The removal of chlorine-based detergents was the primary focus of the recent Teagasc milk quality workshop.
In its use in detergents, chlorine has been identified as a cause of two different residues in milk – trichloromethane (TCM) and chlorate.
Current targets for TCM and chlorate in milk are 0.00124mg/kg and 0.01mg/kg, respectively.
Following very significant efforts by milk suppliers, milk quality advisory personnel and testing of milk (more than 35,000 samples in 2020), the target for TCM levels in butter has been achieved and are now being maintained.
Chlorate, the control of which is important in milk powder for use as an ingredient in infant milk formula, is currently within specification and this is assisted by the removal of chlorine from washing protocols on farm and in factories.
Vigilance is also required with regard to water quality and chlorine treatment of water
However, removal of chlorine-based detergents needs to be done in conjunction with microbiological studies, because any efforts to reduce chlorate residues must ensure the absence of any negative impact on the microbial quality of milk.
Vigilance is also required with regard to water quality and chlorine treatment of water, as well as ensuring that no alternative residues arise due to the inclusion of new detergent products.
Research at Teagasc has shown that chlorine-free cleaning methods are effective for milking machines and bulk tanks, when used correctly and, critically, with sufficient hot water.
When the farmer transitions to non-chlorine-based cleaning protocols, it is crucial that a number of measures are put in place as follows:
To understand if new chlorine-free-based cleaning protocols cause changes in the bacterial population in milk, bulk tank milk from 57 commercial farms from four milk processors across Ireland were sampled in three months (April, August and November).
The bacteria in these samples were analysed using state-of-the-art DNA-based approaches.
Results showed that the raw milk from farms that used chlorine for their cleaning and those that used chlorine-free agents had similar microbial compositions, suggesting that chlorine-free approaches did not negatively affect the microbiological quality of raw milk.
Samples from different locations were also found to have distinctly different microbial profiles
Similarly, no differences in microbial composition were found when comparing raw milk with chlorine residue detected and those with no chlorine residues detected.
As was expected, samples taken in November were found to have a different microbial profile than the other two months, with higher proportions of cow-related bacteria present, which reveals that farming practices in winter affect the microbial composition of raw milk.
Samples from different locations were also found to have distinctly different microbial profiles.
This study provides evidence that chlorine-free cleaning methods are comparable with chlorine cleaning, and seasonality and geography had a greater and more significant impact on the microbial composition of raw milk samples.
The challenges experienced by the farmer in transitioning to chlorine-free detergents are also experienced by processors.
Chlorine-free cleaning is now used in CIP systems in processing plants.
The focus in both cases is on the cleaning of plant and equipment and the overall usage of hot water as part of the cleaning operation.
The challenge for the primary producer and the manufacturer is one of control: control of water disinfection, control of the cleaning operation and verifying that both processes are working effectively. This will ensure full compliance and efficient operation.
Both can be achieved by ensuring that plant and equipment is fit for purpose, personnel are adequately trained and support is availed of from chemical and equipment suppliers.
This is essential for the purpose of monitoring performance, introducing the latest technical innovations, chemical developments and optimisation of the entire process.
The correct cleaning of equipment is a prerequisite, be it a milking parlour or a processing plant.
It is critical that the cleaning process provides a plant that is fit for purpose and ready to handle a high-quality product on its next production without affecting that quality in any way.