Oil and Fats : General description with special reference to - PowerPoint Presentation

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Oil and Fats: General description with special reference to Arachis hypogaea(Groundnut)

GE IV

Sem

: Eco Bot and Biotech

Paper code: 32165401

By: Dr. Neha Yadav

Deshbandhu College

Oil, Fats and Waxes

Arachis

hypogaea

L.

Like Carbohydrates , Fats and

Oils contain only C, H and O

Though the proportion of three is

different

Have a relatively low percentage

of

Oxygen

Oils are liquid at room temperature

Fats are solid or nearly solid

Vegetable oil and Fats are triglycerides of complex organic fatty acidsNaturally occurring fats are usually mixtures of triglycerides of various fatty acids with a general formula

Fatty acids TypesFatty Acids are of two principal kinds: Saturated and UnsaturatedCommon saturated fatty acids in fats are Palmitic (abundant in vegetable fats) and Stearic acidCommon unsaturated fatty acids in fats are Oleic acid (one double bond)

Linoleic (two

double bond

) Linolenic (three double bond)Q. Differentiate between Saturated and Unsaturated Fatty acids?

How vegetable oils is different from essential oils (volatile oils/ethereal oils)?They do not volatilise at room temperatureThey cannot be distilled without being decomposedLeave a permanent greasy stain on paperBeing glycerides they form soap with alkali

Lack strong taste and

odour

of essential oils

Become rancid on long exposure to airEx: coconut oil, palm oil, soybean oil, olive oil etc.

Classification of Vegetable oils(Depends on the ability to absorb Oxygen from atmosphere)Three types:

Non-drying oils

- Remain liquid at room temperature, incapable of forming elastic films

(

they do not react with atmospheric oxygen),

Glycerides of saturated acids and oleic acid with little or no linoleic and linolenic acid, iodine number less than 100, never undergo Oxidation to form a fil and hence not used in paints and varnishes, useful in manufacturing of soaps, as lubricant and as food, these oils are found notably in plants of tropical regions. Example : Groundnut, Palm, Olive, Almond oil etc.

2. Semi-drying oils- Intermediate between Drying and non-drying oils, characteristic in having linoleic and saturated acids, absorbs atmospheric oxygen slowly, produces soft film even after long exposure to air (never form a tough elastic film like Drying oils), iodine number lies between 100-130. Example: cootonseed sesame, corn oil etc.

3. Drying oils: These oils are fairly rich in Glycerides of unsaturated fatty acids, particularly Linoleic and Linolenic acids

with few oleic

compounds, such oils readily absorb oxygen on exposure to air and form a tough, elastic and resistant film, thus important in paint and varnish industries, have high iodine number, usually more than 130. Example: temperate plants like Linseed, safflower,

soyabean

etc

included in this category.

Q. Differentiate between the tree types of vegetable oils?

Q. Write short note on drying oil or semi-drying or Non-drying oil

Location of oil in plant cells and methods of obtaining oils (For 1Mark Q’s)

Vegetable oil and fats

are located in the form of small insoluble oil droplets within the plant cells. Occur predominantly in

seeds

, mostly in endosperm and cotyledons.

In case of

cereals

, fat occurs almost exclusively in

embryo

Olive oil

and

palm oil

are examples where oil is obtained from

Fleshy pericarp of Fruit

Sometimes oils and fats are also extracted from roots, stems and foliage.

Methods of obtaining oils

1.Rendering

2.Mechanical Expression

3.Solvent Extraction

Utilization of Vegetable Oils and Fats

As food (concentrated reserve of energy as they contain very little oxygen, have high caloric value, have a role in satiety value of food, delays onset of hunger as fats retard the rate at which food leaves the stomach, adds

flavour

to food, acts as solvent for fat soluble vitamins, many oils are being used as cooking oil, residue left after extraction of oil called as oil-cake serves important livestock feed)

For industrial purpose (employed in non-edible products such as Paints and Varnishes and Lacquer, soaps, detergents, synthetic

fibres

, polishes, candles, cosmetics

etc

)

In Pharmaceuticals (Fixed oils and fats are used for their soothing properties)

Refer: Economic Botany in the Tropics, Fourth edition by S.L. Kochhar (2012)