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Thermoduric Bacteria

13 April 2020
Type Media Article

DAIRY: Thermoduric Bacteria are heat resistant bacteria in milk that survive pasteurisation.

Thermoduric Bacteria are heat resistant bacteria in milk that survive pasteurisation. Milk processors test the milk for thermoduric bacteria as they have significant implications on the quality and type of products that can be produced from the milk. The most effective way to reduce the number of thermoduric bacteria in the entire process from the farm to the processor is to remove them at farm level.  This is done through good management, maintenance and cleaning of the milking plant and milk storage facilities.

We have produced a 3 part series of videos to show farmers how to reduce thermoduric bacteria.

  1. Clean yards and roadways: A clean approach to the parlour and collecting yard is very important as these bacteria are produced when dirt gets in contact with milk. Cow preparation before milking by pre spraying and dry wiping any dirty cow is important to help eliminate the risk.
  2. Milking Plant: There are many parts of the milking parlour that can hold Thermoduric Bacteria. Ensure the jetters and trays are clean and check for any cracks in the rubberware. All rubber tubes should be replaced twice per year. Silicon tubing should be considered as it has a much longer life span as it is much more resistant to wear and tear. The glass claw piece should be clean and smooth and the seals clear of contaminants. The dump bucket can be a source of thermoduric bacteria if it’s not cleaned properly after use as thermoduric bacteria are spore forming and can travel in the air.
  3. Washing Cycle: You need to ensure the washing system is working correctly and that there is enough pulses in the wave purge system. The target is 12-15 pulses per wash cycle i.e. in a 10 min wash there should be 1 pulse every 40 seconds.
  4. Wash Trough Capacity: Measure the capacity of your wash trough to ensure it holds the correct volume of water for the number of units in your parlour. Every unit requires 14L of water for both first and final rinse. 9L/unit is required for the detergent wash.
  5. Water Volumes: During the wash cycle the receiving jar should never be more than 1/3 full, otherwise this indicates that the plant is not being washed correctly. The connector pipe between the receiving jar and sanitary trap should be washed twice daily if is not part of the wash cycle. Separate dump lines should also be washed twice daily, even when not in use. Ensure the vacuum line is washed at every service. When doing a hot wash the water needs to be 75-80°C but more importantly water should be >50°C when exiting the plant. Below this temperature you can get a build-up of fat and protein residues in the plant.
  6. Milk Sock/Filter: The milk sock/filter should always be in place during the rinse and wash cycles to avoid contaminates entering the plate cooler. Always remember to turn off the plate cooler during the wash cycle as not to reduce the temperature of the hot water.
  7. Bulk Tank: When washing the bulk tank use water <70°C. Ensure all the tank is cleaned correctly. Use a detergent and descale wash. Milk should be cooled at 3°C.

If these steps are followed thermoduric bacteria should be reduced at farm level.   Contact your local Teagasc dairy advisor or milk quality advisor for more detailed advice.