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KMID : 1160620170220040345
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Preventive Nutrition and Food Science
2017 Volume.22 No. 4 p.345 ~ p.352
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Enhancement of Phenolic Production and Antioxidant Activity from Buckwheat Leaves by Subcritical Water Extraction
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Kim Dong-Shin
Kim Mi-Bo
Lim Sang-Bin
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Abstract
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To enhance the production of phenolic compounds with high antioxidant activity and reduce the level of phototoxic fagopyrin, buckwheat leaves were extracted with subcritical water (SW) at 100∼220oC for 10∼50 min. The major phenolic compounds were quercetin, gallic acid, and protocatechuic acid. The cumulative amount of individual phenolic compounds increased with increasing extraction temperature from 100oC to 180oC and did not change significantly at 200oC and 220oC. The highest yield of individual phenolic compounds was 1,632.2 μg/g dry sample at 180oC, which was 4.7-fold higher than that (348.4 μg/g dry sample) at 100oC. Total phenolic content and total flavonoid content increased with increasing extraction temperature and decreased with increasing extraction time, and peaked at 41.1 mg gallic acid equivalents/g and 26.9 mg quercetin equivalents/g at 180oC/10 min, respectively. 2,2-Diphenyl-1-picrylhydrazyl free radical scavenging activity and ferric reducing ability of plasma reached 46.4 mg ascorbic acid equivalents/g and 72.3 mmol Fe2+/100 g at 180oC/10 min, respectively. The fagopyrin contents were reduced by 92.5∼95.7%. Color values L* and b* decreased, and a* increased with increasing extraction temperature. SW extraction enhanced the yield of phenolic compounds with high antioxidant activity and reduced the fagopyrin content from buckwheat leaves.
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KEYWORD
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buckwheat leaves, subcritical water extraction, phenolic compounds, antioxidant activity, fagopyrin content
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