• 분석과학
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• 제13권4호
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• pp.511-519
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• 2000

물은 초임계 상태($T{\geq}374^{\circ}C$, $p{\geq}221$ atm)에서 비극성 유기오염물질에 대해 좋은 용매로 작용 하지만 부식성이 강하게 나타난다. Subcritical water extraction (이하 SWE)은 토양이나 저니토에 흡착되어 있는 비극성 유기오염물을 신속하고 효율적으로 추출할 수 있다. Subcritical 조건 하에 있는 물은 다양한 비극성 유기물들을 추출할 수 있다. SWE를 이용하면 토양이나 저니토로부터 수 분 이내에 PCBs를 완전히 제거할 수 있으며, 50 atm, $260^{\circ}C$의 subcritical 상태에 있는 물을 추출에 이용한다.

• Journal of Ginseng Research
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• 제38권4호
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• pp.289-292
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• 2014

Ginseng leaf/stem extract produced by subcritical water extraction at high temperature ($190^{\circ}C$) posses higher cytotoxic activity against human cancer cell lines than ethanol extract. Subcritical water extraction can be a great candidate for extraction of functional substance from ginseng leaves/stems.

• Environmental Engineering Research
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• 제19권1호
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• pp.41-45
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• 2014

The peels of Carya cathayensis Sarg. (PCCS) were treated under subcritical water conditions ($130^{\circ}C$ to $280^{\circ}C$ for 0 to 120 min). The extract from PCCS included reducing sugar, proteins, and compounds with radical scavenging activity. Addressing the reducing sugar that is a resource of bioethanol, we could maximize the reducing sugar under the subcritical water ($190^{\circ}C$ for 60 min) and obtain 0.24 g/g-sample together with 9.7 units/mg-sample of radical scavenging activity. The obtained extract was estimated to correspond to 1 L of bioethanol/100 g-sample. It was therefore considered that the treatment by subcritical water could yield reducing sugar and natural compounds with radical scavenging activity.

• 한국응용과학기술학회지
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• 제41권3호
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• pp.543-554
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• 2024

본 연구에서는 편백나무(Chamaecyparis obtusa) 잎 아임계 수 추출물의 항염, 항균 및 항산화 효능을 열수 추출물과 비교 분석하였다. 아임계 수 추출물 중 165℃ 이상의 조건으로 추출한 아임계 수 추출물의 수율이 39.4~48.5%로 열수 추출물(31.5%) 보다 높게 나타났다. Lipopolysaccaride (LPS)로 자극된 RAW 264.7 대식세포를 이용한 nitric oxide (NO) 생성 억제 활성 실험 결과, 아임계 수 추출물이 세포 독성 없이 농도 의존적으로 NO의 생성을 저해시키는 효과가 우수함을 확인하였다. 또한 Cutibacterium acnes 및 Staphylococcus epidermidis를 이용한 항균 활성 실험 결과, 아임계 수 추출물이 열수 추출물보다 효능이 우수하게 나타났다. DPPH 및 ABTS 양이온 라디칼 소거 활성 실험 결과, 아임계 수 추출물의 라디칼 소거능이 열수 추출물과 유사하게 나타났으며, 아임계 수 추출물(165℃, 80 bar)은 과산화수소(H₂O₂)로 유도된 세포 손상에 대한 세포보호 효과를 보였다. 이상의 연구 결과를 바탕으로 편백나무 잎 아임계 수추출물은 항염, 항균 및 항산화 효과를 갖는 천연 화장품 소재로써 활용 가능할 것이라 사료된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권6호
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• pp.95-102
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• 2015

The purpose of this study is to compare the degradation characteristics by subcritical water of RDX contaminated soil using batch mode and dynamic mode devices. First, upon application of RDX contaminated soil, RDX treatment efficiency was increased with increasing the temperature in both modes. At 150℃, the treatment efficiency was 99.9%. RDX degradation efficiency got higher with lower ratio of solid to liquid. However, the treatment efficiency in the dynamic mode tended to be decreased at a certain ratio of solid to liquid or lower. The treatment efficiency was increased when it took longer time for the reactions in both modes. As the results of analysis on concentration of treated water after subcritical water degradation, the RDX recovery rate of dynamic and batch modes at 150℃ was 10.5% and 1.5%, respectively. However, both modes showed very similar recovery rates at 175℃ or higher. RDX degradation products were analyzed in treated water after it was treated with subcritical water. According to the results, RDX degradation mechanism was mostly oxidation reaction and reduction reaction was partially involved. Therefore, it suggested that most of RDX in soil was degraded by oxidation of subcritical water upon extraction. According to this result, it was found that both batch and dynamic modes were very effectively applied in the treatment of explosive contaminated soil.

• 한국축산식품학회지
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• 제36권1호
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• pp.8-13
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• 2016

This study investigated the effect of soy protein hydrolysates (SPH) prepared by varying subcritical media on the physicochemical properties of pork patties. For resource of SPH, two different soybean species (Glycine max Merr.) of Daewonkong (DWK) and Saedanbaek (SDB) were selected. SPH was prepared by subcritical processing at 190℃ and 25 MPa under three different of media (water, 20% ethanol and 50% ethanol). Solubility and free amino group content revealed that water was better to yield larger amount of SPH than ethanol/water mixtures, regardless of species. Molecular weight (Mw) distribution of SPH was also similar between two species, while slightly different Mw distribution was obtained by subcritical media. For pork patty application, 50% ethanol treatment showed clear red color comparing to control after 14 d of storage. In addition, ethanol treatment had better oxidative stability than control and water treatment based on thiobarbituric acid-reactive substances (TBARS) analysis. For eating quality, although 20% ethanol treatment in SDB showed slightly higher cooking loss than control, generally addition of SPH did not affect the water-binding properties and hardness of pork patties. Consequently, the present study indicated that 50% ethanol was the best subcritical media to produce SPH possessing antioxidant activity, and the SPH produced from DWK exhibited better antioxidant activity than that produced SDB.

• 물과 미래
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• 제26권3호
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• pp.103-111
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• 1993

자연하천의 수면곡선을 계산하기 위하여 표준축차계산법에 근거하 HEC-2모형을 이용하는 것이 일반적이다. 상류흐름에서 수면곡선의 계산은 일반적으로 하류에서 상류로 수행해 나간다. 그러나 이와 반대로 기준수면고가 상류지점에만 있는 경우, 하류쪽의 수면고들을 계산하고자 할 때는 많은 노력과 시간이 필요하게 된다. 이러한 경우에도 HEC-2를 이용하여 간편하게 상류에서 하류로 수면곡선을 계산하는 방법을 제안하였으며, 이 방법을 균일수로와 자연하천에 적용하여 타당성과 정밀도를 검토하였다.

• 청정기술
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• 제30권3호
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• pp.195-202
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• 2024

Plant polyphenols have attracted attention recently because of their abundance in the human diet, high antioxidant effects, and ability to prevent various diseases associated with oxidative stress, such as cancer and cardiovascular and neurodegenerative diseases. Therefore, this study demonstrated the extraction of bioactive phenolic compounds from Allium hoorkei root (AHR) using subcritical water extraction (scWE) under various temperatures (120 ~ 160 ℃) and times (30 ~ 180 min) at a fixed pressure (10 MPa) and AHR to water ratio (1:20, w/w). Furthermore, this study used severity factors, the combined effect of the temperature and time, in order to optimize the conditions for achieving a high yield and efficient recovery of target bioactive phenolic compounds while minimizing the degradation of the extracted products and maintaining a high selectivity. Subcritical water extraction at 160 ℃ for 30 min (severity of 3.24) produced a relatively high yield (88%) and high number of bioactive compounds including total phenolic contents (31.3 mg GAE/g dry AHR) and rare sugars (D-picose, D-talose, and D-tagatose) compared to Soxhlet extracts obtained from extraction for 8 h with water and 75% ethanol. As a result, the extracts obtained from the green scWE process may have high potential applications in medicines and functional foods because of their high bioactivity and safety.

• 한국축산식품학회지
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• 제35권2호
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• pp.265-271
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• 2015

In a previous study, hydrolysates of porcine placenta were obtained and the extraction efficiency for proteins and amino acids was compared between sub- and super-critical water extraction systems; optimum efficiency was found to be achieved using subcritical water ($170^{\circ}C$, 10 bar). In this study, the effects of adding ethanol to the subcritical water system were investigated. The lowest-molecular-weight extraction product detected weighed 434 Da, and the efficiency of extraction for low-molecular-weight products was increased when either the concentration of ethanol was decreased, or the extraction time was lengthened from 10 min to 30 min. The highest concentration of free amino acids (approximately 8 mM) was observed following 30 min extraction using pure distilled water. The concentration of free amino acids was significantly lower when ethanol was added or a shorter extraction time was used (p<0.05). Color change of the solution following extraction was measured. There were no significant differences in color between lysates produced with different extraction times when using distilled water (p>0.05); however, using different extraction times produced significant differences in color when using 20% or 50% ethanol solution for subcritical extraction (p<0.05). The range of pH for the hydrolysate solutions was 6.4-7.5. In conclusion, the investigated extraction system was successful in the extraction of $\leq$ 500 Da hydrolysates from porcine placenta, but addition of ethanol did not yield higher production of low-molecular-weight hydrolysates than that achieved by DW alone.

• 한국식품영양학회지
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• 제24권3호
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• pp.458-463
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• 2011

The effect of subcritical water for the extraction of total polyphenols and flavonoids from apple peel was investigated, and then the antioxidant activity of the extracts was estimated. Maximum yields of total polyphenolic compounds($36.4{\pm}1.9mg$ quercetin equivalent(QE)/g dried material) and flavonoids($9.9{\pm}0.8mg$ QE/g dried material) were obtained by subcritical water extraction(SWE) with operating conditions of $190^{\circ}C$, 1,300 psi, and 20 min. Furthermore, the highest antioxidant activity($76.1{\pm}1.1%$) was observed in the extract obtained from SWE using the same conditions. The flavonoids from the SWE of apple peel were compared to three conventional extraction methods in terms of their extraction efficiency and antioxidant activity. The SWE was significantly more effective than hot water ($90^{\circ}C$), methanol, and ethanol extraction for flavonoid yield by 4.7-, 2.2-, and 1.3-fold, respectively, and for antioxidant activity by 11.0-, 4.9, and 2.8-fold, respectively.