Domestic processing of onion bulbs (Allium cepa) and asparagus spears (Asparagus officinalis): Effect on flavonol content and antioxidant status

Two commonly consumed plant foods, onion bulbs and asparagus spears, were s ubjected to typical domestic processing, including chopping, maceration, an d boiling. The impact of these processes on flavonol content was assessed. Further, the consequences of these processes on the antioxidant capacity of the tissues were evaluated with the beta -carotene bleaching method. Chopp ing significantly affected rutin content in asparagus, yielding an 18.5% de crease in 60 min; but in onions, quercetin 3,4 ' -diglucoside (Q(DG)) and q uercetin 4 ' -glucoside (Q(MC)) were virtually unaffected by chopping. Boil ing for 60 min had more severe effects, as it caused overall flavonol losse s of 20.6 and 43.9% in onions and asparagus, respectively. Chopping of tiss ues did not considerably influence the antioxidant capacity, but boiling di d provoke notable changes.