Examples of Antioxidants

What are Antioxidants?

Antioxidants are defined as substances that when present in food, delay, control or inhibit oxidation and deterioration of food quality. Antioxidants are compounds that inhibit oxidation.

An antioxidant is a substance that when present at low concentrations compared to those of oxidisable substrates, significantly delays or inhibits oxidation of that substrate. Use of antioxidants in food was unintentionally practised since antiquity, with populations living in hot climates in countries like India.

Antioxidant herbal medicines protect against oxidation and free radical damage. The term ‘antioxidant’ is derived from the Greek anti, meaning ‘against’, and the English oxidant, meaning  substance that can cause oxidation or is oxidising in action.

Table of Contents

• Recommended Videos
• Synthetic Antioxidants
• Natural Antioxidants
• Antioxidant-Mechanism of Action
• Antioxidants Health Hazards
• Frequently Asked Questions on Examples of Antioxidants

Recommended Videos

Synthetic Antioxidants

Synthetic antioxidants are of potential use in chemistry, the food industry and medicine. Some of these compounds retain functional group chemistry analogous to that of “natural” antioxidants and introduce new chemical groups that enhance their range of cellular action or make them available to cell sites hitherto restricted. Alternatively, some synthetic antioxidants bear no structural analogy with natural antioxidants and exhibit a high reactivity toward reactive oxygen species and display selective protection in certain tissues.

A large number of synthetic antioxidants are available for the stabilisation of nonfood materials such as plastics, rubber and polymers. However, the use of synthetic antioxidants in foods requires that different aspects be taken into consideration including technological necessity, the toxicology of lipid oxidation products and the toxicology of antioxidants.

Natural Antioxidants

Plants are persistently the generous source to supply man with valuable bioactive substances and thus different plant products are being evaluated as natural antioxidants to improve the overall quality of meat and meat products. The focus on using natural antioxidants for the effective preservation of meat or meat products has almost exclusively been on the use of plant phenolics or phenolic-containing extracts.

Phenolic compounds are plant secondary metabolites commonly found in herbs and fruits, vegetables, grains and cereals, tea, coffee and red and white wines. Phenolic acids are phenols that possess carboxylic acid functionality. Phenolic compounds can be broadly divided into two categories. Among phenolic compounds found in plants, flavonoids are the most widely studied class of polyphenols with respect to their antioxidant and biological activities.

Antioxidant – Mechanism of Action

Antioxidants are substances that at low concentrations retard the oxidation of easily oxidizable bio-molecules, such as lipids and proteins in meat products, thus improving the shelf life of products by protecting them against deterioration caused by oxidation.

According to their mechanism,

• Antioxidants act as radical scavengers. Examples of antioxidants which scavenge free radicals are phenolic compounds, ligands, flavonoids and phenolic acids.
• Antioxidants react with transition metals to form complexes and thus avoid the catalytic effect of the metals in the oxidation process.
• Antioxidants that decompose peroxides and produce stable substances which are unable to produce radicals such as selenium containing glutathione peroxidase, an antioxidative enzyme which inactivate free radicals and other oxidants, particularly hydrogen peroxide.
• Antioxidants which inactivates the singlet form of oxygen, In the presence of photosensitizers such as chlorophyll and pheophy-tins, singlet oxygen may be formed from ordinary triplet oxygen by the action of light.
• Antioxidants prevent the enzymatic activity required for auto-oxidation. Examples are flavonoids, phenolic acids and gallates which deactivate the lipoxygenase.

Antioxidants Health Hazards

Humans are impacted by many free radicals both from inside our body and the surrounding environment, particularly reactive oxygen species generated in living organisms during metabolism. Antioxidants may have a positive effect on human health since they can protect the human body against deterioration by free radicals.

However, the use of synthetic antioxidants must be strictly controlled due to potential health hazards. Hence, the search for natural antioxidants as safe alternatives to synthetic products is important in the food industry. Therefore the use of natural antioxidants available in food and other biological substances has attracted significant interest due to their presumed safety and nutritional and therapeutic values.