Antioxidant activity of several Allium members

A liposome model was used to examine the antioxidant activity of several members of the Allium family, including garlic bulb, bakeri garlic bulb, Chinese leek, Chinese chive, onion bulb, scallion, and shallot bulb. Allicin formation of these plants was analyzed. The influence of heat, pH, and salt upon the antioxidant activity of these foods was studied. The results showed that part of the Allium family possessed antioxidant capability (p < 0.05). Beside onion, allicin was present in other tested Allium members. Beside allicin, other compounds could be involved in the antioxidant activity performance because the allicin concentration was not strongly correlated to the antioxidant activity observed in these Allium foods. Heat treatments at 65 or 100 degrees C and acid treatment at pH = 2 reduced the antioxidant activity for most foods (p < 0.05). The pH treatments at values of 4, 6, and 8 as well as the salt treatments at concentrations of 0.2 or 0.4 M did not affect the antioxidant or prooxidant activity of these plant foods (p > 0.05). The combined treatments of heat and acid showed a greater negative impact upon the antioxidant activity for most food samples (p < 0.05). Heating and the use of acid should be carefully considered when Allium plants are used for antioxidant protection in food preparation or food processing, while the presence of NaCl should be safe.