Food consists of major constituents or materials. Its composition will affect nutritional and sensory quality of food product, therefore elucidating the composition of food is very essential for food production chain. The major compositions of most foods are including water, lipid, protein, carbohydrate, and enzyme. Each component has its own physical and chemical characteristics which contribute to the final properties of food products.

1. Properties of Food Components –
An Introduction
R.Subha, M.Sc., M.Phil., D.C.T.,
Assistant Professor
Department of Home Science,
V.V.Vanniaperumal College for Women,
Virudhunagar.

2. Introduction
• Foods are complex materials.
• The components of food which are needed by our body for
growth and development are called NUTRIENTS.
• The major nutrients are:
(i) Carbohydrates - provide energy.
(ii) Fats - concentrated sources of energy, carriers of fat-soluble vitamins
(iii) Proteins - building of new tissues and maintenance and repair body
tissues
(iv) Vitamins – need for growth and for regulation of body processes.
(v) Minerals - body-building and regulation
• Properties of food components determine the quality of
food.
• Food components are in the form of solids, in solutions or in
the form of colloids – sols/emulsions.

3. Colloids
• Foods contain high percentage of water –
which other nutrients present are dispersed.
• Existence of colloidal state was first recognized
by Thomas Graham (1850) – father of colloidal
chemistry.
• Classified organic compounds present in foods
into two categories
– Colloids
– Crystalloids

4. Colloid and Crystalloids - Difference
• Colloid – Greek word – kolla –
“glue” – defined as a system
containing particles of size from
one millimicron to 0.1 micron
(10-6 to 10 -4 mm).
• Colloids – compunds with large
molecular weights, form
dispersion with water
• Eg. Starch, proteins, glucogen
and agar-agar.
Solids, Liquids and Gases –
dispersed in water to form
either solutions or colloids
• Crystalloids –
compounds with small
molecular weights,
form true solutions.
• Eg. sugars and amino
acids.

5. Solution and Colloids - Difference
Solution
- Homogenous mixture of
2 or more substances.
- Eg. Salt in water –
solution
- Dissolved
substances(salt-
solute)& medium which
they are
dissolved(water –
solvent) uniformly
distributed
• Colloidal System –
heterogeneous system
• Material form base of
the system – dispersion
medium/ continuous
phase.
• Material exist in
colloidal condition –
dispersed
medium/discontinuous
phase

7. Dispersed System
The term "Disperse System" refers to a system in
which one substance (the dispersed phase) is
distributed throughout a second substance (the
continuous phase). Each phase can exist in solid,
liquid, or gaseous state.
Types of disperse systems:
1. Heterogenous dispersion - > 1μm
2. Colloid dispersion - 1 – 1000 nm
3. True solution - < 1 nm

8. References
• http://ecoursesonline.iasri.res.in/mod/page/vi
ew.php?id=96471
• https://drive.google.com/file/d/1Yo09mqCv6e
JAfEt5xQt67Pw2lcGzFTsW/view
• https://www.youtube.com/watch?v=cuEHseI3
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