G. Gazzani et al., ANTIOXIDANT AND PROOXIDANT ACTIVITY OF WATER-SOLUBLE COMPONENTS OF SOME COMMON DIET VEGETABLES AND THE EFFECT OF THERMAL-TREATMENT, Journal of agricultural and food chemistry, 46(10), 1998, pp. 4118-4122
The pro-antioxidant activity of carrot, cauliflower, celery, eggplant,
garlic, mushroom, onion, white cabbage, white potato, tomato, yellow
bell pepper, and zucchini was investigated. Juices obtained by centrif
ugation of vegetables were treated at different temperatures (2, 25, 1
02 degrees C) and assessed for antioxidant activity (AA) using a model
system beta-carotene-linoleic acid. Antioxidant activity of all veget
able juices showed a linear correlation with time. The equations of al
l straight lines obtained showed positive slope values indicating eith
er an increase in antioxidant activity or a decrease in prooxidant act
ivity during the reaction. Negative intercept values were found when t
he juices showed prooxidant activity at least during the first phase o
f the reaction. Mushroom and white cabbage always showed more than 80%
AA, while cauliflower, celery, and eggplant showed such high AA only
after boiling. Tomato and yellow bell pepper were always prooxidant. C
luster analysis allowed the vegetables to be divided into five groups
according to their anti- and prooxidant behavior as a function of ther
mal treatment and reaction time. Vegetable juice components were separ
ated on a Bakerbond C-18 solid-phase extraction cartridge according to
their polarity, and the AA of the bound and unbound fractions of each
vegetable was also tested.