This has to do with the preliminary tests at the farm level, at the processing plant, and at the milk collection centre. As it is simple and quick, one can easily differentiate good and substandard quality milk. It involves the tester using senses of sight, smell, and touch to determine the quality of the milk.
Clot on Boiling Quality
This is another quick quality test to check the acidity of the milk. A small amount is boiled in a test tube and examined for signs of coagulation. If this is present, the milk has high acidity, and will not be able to withstand processing
This can be done by the PH method or by titration. It is done to check whether the milk is stored in ideal conditions for the growth of microorganisms. This can help with further processing, for example, in the case of yoghurt preparation.
PH Determination Test
This reveals the concentration of hydrogen ions in milk. It can be done via a calorimetric method, or via an electrometric method. The results of these tests will reveal how the milk will react upon further processing.
Inhibitor Quality Tests
These are carried out to check for antibiotics and drug residue in milk. Such antibiotics can be present when the cows are undergoing treatment. Thus, this is an important test to consider when dealing with fermented milk products.
A lactometer is a type of hydrometer. It works on the principle of fluid displacement to measure the specific gravity of milk. The addition of water to milk tends to decrease the specific gravity. Fat content also reduces the specific gravity since fat is the lighter portion.
Freezing Point Test
This is the most accurate test for milk adulteration by the addition of water. As milk and water have different freezing points, it is easy with this test to ascertain additional water content if it is present.
Dye Reduction Test
These tests will reveal the comparative activity of micro-organisms. This is done with the addition of a blue dye that reveals micro organic activity. The longer it takes for the colour to change, the lower the microbial load.
Butterfat Quality Test
This is done to ascertain the level of butterfat in milk and milk products. Valuation and further use of milk can depend on butterfat content. Hence this is an important test. Such detection is mainly done via a device known as a Gerber butyrometer.