• Korean Journal of Food Science and Technology
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• v.52 no.2
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• pp.119-124
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• 2020

Populus Tomentiglandulosa (PT) is known for pharmacological effects against ischemia-injury and immune activity. This study aimed to investigate the nutritional components, total phenol and flavonoid contents, antioxidant activities of PT extract. Among the mineral contents, the K content (907.5 mg/100 g) was the highest in the PT extract. Vitamins C (6.1 mg/100 g) and nicotinic acid (3.1 mg/100 g) were also found in high amounts. Fructose (2.2%) and glucose (1.6%) were found as free sugars in the PT extract. The total phenolic and flavonoid contents of PT extract were 115.4±0.85 mg GAE/g and 20.9±1.14 mg QE/g, respectively. Results of HPLC analysis of PT extract identified catechin (9.1±0.27 mg/g), caffeic acid (4.1±0.57 mg/g), p-coumaric acid (2.1±0.49 mg/g), chlorogenic acid (1.6±1.86 mg/g), and gallic acid (1.4±0.35 mg/g), respectively. These results suggest that the PT extract possesses high nutritional component and antioxidant properties, which can be used as functional bioresources.

• Korean Journal of Food Science and Technology
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• v.31 no.4
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• pp.1024-1028
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• 1999

Green tea infusions were prepared by extracting them with aqueous solution of different pHs and their physicochemical properties were analyzed. Yellowness, chroma and total color difference values were increased as pH increased. The content of total amino acids in the green tea infusion was not influenced by pH values. Total catechin contents of the green tea infusion extracted at pH 4.0, 5.0, 6.0 and 7.0 were 32.28, 31.84, 31.14 and 14.70 mg/g, respectively. Among the four catechins investigated, epigallocatechingallate and epigallocatechin are more unstable as the pH was changed from 6.0 to 7.0. As pH increased, the extraction of caffeine was also increased. In conclusion, extraction at low pH is preferred for the preparation of green tea infusion.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3567-3572
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• 2010

Black pine barks from the southern region of Korea were extracted using pressurized hot water and the water soluble extracts were then separated in a stepwise fashion using a variety of solvents, column chromatography (CC), thin layer chromatography (TLC), and high pressure liquid chromatography (HPLC). The antioxidant activities of each fraction and the active compounds were determined based on the radical scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH), reductive potential of ferric ion, and total phenol contents. A DPPH test showed that the half maximal effective concentration ($EC_{50}$ value : $6.59{\pm}0.31\;{\mu}g/mL$) of the ethyl acetate fraction (ca. 0.67%) was almost the same as that of the control compounds and inversely proportional to the value of the total phenol contents. The cell viability of the water extracts was confirmed by methyl thiazol-2-yl-2,5-diphenyl tetrazolium bromide (MTT) with enzyme linked immune sorbent assay (ELISA). Catechin, epicatechin, quercetin and ferulic acid were isolated from the ethyl acetate fraction as active compounds and identified by nuclear magnetic resonance. The antioxidant activity as value of DPPH of each of the separated compounds was lower than the ethyl acetate fraction, and ferulic acid was the lowest among these compounds.

• Food Science and Preservation
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• v.16 no.6
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• pp.946-952
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• 2009

We investigated the physicochemical properties and antioxidant activities of green tea with respect to extraction conditions. The values of pH, and the L, a, and b Hunter parameters of green tea beverage 1 (GTB 1), green tea beverage 2 (GTB 2), and commercial green tea beverage (CGTB) were 6.22, 96.91, -1.06, and 7.77 5.40, 96.39, -1.73, and 13.68 and 6.20, 95.40, -4.75, and 25.51, respectively. The total free amino acid content of GTB 1 and 2, and CGTB, were 253.21, 262.65, and 58.36 mg/100 mL, and the major free amino acids were aminoadipic acid (102.56, 136.29, and 27.02 mg/100 mL), arginine (23.32, 30.75, and 7.31 mg/100 mL), and serine (18.22, 17.96, and 5.94 mg/100 mL). The levels of total phenolics and caffeine were higher in GTB 2 (852.58 and $225.51\;{\mu}g/mL$) than in GTB 1 (500.65 and $317.34\;{\mu}g/mL$) or CGTB (387.14 and $164.53\;{\mu}g/mL$). The catechin content of GTBs 1 and 2, and CGTB, were 294.8, 415.7, and $130.99\;{\mu}g/mL$, respectively. The major catechins of GTB 1 and 2, and CGTB were epigallocatechin, catechin, and epigallocatechin gallate, in that order, and the epigallocatechin contents were 186.50 in GTB 1, 268.10 in GTB 2, and $82.26\;{\mu}g/mL$ in CGTB. GTB 1 and 2 and CGTB showed substantial dose-dependent antioxidative activities. The DPPH radical-scavenging activities of GTB 1 and 2, and CGTB, were 85.48, 87.09, and 87.03%, respectively at a concentration of $125\;{\mu}g/mL$. The ferric reducing/antioxidant activities (FRAPs) of GTB 1 and 2 and CGTB were 2.66, 2.70 and 2.67 absorbance at a concentration of $1,000\;{\mu}g/mL$. Sensory evaluation tests revealed no significant differences among the three green tea beverages.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.3
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• pp.333-338
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• 2008

The tea has traditionally been used as a foodstuff by unique flavor, however recently not only the diversity of consumer demands but also the public interest in unique favorite and functional aspects have increased. It has been also reported that the main components contained in the leaves of tea (Camellia sinensis) include total nitrogen, free amino acids, polyphenols, and fiber, of which catechin has powerful bioactive effect such as anti-cancer, anti-aging, and anti-diabetic. (-)-Epigallocatechin gallate (EGCG) which is a major phenolic constituent of green tea extract has received considerable attention for a variety of important bioactivities. This study was carried out to obtain useful information for tea breeding programs, and to investigate the concentration of quality and functional related components in Korean indigenous tea germplasms. Korean indigenous tea lines were classified into three groups of sprout time, i.e, early, medium and late sprout time, and the ratio were 20%, 43% and 37%, respectively. There was a difference in characteristics among these Korean indigenous tea lines, leaf width of those ranged from 19.8 to 75 mm, leaf length was 35.5-160.0 mm, and leaf area was $660-8,400\;mm^2$. Experimental data on chlorophyll content (SPAD value) of Korean indigenous tea genetic resources ranged from 51.3 to 82.3. The concentrations of the total nitrogen, total free amino acids, and theanine were ranged 4.18-6.07%, 2.87-4.58%, and 1.64-2.66%, respectively. Also, catechin concentration showed from 11.54 to 15.07%, and concentration of caffeine was 2.82-4.23%. These results indicated indicated that it is possible to select elite lines with high concentration of quality related components and low concentration of caffeine from Korean domestic tea germplasms.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.3
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• pp.238-245
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• 1998

The reasonable level of nitrogen fertilizer is a key factor to reduce environmental contamination as well as to increase crop yield and quality. The treatments are $N=42kg\;10a^{-1}$, $N=48kg\;10a^{-1}$, $N=54kg\;10a^{-1}$. $N=60kg\;10a^{-1}$. $N=72kg\;10a^{-1}$ and $N=150kg\;10a^{-1}$. Analytical results of yield and quality of tea leaves harvested the second time are summarized as follows: The soil of experimental field was higher in organic matter($49.9g\;kg^{-1}$) and available phosphate($937mg\;kg^{-1}$) compared to the general field but lower in pH(5.07) compared to the general field. When the amount of nitrogen fertilizer application was raised, the yield of tea leaves, the content of nitrogen, total free amino acids, caffeine and chlorophyll increased: however, the yield of tea leaves increased to excessive levels. On the other hand, the increased level of nitrogen fertilizer did not show any difference in the contents of vitamin C and tannin. Eleven kinds of amino acids were isolated from second harvested leaves of tea where the content of theanine occupied over 50%, and content of $665{\sim}763mg\;100g^{-1}$. The contents of fatty acids and catechin did not show correlation with application level of nitrogen fertilizer. The content of fatty acid was produced $1,742{\sim}2,643mg\;100g^{-1}$, and content of catechin was produced 12.47~13.54%. In scoring test, $N=60kg\;10a^{-1}$ treatment was 0.5~6.0 point higher compared to other treatments. Consequently, $N=60kg\;10a^{-1}$ is considered to be the best level of nitrogen fertilizer in terms of decreased environmental contamination as well as to increase crop yield and quality.

• Journal of Applied Biological Chemistry
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• v.65 no.4
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• pp.421-427
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• 2022

In this study, Jeju Tatary buckwheat tea's chemical composition and physiological activities were compared according to the leaching temperature (60, 80, 100 ℃). As the leaching temperature is increased, the degree of browning is induced. However, there was no significant change in pH. The total polyphenol content was higher at 80 ℃ than at 60 ℃ leaching temperature, but significantly decreased at 100 ℃ leaching temperature (60 ℃: 17.06 mg GA/g, 80 ℃: 20.09 mg GA/g, 100 ℃ :18.45 mg GA/g). There were high content of flavonoid and rutin as the leaching temperature increased. Consistently, 2,2-diphenyl1-picrylhydrazyl (DPPH) radical scavenging activity and tyrosinase inhibitory activity were significantly higher with increasing temperature (DPPH % inhibition: 60 ℃: 41.88%, 80 ℃: 46.01%, 100 ℃: 46.80%/tyrosinase inhibitory activity: 60 ℃: 9.38%, 80 ℃: 22.94%, 100 ℃: 28.17%). However, there was no significant difference in DPPH radical scavenging activity between 80 and 100 ℃. A cytotoxicity test was performed by treating with Jeju Tatary buckwheat extract into mouse macrophage cells (Raw264.7). 100 and 200 ㎍/mL treatment (100 ℃ extract) were significantly upregulated the survival rate, but there was no significant difference in other concentrations. Collectively, most of the bioactive components, antioxidant activity, and tyrosinase inhibitory activity were induced as the leaching temperature increased. However, the content of polyphenols which are known to have antioxidant activity, was significantly reduced at 100 ℃ leaching temperature. Several reports have demonstrated that leaching at too high temperature lowered the overall acceptability, so the optimal leaching condition of Tatary Buckwheat is 80 ℃, 5 min in this study.

• The Korean Journal of Food And Nutrition
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• v.31 no.1
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• pp.17-23
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• 2018

The objective of this study was to compare physicochemical, microbial, and antioxidant properties of domestic and imported wheat kernels for bread making. Two domestic (JK1, 2) and three imported (ND, DNS, and CWRS) kernels were compared. Domestic kernels had higher moisture contents, and lower ash and protein contents (p<0.05). In grain characteristics, JK1 had 13.62% of damaged kernels, which was the highest among the samples (p<0.05). JK2 was similar to imported kernels in the ratio of sound kernels, foreign materials, and damaged kernels. Kernel size of JK1, 2 was larger than the imported kernels; therefore, kernels area and perimeter were higher by the image analyzer. Domestic kernels hid lower total aerobic counts the imported kernels (p<0.05). Domestic kernels and DNS had no yeast, while NS and CWRS had yeast in kernels. DNS (3.08 mg gallic acid equivalent (GAE)/g) had the highest total polyphenol content (TPC), followed by JK1 (2.81 mg GAE/g). JK2 had the lowest amount of TPC as 2.26 mg GAE/g. Total flavonoid content (TFC) was the highest in DNS as 0.44 mg catechin equivalent (CE)/g and JK2 was the lowest as 0.12 mg CE/g. Domestic wheat kernels had lower protein content and lightness than the imported wheat kernels so that flour from domestic wheat kernels may have lower quality for baking.

• Preventive Nutrition and Food Science
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• v.20 no.1
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• pp.22-28
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• 2015

Phenolic rich ethyl acetate fraction (EAF) from lotus leaves was prepared and its bioactive components, antioxidant and cytoprotective effects were investigated. EAF showed high total phenolic content and flavonoid content and contained rutin ($11,331.3{\pm}4.5mg/100g\;EAF$), catechin ($10,853.8{\pm}5.8mg/100g\;EAF$), sinapic acid ($1,961.3{\pm}5.6mg/100g\;EAF$), chlorogenic acid ($631.9{\pm}2.3mg/100g\;EAF$), syringic acid ($512.3{\pm}2.5mg/100g\;EAF$), and quercetin ($415.0{\pm}2.1mg/100g\;EAF$). EAF exerted the $IC_{50}$ of $4.46{\mu}g/mL$ and $5.35{\mu}g/mL$ toward DPPH and ABTS cation radicals, respectively, and showed strong reducing power, which was better than that of ascorbic acid, a positive control. Additionally, EAF protected hydroxyl radical-induced DNA damage indicated by the conversion of supercoiled pBR322 plasmid DNA to the open circular form and inhibited lipid peroxidation of polyunsaturated fatty acid in a linoleic acid emulsion. In cultured hepatocytes, EAF exerted a cytoprotective effect against oxidative stress by inhibiting intracellular reactive oxygen species formation and membrane lipid peroxidation. In addition, depletion of glutathione under oxidative stress was remarkably restored by treatment with EAF. The results suggest that EAF have great potential to be used against oxidative stress-induced health conditions.

• Korean Journal of Food Science and Technology
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• v.52 no.4
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• pp.350-356
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• 2020

This study was conducted to investigate the antioxidant compounds and activities of Prunus yedoensis Matsumura bark (PYMB) ethanol extracts (EE) and various other fractions. Among them, the highest total phenol content was 496.80 mg gallic acid equivalent/g in the ethyl acetate fractions (EAF). The flavonoid contents were 7.26-265.52 rutin equivalent mg/g, with the EAF showing the highest levels. The highest proanthocyanidin content was determined to be 326.31 catechin equivalent mg/g in the EAF and the remaining values in descending order were as follows: n-butanol, ethanol, dichloromethane, water, and n-hexane. EAF exhibited the highest DPPH, ABTS⁺, superoxide^- radical scavenging activities, and reducing power, whereas the nitrite scavenging activities were the highest in the case of the EE. The n-hexane and water fraction antioxidant compounds and activities were lower than those of the other fractions. In summary, these results suggest that the PYMB EAF is a potential source of natural antioxidants.