Protecting your milk quality

31 March 2015

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Focusing on early intervention is the best tool you have to prevent thermoduric bacteria and residual demerits.

Thermoduric bacteria are heat-resistant bacteria that can survive pasteurisation. As they start to grow, thermoduric bacteria can reduce the shelf life and impact the flavour of a food product. Evidence of thermoduric bacteria can include:

  • Protein build-up on all interior surfaces of the plant and vat due to ineffective hot water temperature or infrequent alkaline washes
  • Aged deposits in areas that include the thread and button area of the claws, the inside lips of liners, deposit rings in the main milk line, airlines, the sanitary trap, perished seals and unions, milk cooler plates, the vat inlet valve, manhole door seal and inside of test bucket hoses
  • Perished and aged rubber-ware
  • Blocked or insufficient flow through jetters
  • Washline injectors not creating sufficient turbulence
  • Poor quality silage – look for the spore alert on your tanker docket.

Prevention is the best cure

Early intervention is the best tool you have to prevent thermoduric demerits. To avoid protein deposit build-up, the following things should be managed carefully:

  • Quantity of hot water – 10 litres per set of cups. For your vat, you should have a minimum of 2% of the vat capacity available for cleaning. If you are not recycling, you may need more than 2% (probably 4%) to achieve five minutes of contact time
  • Frequency of alkali washing – as a minimum this should be done twice a week. More often is better, particularly during the hot summer months. A chlorinated alkali is more effective, as the chlorine helps break down the fat and protein
  • Hot water temperature: 80-85°C. You should dispose of your alkali wash water to waste before the temperature gets below 55°C
  • Detergent concentration – as per the label
  • Contact time – a minimum of five minutes.


All farm dairy detergents must be thoroughly rinsed from the dairy plant prior to the next milking to reduce the risk from residual chemical contamination of your milk. It’s crucial to use teat sprays and cleaning chemicals correctly and always rinse off cleaning chemicals after use.

Maintaining and documenting the rinsing programme is good practice and makes sure everyone involved in the farm dairy is up-to-date on how the process works. Teat Spray tips – to reduce risks of a positive test result:

  • Use a teat spray mix at the lowest concentration rates according to the label (iodine-based or chlorhexidine-based products)
  • Add extra emollient during bad weather to maintain teat condition
  • Apply 15-20mls per cow per milking of the mixed product
  • Adjust automatic spray equipment to optimise teat spray application
  • Make sure farm staff are trained in correct mixing and application procedures.

Talk to your local Technical Sales Rep or visit your local store to make sure the product you are using is right for your farm and plant.

Remember to ask if the products are QAC and NPE free and identify any risks the products may pose to your operations. QAC and NPE are ingredients in some detergents and teat sprays, but they are being phased out of the industry. Contact your chemical supplier to determine if these ingredients are in the products you are using.

  • Call the Fonterra Suppliers Service team on 0800 65 65 88.
  • If you have received residual demerits, you can seek assistance from your Farm Dairy Assessor. They will do a free trace- back on-farm and check your set-up, including flow, turbulence, drainage and air purging.

Ask local Technical Sales Rep about our two handy factsheets available, covering Food Safety (Teat Sprays) and (Detergents).