Processing of Milk - Clarification,Pasteurization

milk processing
clarification
pasteurization
homogenization

1. PROCESSING OF MILK B.Ameena Beebi Assistant Professor of Home Science V V Vanniaperumal College for Women Virudhunagar

2. PROCESSING Processing helps to produce milk that has initial low bacterial count,good flavour and satisfactory keeping qualities. There are three operations of milk processing and they are clarification , pasteurisation and homogenation .

3. CLARIFICATION Milk is passed through a centrifugal clarifier. The speed is adjusted in such way that cream is not separated but dirt, filth and cells from the udder and some bacteria are removed. The clarified milk is ready for pasteurisation.

4. PASTEURISATION Pasteurisation derives its name from the French scientist Louis Pasteur. Heating of certain liquids to a high temperature which improved their keeping quality. Pasteurisation is the heating of milk to a temperature which destroys organisms responsible for tuberculosis and fever and other microbes present in the product without affecting the composition and properties of product. It also inactivates some of the natural enzymes like lipase.

5. METHODS OF PASTEURISATION Holding or Batch system High Temperature Short Time Method (HTST)or the continuous system Ulta High Temperature System (UHTS).

6. HOLDING OR BATCH SYSTEM The holding system consists in bringing the milk or cream to a temperature usually 65◦c and holding at that point for at least 30 minutes followed by rapid cooling. A higher temperature is sometimes used in which case the time of holding may be shortened. In most recent years it is found that the organisms causing Q fever, coxiella burnetti is more resistant than tuberculosis organism and required a treatment of 63◦c for 30 minutes to ensure its destruction.

7. HIGH TEMPERATURE SHORT TIME METHOD The machine used are so constructed as to make possible continuous operation and for this reason of the system is called as flash pasteuriser. This system depends upon the raising of the temperature of the milk atleast 72◦c for 15 minutes as it passes through machine and quick cooling. This does not impart cooking flavour and cream line is not affected.

8. ULTRA HIGH TEMPERATURE SYSTEM This UHTSsystem results in a complete pasteurisation of milk. In this method the milk is held for 3 seconds at 93.4◦c or for one second at 149.5◦c. After pasteurisation the milk is cooled rapidly to 7◦c or lower. Pasteurised milk is not sterile. It must be quickly cooled following pasteurisation to prevent multiplication of surviving bacteria.

9. HOMOGENISATION The process of making a stable emulsion of milk fat and milk serum by mechanical treatment and rendering the mixture homogeneous is homogenisation. Milk and cream have fat globules vary from 0.1 to 20µm in diameter. Homogenised milk fat globules size is 2µm. The fat globules have a tendency to gather into clumps. Homogenisation is done before pasteurisation.

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