• Food Science and Biotechnology
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• v.16 no.2
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• pp.177-182
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• 2007

The beneficial effects of fruits, vegetables, and beverages on human health have been attributed to their antioxidant activities. Therefore, antioxidant activity of food products is recognized as one of the important parameters in determining their functional values. Until now, antioxidant activity has been measured by various chemical and biological methods; however, many factors confound the reliability and reproducibility of measurements of antioxidant activity of food. In vitro methods may provide a useful indication of antioxidant activity but their results may not translate to the human biological system, while in vivo tests are difficult to carry out due to the intricate processes of uptake, cellular transportation, and metabolism of individual antioxidant components. Therefore, as long as these limitations exist, our best option is to measure the antioxidant activity in food directly. This review briefly summarizes currently available methods for the measurement of antioxidant activity in food and examines their respective validity.

• Preventive Nutrition and Food Science
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• v.11 no.1
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• pp.6-9
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• 2006

This study was conducted to evaluate the antioxidant activity of each fraction from Sedum sarmentosum. Antioxidant activity of each fraction was measured using the DPPH radical assay, the ferric thiocyanate (FTC) method, and thiobarbituric acid (TBA) method. The antioxidant activities were then compared with that of BHT(synthetic antioxidant). The ethyl acetate and butanol fractions were found to have significant DPPH radical scavenging activity, with scavenging potencies showing 90.61 % and 87.02%, respectively. Total phenolic compound contents, determined according to the Folin-Denis method, were found to be in the order of ethyl acetate>butanol>ethanol>chloroform>aqueous fraction. From the results, we have been able to establish a positive correlation between the antioxidant activity and the total phenolic compound content of the sample. The antioxidant activity in a linoleic acid system was measured using the ferric thiocyanate (FTC) method and thiobarbituric acid (TBA) method. The ethyl acetate fraction had the highest antioxidant activity among the tested fractions. On the basis of these results, the ethyl acetate fraction provided equivalent or higher antioxidant activity as compared to BHT. These results suggest that Sedum sarmentosum is a potentially useful antioxidant for foods, cosmetics, and medicine.

• The Korean Journal of Food And Nutrition
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• v.8 no.2
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• pp.88-92
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• 1995

The antioxidant activity of synthetic antioxidants, BHA, BHT and TBHQ and natural antioxidants, rosemary extract, sesamol, caffeic acid and pyrogallol In a skip jack oil were studied. A control and substrates containing synthetic(0.02%) and natural antioxidant (0.05%) were stored in an incubator kept at 37$^{\circ}C$ for 8 days. The antioxidant activity of synthetic and natural antioxidants was investigated by comparing peroxide values. The results of this study were as follows All the synthetic antioxidants used for this study exhibited antioxidant activity in skip jack oils. The antioxidant activity of TBHQ was greater than that of BHA and BHT. The rosemary extract did not show antioxidant activity in skip jack oils. The antioxidant activity of sesamol and caffeic acid were greater than those of BHA. Especially Pyrogallol exhibited very strong antioxidant activity, comparable to that of the TBHQ. The antioxidant activity of the sesamol, caffein acid and pyrogallol used skip lack oil, In decreasing order as follows : pyrogallol>caffeic acid> sesamol.

• Natural Product Sciences
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• v.22 no.4
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• pp.270-274
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• 2016

Green tea, the leaves of Camellia sinsneis (Theaceae), is generally acknowledged as the most consumed beverage with multiple pharmacological functions including antioxidant activity. This study was performed to analyze the effect of extraction conditions of green tea on its antioxidant effects using DPPH assay. Three extraction factors such as extraction solvent (EtOH, 0 - 100%), extraction time (3 - 15 min) and extraction temperature ($10-70^{\circ}C$) were analyzed and optimized extraction condition for antioxidant activity of green tea extract (GTE) was determined using response surface methodology with three-level-three-factor Box-Behnken design (BBD). Regression analysis showed a good fit of data and the optimal conditions of extraction were found to be 57.7% EtOH, 15 min and $70^{\circ}C$. Under this condition, antioxidant activity of experimental data was 88.4% which was almost fit to the ideal value of 88.6%. As epigallocatechin gallate (EGCG) is known for the major ingredient for antioxidant activity of green tea, we investigated the effect of EGCG on antioxidant activity of GTE. EGCG showed antioxidant activity with the $IC_{50}$ value of $4.2{\mu}g/ml$ and a positive correlation was observed between EGCG content and the antioxidant activity of GTE with $R^2=0.7134$. Interestingly, however, GTE with 50 - 70% antioxidant activity contain less than $1.0{\mu}g/ml$ of EGCG, which is much lower than $IC_{50}$ value of EGCG. Therefore, we suppose that EGCG together with other constituents contribute to antioxidant activity of GTE. Taken together, these results suggest that green tea is more beneficial than EGCG alone for antioxidant ability and optimal extraction condition of green tea will be useful for the development of food and pharmaceutical applications

• Journal of Radiation Industry
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• v.5 no.2
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• pp.165-168
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• 2011

The antioxidant activity was analyzed in gamma-irradiated cooking juices. Because the activities of antioxidants have been attributed to various mechanisms, different assay methods including 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP), have been conducted and compared. All of these antioxidant assay showed that the antioxidant activity of cooking juice was increased by gamma-irradiation. To investigate this increase of antioxidative activity, the protein was extracted from cooking juices and its antioxidant activity was measured. From the results, it was thought that the modification of protein in cooking juiced by irradiation caused the increase of antioxidant activity of cooking juice. Therefore, gamma irradiation could be an promising method for a sterilization of cooking juice with increased antioxidant activity.

• Korean Journal of Plant Resources
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• v.19 no.6
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• pp.670-676
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• 2006

Tea polysaccharide had high antioxidant activity and it could be used to cure diabetes. Antioxidant activity of tea poly-saccharide (TPS) from three kinds of tea (green tea, oolong tea and black tea) were compared, the result indicated that oolong tea polysaccharide (OTPS) had the highest antioxidant activity. In order to explicate the mechanism of antioxidant and hypoglycemic activity, the streptozotocin (STZ)-induced diabetes mice model (DM) was established. The influence of OTPS on blood-glucose, content of MDA and NO, and activities of GSH-PX, SOD, NOS in serum, kidney and liver were investigated. The result showed that after four weeks injection of OTPS to DM mice, the blood-glucose of three treatment group reduced by 14.5%,21.5% and 33.3%, respectively, comparing to the model control. The reduction effect of OTPS increased with the rise of dose. The activity of SOD and GSH-PX elevated significantly, while the activity of NOS decreased. The content of MDA and NO reduced significantly. The above results imply that antioxidant activity was enhanced. Comparing to XKW treatment, the effect of a dose of 300mg/(kg. bw) OTPS was much better. The research showed that the OTPS had a significant effect on reducing blood glucose, and could enhance the antioxidant activity of DM mice.

• Korean Journal of Medicinal Crop Science
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• v.14 no.2
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• pp.82-86
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• 2006

Antioxidant activity of the extract fractions from leaves, stems, roots and flowers of Cirsium pendulum Fisch. was investigated. The results showed the greatest antioxidant activities in leaves by Rancimat, TBA and DPPH methods. Extracts of common thistle plants dose-dependently increased DPPH free radical scavenging activity, The extract from flowers and its hexane fraction showed the strongest antioxidant activity. HPLC analysis showed that BuOH fraction of the leaves had the highest amount of antioxidant chlorogenic and p-coumaric acids at 5.38 and 9.71 mg $100\;g^{-1}$, respectively. It implies that common thistle plants had potent antioxidant activity, and their activities were differently exhibited depending on plant part and solvent fraction.

• Food Science and Biotechnology
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• v.14 no.2
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• pp.177-180
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• 2005

Antioxidant activity of crude extracts from colored sweet potato cultivars by plant parts such as root, stem and leaf was evaluated. The highest TBARS values were obtained from root samples of sweet patato, and followed by stems and leaves, indicating that leaf sample showed the strongest antioxidant activity. Sweet potato cultivars with yellow flesh and leaf part exhibited strong antioxidant activities. Antioxidant activities of leaf and stem extracts were maintained for 21 days and were a little lower than that of BHT. The DPPH radical scavenging activity was the highest in "Sinhwangmi" leaf, and followed by "Jami" root. Chlorogenic acid was detected as the most abundant antioxidant substance among all fractions. These results suggest that the antioxidant activity of sweet potato differs depending on plant part and cultivar.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.521-528
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• 2016

The antioxidant activity of 70% methanol, 70% ethanol and chloroform-methanol (CM, 2:1, v/v) extracts from turmeric (Curcuma longa L.) was investigated in this study. The antioxidant potential of various extracts of turmeric was evaluated by using different antioxidant tests, namely DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, ABTS [2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] radical scavenging activity, ferric reducing antioxidant power and ${\beta}$-carotene bleaching assays as well as total phenol content and total flavonoid content. All extracts exhibited abundant total phenol content, total flavonoid content and strong antioxidant activity. Particularly, higher activity was exhibited by CM extract with $46.32{\pm}0.35mgCAE/g$ and $15.58{\pm}0.39 mgQE/g$ of total phenol content and total flavonoid content. Generally, antioxidant activity of various extracts from turmeric increased in the following order: 70% methanol extract, 70% ethanol extract and CM extract, respectively. Results suggested that turmeric could be widely used as a source of antioxidant and a kind of functional material in food.

• 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.