Antioxidants are substances that can delay or slow oxidation. Common natural antioxidants include vitamin C, vitamin E, beta-carotene, and selenium, which are found in fruits, vegetables, nuts, seeds, and oils. Synthetic antioxidants used in foods contain phenolic groups and tertiary butyl groups that act as free radical scavengers to prolong shelf life. Natural antioxidants may provide health benefits but are more expensive and less effective than synthetic antioxidants.

1. 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.

2. 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.

3. • Advantages and disadvantages associated with natural and
synthetic antioxidants.
Advantages Disadvantages
Naturally occuring vitamin C, E, and Consumer perceive synthetic antioxidants
carotenoids reduce the risk of cancer and to be less safe as they do not occur
heart disease by inhibiting the formation naturally.
of free radical
Vitamin C is vital for the production of Natural antioxidants are more expensive
hormones and collagen. 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 Synthetic antioxidants are classified as
margarine to provide it with a yellow food additives and need to be regulated by
colour and act as a precursor for vitamin A policies and regulation to ensure their safe
synthesis use in food.
They are believed to enhance the health Policies regarding the safe use and
effects of other foods and boost overall labelling of food additives may be difficult
health and resilience to implement esp in develeping countries
and across international boarders.

4. 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.