How Do Leading Dairy Plants Prevent Recontamination of Milk?

You all have heard about the contamination of milk, but, by seeing the title, you might wonder what is “recontamination”. Leading dairy plants through its modern and state-of-the-art technical infrastructure take all necessary steps to ensure the purity of packaged milk and make it safe for human consumption. Steps to prevent decontamination of milk in the process ensure that you have the safest milk in your glass. 

Recontamination of milk occurs when milk is contaminated after pasteurization. Pasteurization destroys many microorganisms in milk, but it doesn’t destroy organisms that grow slowly or produce spores. Some bacteria can survive in pasteurization and recontaminate milk. Furthermore, if milk comes into contact with contaminated equipment, surfaces, or improperly sanitized containers after pasteurization, it can become recontaminated.

Milk and dairy processing plants are extra cautious to take necessary steps to prevent this hazard because, recontamination of milk can: 

• Limit the quality and shelf life of pasteurized milk
• Cause off-odors and flavors
• Cause visible changes in color or texture
• Pose a risk to the consumer

Prevention of recontamination of pasteurized milk is of major importance in the production of pasteurized milk that is both safe and of satisfactory shelf-life. Some control measures against contamination of milk with specific pathogens are modern equipment such as plate pasteurizers and filling machines that can minimize the possibility of contamination of pasteurized products. 

However, to deliver you consumption-safe dairy products and prevent recontamination of milk, some of the important precautions taken by leading milk and dairy processing plants like Dollon’s are as follows:

Contamination Source: Plant Environment

Pathway

Usually indirect via contamination of equipment.  Also possible via personnel and packaging.  

Precautions

1. Eliminate contamination of pasteurized milk side of regenerator of pasteurizer by leakage etc. from raw milk and coolant sides.
2. Correct environmental sanitation.

Contamination Source: Equipment

Pathway: Direct as follows

• Contamination of equipment by raw milk, and coolant leaked in the regenerator or cooling section, respectively, due to gasket failure, splits or pins, hones in pasteurizer plates, and improper pipelines/valves arrangement. 
• Contamination by stagnant milk or milk deposits at dead ends, valves, gaskets, etc. 
• Inadequate CIP and manual cleaning, where necessary, such as valves and sampling cocks; development of biofilms and colonization of milk contact surfaces by micro-organisms.  

Precautions

1. Vent interspace between seals to the atmosphere to provide an immediate visual indication of gasket failure.
2. Maintain a positive pressure balance, at least 0.5 bar (0.5 kg/sq. cm), between pasteurized milk and raw milk in the regeneration section.
3. Ensure correct positioning of the flow diverter and associated pipework to avoid contamination of pasteurized milk when forward flow resumes after diversion. 
4. Testing for corrosion cracks and pinholes by a lithium injection test twice a year.
5. Visual inspection every day for back pressure control.
6. Milk contact surfaces of pasteurizing plants should be fabricated from high-grade stainless steel and polished by electro-polishing to avoid crevices and consequent entrapment of soil.  Welds, joins, etc. should be finished to the highest possible standard.
7. Follow suitable cleaning and sanitization programs for pasteurizers, storage tanks, silos, etc.
8. Extra cleaning in case of more than 3 days between processing runs.
9. Dismantling and inspection every 5 years.

Contamination Source: Raw Milk

Pathway

• Direct or indirect via contamination of plant environment, passive transfer or hands of personnel, etc.

Precautions

1. Correct design of equipment and related pipework.
2. Correct operation and maintenance of pasteurizer. 
3. Correct plant layout. 
4. Control of personnel movement and avoidance of ‘hands-on’ operations involving milk or milk contact surfaces.

Contamination Source: Personnel

Pathway

• Direct due to personnel suffering clinical illness or being a chronic carrier of pathogens.
• Indirect due to the introduction of plant contamination from the outside environment.

Precautions

1. Follow appropriate medical and exclusion policies.
2. Ensure good personal hygiene and correct use of protective clothing and footwear. 
3. Prohibit raw produce such as eggs being brought into the plant by farmers or workers for sale to fellow workers.

Contamination Source: Packaging

Route

• Failure to adequately sterilize the packaging film in the packaging machine.
• Contamination of packaging from plant environment, etc.

Precautions

1. Ensure the correct functioning of a required ultra-violet light system so that the packaging film is properly sterilized.
2. Protect packaging from contamination.
3. Cleaning and disinfection of packaging machine and buffer storage tanks according to confirmed procedures. Avoid rinsing with water during filling.
4. Disinfection of specific machine parts by alcohol spraying.
5. Adherence to hygienic conditions during filling.
6. Follow conformed procedures regarding start, stop, and interruptions.

Furthermore, milk processing plants ensure that there is no cross-connection between raw milk equipment and pipeline with that of the pasteurized one. CIP systems of leading dairy production plants are also installed and maintained separately without any cross-connection with each other to prevent recontamination of milk. 

All of so much – just to deliver consumers the safest and most tasty milk and dairy products they love!