“Dairy companies have trade, moral and legal obligation to maintain high hygienic standards.”
Dairy companies are obliged to maintain high hygienic standards and ensure that safe food reaches to the plates of the consumer. It is necessary for a milk processing plant to have a proper CIP system in place.
What kind of dirt is it that is present on the surfaces of dairy equipment and needs to be removed?
Heated Surfaces: When milk is heated above 60 °C, milk fouling starts to form. There is a deposit of calcium (and magnesium) phosphates, proteins, fat, etc. The deposits stick tight to the surfaces, and after runs of more than eight hours, a change of color from whitish to brownish can also be observed.
Cold Surfaces: A film of milk adheres to the walls of pipelines, pumps, tanks, etc. (‘cold’ surfaces). When a system is emptied, cleaning should start as soon as possible, or otherwise this film will dry out and be harder to remove.
Stages in CIP
The cleaning cycle in dairy comprises of the following stages:
I. Recovery of product residues by scrapping, drainage, and expulsion with water or compressed air
- This will minimize product losses, facilitate cleaning and reduce the load on the sewage system.
II. Pre-rinsing with water to remove loose dirt
- Milk fat residues are more easily flushed out if the pre-rinsing water is warm, but the temperature should not exceed 55 degrees Celsius to avoid coagulation of protein.
- Pre-rinsing must continue until the water leaving the system is clear.
“Product recovery is crucial step in the CIP. It is done to minimize product losses, facilitate cleaning and reduce the load on the sewage system.”
III. Cleaning with detergent
- The heated surfaces are usually washed off with alkaline and acid detergents with intermediate water flushing, whereas cold surfaces are cleaned with alkalis and only occasionally with an acid solution.
- To ensure that all the dirt is removed, a surfactant may be added to lower the surface tension of the liquid and to obtain good contact between the alkaline detergent solution (e.g caustic soda) and the film of the dirt.
IV. Rinsing with clean water
- After cleaning with detergent, the surfaces must be flushed with water long enough to remove all traces of the detergent.
V. Disinfection by heating or chemical agents followed by a final rinse
- Dairy equipment can be disinfected in the following ways:
1. Thermal disinfection (boiling water, hot water, steam)
2. Chemical disinfection (chlorine, acids, iodophors, hydrogen peroxide, etc.)
- CIP results are usually checked by cultivating coliform bacteria through swab test; the criterion is less than one coli bacterium per 100 cm2 of the checked surface. The result is unacceptable if the count is higher.
- All products must be checked for bacteriological quality in their packages to obtain full quality control of the manufacturing process.
For Effective CIP in dairy industry,
1. Equipment must be connected in cleaning circuit.
2. All the surfaces that are to be washed must be accessible to detergents.
3. The circuit must allow proper and efficient drainage.