3.4.2.1 Test for milk:-
1. Determination of SNF in milk
AIM: - to determine the SNF of milk
Apparatus: - lactometer jar, lactometer and thermometer
Principle: - It is calculated by using lactometer method.
Procedure:-
Warm the milk sample to 40 to 45oCand maintain at this temperature till 5 min.
Mix the contents by rotating and inverting the bottle, taking care to avoid the formation of air bubbles.
Cool the sample to 15.5oC
Invert the sample bottle 2 to 3 times; pour enough milk into the lactometer jar, do not let the air bubbles to form, so that some milk overflows when the lactometer is inserted.
The lactometer should float freely and not touch the sides of cylinder.
Allow the lactometer to remain steady in the milk. Take the …show more content…
Determination of fat in milk
AIM: - To determine the fat content by using gerber method.
Principle: - The milk is mixed with sulphuric acid and iso-amyl alcohol in a special Gerber tube, permitting dissolution of the protein and release of fat. The tubes are centrifuged and the fat rising into the calibrated part of the tube is measured as a percentage of the fat content of the milk sample.
Apparatus: - Butyro meter, 10.75ml pipette,amyl alcohol, stoppers, gerber centrifuge, water bath.
Reagents:-Sulphuric acid, amyl alcohol.
Procedure:-
Transfer 10 ml of sulphuric acid in to butyro meter .
Warm the sample approximately to 270C and mix thoroughly but do not shake it so vigorously as to cause churning of the fat. Allow the sample stand for 3-4 min. to avoid air bubbles Invert the sample bottle 3-4 times immediately prior taking milk for test.
Transfer 10.75ml sample into the butyro meter .
Add 1ml of amyl alcohol and close the neck of butyro meter firmly with the stopper without disturbing the contents. Shake the butyrometer carefully and invert it 2-3 times so that the sample is thoroughly …show more content…
Procedure for adulteration tests:-
A. Test for detection of Sugar test:-
Principle:- sugar was added to increase the density to prevent detecting of added water. Generally cane sugar is mixed in milk to increase the percentage solids content of milk i.e., to increase the lactometer reading of milk, that was already diluted with water.
Take 10 ml of milk in a test tube. Add 5 ml of hydrochloric acid along with 0.1 g of resorcinol. Shake the test tube well and place it in a boiling water bath for 5 min. Appearance of red color indicates the presence of added cane sugar in milk.
Dark brick red color indicated adulteration. (-ve) (+ve) Fig:- 2
B. Test for Detection Of Starch
Principle: - Starch was added to musk adulteration of milk with water to increase viscosity & lactometer reading. Addition of starch increases the SNF content of milk. Wheat flour, arrowroot, rice flour, etc., can also be added for increasing the SNF content.
Take 5 ml milk in a test tube and boil it thoroughly. Cool and add a few drops of starch reagent. Change of color to blue indicates that the milk is adulterated with
1. Determination of SNF in milk
AIM: - to determine the SNF of milk
Apparatus: - lactometer jar, lactometer and thermometer
Principle: - It is calculated by using lactometer method.
Procedure:-
Warm the milk sample to 40 to 45oCand maintain at this temperature till 5 min.
Mix the contents by rotating and inverting the bottle, taking care to avoid the formation of air bubbles.
Cool the sample to 15.5oC
Invert the sample bottle 2 to 3 times; pour enough milk into the lactometer jar, do not let the air bubbles to form, so that some milk overflows when the lactometer is inserted.
The lactometer should float freely and not touch the sides of cylinder.
Allow the lactometer to remain steady in the milk. Take the …show more content…
Determination of fat in milk
AIM: - To determine the fat content by using gerber method.
Principle: - The milk is mixed with sulphuric acid and iso-amyl alcohol in a special Gerber tube, permitting dissolution of the protein and release of fat. The tubes are centrifuged and the fat rising into the calibrated part of the tube is measured as a percentage of the fat content of the milk sample.
Apparatus: - Butyro meter, 10.75ml pipette,amyl alcohol, stoppers, gerber centrifuge, water bath.
Reagents:-Sulphuric acid, amyl alcohol.
Procedure:-
Transfer 10 ml of sulphuric acid in to butyro meter .
Warm the sample approximately to 270C and mix thoroughly but do not shake it so vigorously as to cause churning of the fat. Allow the sample stand for 3-4 min. to avoid air bubbles Invert the sample bottle 3-4 times immediately prior taking milk for test.
Transfer 10.75ml sample into the butyro meter .
Add 1ml of amyl alcohol and close the neck of butyro meter firmly with the stopper without disturbing the contents. Shake the butyrometer carefully and invert it 2-3 times so that the sample is thoroughly …show more content…
Procedure for adulteration tests:-
A. Test for detection of Sugar test:-
Principle:- sugar was added to increase the density to prevent detecting of added water. Generally cane sugar is mixed in milk to increase the percentage solids content of milk i.e., to increase the lactometer reading of milk, that was already diluted with water.
Take 10 ml of milk in a test tube. Add 5 ml of hydrochloric acid along with 0.1 g of resorcinol. Shake the test tube well and place it in a boiling water bath for 5 min. Appearance of red color indicates the presence of added cane sugar in milk.
Dark brick red color indicated adulteration. (-ve) (+ve) Fig:- 2
B. Test for Detection Of Starch
Principle: - Starch was added to musk adulteration of milk with water to increase viscosity & lactometer reading. Addition of starch increases the SNF content of milk. Wheat flour, arrowroot, rice flour, etc., can also be added for increasing the SNF content.
Take 5 ml milk in a test tube and boil it thoroughly. Cool and add a few drops of starch reagent. Change of color to blue indicates that the milk is adulterated with