on the other side. Zeiss Immersion Refractometer is used made by a
Germen company; it is a handy instrument and has digital display.
is the natural source of variable variety of fatty acids diversified
in nature. It is separated to make the cream and sold at high
prices. People separate the cream from the milk and add vegetable
fat into the milk and then sell it after homogenization. Vegetable
fat is unsaturated and it get oxidized and becomes rancid when
exposed to air so become hepato-toxic and may cause liver cirrhoses.
Small milk globules become rancid when oil and vegetable fat is
being added and interesting thing is that colour and consistency of
the milk remains normal.
Detection of Vegetable Fat in Milk:
Take 1 ml milk and 9 ml absolute alcohol. Mix and shake well and
then stand it for 5 minutes.
fat globules start floating on the top this is natural fat but if
they sunk in the bottom then it indicates the addition of vegetable
fat in the milk sample.
fat floats because its globule has pits in it and air entrapped in
those pits that makes the globule lighter and these float on the
surface. There are no such pits in the vegetable fat globule.
Formaldehyde in the Milk
frequently used in the milk as preservative. It is highly toxic to
the kidneys (nephrotxic). It forms aldehyde compounds and fix the
proteins that leads to toxic syndrome. Adulteration of formaldehyde
in the milk is not recommended and discouraged all over the world.
Its use is illegal from any point of view. Under specific
circumstances (for research purpose), it is allowed to use 1 part of
formaldehyde in 200,000 parts of milk as milk preservative
(1:200,000). It is recommended for those patients having gastric
ulcers. As formaldehyde will precipitate the protein, so in such
patients it will absorbed from the intestine rather than the
for Formaldehyde Detection:
Test to declare the milk as formaldehyde free or not is very
simple. Take 10 ml milk sample and add 5 drops of ferric chloride
(10%). Then, add 2 ml of H2SO4. Shake it well
and then stabilize it. There will be orange red colored ring at top
of milk sample. This ring indicates the presence of formaldehyde in
the milk. Negative test presents no such ring formation.
practice of milk is done in order to enhance the keeping quality of
the milk. Boiling procedure is safe, and milk does not contain any
toxin after boiling. But a variety of vitamins, essentials enzymes
and amino acids are lost through boiling of milk.
for Boiled Milk:
Take 15 ml milk & add 2-3 drops of starch solution (10%). Then
add 5-6 drops of KI (10 %) and finally 1-2 drops of H2O2.
milk remains white colored, it indicates boiled milk.
blue color appears, it indicates milk is not boiled; it is raw
Somatic Cell Count
are epithelial cells and leukocytes coming down in the milk. Somatic
Cell Count (SCC) for milk of healthy cow is 200,000/ml. If there is
an increase in SCC upto 300,000/ml; it means milk is from mastitic
cow. SCC in the milk is the big indicator for health of the animal.
Somatic Cell Count (SCC) provides three important functions:
Monitoring of prevalence of mastitis in dairy cows
as indicator of raw milk in all processes
as indicator of hygienic conditions of milk at a dairy farm
Grading of Milk
(According to Somatic Cell Count):
< 30,000 cells/ml
B 30-50,000 cells/ml
C 50-100,000 cells/ml
Drug Residues in
Treatment of animals with various antibiotics is a normal
phenomenon. Physicians neglect the withdrawal period of every
product which depends upon the half life of drug. As a result drug
residues come in milk.
Effects of Drug Residues:
Consumers may acquire drug resistance
Allergic reactions may occur
Sensitization to various kinds of drugs may occur
Consumer may have complaint for vomiting, diarrhea and enteritis
Beside other effects, economic impact of industry is also
hampered due to presence of drug residues in the milk.
Permissible Level of Drug:
It is level of drug residue in the milk which has no deleterious
effect on the consumers’ health. It is determined by FDA. FDA
recommendations for standard drug residues are accepted by health
monitoring authorities of all countries irrespective to the quality
of the milk.