• Korean Journal of Food Science and Technology
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• v.44 no.5
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• pp.540-544
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• 2012

The aim of this study was to evaluate the antioxidant activity, total phenolics, flavonoids, and vitamin C contents in peels of 11 commercial fruits commonly consumed in the Republic of Korea. The antioxidant activities were evaluated by ABTS, DPPH radical scavenging methods and reducing power. The peels of plum (Prunus spp.) and golden kiwifruit (Actinidia chinensis) exhibited the highest values of antioxidant activity and total phenolics, while the highest level of ascorbic acid was recorded in the peel of citrus fruit (p<0.05). There were positive correlations between the antioxidant activity assessed by both reducing power and ABTS methods and total polyphenol content ($R^2$=0.6356), suggesting that phenolic compounds are the major contributors to these activities. The results indicate that plum and golden kiwifruit peels can be used as natural antioxidant ingredients and in production of functional foods in the Korean diet.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.5
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• pp.723-727
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• 2003

The antioxidant activities and their antioxidant compounds of a group of teas obtained in local markets were investigated. A total of 18 teas were tested for their antioxidant activities based on their ability to scavenge ABTS (2,2'-Azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) cation radical and DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical. The former was expressed as mg of ascorbic acid equivalents per 1 tea bag (L-ascorbic acid equivalent antioxidant capacity, AEAC) and the latter was expressed as percentage of electron donating activity (EDA%). A good correlation of AEAC and EDA was observed between the two methods. The concentrations of total polyphenolics and flavonoids in tea extracts were measured by spectrophotometric methods. Total ascorbic acid was determined via the 2,6-dicholoroindophenol titrimetric method. According to the AEAC value and EDA, black tea, brown rice green tea, green tea, herb tea and malva tea showed relatively high antioxidant activities. Polyphenolic compounds were the major naturally occurring antioxidant compounds found in teas and the high concentrations of polyphenolic compounds were observed in black tea, green tea and herb tea. Overall, six teas out of 18 teas tested in the study showed better antioxidant activities and higher amounts of total polyphenolic compounds.

• Journal of Life Science
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• v.21 no.10
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• pp.1393-1400
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• 2011

We investigated the mineral content and antioxidant activity of Portulaca oleracea for biological properties. Total mineral content was 6025.80 mg/100 g, and potassium was the highest at 3846.99 mg/100 g. Water and 80% ethanol extract yields were 14.84% and 24.93%, respectively. The contents of phenolic compounds and flavonoids of ethanol extract were 58.16 mg/g and 20.08 mg/g, and were significantly higher than that of its water extract (49.09 mg/g and 14.98 mg/g, respecitvely). Antioxidant activities and nitrite scavenging activity was significantly elevated in a dose-dependent manner, and that of ethanol extract was higher than that of the water extract. ${\alpha}$-Glucosidase inhibition activity of ethanol extract was significantly higher than the water extract as well. We suggest that the biological properties of Portulaca oleracea are due to its mineral and phenolic contents.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.8
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• pp.1162-1169
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• 2016

A new method based on accelerated solvent extraction (ASE) combined with response surface methodology (RSM) has been developed for optimization of the extraction of ginsenoside [Rb1, Rg1, and Rg3(20S)], total phenolics, and benzopyrene in red ginseng. The RSM method, based on a five level and two variable central composite design, was employed to obtain the optimal combination of extraction conditions. In brief, ginsenosides Rb1, Rg1, and Rg3(20S) and total phenolics with undetectable benzopyrene were optimally extracted with 50% ethanol as an extraction solvent, extraction temperature of $158^{\circ}C$, extraction time of 20 min, extraction pressure of 2,500 psi, flush volume of 60%, and one extraction cycle. The contents of ginsenosides and total phenolics in red ginseng extracted by ASE under optimum conditions were significantly higher than those extracted by sonication and reflux extraction.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.9
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• pp.1146-1150
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• 2006

In the present study, the Lycium chinensis Miller was harvested at intervals of one month in order to distinguish outstanding species and to determine optimal harvest time. From these harvests, extracts were prepared from ethanol. The total usable sugar, betaine, and phenolic acid contents as well as electron donating ability and SOD liked activity of the extracts were then measured. While sugar content of the Lycium chinensis Miller showed no significant difference among the various species examined, usable sugar content of the crop harvested in November was higher than that of the crop harvested in August. The Lycium chinensis Miller was picked in August, September, October, and November and analyzed for betaine content. According to this analysis, betaine content was higher in the crop harvested in November than in that harvested in August. In particular, considerable difference in betaine content per species or harvest time was exhibited. The SOD-liked activity in all of the Lycium chinensis Miller extracts showed an alleviation effect of at least 90%. In addition, there was no significant difference according to either species or harvest time. On the other hand, SOD liked activity was higher in November than in August.

• Journal of Life Science
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• v.29 no.11
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• pp.1241-1250
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• 2019

Artemisia argyi H. has been used for centuries as a traditional medicine and food supplement in Asian countries. The objective of this study was to investigate the physiological activities of Artemisia argyi H. extracts prepared by butanol, chloroform, ethyl acetate, ethyl ether, hexane, and methanol extraction. We evaluated total phenol and flavonoid content, antioxidant activity, nitric oxide (NO) and reactive oxygen species (ROS) release, and osteoclastogenesis inhibition. The total phenolic and flavonoid contents were highest in the methanol extract (49.46 mg GAE/g and 24.32 mg QE/g, respectively). The methanol extracts also had the highest antioxidant activity (DPPH and ABTS radical scavenging ability and ferric reducing antioxidant power), while the hexane extract had the lowest. The release of NO and ROS was dose-dependently decreased by pre-treatment with all solvent extracts. At the same concentrations, the ethyl acetate and butanol extracts showed higher inhibition of NO and ROS production when compared with the other extracts. The butanol extract, at a concentration of $20{\mu}g/ml$, inhibited about 89% of the activity of the osteoclast marker, tartrate resistant acid phosphatase (TRAP). These results suggest that butanol extracts of Artemisia argyi H. may be effective natural medications for the prevention and treatment of osteoporosis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1668-1674
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• 2011

We investigated the physical characteristics and changes in the functional components of red pepper paste, or gochujang, during fermentation at $20^{\circ}C$ for 90 days with different amounts of sweet persimmon powder. The viscosity of the paste decreased a little with increasing fermentation time. There was no significant difference (p<0.05) in all the treatments during fermentation. The L value, a value, and b value showed a tendency to gradually decrease with increasing fermentation time. And the samples with sweet persimmon powder showed a lower values compared to the control during fermentation. The phenolic compound content of the paste with sweet persimmon powder ranged from 13.72 mg% to 16.13 mg% at an early stage of fermentation, showing a significantly higher value (p<0.05) when increasing the amount of the powder. The content was in the range of 13.72~16.09 mg% on the 90th day in the final stage of fermentation, showing no significant difference (p<0.05) compared to those content at an initial stage of fermentation. The carotenoid content showed significantly higher values (p<0.05) when increasing the amount of sweet persimmon powder. In conclusion, sweet persimmon powder in the red pepper paste would gives a more functional effect which could be from bioactive components, such as phenolic compounds and carotenoids. But, it did not positively affect the color of the red pepper paste.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.3
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• pp.381-388
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• 2014

The antioxidant activities of extracts from Rubus coreanus Miquel (black raspberry) and Morus alba L. (mulberry) fruits were investigated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, 2,2-azino-bis-(3-ethylbenzo-thiazoline-6-sulfonic acid) (ABTS) assay, and reducing power assay. Aqueous mixtures of ethanol, methanol, and acetone were analyzed in order to determine the most effective extraction solvent for the two fruits. Black raspberry and mulberry extracts with the 60:40 acetone-water mixtures (v/v) showed the highest DPPH radical scavenging activities (56.2 and 85.2%, respectively) compared to the other extraction solvents. The 60% acetone extract was finally selected as an extraction solvent and then sequentially fractionated according to solvent polarity. Among the fractions of the two fruits, the ethyl acetate fraction showed the highest antioxidant activity as well as total phenolic and total flavonoid contents. In addition, there were high correlation coefficients between antioxidant activities and their contents. The $EC_{50}$ value of the ethyl acetate fraction from mulberry fruit was 2.2 times lower than that of butylated hydroxytoluene (BHT) in DPPH assay. The major phenolic acid and anthocyanin of the two fruits were protocatechuic acid and cyanidin-3-glucoside, respectively.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.451-459
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• 2013

Korean black raspberry fruits (bokbunja) were collected from 11 different producing regions, and commercial black raspberry wines were obtained from 24 manufacturers. Samples were analyzed for soluble solids, titratable acidity, pH, reducing sugar content, hunter color values, intensity, hue, total phenolic content, and organic acids. The fruit samples showed similar pH levels (3.43-3.52), but significantly differed in total acidity levels (9.98-16.2 g/L). The predominant organic acids in the fruit samples were citric acids (1.39-5.63 mg/mL) and succinic acids (0.25-6.53 mg/mL). Among the samples, black raspberry fruits from Goksung and Nonsan showed the lowest levels of total phenolic content, and the lowest values in intensity. The fruits from Jeongeup and Sunchang showed higher levels of phenolic content, soluble solids, and intensity. Some wine samples, including BH, KO, SR, and SE, showed overall high levels of phenolic content, organic acids like citric and succinic acid, and color values such as $a^*$, $b^*$, and intensity. Other wine samples, including DW, SC, GJ, and NB, were high in acetic acid, color values like $L^*$, and hue.

• Korean Journal of Food Science and Technology
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• v.49 no.5
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• pp.532-537
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• 2017

The purpose of this study was to examine the best cooking condition to decrease 4'-O-methylpyridonxine (MPN, ginkgotoxin) and increase the antioxidative effect. We also examined the change in color of ginkgo biloba seeds after different cooking methods and times. MPN content was decreased with an increase in the cooking time. For the reduction of MPN content, the most efficient cooking method was pan-frying. In particular, MPN content was largely reduced after 8 min of pan-frying. 1,1-Diphenyl-2-picrylhydrazyl radical scavenging activity and total flavonoid content were increased after 11 min of pan-frying and this level was maintained until 14 min. The total phenolic compound content was maintained for up to 30 min by steaming and 11 min by pan-frying. Therefore, the optimum condition was established by pan-frying from 8 to 11 min.