Milk testing and quality control are a vital part of the milk processing industry. As milk is composed of 87% water, it is unfortunately prone to impurities and adulteration, whether in transport or by dodgy middlemen.
The high nutritive value of milk makes it an ideal medium for multiplication of bacteria. This can happen under sub-optimal production and storage at incorrect temperatures.
It's essential, then, that quality tests are carried out at various stages of transportation- Producer to the processor and finally to the consumer.
There are many such tests done at our milk and dairy products testing lab in Chennai, depending on the desired outcome. Here are some of them:
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.
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.
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.
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.
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.
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.
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.