• The Korean Journal of Food And Nutrition
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• v.26 no.4
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• pp.706-712
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• 2013

This is the basic study on the extraction characteristics of Omija (Schizandra chinensis) for juices of Korean traditional foods. Extraction is being performed as 25 times of the solvent ratio at room temperature and at $65^{\circ}C$ with deionized water, tap water and Cheong-song mineral water which have high contents of Ca and Mg. The overall good results of the extraction conditions are calculated from the values of L (Lightness), redness (a), yellowness (b), soluble solids content, acidity, pH levels and the DPPH radical scavenging activity by using the electron donating ability (EDA). The results are as follows: 12 hours of room temperature and 6 hours at $65^{\circ}C$ were good extraction times. The Cheong-song mineral water at $65^{\circ}C$ is available for rapid extractions when compared to deionized water and tap water. A longer extraction time shows lower values of acidity but increasing values of soluble solids content and DPPH radical scavenging activity when using the electron donating ability. The best sequences for the extractions are Cheong-song mineral water followed by tap water and distilled water after overall consideration.

• Korean Journal of Food Science and Technology
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• v.52 no.5
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• pp.503-509
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• 2020

The present study investigated the effects of dry and moist heat treatments on total phenols, total anthocyanins, and antioxidant activity levels in black chokeberry (Aronia melanocarpa) fruits. Lyophilized chokeberry powder samples were heated in a drying oven at 60, 100, 160, 180, and 200℃ for 20, 40, or 60 min. Finely ground fresh chokeberry fruits were heated in water at 60, 80, and 100℃ for 20 min, and bioactive compound and antioxidant activity levels were measured. The bioactive compounds and antioxidant activity decreased with increasing temperature and treatment duration. Antioxidant activity was preserved at 160℃ or lower without significant loss for dry heating, whereas moist heat treatment increased both bioactive compounds and antioxidant activity with increasing temperature.

• The Korea Journal of Herbology
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• v.32 no.4
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• pp.39-46
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• 2017

Objectives : This study aims to provide basic data about Portulacae Herba (PH) extracts as natural antioxidants by considering diverse antioxidant activities of PH depending on solvents. Methods : The samples of PH were pulverized, and A hot water and a 70% EtOH were stir-extracted for two hours three times repeatedly in a water bath with a temperature of 95 degrees and at room temperature respectively to measure 7 kinds of antioxidant activities. Results : There were significant differences in total phenol content, because the total phenol content of the 70% EtOH extract was higher than the hot water extract's, and the total flavonoid content of the 70% EtOH extract($4.40{\mu}g/mg$) was nearly 3.8 times higher than the hot water extract's($1.16{\mu}g/mg$). DPPH and ABTS radical scavenging activities were 70% EtOH extract showed a little higher activity than the hot water extract, and at a concentration of $500{\mu}g/mg$, the highest scavenging activity was found in the 70% EtOH extract, not in the control group. Hydroxyl radical and $Fe^{2+}$ chelatingactivities were slightly higher in hot water extract than in 70% EtOH extract, and increased in a dose-dependent manner. Nitrite scavenging activities increased dose-dependently in the hot water and the 70% EtOH extract, regardless of the pH level, and scavenging activity of the 70% EtOH extract was higher at pH 1.2 than at pH 3.0. Conclusions : In conclusion, it is thought that PH hot water and 70% EtOH extract have antioxidant activities, and can be used as natural antioxidants in future.

• Clean Technology
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• v.29 no.1
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• pp.39-45
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• 2023

To investigate the effects of Mg addition at different aging times and temperatures, Cu/MgO/Al₂O₃ catalysts were synthesized for the low-temperature water gas shift (LT-WGS) reaction. The co-precipitation method was employed to prepare the catalysts with a fixed Cu amount of 30 mol% and varied amounts of Mg/Al. Synthesized catalysts were characterized using XRD, BET, and H₂-TPR analysis. Among the prepared catalysts, the highest CO conversion was achieved by the Cu/MgO/Al₂O₃ catalyst (30/40/30 mol%) with a 60 ℃ aging temperature and a 24 h aging time under a CO₂-rich feed gas. Due to it having the lowest reduction temperature and a good dispersion of CuO, the catalyst exhibited around 65% CO conversion with a gas hourly space velocity (GHSV) of 14,089 h-1 at 300 ℃. However, it has been noted that aging temperatures greater or less than 60 ℃ and aging times longer than 24 h had an adverse impact, resulting in a lower surface area and a higher reduction temperature bulk-CuO phase, leading to lower catalytic activity. The main findings of this study confirmed that one of the main factors determining catalytic activity is the ease of reducibility in the absence of bulk-like CuO species. Finally, the long-term test revealed that the catalytic activity and stability remained constant under a high concentration of CO₂ in the feed gas for 19 h with an average CO conversion of 61.83%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1297-1301
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• 2003

The response surface methodology was peformed by central composite design based on drying temperature and time of Citrus, to monitor quality property change caused by drying and make dried products with a good overall palatability. In result, water activity, hardness and softness were affected by drying temperature; water activity decreased and hardness increased with increase of drying temperature. Softness was also high at low temperature and short time of drying. In the range of overall palatability having high score, hardness was shown in 2.01 ∼ 3.20${\times}$10$^{6}$ dyn/$\textrm{cm}^2$ and softness was 62.54 ∼ 146.37 cm/kg. Drying conditions satisfying this range were predicted as 66 ∼ 75$^{\circ}C$ of drying temperature and 8 ∼ 14 hr of drying time.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.122-122
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• 2017

Recently, environmental problems have become an area of growing interests. In-situ monitoring of water quality is fundamental to most environmental applications. The accurate measurement of nitrate concentrations is fundamental to understanding biogeochemistry in aquatic ecosystems. Several studies have reported that one of the most feasible methods to measure nitrate concentration is the use of Ion Selective-electrodes (ISEs). The ISE application to water monitoring has several advantages, such as direct measurement methodology, high sensitivity, wide measurement range, low cost, and portability. However, the ISE methods may yield inconsistent results where there was a difference in temperature between the calibration and measurement solutions, which is associated with the temperature dependence of ionic activity coefficients in solution. In this study, to investigate the potential of using the combination of a temperature sensor and nitrate ISEs for minimizing the effect of temperature on real-time nitrate sensing in natural water, a prototype of on-site water monitoring system was built, mainly consisting of a sensor chamber, an array of 3 ISEs, an waterproof temperature sensor, an automatic sampling system, and an arduino MCU board. The analog signals of ISEs were obtained using the second-order Sallen-key filter for performing voltage following, differential amplification, and low pass filtering. The performance test of the developed water nitrate sensing system was conducted in a monitoring station of drinking water located in Jeongseon, Kangwon. A temperature compensation method based on two-point normalization was proposed, which incorporated the determination of temperature coefficient values using regression equations relating solution temperature and electrode signal determined in our previous studies.

• Korean journal of food and cookery science
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• v.12 no.4
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• pp.493-498
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• 1996

The effective extraction of antioxidative substances from soybeans was studied by the mixed solvents of methanol or ethanol with water at 30$^{\circ}C$ and 85$^{\circ}C$. At accelerated peroxidation condition, POV (peroxide value) of soybean oil and TBARS (thiobarbituric acid reactive substances) value of egg yolk liposome with extracts added, were applied for the evaluation of antioxidative activity of the extracts. In the peroxidation of soybean oil, antioxidative substance of soybeans was extracted more effectively by methanol and at higher temperature 85$^{\circ}C$, and the deffated and roasted soybean extract (DRS) showed higher antioxidative activity. But in the Peroxidation of egg yolk liposome, methanol extract from the roasted soybeans (ROS) showed higher activity.

• Journal of Nutrition and Health
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• v.52 no.4
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• pp.399-407
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• 2019

Purpose: This study was conducted to evaluate the physicochemical properties of different batches of Saururus chinensis using different roasting temperature that were dried at different using different roasting temperatures and their were determined the antioxidative activities of water and 70% ethanol extracts. Methods: Extracts were examined for the total phenolic acid content, the and flavonoids contents and the antioxidant properties, including DPPH radical scavenging activity, ABTs scavenging activity and, the reducing power. Results: Moisture content was significantly higher in the LSC and the crude ash content was significantly higher in the HSC. The crude protein content was higher in the LSC (although not significantly), and the crude fat and carbohydrate contents were higher in the HSC (although not significantly). The total phenolic content was lower in the samples extracted with water, but there was no significant difference. However, the extracts extracted with 70% ethanol at a high drying temperature were significantly higher. The low temperature and high drying temperature batches of Saururus chinensis were significantly higher in the samples extracted with 70% ethanol than those extracted with 70% ethanol. The total phenolic acid content, the total flavonoid content and the electron donating ability were highest in the ethanol extract of Saururuschinensis treated at a high temperature. However, the ABTs radical activity was highest in the water extracted, high-temperature treated Saururuschinensis. The 70% ethanol extract of high temperature roasted Saururuschinensis had the highest antioxidative activities of all the Saururuschinensis batches. Conclusion: The total phenolic acid contents, total flavonoid contents, electron donating activity and reducing power activity were highest in all the 70% ethanol extraction batches of the high-temperature treated samples.

• Natural Product Sciences
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• v.18 no.3
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• pp.171-176
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• 2012

We previously isolated cordycepin, guanosine and tryptophan from Cordyceps militaris as antiadipogenic constituents. For the quality control of C. militaris for anti-adipogenic activity, simultaneous analytical method using high-performance liquid chromatography (HPLC)-diode array detection (DAD) was developed and validated. Quantitation of these compounds in various Cordyceps samples from different sources and various extraction methods were conducted using developed method. Our study shows that natural Cordyceps and host insect possess higher content than cultured ones and fruiting bodies, respectively. The content of cordycepin showed great difference in different C. militaris samples whereas trytophan content was similar in tested samples. Addition of water to extraction solvent greatly increased the yield of guanosine and tryptophan. High temperature and longer extraction time increased yield of guanosine, whereas the content of trytophan was decreased in high temperature during extraction with water. Extraction using ultrasonic apparatus slightly increased extraction efficiency. Cordycepin, however, has little variation in different extraction method tested. Strong anti-adipogenic activity was observed in the samples that contain all the three constituents. Taken together, quantitation of these compounds using developed analytical method might provide basic requirement for the anti-adipogenic activity of C. militaris.

• International Journal of Industrial Entomology and Biomaterials
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• v.41 no.2
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• pp.36-44
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• 2020

Mulberry root bark is one of potential plant sources for antioxidant materials which can be used for the relief of oxidative stress. To explore the effects of solvent type and temperature on the structural characteristics and antioxidant activity of the root bark extracts, we prepared various extracts of mulberry root bark (Morus alba L.) using 0 - 100 % ethanol (EtOH) at RT - 100℃. EtOH concentration and temperature critically affected the extraction yields, the content of bioactive components, and antioxidant activity of the extracts. Use of high content of EtOH solvent and low temperature resulted in the low extraction yield. Meanwhile, it was revealed that the extract prepared using absolute EtOH at room temperature contained polyphenols and flavonoids with the highest contents among other extracts. Interestingly, the temperature differently affected the polyphenol and flavonoid contents according to the solvent types. In the case of 30% EtOH solvent, polyphenol and flavonoid contents increased with an increase in temperature, whereas in the case of 70 and 100 % EtOH, these contents decreased. Using the radical scavenging assay, it was confirmed that the 100% EtOH extracts had higher antioxidant activity compared to distilled water (DW) extracts regardless of temperature. Also, heating might extract more antioxidant components from the root bark. Especially, the extract prepared using 30% EtOH solvent at 100℃ showed the highest antioxidant activity. Taken together, these experimental results imply that the extraction parameters should be designed carefully considering the productivity, the extracted bioactive components, and antioxidant activity.