Objective of the topic
•Know the processing of milk
•Identify various types of milk
•Understand pasteurization and
Milk generally refers to milk from cows,in certain
parts of the world the milk of
camels, sheep, buffall or mares also plays an
Milk( lait) is a nutritious food. It is very commonly
used in many dishes such as
soups, sauces, puddings, desserts, cakes and for
hot & cold drinks
Milk has sugar called lactose and this is the
reason why milk changes colour when heated for
Composition of milk
Percentage present in milk
Processing of milk
To ensure safe milk free from disease- producing
bacteria, toxic substances and foreign
flavours, fresh whole milk is to be processed
before marketing. milk processing operations
consist of :-
Noticeable quantites of foreign materials, such as
paricles of dust, dirt and many undesirable
To remove this , milk is generally passed through
a centrifugal clarifier.
The speed of the clarifier will be such that there
is little seperation of cream
This operation removes all dirt, filth, cells from
udder and some bacteria.
Clarification does not remove all pathogenic
bacteria from milk.
Pasteurization is the heating of liquids, to high
temperature improves their keeping quality.
The aim of pasteurization of milk is to get rid of
any disease-producing bacteria.
2 methods are employed for Pasteurization are
1. The Flash method:- milk is brought to 72⁰C and
held for not less than 15 sec ( HTST)
2. Holding method:- milk is heated to 63⁰C and
held at this temp. for not less than 30
Another treatment is given called ultra – high
treatment at 149.5⁰C for 1 sec.
As pasteurized milk is not sterilized , it must be
quickly cooled after pasteurization to prevent
multiply of surviving bacteria.
Pasteurization does not produce an objectionable
cooked flavour and no important change in
The process of making a stable emulsion of milk
fat and milk serum by mechanical treatment and
rendering the mixture homogenous.
Types of milk
Whole milk:- this milk contains at least 3.5per
cent of butter fat, which gives it the wholesome
Homogenised milk :- this milk that has been
processed so that the cream does not separate
and form a layer of the milk.
Sterlised/ ultra heat teatred(UHT):- this is
homogenesed milk heated to a high temp. for
very short time. This product have shelf life of 6
months without refrigration.
Skimmed milk:- this milk contains very small
percentgae of the milk fat but all minerals and
proteins of whole milk.
Butter milk:- it is a by product of butter making
and contains much of the mineral and protien
content of the whole milk.
Condensed milk:- it is milk from which a large
proportion of the water has been removed. Sugar
may be added. It is used in sweet dishes.
Evaporated milk:- it is similar to condensed milk
but without added sugar and with more water.
Dried Or Powdered milk:- prepared from skimmed
milk, from which most of the water content has