• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.855-863
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• 1999

To develop new natural antioxidants, antioxidative activity of ethanol (75%) extracts from 50 edible or medicinal plants were examined on lard and palm oil by Rancimat method ($120^{\circ}C$, 20 L/hr). The extracts from Rhus verviciflua STOKES showed comparatively strong antioxidative activity on test. Of the solvents used for extraction, chloroform extract exhibited the strongest antioxidant activity. AI (antioxidant index: induction period of oil containing extract/induction period of control oil) of chloroform extract was higher than that of commercial antioxidant, such as BHT, BHA and ${\delta}-tocopherol$. Free phenolic acid fraction (200 ppm) of the chloroform extract from 75% EtOH extract of Rhus verniciflua STOKES (RCF) showed stronger activity than that of BHT, BHA, and ${\delta}-tocopherol$ at the same concentration. RCF-11 and RCF-13 fractions separated by silicagel column chromatography from the RCF showed stronger activity than other fractions by the Rancimat method.

• Applied Biological Chemistry
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• v.38 no.5
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• pp.425-430
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• 1995

The effects of oxidation stability and flavor acceptability of soybean oil by roasting and refining treatment were investigated in this study. The peroxide values of crude oil from unroasted soybean(COUS) were more increased than those of crude oil from unroasted soybean(CORS) during storage under fluorescence light at $45^{\circ}C$. Induction time by the Rancimat Method was 44.9 and above 88.7 hours on COUS and CORS respectively. The order of oxidation stability of oil was crude>degummed>alkali-refining>deodorized>bleached oil in terms of peroxide value, while that of oxidation stability of oil was crude>degummed>deodorized>alkali-refining>bleached oil in regard to induction time by the Rancimat Method. The correlation coefficients between induction time and two charateristics(absorbance of browning reaction products and phosphorous contents) were highly significant, while that between induction time and tocopherol contents was not high during refining stages. The scores for the sensory evaluation of flavor on sesame oil and CORS was 9.269 and 8.269 respectively, but it was not significant between two oils.

• Plant Resources
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• v.7 no.1
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• pp.47-53
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• 2004

Several wild plant species are known to contain biologically active substances that are allelopathic to weed species as well as antioxidant to foods. Plant extracts or residues from leaves of 4 species, Achyranthes japonica (speedwell), Cucumis sativus (Cucumber), Trifolium repens (white clover), and Vicia angustifolia (narrowleaf vetch) were bioassayed against Medicago sativa (alfalfa) or Echinochloa crus-galli (barnyard grass) to determine their allelopathic effects, and used for measurement of antioxidant activities. The aqueous extracts applied on filter paper significantly inhibited root growth of alfalfa. Aqueous extracts or residues from V. angustifolia showed the most inhibitory effect on alfalfa or barnyard grass seedling growth and followed by A. japonica and T. repens. Oxidative stability by Rancimat method, antioxidant activity by TBA (2-thiobarbituric acid) method and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity for the ground samples or methanol extracts were the greatest in V. angustifolia, although were less than those of commonly used antioxidants, BHT (butylated hydroxytoluene) and ascorbic acid. These results suggest that the wild plant species had potent allelopathic and antioxidant activities, and that their activities differed depending on plant species.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.2
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• pp.207-210
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• 2003

This study was designed to investigate the antioxidative effect of glasswort (Salicornia herbacea L.) grown in closed sea beach. To compare antioxidant effects of glasswort plant parts, dried ground leaves, stems, and roots of glasswort were exploited for investigation of antioxidant activity Antioxidant activity for the samples was investigated by Rancimat and TBA method. The oxidative stability determined by the Rancimat technique showed a variation in antioxidative index (AL) between the different plant parts, ranging from 1.0 to 3.6. Oxidative stability from ground stem sample of glasswort harvested in the closed sea beach was the highest, and followed by leaf and root. Stem had higher oxidative stability than ascorbic acid. Antioxidatiue effects of glasswort were increased in dose-dependent manners, and antioxidant activity by addition of glasswort with same amount to 4% oil was similar to the activity of ascorbic acid. Specially, 8~10% glasswort addition to oil showed similar antioxidative effect to 1% $\alpha$-tocopherol.

• Journal of Applied Biological Chemistry
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• v.57 no.4
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• pp.353-358
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• 2014

Antioxidant activities of ethanol and water extracts of flesh, leaves, and peels of green and purple Kohlrabi were measured by rancimat method, total phenolic compound (TPC), DPPH radical scavenging effect, chelating effect, and reducing power analysis. The highest TPC was observed in ethanol extract from green peel and water extract from purple leaf with 12.00 and 11.70 mg/g of dry sample, respectively. The ethanol extracts from purple Kohlrabi leaf and peel exhibited strong DPPH radical scavenging effects with reducing power while water extracts from purple Kohlrabi leaf and peel also showed strong DPPH radical scavenging with chelating effects. Antioxidant index of ethanol and water extracts from green and purple Kohlrabi measured by rancimat was lower than butylated hydroxytoluene. These results suggest that extracts from purple Kohlrabi leaf and peel exhibited higher antioxidant activities than those of green Kohlrabi, and can be potentially used as proper natural antioxidants.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1654-1660
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• 1999

The free phenolic acid fraction of the chloroform extract from 75% ethanol extract of Rhus verniciflua STOKES (RCF) showed stronger antioxidative activity than BHT, BHA and ${\delta}-tocopherol$ at the same concentration. RCF components were isolated and identified by silica gel column chromatography, thin layer chromatography, mass spectrometer and $^1H-NMR\;and\;^{13}C-NMR$. The antioxidative activity was confirmed by electron donating activity, Rancimat method and thiobarbituric acid test in liposome system. RCF-11 could be further separated into three fractions. The antioxidative active compounds were purified and identified as gallic acid, butin and butein. The RCF-13 was purified and identified as sulfuretin.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.12-18
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• 2001

The water-soluble extracts of plants used as tea materials were investigated for their antioxidant activities and active components(total phenolics, ascorbate and selenium). Antioxidant activities of the plant extracts were determined by measuring the changes in both peroxide values(POV method) during storage(36 day, $55^{\circ}C$) and conductivity of soybean oil at $110^{\circ}C$(Rancimat method). Soybean oil without any additive was used as a control. Soybean oil treated with 0.02% BHT was used as a positive control. The test samples were prepared by mixing the plant extracts with soybean oil in 0.02% concentration by weight. The water-soluble extracts of lycii fructus(23 d), oolong tea(23 d), orange peel(23 d), citron(22 d), and apricot(22 d) showed longer induction periods, compared to control(21 d) and BHT(21 d) by POV method. Also water-soluble extracts of oolong tea(12 h), instant coffee(11 h), citron(10 h), cinnamomi cortex(10 h), schizandrae fructus(10 h), lycii fructus(10 h) and apricot(10 h) demonstrated longer induction periods, compared to control(8 h) and BHT(8 h) by Rancimat method. The contents of total phenolic compounds were observed to be high in water-soluble extracts of oolong tea, green tea, black tea, coffee, cinnamomi cortex, and cassiae semen. Ascorbate contents were found to be high in coffee, eucommiae cortex, black tea, ganoderma, cinnamomi cortex, persimmon leaf, chicory, green tea and oolong tea extracts. The selenium contents were not detected in all the extracts. The antioxidative effects of some plant extacts were seemed to be the combined effects of various antioxidant components such as phenolics and ascorbate.

• Tribology and Lubricants
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• v.31 no.6
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• pp.258-263
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• 2015

Biodiesel is an environmentally-friendly fuel with low smoke emission because it contains about 10% oxygen. Biodiesel fuel prepared by transesterification of vegetable oil or animal fats is susceptible to auto-oxidation. The rate of auto-oxidation depends on the number of methylene double bonds contained within the fatty acid methyl or ethyl ester groups. Biodiesel may be easily oxidized under several conditions, i.e., upon exposure to sunlight, temperature, oxygen environment. Maintenance of the fuel quality of biodiesel requires the development of technologies to increase the resistance of biodiesel to oxidation. Treatment with antioxidants is a promising approach for extending the shelf-life or storage time of biodiesel. The chemical properties of various amine-based antioxidants were evaluated after synthesis of the antioxidants by condensation of phenylenediamine with alkylamines at room temperature. In general, the oxidative stability can be assessed based on various experimental parameters. Such parameters may include temperature, pressure, and the flow rate of air through the samples. The Rancimat method (EN14112) was selected because it is a rapid technique that requires very little sample and provides good precision for oxidative degradation analysis. Specifically, the EN 14112 technique provides enhanced efficiency for oxidative stability evaluation when a larger ester head group is utilized. Therefore, this technique was employed for evaluation of the oxidation stability of biodiesel by the Rancimat method (EN14112).

• Journal of Life Science
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• v.17 no.9 s.89
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• pp.1237-1243
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• 2007

This study was investigated on the antioxidant capacity of 80% ethanol extract of lotus root in vitro. The ex-traction yields of 80 % ethanol extract was 9.14%. Lotus root ethanol extract was fractionated by the following: n-hexane, chloroform, ethylacetate and n-butanol. n-Butanol fraction showed the highest ex-traction yield of all fractions. Antioxidative activities of different fractions were examined by l.l-diphenyl-2-picrylhydrazyl(DPPH) radical generation, the Rancimat test, the nitrite scavenging ac-tivity and the thiobarbituric acid(TBA) method, and compared with the properties of the commercial antioxidant butylated hydroxytoluene(BHT). The antioxidative capacity of the ethylacetate fraction was the highest among fractions and its fraction showed higher contents of total polyphenol. Furthermore, the antioxidative capacity of the ethylacetate fraction was similar to that of BHT. In conclusion, these results suggest that lotus root may be a good candidate as a natural antioxidant source.

• Microbiology and Biotechnology Letters
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• v.45 no.2
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• pp.118-123
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• 2017

This study was conducted to determine the antioxidant activities of ethanol and water extracts of Sargassum hemiphyllum. Antioxidant activities were evaluated by assessing total phenolic contents, 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, chelating effect, reducing power, and using the rancimat method. Total phenolic contents in the ethanol and water extracts were 17.91 and 13.44 mg gallic acid equivalents/g, respectively. Ethanol extract showed higher DPPH radical scavenging activity than water extract and similar activity to that of BHT. The reducing power of ethanol and water extracts increased in a concentration-dependent manner. Particularly, ethanol extract was more effective than water extract. Water extract showed a higher chelating effect compared to ethanol extract. The antioxidant index measured by rancimat was lower than those in BHT, but the ethanol extract showed a higher value than the water extract. The ethanol extract showed higher antioxidant activity than the water extract, except for the chelating effect. These results suggest that the ethanol extract of Sargassum hemiphyllum has more potent antioxidant activity and may be used as a source of natural antioxidants.