Define the term antioxidant• Substance that can delay the onset of oxidation, or slow down the rate at

which it occurs.

Examples of common naturally antioxidants and their sources Antioxidants sources

Vitamin C (ascorbic acid) - Found in citrus fruits,green peppers, broccoli,green leafy vegetables,strawberries and etc.

Vitamin E (tocopherols) - Found in wheat germ, nuts, seeds, whole grains, green leafy vegetables, vegetables oils(conola) and soya beans

ß-carotene - Found in carrots,squash ,broccoli,sweet potatoes,tomatoes,kale,contaloupe,melon,peaches and apricots

Selenium - Found in garlic, fish, shellfish, red meat, eggs, grains and chicken.

The structural features of the major synthetic antioxidants in food.

• All of them contain a phenolic group. C-OH joined directly to a benzene ring

• Many contain a carbon atom bonded directly to three methyl groups on a central carbon atom which is known as tertiary butyl group [ C(CH3)3 ]

• Both the phenolic group and the tertiary butyl group are free radical scavengers.

• They react with and remove the free radicals involved in the oxidation of the food and thus prolong the shelf life.

• Advantages and disadvantages associated with natural and synthetic antioxidants.

Advantages Disadvantages

Naturally occuring vitamin C, E, and carotenoids reduce the risk of cancer and heart disease by inhibiting the formation of free radical

Consumer perceive synthetic antioxidants to be less safe as they do not occur naturally.

Vitamin C is vital for the production of hormones and collagen.

Natural antioxidants are more expensive ans less effective than synthetic antioxidants and can also add unwanted colour and leave an after taste to food

ß-carotene can be used as an additive in margarine to provide it with a yellow colour and act as a precursor for vitamin A synthesis

Synthetic antioxidants are classified as food additives and need to be regulated by policies and regulation to ensure their safe use in food.

They are believed to enhance the health effects of other foods and boost overall health and resilience

Policies regarding the safe use and labelling of food additives may be difficult to implement esp in develeping countries and across international boarders.

Antioxidants found in the traditional foods of different cultures that may have health

benefits.• Vitamin C and carotenoids

(fruits and vegetables)• Flavonoids [citrus fruits, green tea, red wine,

oregano, dark cocoa and etc.]• Have been linked to lowering levels of LDC

(low density lipoprotein) cholesterol and blood sugar levels which reduce high blood pressure and to prevent the development of cancerous cell.