In plants producing fluid milk or milk product, all equipment, including tanks or vats, pasteurizers and coolers homogenizers, pipe lines and pumps, should be of sanitary design.
There should be no threaded pipe. Joints should be of the clamp type that can be easily disassembled for cleaning and sanitizing.
All surfaces contacting milk or milk products shroud be readily accessible for cleaning and sanitizing regardless of whether they are to be cleaned in place (CIP) or disabled.
The suitability of equipment for cleaning and sanitizing and the frequency with which this is done are equally important.
Skim milk (0.5% fat) and low fat milk (0.5 – 2.0% fat) are produced from whole milk passed through a centrifuge at high speed, after the milk has been heated to 90 – 110 degree C (32.2 – 43.3 degree C), to remove the butterfat as cream.
These products are usually fortified with vitamins A and D prior to pasteurizing and cooling.
In some cases, sodium caseinate (a derivative of casein, the main protein in milk) is also added.
The cream from the centrifuge may be separated as approximately 40% butterfat (heavy cream), 30% butterfat (all purpose cream), or 20% butterfat (light cream).
The creams may higher in butterfat may also diluted with skim milk to provide the various fat densities or to produce a product known as half and half (about 10.5% butterfat).
Since cream tends to spoil more quickly than milk, during pasteurization it is given a more drastic heat treatment than that given to milk.
When batch pasteurization is used cream is heated to 150 – 155 degree F and held at this temperature for 30 min prior to cooling.
When HTST method is used, cream is heated to 166 – 175 degree F and held at this temperature for 15 sec prior to cooling.
Table cream light cream r half and half) is usually homogenized after pasteurization.
All cream, after pasteurization, should be quickly cooled to 35 degree F and containerized.
It should be held at 35 – 40 degree F until consumed or subjected to additional processing.
Processing of Milk – skim milk and low fat milk
