Analysis of the Major Flavonol Glycosides Present in Four Varieties of Onion (Allium cepa) and Changes in Composition Resulting from Autolysis

摘要: The major flavonoids of mature onion bulb were confirmed as the 3,4′-O-diglucoside (Qdg) and 4′-O-monoglucoside (Qmg) quercetin using a combination chromatographic comparisons, mass spectrometry nuclear magnetic resonance spectroscopy. These two components account for over 85% total in three varieties with Qdg main component. Quercetin is detected these long stored onions but only at low levels less than 2% total. remaining flavonoid fraction (approx 15%) comprises upto 17 different which quercetin-3-O-glucoside isorhamnetin glucoside are prominent members although each contribute 1% fraction. There significant differences Qmg between four analysed; varying from 50–1300 mg kg-1 fresh tissue 36–394 kg-1. Maceration tested led to loss appearance free quercetin. In variety Rijnsburger 50% was degraded 5 h had completely disappeared after 24 h. changes can be quantitatively explained by increases possible significance glycosides diet discussed. © 1997 SCI