How do antioxidants act?


1. Primary antioxidants, also called  FREE RADICAL SCAVENGERS, are molecules capable of blocking lipid radicals (L°, LO°, LOO°) by hydrogen transfer. Example: LOO° + AH ⇒ LOOH + A°… This group consists nearly exclusively of phenolic compounds: synthetic antioxidants (BHA, BHT, TBHQ, gallates), tocopherols and phenolic compounds from plants (flavonoids, phenolic acids, diterpenoids…).

2. Secondary antioxidants, or PREVENTIVE ANTIOXIDANTS, act on the factors that promote oxidation: they chelate metallic ions (EDTA, citric acid, certain phenolic compounds), reduce oxygen (ascorbic acid), deactivate singlet oxygen (β-carotene)…

The presence or addition of an antioxidant is characterized by a delay effect or a slowing down of the onset of oxidation, an effect which varies depending on the nature of the antioxidant and its concentration.

Illustration of the delay effect. 2 curves with the same point of origin and the same shape are shifted along the time axis in abscissa. On the ordinate the oxidation index.
Illustration of the delay. 2 curves with the same point of origin and the same shape are shifted downwards, according to the axis of the oxidation index in ordinate. In abscissa the time.
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