Due to more stringent product specifications, particularly in relation to residues such as trichloromethane (TCM) and chlorates, it is becoming increasing difficult to achieve end-product specifications when chlorine-based products are used as part of the milking equipment cleaning protocols.
Products that contain chlorine are generally referred to as detergent sterilisers, which contain varying levels of sodium hydroxide (caustic soda) and sodium hypochlorite (chlorine).
Detergent sterilisers tend to be liquid-based products and are widely used in automatic wash units in milking parlours and bulk tanks.
Traditionally, powder-based “cold wash” cleaning protocols have been used by dairy farmers and they have proven to be satisfactory from a microbiological point of view.
The use of powder-based cleaning products is most suitable when manual washing is normally used and for small to medium plants (five to 15 units), without auxiliary equipment like milk meters.
It is less satisfactory where automatic systems are in place for cleaning both machine and bulk milk tank.
The vast majority but not all powder products contain no chlorine. Powder products contain much higher levels of caustic (76%) compared to most liquid caustic products (21 to 29%).
This is why these powder products can be used cold or hot compared to liquid products which contain the lower caustic levels and should be used with hot water.
Many milk processors are now insisting on chlorine-free wash routines. Most of these routines involve doing more hot washes and doing more acid washes.
Steps
If changing from chlorine-based detergent steriliser products to non-chlorine (caustic) products, it is critical that re-calibration of automatic detergent dosing systems for both machine and bulk milk tank is carried out.
Take-up rates may be lower for products that do not contain chlorine and that have slightly higher caustic content than products previously used.
To check if the correct quantity of product is being used, the following steps should be taken:
Sourcing advice from chemical product distributors is also an important consideration when changing products for non-chlorine cleaning as product technical personnel are best placed to advise on their own product range and routines.
Potential risks
There are a number of other potential risks of residues from farm dairy tasks, such as dipping clusters between individual cow milkings and disinfection of own water well source using hypochlorite products.
Peracetic acid-based products are available which can be used as a direct replacement for hypochlorite for these tasks.
It has to be acknowledged that mains water supplies do contain added hypochlorite but at measured levels which may contain a level of chlorates.
Chlorine dioxide-based teat disinfectants are known to be effective against mastitis-causing bacteria.
However, they also contain a level of chlorates which may impact on milk residues unless good teat preparation is carried out prior to milking.