Milk and Milk Products Technology

Cream separator

PREPARATION OF CREAM AND ANALYSIS

• Cream may be defined as that portion of milk in to which milk fat has been gathered or which is rich in fat. According to PFA rules (1976) cream, excluding sterilised cream is the product of cow or buffalo milk or combination there of which contains not less than 25 per cent milk fat. Cream is rich in fat soluble vitamins A,D,E & K. Milk can be converted into cream and skim milk by using cream separator. Cream can be broadly classified as Market cream (which is used for direct consumption) or Manufacturing cream (which is used for the manufacture of dairy products). Based on the fat content it may be Light/coffee cream (20-25 per cent), whipping cream (30-40 per cent) and heavy/plastic cream (65-85 per cent).

Centrifugal cream separator

Parts of open-bowl type clarifier / cream separator

• Supply can
• Faucet
• Regulating chamber with float
• Cream or skim milk screw
• Bowl shell
• Milk distributor
• Cream spout
• Skim milk spout
• Top disc
• Discs with perforated holes and button like structures (on the upper surface of cone or inverted cup shaped disc for allowing milk to flow in between and move upwards. The bottom disc will have buttons on both sides)
• Bowel nut with lock holes for the locking handle to fix in
• Rubber ring
• Spindle
• Set of Gears
• Crank handle, etc

(Draw a neat diagram of lab model cream separator and label the parts)

Cream separation

• When milk is allowed to enter the separator at controlled speed by the float, milk flows down through the central inlet of the axis and is uniformly distributed by the milk distributor. Milk will be subjected to tremendous force and moves towards the periphery as well as rises upwards through the holes in the disc. Denser skim milk towards periphery and lighter cream at the centre builds up as two columns separated by thin zone of diffusing composition. At the level with the upper disc, skim milk outlet is located and skim milk is collected through skim milk spout. The cream still moves upwards and drains off through the cream outlet cum screw in to cream spout. The lightest column of cream rich in fat will be close to the axis of rotation and further proceeds outward with reduced fat content. Thus, moving the cream screw towards the centre will allow cream with high fat content or thicker cream to flow out and vice versa. The fat loss in skim milk increases with collection of high fat cream. Thus based on the purpose; the position of the cream screw can be adjusted.