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KMID : 0380620220540020115
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Korean Journal of Food Science and Technology
2022 Volume.54 No. 2 p.115 ~ p.125
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Acid treatment effects on the contents of quercetin glycosides and aglycone in red onion powder
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Kim Mi-Ryung
Lim Jun-Hyung
Song Ji-Su
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Abstract
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Flavonoids are bioactive plant metabolites that have a range of beneficial effects on human health. Quercetin 4′-glycoside (Q4′G), quercetin 3,4′-diglycoside (Q3,4′G), and quercetin aglycone (QA) are the main flavonoids found in onions. QA, in particular, is likely to have a greater biological effect than glycosides. To develop an onion extract with high quercetin content, the optimal extraction conditions for red onion powder containing the outer layer of the onion were determined. The effects of acid treatment on the concentration of quercetin glycosides and QA were evaluated. The flavonoids of red onion powder were optimally extracted under 60-70% ethanol at 70oC for 2 h. The deglycosylation of Q3,4′G and an increase in Q4′G content occurred within 6 h of 0.2% acetic acid treatment. The QA content and deglycosylation of Q4′G eventually peaked at 24 h. In addition, QA content and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity were highly correlated, with a correlation coefficient of 0.90.
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KEYWORD
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onion, flavonoid, quercetin glycoside, quercetin aglycone, acid treatment
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