MINIMIZING CHLORATE LEVELS IN THE DAIRY CHAIN

MINIMIZING CHLORATE LEVELS IN THE DAIRY CHAIN

David Gleeson and Bernadette O’Brien

Chlorate residue in milk products is a new emerging food safety concern for the international dairy industry, including that of Ireland. Chlorate is formed as a by–product when chlorine, chlorine dioxide or hypochlorite is used for the disinfection of drinking water and cleaning of surfaces coming into contact with food. Chlorate levels in foods are a concern since chlorate is a competitive inhibitor of iodine uptake in the thyroid. Chlorate residues in food result mainly from the use of chlorinated water for food processing and from the disinfection of surfaces and food processing equipment coming into contact with food. There are two potential stages between milk production and consumption of dairy products where chlorate could accumulate, that is (i) the milk production process on the farm;(ii) the manufacturing process at plant level.

ENSURE MINIMAL CHLORATE CONTAMINATION OF MILK DURING THE MILK PRODUCTION PROCESS ON THE FARM – WHAT CAN FARMERS DO TO MINIMIZE THIS RISK?

Guidelines on best practise for use of cleaning products and protocols on–farm are available

on the Teagasc website

https://www.teagasc.ie/animals/dairy/milk-quality/chlorates/

SUMMARY OF KEY PRACTISES TO MINIMIZE CHLORATE CONTAMINATION OF MILK AT FARM LEVEL

Only use cleaning products within best before date and minimize storage period on the farm, that is, do not stock–pile chemicals
Store chemicals correctly out of direct sunlight and protect from frost
Choose products with the recommended level of chlorine (<3.5%)
Consider using alternate cleaning products to chlorine such as peracetic acid to sterilise a milking plant or bulk milk tank
Use adequate volumes of water to rinse cleaning chemicals from milking and cooling plant surfaces
Avoid teat disinfectants that contain chlorine dioxide/chloride (recently found to contain chlorate)
Use chlorine-free detergents for the cleaning of milking equipment

It has been shown that when the above precautions and recommendations are followed at the milk production stage, milk with sufficiently low levels of chlorate can be produced, such as would not be an issue in a subsequent product (assuming no further added chlorate during the process).Thus the process of conversion from milk to dairy product must also be examined.

Ensure minimal chlorate contamination during the conversion (drying) process of milk to powder-what can processors do to minimize this risk?

The two potentially significant sources of chlorate contamination within the processing plant are associated with (a) the water supply and (b) the use of products containing chlorine for cleaning routines within the plants. Processing plant personnel are currently actively investigating alternative options to chlorine use to optimize water quality such as the installation of chlorine gas systems.

Regarding the use of hypochlorite for cleaning routines within the processing plants, the same rules apply as to the use of such products for cleaning the milking machine and bulk tank on–farm. As outlined previously, the guidelines include the use of low chlorine products, regular purchase of cleaning products, reducing on–site storage time of products (to <50 days), correct conditions of storage, mixing strictly according to recommendations and ensuring sufficient rinsing after washing. Products with higher chlorine levels experience greater degradation resulting in earlier and increased development of chlorates. Processing plant personnel are currently ensuring such optimum conditions within the plants to ensure that chlorate development is absolutely minimized. There are also more long–term studies investigating possibilities such as the total removal of hypochlorite as a cleaning agent within the processing plants.

Teagasc as the national agricultural research and advisory body is currently engaged in various roles to give guidance to Industry on minimizing chlorate levels in milk and dairy products. Some activities include:

Measurement of chlorate levels on a number of farms that have different cleaning protocols in place to establish critical control points for chlorate development
Progressing the development of chlorate analysis methodology
Establishing a strategic plan to enable dairy industry processors to access fast and efficient chlorate analysis of milk and dairy products
Continuing research on chlorate development along the milk production line within the processing plant
Focusing on accumulation of new information and data and communication with the milk processing industry through workshops and Industry Milk Quality forum
Highlighting the dissemination of information to dairy farmers on minimizing milk chlorate levels through the Knowledge Transfer ‘Discussion group’ model
Developing chlorine-free cleaning protocols for cleaning milking equipment

In conclusion, it must be emphasized that any efforts to reduce chlorate residues during the milk production and dairy processing stages should ensure the absence of any negative impact on microbiological food safety.