2. Composition of food
 The term “food” refers to the broad range of edible
materials that comprise the essential body nutrients
required for life and growth, such as
proteins,carbohydrates,fats, vitamins, or minerals.
 Food contains chemical molecules.Chemical composition
may be determined in laboratory

3. Cont…
 Chemical substances found in the largest amounts
in food:
 Carbohydrates
 Fats
 Protein
 Water
 found inside cells in plants and animals
 Vitamins
 Minerals

4. Carbohydrates
 Carbohydrates are organic compounds of carbon , hydrogen
and oxygen. There are two major types of carbohydrates in
food :
 Sugar and Starch.
 The body's principal source of energy. All sugars and starches
that we consume are carbohydrates.
 Examples include table sugar, whole
grains, pasta, fruit, popcorn, vegetables and more . One gram
of carbohydrates yields about 4 Kilocalories of energy. Excess
of carbohydrates in the body is converted into fat which is
stored in the body.

5. Chemical classification of sugar
 Carbohydrate are classified on the basis of number of
basic sugar units linked together
 Monosaccharide – One unit
 Disaccharides – Two units
 Oligosaccharides – 10 or fewer units
 Polysaccharides – Up to 1000 units

6. Monosaccharides
 Glucose
 Fructose
 Galactose

7. Disaccharides
 Sucrose
 Glucose + Fructose
 Lactose
 Glucose + Galactose
 Maltose
 Glucose + Glucose

8. Oligosaccharides
 Raffinose and Stachyose
 Not broken down by digestive tract
 Found in dried beans

9. Polysaccharides
 Starch
 Amylose
 Amylopectin
 Dextrins
 Produced when starch molecules are partially broken
down by enzymes, acid, or heat.
 Less thickening power than starch
 Glycogen
 Plant Fiber Components

10. Plant Fiber Components
 Called dietary fiber / roughage / bulk
 Cellulose forms the fiber content in food and is called Roughage.
Roughage does not provide any nutrients to our body but it is an
essential ingredient of our food as it helps our body to get rid of
undigested food.
 It mainly consists of
 Cellulose
 Hemicellulose
 Beta-glucans
 Found in oats and barley
 Associated with reduced risk of heart disease
 Pectic substances
 Pectin forms gels in jams, jellies, and preserves
 Vegetable gums

11. Protein
Protein is the basic material of life. It makes up 3/4's of
our body tissue. Without dietary protein, all body
functions would not take place. Proteins can be broken
into complete and incomplete proteins. Complete
proteins supply a sufficient amount of the nine
essential amino acids . Animal proteins are called First
class proteins because they contains all the essential
amino acids . Plants proteins are called Second class
proteins because they do not have all the essential
amino acids. Beans, peas, milk, white portion of
eggs, etc are some examples of proteins.

12. Composition of protein
 Protein Contain
 Carbon
 Hydrogen
 Oxygen
 Nitrogen
 Potentially also sulfur, phosphorus, iron
 Large molecules
 Hundreds or thousands of amino acids joined with
peptide linkage

13. Protein Structure
 Primary
 Long chains
 Secondary
 Springlike coiling - Alpha helix
 Tertiary
 Folding of coils forming globular shape
 Quaternary
 Combining of globular proteins

14. Protein Quality
 Amino acids used as
building blocks for
proteins
 Nine amino acids
are essential for
adult human
nutrition
 Complete proteins
include essential
amino acids
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Histidine

15. FATS
Fat is composed of carbon, hydrogen and oxygen. Fats are
essential for the proper functioning of the body. We need
to consume some fats to remain healthy. Fats supply
necessary fatty acids, acids and glycerol that the body can
only get from foods. Fats also serve as the storage
substance for the body's excess calories. When the body
has depleted its carbohydrate stores, it draws on fat. One
gram of fats give 9 kilocalories of fats.

16. Lipids or fats
 Insoluble in water
 Feel “greasy”
 Three major groups
 Triglycerides
 Phospholipids
 Sterols

17. Triglycerides
 Account for 90-95 percent of fatty substances in food.
 Composed of
 3 fatty acids
 linked atoms of carbon with organic acid group
 One molecule glycerol
 3 carbon atoms and three hydroxyl groups

18. Fatty Acids
 Most fatty acids in foods are combined in
triglycerides.
 Fatty acids differ
 Number of hydrogen atoms attached
 Length of carbon chain
 Carbon chains
 Usually even numbered

19. Types of Fatty Acids
 Saturated fats
 No double bonds between carbon atoms, so no more
hydrogen can be added
 Unsaturated
 Double bonds between some of the carbon atoms that
can be broken to add hydrogen
 Monounsaturated
 One double bond

20. Omega 3 fatty acids
 Polyunsaturated fatty acids with double bond between
3rd and 4th carbon from the left on the structure.
 Found in fatty fish
 Protective for heart disease

21. Linoleic Acid
 An essential fatty acid
 Cannot be made by the body – must be consumed in
food

22. Cis – Trans Configuration
Cis
 Hydrogen atom on both sides of bond
Trans
 Hydrogen atoms on opposite sides of
bond

23. Phospholipids
 Found in food in relatively small amounts
 Function as emulsifiers
 One side of molecule attracts fat
 One side attracts water
 i.e. Lecithin

24. Sterols
 Cholesterol
 Widely known sterol
 Found ONLY in animal foods
 Is associated with coronary heart disease
 Our bodies also make cholesterol
 Plant sterols
 Phytosterols
 Interfere with absorption of cholesterol

25. Water
 Water is essential to human life. Half of our weight is water.
The body loses and needs to replace water every day. The
typical suggestion is 6-8 glasses of liquid every day.
Recently reports have come out that you need to drink
enough water to quench your thirst.

26. Cont…
 All foods contain at least some water
 Free water
 Held inside cells
 Maintains properties of free water
 May be removed by pressure
 Bound water
 Is part of molecule structure
 Reduced mobility
 Does not retain properties of free water

27. Minerals
Minerals act as nutrients and are essential to many
processes in the body, including the functioning of the
heart and digestive system and bone formation. Some
key minerals we need include Boron, Calcium,
Chloride, Chromium, Copper, Iron, Fluoride, Iodine,
Magnesium, Manganese , Molybdenum , Phosphorus,
Potassium, Selenium, Sodium and Zinc .

28. Vitamins
Without vitamins, we could not exist . They affect all
functions in the body and help regulate them. Most
vitamins must be obtained from food. We need 13
vitamins: A, C, D, E, K, B (8 different B Vitamins).
Vitamins are mainly of two types:- Water-soluble : B
and C F at-soluble : A, D, E AND K. Each vitamin
carries out specific functions. If your diet is lacking in
a certain vitamin, you may develop a deficiency disease

29. THANKS
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