2. “MILK OR MILKY”
AIM:-
To understand various adulterations found in the milk in India and China and
develop inexpensive tests to characterize the purity of milk.
Working Principle:-
Various tests are conducted in our puritymeter to check the purity of milk
which are based on following principles-
1. To check water percentage – specific Gravity of water mixed milk is different as
compared to pure milk.
2. To check various other adulterated chemical components – After reacting with
various chemical species, different adulterated component indicates characteristic
color change .
DIAGRAM
3. WORKING :-
A- To test water-
Milk is added in container 1 and water in container 2 . Using bubble system
of specific gravity measurement, Reference column method and differential pressure
transmitter the difference in density of two liquids is measured. It operates on the
principle that the pressure at a point due to a liquid column is equal to g times the
product of depth of the point below the surface and the density of the liquid. The
pressure due to a fixed depth of liquid is therefore a measure of the density of the
liquid. As shown in above diagram the two column are taken and the compressed air is
passed in liquids columns up to the point when just bubble starts forming. At this point
the air pressure in the bubble tube is a function of the specific gravity of the liquid. The
measured in pressure of compressed air gives the reading of pressure of a particular
column. Then they are connected through differential pressure transmitter which gives
the difference in pressure of both columns in terms of voltage difference. This voltage is
measured by voltmeter which is modified and calibrated differently to a PURITYMETER
which measures purity of given milk. The difference in pressure gives the difference in
density of two liquids which gives purity.
Calibration – Firstly pure water is added in container 1 and noted the voltmeter
reading then pure milk is added in container 1 and again note the voltmeter
reading. Then make a new scale of value zero to 100 in which zero correspond to
pure water voltmeter reading and 100 correspond to pure milk voltmeter reading.
B- To test various other components-
After testing of amount of water in milk the milk is transported to another
section of above instrument where it is divided in different required quantities.
Different chemical test are performed on different parts to check the particular type of
impurity present in milk. Due to present of various adulterations the different parts
gives characteristic color. The various parts are gone through the following tests.
To test neutralizers - In milk neutralizers like hydrated lime, sodium hydroxide,
sodium carbonate or sodium bicarbonate are added which are generally
prohibited.
First part of the milk is transferred to a transparent small glass container which
collects upto 5 mL of milk then in it 5 ml of the alcohol is added with 4-5 drops of
rosalic acid . If color of milk changes to pinkish-red then neutralizer is present.
The waste mixture is removed by using drain valve.
4. To test starch- Addition of starch also increases the SNF content of milk. Apart
from the starch, wheat flour, arrowroot, rice flour are also added.
Second part of milk is also transferred to a transparent small glass container
which collects upto 3 mL of milk then 2 to 3 drops of 1% iodine solution is added
. If color of milk changes to blue then starch content is present. The waste
mixture is removed by using drain valve.
To test sugar- Generally sugar is mixed in the milk to increase the solids not fat
content of milk i.e. to increase the lactometer reading of milk, which was already
diluted with water.
Third part of the milk is also transferred to a boiling water bath container which
collects upto 10 mL of milk then add 5 ml of hydrochloric acid along with 0.1 g of
resorcinol .then burner of water bath is on and wait until the water boils for 5
minutes .If colour of milk changes to red then sugar content is present. The
waste mixture is removed by using drain valve.
To test acids- Many acids are harmful for body . They may cause several
diseases/infections to human body so they must be prohibited .
Fourth part of milk is also transferred to a transparent small glass container
which collects up to 5 mL of milk then add few drops of Conc. Sulphuric acid and
add 0.5% ferric chloride solution drop. If color of milk changes to violet/buff then
acid is present.
To test formalin- Formalin is poisonous so it is dangerous to health hence it
should be prohibited but it is also helpful because it can preserve milk for a long
time.
Fifth part of milk is also transferred to a transparent small glass container which
collects upto 10 mL of milk then 5 ml of conc. sulphuric acid is added dropwise
to the wall of container. If ring of violet colour appears at the mixing point of
sulfuric acid and milk then formalin is present.
All the above are chemical tests done in our instrument. The colour change indicates
adulteration or impurity in milk.
5. Estimated cost:- Three thousand rupees only.
Advantages:-
The different advantages of using our instrument are as follows-
The exact amount of purity in terms of water content can be measured with the
help of calibrated voltmeter which is our purifymeter .
We can check whether our milk is qualified for drinking purpose.
We can check different chemical components individually which means whether
one or more adulterated component is present we can identify it .
It is multi functional means gives test of both water and chemical components.
It is easy to handle for checking water content, only we have to add milk in a
container and water in another the rest of the reading we get from our meter.
Disadvantages:-
The different disadvantages of using our instrument are as follows-
Too much expensive , the various chemicals we use for test are very expensive
and also the pressure differential transmitter is high in cost.
Covers large area, our instrument is very big in size so it take a lot of space.
Importable, due to heaviness and size of instrument it can not be taken from one
place to another easily .
Hard to handle the chemical part.
Chances of errors , we have to add different quantity of chemical manually in our
instrument so possibility of error is high.
