Rapid Quantitative Analysis and Distribution of Free Quercetin in Vegetables and Fruits.

Abstract

The rapid and quantitative analysis of free quercetin in vegetables and fruits was studied. High-performance liquid chromatography (HPLC) techniques after preparation with Sephadex LH-20 were found to be suitabie for determining it and could be applied even to the crops containing small amounts of quercetin such as orange, potato, pea and celery. Onion contained the largest amount of free quercetin in the examined vegetables and fruits and its content was 29.1μg per 100g fresh weight. The crops in Liliaceae such as garlic and leek in addition to onion contained free quercetin relatively in large quantity. Quercetin in onion was almost completely localized upon the first and second scales from exterior, and the contents in the two scales were approximately 90% of all the parts. Quercetin was found to be stable when heated to 210°C for 20 min, but it was unstable to light. When it was illuminated with 15000 1x, the contents rapidly decreased and reached to half of the origital contents after 48h.