Various transition metal oxides are deposited on the surface of materials such as stainless steel, which is used in the coolant systems of nuclear power plants. The task of removing harmful radionuclides can be solved through the dissolution reaction of the deposited corrosion oxide layer. In this study, for the first time, the reaction thermodynamics of the hydrazine-based reductive metal ion decontamination (HyBRID) reaction developed by the Korea Atomic Energy Research Institute were studied considering the formation of a strong ion − ligand chemical bond complex between Cu ions and hydrazine. When considering complex formation, we found that it had a significant impact on the thermodynamic decontamination reactions of magnetite, nickel ferrite, and chromite. The reactions were proven to be much more thermodynamically favorable than the reaction energies reported thus far, which did not consider complex formation. We demonstrated that not only the thermodynamic energy but also the structures of the HyBRID reaction products can be significantly changed, depending on complex formation considerations.

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.

Effects of a commercial scale intervention system combining ultraviolet (UV)-C and plasma treatments on the microbial decontamination of black pepper powder were investigated. The process parameters include treatment time, time for plasma accumulation before treatment, and water activity of black pepper powder. A significant reduction in the number of indigenous aerobic mesophilic bacteria in black pepper powder was observed after treatments lasted for ≥ 20 min (p<0.05) and the reduction was differed by powder manufacturer. The microbial reduction rates obtained by individual UV-C treatment, individual plasma treatment, and UV-C/plasma-combined treatment were 0.2, 0.5, and 1.0 log CFU/g, respectively, suggesting that the efficacy of the microbial inactivation was enhanced by treatment combination. Nonetheless, neither plasma accumulation time nor powder water activity affected the microbial inactivation efficacy of the combined treatment. The UV-C/plasma-combined treatment, however, decreased lightness of black pepper powder, and the decrease generally increased as operation time increased. The plasma accumulation time of 20 min resulted in significant reduction in both lightness and brown color. The results indicate that the commercial-scale intervention system combining treatments of UV-C and plasma has the potential to be applied in the food industry for decontaminating black pepper powder.

Curry ingredients such as turmeric, coriander, cumin, fennel, fenugreek often contain microbial contaminants. Our preliminary analysis showed that microbial contamination in fenugreek was relatively higher than other ingredients, and therefore the decontamination using a non-thermal plasma was performed to enhance its microbial quality. Corona discharge plasma jet (CDPJ) was used for the decontamination of fenugreek seeds. The results showed that aerobic bacteria were decreased by 0.88 - 2.51 log units, and yeast and mold exhibited the reduction of 0.58-1.95 log units with the treatment for 20 min. For the microbial inactivation pattern, the Weibull model gave the best distribution fit among the models tried. The decontamination effect of the CDPJ was enhanced with the decrease of the distance from the plasma electrode, and with the increase of the current intensity. The effect of the plasma treatment on antioxidant capacity of fenugreek seed was also investigated, and the obtained results indicated that total phenolic content and DPPH radical scavenging ability were unaffected by the treatment at a current intensity of 1.00 A regardless the treatment distance from the electrode, whereas significant increases were observed with the treatment at 1.25 A and 1.50 A currents.

A nonthermal method of decontamination using electrolyzed water (EW) or/and ultrasonification (US) was used for microbial reduction of black pepper. Aerobic bacteria and yeasts and mold in commercial black pepper powder were found to be 8.29 and 7.72 log(CFU/g), respectively. The optimum EW was produced at flow rates of brine and water of 100 mL/min and 300 mL/min, respectively. Using EW, reducing by 1.36 log of aerobic bacteria and 1.15 log of yeasts and mold were observed. The combination of US with distilled water (DW) treatment reduced aerobic bacteria by 0.74 log and yeasts and mold by 1.03 log. The best decontamination results were obtained with US combined with EW, resulting 1.48 log reduction of aerobic bacteria and 1.70 log reduction of yeasts and mold. The inactivation pattern of microorganism by EW or/and US fitted well to first-order-kinetics model. The black pepper quality in terms of color, piperine contents and sensory properties was not changed by any of tried treatments compare to controls.

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.

Non-thermal techniques for microbial decontamination in foods are becoming more promising. This work aims to evaluate suitability and effectiveness of corona discharge plasma jet (CDPJ) for the inactivation of microbial contaminants of dried squid shreds. CDPJ was generated at 20 kV DC and at 58 kHz frequency. Upon the CDPJ treatment for 3 min of the shreds, bacterial contaminants namely aerobic, marine and Staphylococcus aureus were inactivated by 2.0, 1.6, and 0.9 log units, respectively. Also, a 0.9 log reduction of yeasts and molds contaminants was observed. The inactivation pattern fitted well to the pseudo-first-order model rather than first-order kinetic model. The CDPJ treatment did not exert statistically significant (P>0.05) changes in color characteristics and volatile basic nitrogen content of the shreds, as compared to untreated controls. In contrast, the moisture and thiobarbituric acid reactive substances levels were significantly (P<0.05) altered by the plasma exposure. However, the treatment exerted no significant (P>0.05) impact on the sensory characteristics of the shreds. The CDPJ was found effective for bio-decontamination of real-world samples of dried squid. This technology can readily be applied to commercial dried squid processing.

large amount of effluent water would be produced from low temperature coal catalytic gasification (LTCCG) developed by ENN Co, Ltd, which located at Langfang, Hebei Province. Many phenol homologous compounds and a large amount of other organic compounds were contained in this effluent water, but the overall concentration of the organic compounds was not very high (CODCr value was about several thousands mg/L). Too high cost would occur if treating it with a traditional liquid-liquid extraction process, and it was a waste of resources if the effluent water was directly purified with biochemical technology. In this paper, a decontaminating and recycling technique was developed for an effluent water, and a two-step technique includes flocculation-recycling and ion exchange adsorption-elution processes. By this two-step process, the CODCr value of the final outlet water was decreased to meet the related national standards, and at least 90% of the organics in the effluent water could be recovered.

본 논문은 가장 극한 조건(공정모델-2)에서 화학 제염한 경우 원자로 냉각재 펌프용 스테인리스강의 내식성 평가에 관하여 연구하였다. 사이클 경과에 따른 304 스테인리스강의 전기화학적 특성은 다른 스테인리스 강보다 우수한 특성을 나타냈다. 또한 공정모델-1과 공정모델-2의 304 스테인리스강은 가장 낮은 무게 감량을 나타냈다. 공정모델 용액에서 304 스테인리스강, 415 스테인리스강, 431 스테인리스강에 대한 실험 결과 공정모델-1에 대한 공정모델-2의 무게감량비는 각각 2.908, 2.372,그리고 2.370배를 나타냈다. 그 이유는 공정모델-2의 경우가 공정모델-1에 비하여 화학약품 농도나 온도가 높은 가혹한 조건에 기인한 것으로 사료된다.

혼합(混合) 조미료(調味料)의 효과적(效果的)인 살균(殺菌)을 목적(目的)으로 시료에 3~9kGy의 감마선을 조사한 뒤 에서 3개월 동안 저장하면서 미생물(微生物)의 생육도(生有度)와 살균처리(殺菌處理)에 따른 제품의 성분 및 관능적 품질을 평가해 본 결과는 다음과 같다. 1. 시료(試料)의 미생물(微生物) 혼입도(混入度)는 일반세균(一般細菌)이 g당(當) , 대장균군(大腸菌群)이 이었으나 대장균군(大腸菌群)은 3kGy, 일반세균(一般細菌)은 9kGy 미만(未滿) 조사(照射)로서 완전사멸(完全死滅)되었고, 세균(細菌)의 값은 1.94kGy로 나타났다. 2. 시료(試料)의 이화학적(理化學的) 특성(特性)은 살균처리(殺菌處理)에 따라서 거의 변화되지 않았으며, 저장기간이 경과될수록 3~6kGy 조사구는 대조구나 9kGy 조사구보다 성분의 변화가 적었다. 3. 시료(試料)의 관능적(官能的) 품질검사(品質檢査)에서 고선량(高線量) 조사(照射)는 제품(製品)의 풍미(風味)에 변화를 초래하는 것으로 나타나 이에 대한 구체적인 검토(檢討)가 요망(要望)된다.