Flavonoid content of several vegetables and their antioxidant activity

TLDR

The study selected several vegetables to assess their flavonoid contents and antioxidant activities. The authors measured flavonoid levels and antioxidant activities using DPPH, superoxide, hydroxyl radical scavenging assays, reducing power, a linoleic acid system, blanching trials, and storage tests. Sweet potato green and purple leaves and onion outer leaves contained the highest flavonoid levels, exhibiting over 85 % free‑radical scavenging, superior reducing power, and antioxidant activity compared with cabbage, spinach, potato, and crown daisy; brief blanching (30–60 s) preserved flavonoids and activity, and storage at 4–10 °C maintained quality better than room temperature. © 2000 Society of Chemical Industry.

Abstract

Several vegetables were selected to study their flavonoid contents and antioxidant activities. The results showed that both green and purple leaves of sweet potatoes (185.01 and 426.82 mg kg−1 respectively) and the outer leaves of onion (264.03 mg kg−1) possessed higher amounts of flavonoids, and more than 85% of free radical scavenging activities were evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals. In addition, green leaves of sweet potatoes and the outer leaves of onion showed higher reducing power and higher antioxidant activity in a linoleic acid system as compared to cabbage, spinach, potato and crown daisy. Blanching of green leaves of sweet potatoes for 30–60 s retained more flavonoids and higher free radical scavenging activities as compared to more than 1 min of blanching. The storage test showed that green leaves of sweet potatoes stored at 4–10 °C maintained better quality than those stored at room temperature. © 2000 Society of Chemical Industry