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Quantitative analysis of the flavonoid content of commercial tomatoes, onions, lettuce, and celery
- Crozier, A., Lean, M.E.J., McDonald, M.S., Black, C.
- Journal of agricultural and food chemistry 1997 v.45 no.3 pp. 590-595
- apigenin, beef, boiling, celery, cherry tomatoes, fruits, frying, high performance liquid chromatography, lettuce, luteolin, onions, quantitative analysis, quercetin
- Quantitative estimates of conjugated flavonoid content were obtained by using HPLC to analyze the level of free flavonoids present in acid-hydrolyzed extracts from commercial fruits and vegetables. Cherry tomatoes contained 17-203 micrograms of quercetin g-1 fresh weight compared to 2.2-11 micrograms g-1 detected in normal-sized Scottish, Spanish, and Dutch beef tomatoes. The quercetin levels in onions ranged from 185 to 634 micrograms of quercetin g-1 fresh weight. "Round" lettuce contained 11 micrograms of quercetin g-1 fresh weight compared to 911 micrograms g-1 in the outer leaves and 450 mg g-1 in the inner leaves of "Lollo Rosso" lettuce. The conjugated flavonoid content of celery was very variable, ranging from undetectable to 40 micrograms of luteolin and 191 micrograms of apigenin g-1 fresh weight. Cooking lowered the quercetin content of both tomatoes and onions with greater reductions being detected following microwaving and boiling than after frying.