Determination of Antioxidant Activity in Foods

Determination of Antioxidant Activity in Foods

Antioxidants, which delay or prevent the oxidation of biological molecules such as lipids, proteins, and DNA by inhibiting the initiation or development of oxidative chain reactions, are found in all oxygen-consuming organisms. They are available as antioxidants enzymatic or non-enzymatic. The most important antioxidants known as enzymatic are superoxide dismuta (SOD), glutathione peroxidase (GSHPx) and catalase. Ascorbic acid, vitamin E, carotenoids and polyphenols are known as non-enzymatic antioxidants.

The reasons why the above-mentioned compounds are antioxidants:

• Contain oxidizable double bonds or hydroxyl groups
• Being rich in electrons

While non-enzymatic antioxidants such as ascorbic acid, vitamin E and carotenoids show their antioxidant effects by inactivating reactive forms of oxygen, phenolic substances exert their antioxidant effect by binding free radicals, chelating with free metal cations such as iron and copper, and inactivating the lipoxygenase enzyme.

Different methods can be used to determine the antioxidant capacity of foods.

• Electron transfer reaction (ET, Electron Transfer)
• Hydrogen atom transfer (HAT, Hydrogen Atom Transfer)

With the methods based on the electron transfer reaction (ET, Electron Transfer), a redox reaction of a radical compound and an antioxidant material occurs. In methods based on hydrogen atom transfer (HAT, Hydrogen Atom Transfer), on the other hand, there are antioxidant and peroxy radicals formed by the breakdown of lipid and azo compounds as a substrate.