FOOD LIPID

BY

Pintu ChoudharyMaster of Technology

( Food Science and Technology)

Indian Institute of Crop Processing Technology

Ministry of Food Processing Industries

Government of India

Thanjavur - 613005

LIPID

The term “lipid” is applied to a group of

naturally occurring substances characterized

by their insolubility in water, greasy, feel and

solubility in some organic solvent. They occur

in the plant and animal kingdom.

FAMILY OF LIPID

Triglycerides (fat & oil) Glycerol (1 per triglyceride)

Fatty acid (3 per triglyceride)

Saturated

Monounsaturated

Polyunsaturated

Omeg-3

Omega-6

Phospholipid (such as lecithin)

Sterol (such as cholesterol)

TRIGLYCERIDES

Triglycerides: the major class of dietary lipids,

including fats & oils

Made up of 3 units known as fatty acids and 1 unit

called glycerol (backbone)

Comprise about 95% of lipids in food and the

human body

FATTY ACID

Fatty acids:

basic units of fat composed of chains

of carbon atoms

an acid group at one end and

hydrogen atoms attached all along

their length

CONT’DSaturated fatty acid: a fatty acid carrying

the maximum possible number of hydrogen atoms

Animal foods such as meat, poultry and full-fat dairy products

Tropical oils such as palm and coconut

CONT’DUnsaturated fatty acid: a fatty acid with one or

more points of unsaturation.

Found in foods from both plants & animal

sources

Monounsaturated fatty acids (one double

bond)

Polyunsaturated fatty acids (two or more)

CONT’DPolyunsaturated fatty acids: also called a

PUFA; a fatty acid in which two or more point of unsaturation occur

Found in nuts, vegetable oils such as safflower, sunflower and soybean, and in fatty fish

ESSENTIAL FATTY ACIDS

The body can synthesize all of the fatty

acids it needs from carbohydrates, fat

or protein except for two:

1. Linoleic acid

2. Linolenic acid

– PUFAs

– Found in plant & fish oils

CHARACTERISTICS OF FATS IN

FOODS

Liquid vs. Solid

More saturated a fat is, the more solid it is at room temperature

More unsaturated a fat is, the more liquid it is at room temperature

CHARACTERISTICS OF FATS IN FOODS

Hydrogenation

The process of adding hydrogen to

unsaturated fat to make it more solid and

more resistant to chemical changes such

as spoiling

Increasing a fat’s saturation can cause a fat

to lose its unsaturated health benefits

PHOSPHOLIPIDS A lipid consisting of a water-soluble head and a fat-

soluble tail

Contain phosphorous

Component of cell membranes

Serve as emulsifiers (allow fats and water to mix and travel in and out of cells into watery fluid on both sides)

Lecithin is a common phospholipid

Often used as an emulsifier in foods such as margarine, chocolate & salad dressing

CHOLESTEROL – A STEROL Found only in animal products

Also made & used in the body:

Structure of cell membranes

Used to make bile for digestion

Bile: a mixture of compounds, made by the liver, stored in the gallbladder, & secreted into the small intestine

Emulsifies lipids to prepare them for enzymatic digestion

& helps transport them into the intestinal wall cells

Used to make the sex hormones estrogen & testosterone

Made into vitamin D with the help of sunlight

Deposited in the artery walls leading to plaque buildup &

heart disease

FUNCTIONS OF FAT IN THE BODY

Energy source esp. for muscles

Serves as an energy reserve

1% body fat contains 3500 kcal

30-50% of stored fat

Major component of cell membranes

Nourishes skin & hair

Insulates the body from temperature extremes

Cushion the vital organs to protect them from shock

FUNCTIONS OF FAT IN FOOD

Provide calories (9 per gram)

Provide satiety

Carry fat-soluble vitamins & essential fatty acids

Contribute aroma & flavor

FAT IN THE DIET

Food Guide Pyramid

3 groups traditionally account for

nine-tenths of the fat in the Indian diet

Fats, oils & sweets group

Meat, poultry, fish, dry

beans, eggs & nut group

Milk, yogurt & cheese group

Most of the fat in our diets

comes from animal

products

RANCIDITY IN FAT

The development of off-flavor in fat is known as rancidity

Hydrolytic rancidity: When fat is hydrolyzed by lipase,

free fatty acid are formed, the odors of low molecular

weigh fatty acids to the rancidity.

Oxidative rancidity: The oxidation takes place at the

unsaturated linkage (double bond). The addition to the

unsaturated linkage result in formation of peroxide which,

on decomposition , yields aldehydes and ketones having

pronounced off flavor.

REFERENCES

• Maitland, Jr Jones (1998). Organic Chemistry. W W Norton & Co Inc (Np). p. 13.

• Stryer et al., p. 328.

• Stryer et al., p. 330.

• Fahy E, Subramaniam S, Murphy R, Nishijima M, Raetz C, Shimizu T, Spener F,

Van Meer G, Wakelam M and Dennis E.A (2009). "Update of the LIPID MAPS

comprehensive classification system for lipids". Journal of Lipid Research 50

(Supplement).

• Michelle A, Hopkins J, McLaughlin CW, Johnson S, Warner MQ, LaHart D, Wright

JD (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA:

Prentice Hall.

• Vance JE, Vance DE (2002). Biochemistry of Lipids, Lipoproteins and Membranes.

Amsterdam: Elsevier.

• Brown HA, ed. (2007). Lipodomics and Bioactive Lipids: Mass Spectrometry

Based Lipid Analysis, Volume 432 (Methods in Enzymology). Boston: Academic

Press.

• Mandal, Ananya. "Types of Lipids". news-medical.net.

THANKS