• Environmental Engineering Research
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• 제14권4호
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• pp.244-249
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• 2009

Designing an ozone contactor is complicated because the residual ozone, log C. parvum inactivation, and bromate formation should be optimized with fluctuating water quality. OCM software was developed to assist a plant designer or an operator to fulfill the sophisticated optimization required in the design or operation of a new or an existing plant. In this article, numerical simulations were carried out using the OCM software for the design of a new ozone contactor under diverse design factors (i.e., three pHs, three temperatures, low and high dispersion numbers, and four and ten cells with complete mixing) with kinetic parameters obtained from the sand-filter effluent of a water treatment plant treating water from the Paldang impoundment. The results of the simulation suggested that a high residual ozone concentration at low pH and low temperature would be challenging, and PFR-like hydrodynamics could lower the residual ozone concentration. The inactivation of C. parvum oocysts increased at a lower pH. A lower dispersion number and more cell division increased the inactivation efficiency. Bromate was instantaneously formed during the initial ozonation stage. The effluent concentration was much lower than the regulatory levels imposed by the USEPA because of the low bromide level in raw water.

• Preventive Nutrition and Food Science
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• 제9권2호
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• pp.121-125
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• 2004

Effects of chemical treatment with a citric acid solution or ozonated water on microbiological changes in lettuce and cabbage during storage were studied. Fresh lettuce and cabbage samples were cut into small pieces and treated by soaking in either ozonated water or a citric acid solution. After treatment, populations of total bacteria, yeast and mold, and E. coli were determined. Numbers of microorganisms increased during storage, but ozonated water and citric acid treatments retarded the increase in microbial growth. Among treatments, 1 % citric acid treatment was the most effective in terms of microbiological change and inhibition of polyphenoloxidase (PPO). For lettuce, citric acid treatment decreased the microbial growth overall by 1.5 log CFU/g and inhibited the PPO activity by 80%. These results indicate that chemical-treated lettuce and cabbage retained a better quality than those of the control during storage.

• 한국환경보건학회지
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• 제39권2호
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• pp.187-195
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• 2013

Objectives: For the practical application of the dielectric barrier discharge plasma reactor, a plasma reactor able to manage large volumes of water is needed. This study investigated the possibility of the practical application of a multi-plasma reactor which is a scaled-up version of a single plasma reactor. Methods: The multi-plasma reactor consists of several high-voltage transformers and plasma modules (discharge, ground electrodes and quartz dielectric tubes). The effects of water characteristics such as voltage (30-120 V), air flow rate (1-5 l/min), number of high-voltage transformers and plasma modules, and water quality on Escherichia coli (E. coli) disinfection and decrease of COD and $UV_{254}$ absorbance were investigated. Results: The experimental results showed that at a voltage of over 80 V, most of the E. coli were disinfected within 90 seconds. E. coli inactivation was not affected by the air flow rate. E. coli disinfection in the multiplasma process showed the traditional log-linear form of the disinfection curve. E. coli inactivation performance by transformer 3-Reactor 5 and transformer 3-Reactor 3 were similar. The disinfection performance of the UV process was affected by artificial sewage water. However, the plasma process was less affected by the artificial sewage within the standards for effluent water quality. Conclusions: Disinfection performance with several low voltages and plasma modules of three to five in number applied to the plasma process was higher than that concentrating a small amount of high voltage through a single plasma reactor. Removal of COD, $UV_{254}$ absorbance, and E. coli disinfection with the plasma process were better than with the UV process.

• 한국식생활문화학회지
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• 제38권6호
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• pp.434-441
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• 2023

This study investigated quality characteristics and antioxidant activity of beetroots after blanching. Beetroots were blanched in distilled water, 2% NaCl water, and 2% citric acid water at 100℃ for 3 minutes (the blanched group). The moisture content was highest in the control (CON) at 91.30% (p<0.05), and cooking loss was lowest in the water-blanched beetroot (BW) at 5.39% (p<0.01). Chromaticity decreased after blanching compared to CON (p<0.001). Total polyphenol contents (TPC) and total flavonoid contents (TFC) decreased after blanching, and as a result of comparing the True retention (TR) of the blanching treatment group, BW had the highest with TPC TR 91.22% and TFC TR 70.51%. DPPH and ABTS+radical scavenging activities were highest in the CON, and in the blanching group BW was highest scavenging activity. The total number of microorganisms in the CON group was 2.97 log CFU/g, whereas no microorganisms were detected in the blanched groups. Therefore, this study, blanching in water without additives is the most appropriate method for preserving physiologically active substances and nutrients in beetroots and inhibiting microbial growth.

• 생태와환경
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• 제33권3호통권91호
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• pp.304-310
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• 2000

팔당호 지류인 경안천 만입부에서 현장실험조를 이용하여 조류증식 억제 효율을 조사하였다. Microcystis가 우점하고 평균 Chl a 농도가 30${\sim}$50 ${\mu}$g/l를 나타내는 경안천 만입부 현장실험조에서 습체식물 2.5 g/l 투여 결과, 은행잎, 잣잎, 솔잎 투여조는 초기부터 조류증식억제 효과를 보이면서 조류가 최고 성장기에 이를 때까지 높은 효과를 나타내었다. 수생식물중 애기마름 투여조가 다른 식물 투여조에 비해 가장 효과가 좋았다. 7일째에 조류증식 억제율은 솔잎 85%, 은행잎 80%, 잣잎 75%, 애기마름 78%, 줄 59% 창포 투여조 30%순이었고, 갈대 투여조는 효과가 없었다. 솔잎, 잣잎, 은행잎, 애기마름을 건조시켜 0.25 g/l와 1 g/l로 투여한 결과, 솔잎과 애기마름은 0.25 g/l에서 각각 53%, 90%로 좋은 효과를 나타낸 반면, 잣잎과 은행잎은 1 g/l 투여량에서 효과가 좋았다. 조류증식억제 효과 원인을 찾기 위해 식물체내 유기화합물을 분석해 본 결과 애기마름에서는 4-(4-hydroxyphenyl)-2-butanone과 2, 4-bis (1, 1-dimethylethyl)-phenol, p-CYMEN-8-0L이 검출되었고, 잣잎은 2, 4-bis (1, 1-dimethylethyl)-phenol이 검출되었다.

• 한국식품저장유통학회지
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• 제21권5호
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• pp.676-687
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• 2014

본 연구에서는 천일염, 정제염, 해양심층수염을 사용하여 제조한 절임배추의 냉장저장($0^{\circ}C$) 중 품질변화 및 시판제품과의 품질특성을 비교 조사하였다. pH의 경우 저장기간 전반적으로 S, R, D 구가 CS, CR, CD 구에 비해 높았고, 적정산도는 저장기간 전반적으로 CS, CR, CD 구가 S, R, D 구에 비해 높았다. 수분함량은 저장기간이 경과할수록 삼투압 작용에 의하여 모든 실험군에서 감소하였고, 염도는 S, R, D 구가 2.0~2.6%로 CS, CR, CD 구(0.9~1.8%)에 비해 저장기간 동안 유의적으로 높았다. 총균수 및 유산균수는 CS, CR, CD 구가 저장 1주 이후부터 급격히 증가하여 저장기간 동안 S, R, D 구에 비해 유의적으로 높게 나타나 pH 및 적정산도의 변화에 영향을 주었다. 경도와 씸힘성의 경우 모든 실험군에서 저장기간이 경과함에 따라 감소하였고 저장기간 동안 해양심층수염으로 제조한 절임배추(D)의 경도가 다른 실험군에 비해 유의적으로 높게 나타났다. 유리아미노산 총량은 CD 구가 가장 높았고 D 구가 가장 낮았으며, 필수아미노산의 비율은 소금의 종류에 따른 큰 차이를 보이지 않았지만, 비필수아미노산의 비율은 해양심층수염으로 제조 된 시판제품이 가장 높았다. 유기산 총량은 CD 구가 가장 높았고 해양심층수염으로 제조한 D와 정제염으로 제조한 R 구가 가장 낮았다. 무기질 총함량의 경우에도 CD 구가 실험군 중 가장 높았고, D, S, R, CR, CS 순으로 낮게 나타났다. K와 Mg 함량은 해양심층수염으로 제조한 D 구가 실험군 중 가장 높았고, Na 함량은 CD구가 가장 높았다. 관능적 외관, 산미 및 전체적 기호도는 모든 실험군에서 저장기간이 경과함에 따라 감소하였으나 해양심층수염으로 제조한 절임배추(D)의 외관, 산미 및 전체적 기호도는 저장기간 동안 다른 실험군에 비해 유의적으로 높은 평가를 받았다. 즉, 해양심층수염으로 절임배추를 제조할 경우 천일염이나 정제염으로 절임한 배추에 비해 관능적으로 우수하고 무기질, 유기산 함량이 높은 양질의 절임배추를 제조할 수 있을 것으로 사료되었다.

• 한국식품위생안전성학회지
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• 제34권3호
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• pp.296-302
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• 2019

간장게장은 우리나라 전통 식품 중의 하나로 생 꽃게를 세척한 후 간장소스를 첨가하고 저온에서 숙성시켜 포장하여 상업적으로 판매하고 있다. 하지만, 간장게장 제조특성 상 열처리를 하지 않기 때문에, 간장게장의 미생물학적 품질을 유지하는데 어려움이 따른다. 따라서 본 연구에서는 원물 꽃게의 초기 미생물 저감화를 위해 여러 살균세척제의 효능을 비교하고 저장 중 간장게장 제품의 미생물학적 품질을 유지하기 위해 키토산의 항균 효능을 평가하였다. 먼저, 상온에서 생 꽃게를 염소수(50 mg/L), 과초산(40 mg/L), acetic acid (5%), lactic acid(5%)에 각각 10분간 침지시켜 일반세균수를 분석하였다. 결과를 살펴보면, 여러 살균세척제 중 5% acetic acid 세척이 생 꽃게에 존재하는 일반세균수를 약 1.5 log CFU/g까지 감소시켜 가장 효과적인 것으로 나타났다. 키토산 효능을 평가하기 위해 현재 상업적으로 제조되고 있는 간장게장(방법 1; 전해수 세척), 5% acetic acid로만 세척된 꽃게(방법 2), 5% acetic acid로 세척된 꽃게에 0.5%(방법 3)와 1%(방법 4)의 수용성 키토산이 첨가된 간장으로 제조된 간장게장을 각각 $4^{\circ}C$와 $12^{\circ}C$에서 최대 30일까지 저장하면서 일반세균수, 대장균군 및 대장균수를 측정하였다. $12^{\circ}C$에서 저장된 간장게장의 일반세균 수는 7일이 지났을 때 약 8 log CFU/g까지 증가하였다. $4^{\circ}C$의 경우, 1% 키토산이 첨가된 군(방법 4)에서 20일 동안 약 2.9 log CFU/g까지만 증가한 것으로 나타나 키토산 무첨가군(방법 1과2)과 0.5% 첨가군(방법 3)(4.2~4.5 log CFU/g)에 비하여 훨씬 효과적이었다. 본 결과에 따라, 생 꽃게를 5% acetic acid로 세척한 후 간장게장에 1% 키토산을 첨가하여 냉장온도에서 저장한다면 간장게장 제품의 미생물학적 품질 향상에 큰 도움이 될 것으로 여겨진다.

• Asian-Australasian Journal of Animal Sciences
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• 제26권4호
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• pp.596-602
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• 2013

To investigate the synergistic effect(s) of electron-beam (EB) irradiation and leek (Allium tuberosum Rottler) extract on the quality of pork jerky during ambient storage, we irradiated prepared pork jerky samples (control and samples with 0.5% and 1.0% leek extract) with EB technology at doses of 0, 1, 2, and 4 kGy, stored them for 2 months at $25^{\circ}C$, and analyzed them. Water activity was 0.73 to 0.77 in non-irradiated samples, and no significant difference in the water activity was observed between the samples treated with leek and the control. The total aerobic bacterial count was significantly decreased with an increase in the irradiation dose and leek extract addition when compared to that of the control ($4.54{\pm}0.05$ log CFU/g). Further, the Hunter color values ($L^*$, $a^*$, and $b^*$) were found to be significantly decreased following leek extract addition and EB irradiation. However, the color values, especially the $a^*$ value of the irradiated samples significantly increased during storage. Notably, increasing the EB irradiation dose enhanced the peroxide value. Sensory evaluation revealed that irradiation decreased flavor and overall acceptability. Our findings suggest the use of EB irradiation in combination with leek extract to improve the microbiological safety of pork jerky. However, in order to meet market requirements, novel methods to enhance the sensory quality of pork jerky are warranted.

• 한국대기환경학회지
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• 제4권2호
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• pp.57-66
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• 1988

Sandy dust phenomena was observed from April 19 to 23, 1988 in Seoul and suspended particulate was collected by Andersen air sampler during this period. The samples were analyzed for 16 components $(SO_n^{2-}, NO_3^-, Cl^-, PO_4^{3-}, NH_4^+, F^-, Al, Fe, K, Cu, Mn, Na, Pb, Mg, Ca, Cd)$. The conclusions are as follwes: 1. Total suspended particulate concentation during the period of sandy dust phenomena was 489 $\mug/m^3$ (ordinary times: 140-125 $mug/m^3$) 2. The water - soluble ion component concentration of suspended particulate during the period of sandy dust phenomena was few and the metal concentration of that was more than that of ordinary times. 3. The cumulative frequency distribution of suspended particulates in logarithmic diagram did not show similar to normal log distribution during the period of sandy dust phenomena. 4. $SO_4^{2-}, NO_3^-, Cl^-, and PO_4^{3-}$ was onsided to coarse particle, and $NH_4^+$ and F to fine particle in the size distribution of water - soluble ion components during the period of sandy dust phenomena. 5. Metal concentration was high and Al, Fe, Cu, Mn, Na, Mg, and Ca was onsided to coarse particle, and K, Pb, and Cd to fine particle in the size distribution of metal components. 6. During the period of sandy dust phenomena the quantity of respirable particle (< 1 $\mum$) was about 3 times and that of metal components were about 2 - 11 times than that of ordinary times. 7. The concentrations of $NO_3^-, Cl^-, NH_4^+$ at ordinary times were 1.1 - 4 time than that of the period of sandy dust phenomena.

• 한국환경보건학회지
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• 제39권1호
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• pp.32-42
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• 2013

Objectives: Cryptosporidium, a protozoan parasite, has been recognized as a frequent cause of waterborne disease due to its extremely strong resistance against chlorine disinfection. Although there has as yet been no report of a Cryptosporidium outbreak through drinking water in Korea, it is important to estimate the health risk of Cryptosporidium in water supply systems because of the various infection cases in human and domestic animals and frequent detection reports on their oocysts in water environments. Methods: This study evaluated the annual infection risk of Cryptosporidium in tap water using the quantitative microbial risk assessment technique. Exposure assessment was performed upon the results of a national survey on Cryptosporidium on the water sources of 97 large-scale water purification plants in Korea, water treatment efficacy, and daily unboiled tap water consumption. The estimates of the US Environmental Protection Agency on the mean likelihood of infection from ingesting one oocyst were applied for effect assessment. Results: Using probabilistic methods, mean annual infection risk of Cryptosporidiosis by the intake of tap water was estimated to fall within the range of $2.3{\times}10^{-4}$ to $1.0{\times}10^{-3}$ (median $5.7{\times}10^{-4}$). The risk in using river sources was predicted to be four times higher than with lake sources. With 0.5-log higher removal efficacy, the risk was estimated to be $1.8{\times}10^{-4}$, and could then be lowered by one-third. Conclusions: These estimations can be compared with acceptable risk and then used to determine the adequacy and priority of various drinking water quality strategies such as the establishment of new treatment technology.