavor) of the collards compared to negative controls. However, significant alterations in the levels of total phenolics and ascorbic acid were observed post-treatment.

Use of Cold Plasma To Inactivate Escherichia coli and Physicochemical Evaluation in Pumpkin Puree

This work aimed to study the pumpkin puree processing by cold plasma corona discharge as an alternative to heat treatment to reduce Escherichia coli contamination and evaluate physicochemical alterations, using argon (Ar) as the process gas. The treatment time to verify E. coli inactivation was between 2 and 20 min, while physicochemical alterations were analyzed at 5, 10, 15, and 20 min. Cold plasma corona discharge technology to inactivate E. coli proved to be promising, reaching 3.62 log cycles of reduction at 20 min of treatment. The inactivation kinectics showed a tendency of higher decrease with time. Physicochemical characteristics indicate that plasma induces a decrease of pH; however, there is an indication that process gases have an important role and react with the environment and procedure reactive species. This technology may reduce the total carotenoid content of pumpkin puree and in color, mainly the a* parameter, which showed great reduction.

Recent advancements in the application of non-thermal plasma technology for the seafood industry

Non-thermal plasma (NTP) is one of the most promising minimal processing methods for the food industry. However up until recently there are limited studies which would report the application and effect of NTP on processed seafood. The objective of this review is to highlight the recent findings and advancements in the application of NTP within the fish and other seafood industry, including direct application of fresh and dried fish and seafood with as well as indirect application of plasma activated water and seafood industry wastewater purification. The article also summarizes the effect of plasma treatment on microbiological quality, physicochemical and sensory properties and oxidation rate of treated fish and seafood. NTP has high potential to be used within various fields of seafood industry. It is especially effective in treatment of dried seafood products, but the use of plasma activated water during various processing steps such as seafood washing could be also beneficial. Moreover NTP could also be used as a cost effective and environmentally friendly method for seafood wastewater purification.

Effects of approved dose of e-beam irradiation on microbiological and physicochemical qualities of dried laver products and detection of their irradiation status

Most commercial dried laver products show higher microbial contamination. This work evaluated effects of approved dose (7 kGy)-recommended in the Korean Food Code for algal food-of electron beam (E-beam) irradiation on microbiological, physicochemical and luminescence properties of dried laver products. E-beam irradiation caused dose-dependent microbial reductions. For example, a 4 kGy irradiation dose reduced coliform (<2.5 log CFU/g) to undetectable levels (<10 CFU/g), while a 7 kGy irradiation dose reduced total aerobic bacteria count (6.6 log CFU/g) by approximately 2 log cycles. Physicochemical attributes of dried lavers were not significantly (p > 0.05) affected before and after 7 kGy irradiation, but carotenoid content was significantly (p < 0.05) reduced at 10 kGy irradiation. Irradiated samples (>4 kGy) could be detected from non-irradiated ones by luminescence techniques. Overall, results indicated that <7 kGy irradiation is recommended along with other heat treatment for improving microbiological contamination by at most 4 log CFU/g in dried lavers.

Inactivation of Microbial Food Contamination of Plastic Cups Using Nonthermal Plasma and Hydrogen Peroxide

The inactivation effect of the combination of nonthermal plasma and hydrogen peroxide aerosol for the microbial decontamination of inner surface of cylindrical container buckets is studied on one bacterial and seven filamentous micromycete species and on airborne-contaminated cups. While the decontamination by single nonthermal plasma or hydrogen peroxide is not observable after 120 s, the strong decontamination by their combination occurs after 30 s of exposure. Moreover, observed total elimination of airborne contamination of plastic cups predetermines this method as a suitable alternative to the currently used method based on the application of hydrogen peroxide.

Impact of corona discharge plasma treatment on microbial load and physicochemical and sensory characteristics of semi-dried squid (Todarodes pacificus)

The use of corona discharge plasma jet (CDPJ) for the improvement of the sanitary quality of semi-dried squid was investigated. Microbial contaminants, namely aerobic, coliforms, and molds and yeasts, were detected in the samples. The CDPJ generated using 20 kV DC voltage at 58 kHz frequency was used for the decontamination treatment (1-10 min). The bacterial contaminants and molds and yeasts were inactivated in the range of 1.5-2.1 and at 1.9 log CFU/g, respectively. The inactivation pattern was well fitted to the first-order kinetics model. The CDPJ treatment for 10 min did not exert significant changes (p > 0.05) in VBN and the trimethylamine content of semi-dried squid as compared to untreated controls. On the contrary, significant changes (p < 0.05) in moisture content, water activity, pH, color, and TBARS levels were observed upon plasma exposure. However, the CDPJ-treated samples displayed slightly better sensory properties than the controls in terms of appearance, visual color, and flavor.

Effect of corona discharge plasma jet on surface-borne microorganisms and sprouting of broccoli seeds

BACKGROUND

Different pathogenic microorganisms have been reported to cause sprouts-associated outbreaks. In order to sterilise and enhance the germination of seeds, non-thermal plasma has been increasingly investigated in the field of agricultural science as an alternative to the traditional pre-sowing seed treatments. This work aimed to evaluate the effect of corona discharge plasma jet (CDPJ) on disinfection of the natural bio-contaminants of broccoli seed and also studied the plasma effect on sprout seed germination rate and physico-chemical properties of sprouts.

RESULTS

Aerobic bacteria, moulds and yeasts, B. cereus, E. coli, Salmonella spp. were detected on the broccoli seed surface. After 0-3 min treatment using CDPJ, the detected microorganisms were reduced in the range of 1.2-2.3 log units. Inactivation patterns were better explained using pseudo-first-order kinetics. The plasma treatment of seeds up to 2 min exhibited a positive effect on germination rate, seedling growth. The physico-chemical and sensory characteristics of sprouts were unaffected due to the CDPJ treatment of their respective seeds.

CONCLUSION

Corona discharge plasma jet can potentially be used for microbial decontamination of broccoli seeds. In addition, the plasma treatment of broccoli sprout seeds has enabled a significant enhancement in their germination rate and seedling growth without compromising physico-chemical and sensory characteristics of their corresponding sprouts. © 2016 Society of Chemical Industry.