Dishwashing tools such as sponges, scourers, and dishcloths are known to harbor dense and diverse microbial communities, including pathogenic bacteria. In this study, the potential of corona discharge plasma jet (CDPJ) as a disinfectant was tested to improve the hygienic quality of dishwashing tools. For the simulation of microbial contamination, selective pathogenic bacteria (Escherichia coli O157:H7, Staphylococcus aureus, and Pseudomonas putida) were inoculated on selected dishwashing tools (dishcloth, sponge, and scourer) at concentrations of 6.55 to 8.77 log CFU/cm 2 . CDPJ generated at 20 kV voltage and 1.5A current was used for decontamination, whereas a sample-to-electrode distance of 25 mm was maintained during the treatment. Following CDPJ treatment for 5 min, the viable counts of E. coli O157:H7, S. aureus, and P. putida were reduced by 4.30-4.56, 3.71-4.78, and 3.50-3.83 log, respectively. The rates of inactivation were varied among the pathogens, decreasing in the order E. coli O157:H7 > S. aureus > P. putida. Among tested kinetic models, namely log-linear, log-linear with shoulder, and Weibull models, the log-linear with shoulder model was found to be the most suitable model to explain the CDPJ inactivation of the pathogens. In conclusion, CDPJ can be used as a potential sanitizing agent for dishwashing tools.

Benzo[α]pyrene (BaP), a carcinogenic polycyclic aromatic hydrocarbon, is ubiquitous in nature. It is generally found in heat-treated foods like roasted sesame seeds. BaP degradation has attracted attention due to the recalcitrant nature of BaP. In this study, corona discharge plasma jet (CDPJ) was used to degrade BaP on glass slides and in food materials. The plasma discharges were generated using air as working gas under atmospheric pressure conditions and at different currents (1.00, 1.25, and 1.50 A). Optimal BaP degradation was observed upon using CDPJ generated at 1.50 A current and at 15 mm sample-to-electrode distance (STED). Under these conditions, initial BaP concentration on slides was reduced maximally by 87.09% in 30 min. The degradation kinetics were well-fitted by Weibull tail model compared with others. In food commodities (roasted sesame and perilla seeds), the average levels of BaP degradation ranged between 32.96-45.90% following CDPJ treatment for 30 min.

Electrolyzed water (EW) has been regarded as a new sanitizer by food industry. In this study, EW was used for perilla leaves sanitization. The optimum EW was produced at flow rates of brine and water of 100 mL/min and 300 mL/min, respectively. By soaking in EW only, the initial microbial counts of aerobic bacteria were reduced by 1.73 log(CFU/g), while 1.94 log(CFU/g) reduction was noted by using EW soaking followed by CDPJ treatment. In similar manner, counts of yeasts and molds were reduced by 1.83 and 2.06 log(CFU/g); coliform were reduced by 1.13 and 1.3 log(CFU/g), respectively. Combination of EW and CDPJ was more effective for microbial reduction. EW treatment did not affect sensory properties, instrumental color characteristics. However, it was observed that total phenolics and DPPH radical scavenging activity of perilla leaves were significantly increased with EW soaking time.

In this study, the use of corona discharge plasma jet (CDPJ) for the improvement of hygienic quality of semi-dried mackerel pike (Gwamegi) was investigated. Different microbial contaminants, namely aerobic and marine bacteria, coliform bacteria, Staphylococcus aureus and yeasts and mold, were detected in the range 4.2-6.2 log CFU/g in Gwamegi samples. The CDPJ generated using 20 kV DC and at 58 kHz frequency was used for the treatment of Gwamegi for 0-10 min. The bacterial contaminants were inactivated in the range of 1.9-3.3 log CFU/g on the treatment for 10 min. Additionally, yeasts and mold were inactivated by 3.2 log CFU/g. The inactivation pattern fitted well to the first-order kinetics model. The CDPJ treatment for 10 min did not exert statistically significant changes (P > 0.05) in pH, moisture content, water activity, peroxide value, acid value and volatile basic nitrogen content of Gwamegi in comparison to untreated control samples. On the contrary, significant changes (P < 0.05) were noted in color and thiobarbituric acid reactive substances levels upon the CDPJ treatment. However, the CDPJ-treated Gwamegi samples displayed better sensory properties in terms of appearance, visual color, and flavor as compared to controls.

Different pathogenic microorganisms have been reported to cause sprouts-associated outbreaks. 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. Aerobic bacteria, molds 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 positive effects on the germination rate and the seedling growth. The physico-chemical and sensory characteristics of sprouts were unaffected due to the CDPJ treatment of their respective seeds. The CDPJ can potentially be used for microbial decontamination of broccoli seeds.

코로나방전플라즈마제트(CDPJ) 생성장치를 제작하여 조업특성을 조사하고 비가열살균기술로서의 활용가능성을 탐색하고자 E. coli를 대상으로 살균성능을 조사하였다. CDPJ장치는 전력공급장치, 변압기, 전극, 송풍기, 시료처리부 등 다섯 부분으로 구성하였다. 전압 10.0-20.0 kV의 직류전기를 10.0-45.0 kHz 구형파 펄스형태로 텅스텐리드 전극에 투입함으로써 코로나방전 플라즈마를 생성하고 동시에 전극사이로 강한 공기를 주입함으로써 하부방향으로 토출하는 플라즈마제트를 생성하였다. CDPJ 처리는 플라즈마 토출구 하부에 처리대상 물체를 위치하고 일정시간 처리하는 방식으로 시행하였다. 주파수를 높일수록 다량의 전류가 유입되었고, 비례하여 전력소비량도 증가하였다. 플라즈마 생성을 위한 임계전류는 1.0 A, 임계주파수는 32.5 kHz이었으며, 1.5 A 이상 40.0 kHz 이상에서 안정적인 플라즈마제트가 생성되었다. 플라즈마제트의 길이는 전류에 따라 증가하였고, 2분 이하 처리 시 대상물체의 표면온도 상승은 25oC를 하회하였다. E. coli 살균력은 전류세기에 비례하여 증가하였고, 전류 1.5 A에서 1분간 CDPJ처리에 의해 4.5 log 이상의 살균효과를 보였으며, 살균패턴은 2단계 1차 반응으로 확인되었다.