Use: test for screening, rapid assessment of acidity.
Advantages: quick, cheap.
Alternatives: Clot on Boiling (COB) test, Acidity test
Principle:
Proteins in milk that has become sour (i.e. because of lactic acid formation) will coagulate when mixed with alcohol.
Equipment and materials:
- Test tube.
- Pipette.
- 68% ethanol solution (by weight: e.g. mix 68 ml 96% alcohol with 28 ml distilled water) or 75 % ethyl alcohol by volume (density 0.8675 g/ml at 27 °C).
Procedure:
1) Mix equal amounts (e.g. 2 ml) of milk and ethanol solution in test tube with the pipette.
2) Agitate by gentle movement and look for coagulation.
Interpretation
Milk containing more than 0.21% acid and milk that is abnormal (e.g. colostrum or mastitis milk) will not pass the test. This milk is not fit for further processing.
In the alcohol test to determine if its positive or negative do you have to discard the mixture of milk and alcohol or observe it for a few moment ?
In the alcohol test for milk to determine if its negative of positive do you need to discard the mixture o you just observe it for a moment to determine the result ?