2. DEFINITION
Is the study of the composition and properties
of food, the chemical changes it undergoes
during handling, processing and storage, and the
principles underlying the improvement of food

3. F.1.1: DISTINGUISH BETWEEN
FOOD AND NUTRIENT

4. FOOD
• A food may be considered as any substance that we
deliberately take into our mouth and swallow it.
That is any natural or artificial material intended for
human consumption.
• Logically, a food must contain one or more nutrients
which some foods are rich in nutrients, whereas
others have very little nutrient value.

5. NUTRIENT
• A nutrient is a component of food that is used by body to
provide energy, or for the growth and repair of tissue.
• Examples of nutrients:
carbohydrates, lipids, proteins, vitamins, minerals
• Water which is essential for biochemical processes to occur, is
also considered a nutrient
• Malnutrition can occur when either too little or too much of
the essential nutrients are eaten

6. F.1.2: DESCRIBE THE CHEMICAL COMPOSITION
OF LIPID (fats and oils), CARBOHYDRATES
AND PROTEIN

8. • Fats and oils belong to a group of compounds
called lipid which are esters of a glycerol and
three fatty acids
• An average diet should contain about 10-20%
fats
• Lipids are insoluble in water but soluble in
non-polar solvent

9. • As we can see R1, R2, and R3 represent long hydrocarbon
chains, which may be same or different. The hydrocarbon
chains may also:
- Saturated (containing carbon-carbon single bond)
- Unsaturated (containing carbon-carbon double bond)
- Polyunsaturated (containing a number of carbon-
carbon double bonds)

11. • The nature of R group determines the physical and
chemical properties of the lipid:
- Saturated fats tend to be solid at room
temperature
- Unsaturated fats (e.g as in vegetable oils) tend
to be liquid
• Lipid is a source of energy and vital for the construction
of cell membranes
• It provide more concentrated energy source than
carbohydrates

12. • The carbon atoms are less oxidized as the molecules
have fewer oxygen atoms in their molecules.
So, more energy is released when the molecules are
completely oxidized to CO2 and H2O
• The fat stored in adipose tissue provides
insulation, which regulates the temperature of the
body, and protective covering for some part of the
body

14. • Carbohydrates have empirical formula of CH2O and the
simplest carbohydrates are monosaccharides with the
general formula (CH2O)n (n>2)
• Plants are the main source of dietary
carbohydrate, which are produced from CO2 and H2O
by photosynthesis
• Sugars are crystalline solids and dissolve in water to
give sweet solution
• The main function of carbohydrate is as a source of
energy. They also use for construction of cell.

15. • One of the simplest sugars is glucose:

16. MONOSACCHARIDES
• Each monosaccharide contains one carbonyl group
(C=O) and at least two hydroxyl group (-OH).
• They are either aldehyde (aldose) or ketones (ketose)
• Examples of monosaccharides include
glucose, fructose and ribose. They are soluble in
water as the hydroxyl (OH) functional groups are able
to form hydrogen bonds with the water molecules

17. • There are two types of monosaccharides:

18. DISACCHARIDES
• Condensation of two monosaccharides forms a dissacharide
by elimination of one water molecule.
• There are many disaccharides found, but those important to
the food industry are maltose, sucrose and lactose:

19. • Maltose, for example, is formed from the condensation
between two molecules of a-D-glucose which are thereby
joined by a, 1,4-glycosidic bond; the C1 forms the linkage with
the hydroxyl group on the C4 of the second a-D-glucose
molecule

20. POLYSACCHARIDES
• Polysaccharides are condensation polymers formed
from monosaccharides with the elimination of water
molecules
• Carbohydrates comprise sugars and polymers such as
starch and cellulose derived from monosaccharide.
• Starch is a polymer of a-D-glucose.

22. • Proteins are polymers of amino acids
• All proteins contain C, H, O, and N and some also
have S and P
• Based on figure below, R1, R2 and R3 represent the
side chain of amino acids involved and they may be
same or different

23. • As amino acids have both carboxylic acid group and an amino
group, they are able to undergo condensation reaction:
• The product, a dipeptide, is an amide made up of two amino
acids joined by a peptide bond or peptide linkage.

24. • One example of alanine and glycine, for example, can
form two dipeptides:
• The two dipeptides above can be represented as Ala-Gly and
Gly-Ala

25. • The primary structure of a protein is the
sequence of amino acids which form the
protein.
• The secondary structure of a protein
describes the way in which protein chains
fold or align themselves by intramolecular
hydrogen bonding between different groups
at different position.

26. • The tertiary structure describes the overall three-
dimensional shape of the protein and is
determined by a range of interactions such as:
- Hydrogen bonding between polar groups on the side
chain
- Salt bridges (ionic bonds) formed between -NH2 and
–COOH groups
- Dipole-dipole interactions
- Van Der Waals forces between non-polar groups
- Disulphide bridges formed between two cysteine
molecules from different positions along the chain