Milk separation basics
Operation: For the cream separation, microbial reduction, fat standardisation and destruction of all pathogenic organisms in milk.
Requirements: Fot High Temperature Short Time (HTST) Pasteurization the temperature must not be less than 72.4 deg Celsius for 15 seconds and preferably 30 seconds.
Record keeping: It is a legal requirement in most countries to keep signed records of pasteurisation for at least 2 years.
Pre start checks: The operator should ensure sufficient utilities, are available such as; air (oil free, dry and filtered - moist air causes damage to instrumentation), steam, chilled water, soft water and milk are available. Ensure all plant and pipes are clean. Set up the routes to and from silos / milk and cream tanks.
Ensure the Heat Exchanger has a valid leak test certificate.
Start separator and bactofuge followed by the pasteuriser.
Settle the plant down on water, test the pasteuriser divert is operating at 72.4 degrees C.
Ensure Separator and Bactofuge de-sludge and partial de-sludge are operating correctly - critical for efficiency.
In an automated system the CIP age is automatically logged and if “Maximum CIP age” is exceeded the pasteurizer looses status “Clean” and is changed to status “Not clean”.
An initial sterilisation step (85c for 10 minutes) is carried out prior to introducing milk to the pasteuriser. The heating section must never be active if the flow is below “Minimum flow before start heating" as this may cause product burn on.
When introducing milk to the plant there is usually a water push from the silo to the pasteuriser balance tank and to the finished product tanks and this can be done manually or incorporated into an automatic system.
The balance tank level is normally level or float controlled. Operation: The volume, age, quality (Microbial, Fat and SNF and temperature) of milk in the storage tanks must be recorded by the operator at the start and then at frequent intervals. (automated systems will include this data)
The water in the lines is pushed to drain by a predetermined time / volume and ideally incorporating turbidity sensors.
The operator should complete the milk / whey pasteurization log sheet every hour and sign the divert check prior to commencing on product.
End of production: Production ends when the pre-set production volume is reached or the operator manually stops the production. The production ends with a water push to the receiving tanks.
During operation: Monitor how long the separator and Bactofuge take to recover their revolutions after a partial de-sludge and full desludge and correlate this data with the amperage and the fat in skim (if producing skimmed milk) and this will maximise the yield through ensuring optimum operation. A good separator will consistently give skim fat of 0.05% or less ensuring that the fat in powder is less than 1%. In some plants the separators feed the skimmed milk directly to the evaporator and this may give rise to unacceptable fluctuations in skim fat, using a large buffer skim silo ensures that any small lapses in efficiency due to too high a desludge time etc resulting in slugs of high fat skim are balanced out to give a consistent low fat result rather than dried as a high fat slug.
Bactofugation is the removal of microbes by centrifugal force.
Bactofugation can remove up to 99.8 % of all sporeforming bacteria but to get this efficiency will likely require double bactofugation.
The cream is separated prior to bactofugation and high temperature pasteurised before being returned to the milk if producing a standardised product or sent to the cream tanks if producing skimmed milk.
The latest bactofuges incorporate a recirculation loop for the bactofugate to minimise on product losses.
For more information or to discuss your requirements please contact us.