Abstract

The objective of this work was to determine the impact of three cooking modes (boiling, steaming and microwaving) and the conservation of onion at 4°C for 12 days on total polyphenol, flavonoid, tannins, phenolic acids contents antioxidant and anticholinesterase activity of red onion: Allium cepa. The results showed that the three cooking modes caused an increase of the levels of total polyphenols, flavonoids and tannins, but decreased the levels of phenolic acids. Storage at 4°C for 12 days caused a decrease in levels of total polyphenols, flavonoids, tannins and phenolic acids. A decrease in anti-radical activity during storage was found. Three cooking modes resulted in a decrease in antioxidant activity. However, the use of microwave was more effective as' to higher polyphenol contents. The level of anticholinesterase activity steadily decreased during refrigerated storage and after 12 days  it was 1/4 of the value found in the raw material.The raw onion showed a moderate activity which increased after most cooking treatments. The highest level of capacity was observed after microwaving.

Key words: Total polyphenol, flavonoids, tannins, phenolic acid, cooking, conservation, antioxidant activity, anticholinesterase activity, red onion.