Module 8. Cleaning and sanitization

Lesson 38

38.1 Cleaning-In-Place (CIP) Systems

The manual cleaning of dairy equipments done by people equipped with brushes and cleaning solutions is a laborious and ineffective practice. Cleaning-in-place or CIP refers to cleaning of all sanitary pipelines by circulation. It may be defined as circulation of cleaning liquids through machines and other equipments in cleaning circuits without dismantling the equipment. The high velocity flow of liquid over equipment surface generates mechanical scrubbing effect that dislodges deposits from vessels and pipelines. The majority of cleaning and sterilizing liquids used in CIP systems are alkali or acid based. Automated CIP systems allow accurate dosing of the concentrated cleaning agent, normally into water, to give a low strength solution suitable for cleaning process plant. This solution is used within the plant to clean and sometimes, sterilize the system prior to the next production run. CIP can be carried out with automated or manual systems.

38.1.1 Single pass systems of CIP

New cleaning solution is introduced to the plant to be cleaned for each cleaning cycle and then disposed to drain. It would start, in most cases, with a pre-rinse to remove as much soil as possible, followed by the detergent cleaning and a final rinse.

38.1.2 Recirculation system of CIP

The cleaning solutions are mixed in external tanks and introduced into the plant to be cleaned. They are recirculated and topped up as required until the cleaning cycle is complete. It is normal to carry out a final rinse after the detergent rinse. Recirculation systems need more initial investment, bur use less water and cleaning detergents.

38.2 Cleaning Cycle

The sequence of events that are carried out in a dairy through CIP program for different circuits is as follows:

1. Recovery of product residue by drainage

2. Expulsion of non-retrievable residue with water or compressed air

3. Warm water (50-60°C) rinse for 10 min

4. Circulation of alkaline detergent (0.5-1.5% solution) at 75°C for 30 min

5. Warm water (50°C) rinse for 5-8 min

6. Circulation of acidic detergent (0.5-1.0% solution) at 75°C for 20 min

7. Warm water (50°C) rinse for 5-8 min

8. Thermal disinfection (90-95°C) and cooling for 10 min or chemical disinfection with a suitable sanitizer

Soda ash, caustic soda, sodium metasilicate or complex phosphates and a non-foaming surfactant may constitute an alkaline detergent for CIP cleaning. Sufficient hypochlorite solution to produce 25 to 50 ppm available chlorine may be added to help remove milk stones from metal surfaces. Acid solution may be used every 4 to 7 days in cold milk lines, while acid treatment should be a daily chore in cleaning hot milk lines.

38.3 CIP Systems

Generally the CIP station consists of equipment for storage of different cleaning fluids and their distribution to various CIP circuits. Small dairy plants with short communication lines use centralized system by a network of pipes to all CIP circuits in the dairy. De-centralized CIP system (satellite system) is normally prevalent in large dairies where the distance between CIP stations and secondary CIP circuits are extremely large.

38.4 Advantages of CIP

The major advantages of implementing CIP are:

1. Guaranteed and repeatable quality assurance

2. Provision of full data logging for quality assurance requirements

3. Reduction in cleaning costs by recycling cleaning solutions

4. Possibility to clean inaccessible areas on equipment

5. Better safety to operators because hazardous cleaning materials are not handled

6. Reduction in time between two production runs. Safety-operators are not required to enter the plant to clean it.

7. Reduction in labour requirements

8. More effective use and control of cleaning materials

9. Reduction in water consumption

38.5 Sterilization-In-Place (SIP)

Sterilization-in-place (SIP) refers to a continuous commercial scale operation, where essential units can be sterilized. They are very sophisticated in terms of design, installation and operation and needs highly qualified manpower. In addition, the process equipment, pipe work and steam supply equipment must meet preset specifications for materials and for pressure and temperature resistance. The steam has to be extra pure and must pass through a micro-filter before use. The steam quality and cleanliness must be maintained by the use of pressure-grade stainless steel or Teflon®-lined tubing and appropriately constructed pressure control, shut-off valves and pressure gauges.

38.6 SIP Process

Steam under pressure is passed through the entire installation. Air is vented out through vents in the piping or on the equipment. The vents are protected by bacterial filters and remain closed after a suitable period of steaming to allow the steam pressure to build up to a predetermined level. Pressure is maintained for the length of the required period, after which the steam is released through a condenser. The recorded pressure is enough to and must result in achieving the desired time-temperature combination for destruction of all contaminants, as indicated by temperature sensors. The installation is inspected and revalidated at regular intervals to ensure efficiency of the system.

Suggested Readings

Anon. 1992. Advances in detergent and cleaning-in-place system.
Anon. 1994. Revolutionary Cleaning Technology. Dairy Foods 95 (9) 110-111
Britz, T.J. and Robinson, R.K. 2008. Advanced Dairy Science and Technology. Blackwell Publishing Ltd., UK.
Dairy Processing Handbook. 2000. Alfa-Laval AB, Dairy and Food Egg. Division, Sweden. Chapter 21.
Hall, H.S. Tuszynski, W.B. 1984. Maintenance Systems for the Dairy Plant. FAO Animal Production and Health Paper 45. FAO Animal Production and Health Division. Food and Agriculture Organization of the United Nations. Rome.
Marriott, N.G. and Gravani, R.B. 2006. Principles of Food Sanitation. Fifth Edn. Food Science Text Series. Springer Publications. USA.
Last modified: Wednesday, 10 October 2012, 5:22 AM