OILS FATS AND WAXES

Oils--- Oils are esters of higher fatty acids. Oils contain a large proportion of glycerides of unsaturated acid. Melting point of oil is below 20⁰C.

Fats--- Fats are esters of higher fatty acids. Fats contain a large proportion of glycerides of saturated acid. Melting point of fat is above 20⁰C.

Classification of Oils and Fats

(1) Depending on uses oils and fats are two types---

(i) Edible--- Those oils and fats are uses for cooking purpose or eating purpose are known as edible oils or fats.

(ii) Inedible--- Those oils and fats are uses for making soaps, detergents, paintings etc are known as inedible oils or fats.

(2) Depending on nature of the carbon chain, oils and fats are three types---

(i) Non-drying oils or fats--- If the carbon chain present in oil or fat is saturated, then that oil or fat is called non-drying oil or fat.

(ii) Semi-drying oils or fats--- If the carbon chain present in oil or fat have some degree of unsaturation, then that oil or fat is called semi-drying oil or fat.

(iii) Drying oils or fats--- If the carbon chain present in oil or fat is unsaturated, then that oil or fat is called drying oil or fat.

(3) Depending on the source of availabilities oils and fats are three types---

(i) Vegetable oils or fats--- Oils or fats extracted from vegetable source are known as vegetable oils or fats.

(ii) Animal oils or fats--- Oils or fats extracted from animal source are known as animal oils or fats.

(iii) Mineral oils or fats--- Oils or fats extracted from mineral source are known as mineral oils or fats.

Waxes--- Waxes are esters of monohydric alcohols with higher fatty acid. The molecular weight of these alcohols is very large. Waxes are non-crystalline esters.

Depending on the source of availabilities waxes are five types, such as----

(i) Animal waxes

(ii) Vegetable waxes

(iii) Mineral waxes

(iv) Mineralised vegetable waxes

(v) Synthetic waxes

Difference Between Fats and Oils

If we consider the Chemical properties there is no difference between fats and oils, both fats and oils consist of mixed glycerides. The difference between fats and oils is merely physical one of consistency.

(i) Melting point of fat is above 20⁰C, whereas melting point of oil is below 20⁰C. Coconut oil and ghee are fats in winter but oils in summer.

(ii) A large proportion of glycerides of saturated fatty acids are present in fats, whereas a large proportion of glycerides of unsaturated fatty acids are present in oils.

(iii) The iodine value of oils is high due to presence of higher unsaturation in oils, whereas the iodine value of fats is low.

(iv) Due to presence of unsaturation that is double bond in oils, oils can be hydrogenated by using H₂ and Ni catalyst. Since fats contain a large proportion of glycerides of saturated fatty acid, so fats can not be hydrogenated. By heating fats can be converted to oils.

Difference Between Vegetable and Mineral Oils

(i) The vegetable oils have high flash point, and this might be 326⁰C. Whereas flash point is 200⁰C for most mineral oils.

(ii) Mineral oils have zero acid value but vegetable oils have definite acid value.

(iii) Vegetable oils contain a large proportion of glycerides of saturated and unsaturated fatty acids, so they can not be distilled with the steam, and vegetable oils are called fine oils. Mineral oils are mixture of various hydrocarbon such as kerosene, paraffin, petroleum etc. Mineral oils are highly volatile, possess unpleasant smell and can be distilled with steam.

Examples of Animal Oils

(i) Cord-liver oil

(ii) Shark liver oil

(iii) Fish oil

(iv) Whale oil

Examples of Vegetable Oils

(i) Mustard oil

(ii) Coconut oil

(iii) Seed oil

(iv) Linseed oil

(v) Castor oil

Examples of Mineral Oils

(i) Kerosene oil

(ii) Diesel

(iii) Petroleum oil

(iv) Paraffin oil