Milk cooling is a hot topic in the dairy industry.
“And for good reason,” said Geoff Raven, CEO of Dairysafe. “Milk is an ideal breeding ground for bacteria and the sooner milk is cooled, the less likelihood there is of the bacteria multiplying.”
Milk must be chilled to 5°C or less within 3.5 hours from the start of milking, as stated in Food Standards Australia New Zealand (FSANZ) Standard 4.3.4.
“Each dairy’s Food Safety Program identifies how milk chilling capability is checked and the frequency of checks. Records are also kept demonstrating that these requirements are in place and monitored,” Geoff said.
“The Food Safety Program also has records that show milk is maintained at 5°C or less after the primary chilling is completed.
“And the Food Safety Program includes how thermometers are checked for accuracy, how frequently the checks occur, and the records to demonstrate the cooling requirements have been achieved.”
Geoff said it was important for farmers to have their milk cooling systems routinely checked by trained service personnel.
Milk cooling variations
Food Standards Australia New Zealand (FSANZ) guidelines allow manufacturers to collect milk at times and temperatures other than 5°C after 3.5 hours, provided the manufacturer undertakes a risk assessment of the milk and processes it accordingly to ensure its safety.
If milk is collected above 5˚C (for example, if the tanker arrives before chilling is complete), it is the dairy processor’s responsibility to ensure that temperature control procedures are validated and demonstrate equivalent control of food safety risks.
Approval of the validated temperature/time parameters is required prior to milk being collected under these arrangements, after which standard operating procedures can be amended to describe the approved process.
Guidance on validating the time/temperature parameters can be found on the Commonwealth Department of Agriculture and Water Resources website at http://www.agriculture.gov.au/export/controlled-goods/dairy/registered-establishment/raw-milk-temperatures and also on Dairy Australia’s Manufacturing Resource Centre website at https://manufacturing.dairyaustralia.com.au/resource-library/decision-tools.
Ten point plan
The following TEN POINT PLAN developed by Dairysafe highlights key components to consistently produce clean quality milk.
“Given a recent example of high bacterial count in milk on farm it’s opportune to look at a ten point plan to consistently produce clean quality milk,” Geoff said.
- The milk price paid by the majority of dairy processors to dairy farmers is based on milk quality parameters, so it makes sense to produce consistent ‘premium’ quality milk to maximise returns.
- Bacteria have the ability to breakdown lactose, protein (casein) and fat – the major nutrients contained in milk. Pasteurisation destroys pathogenic organisms but does not eliminate bacteria which may cause spoilage, and which also reduce yields and affect product shelf life. This impacts efficiency in milk production and in processing.
- Milk from the udder of a healthy cow has a very low bacterial population. Bacterial contamination usually originates from contaminated surfaces in or on milking machines and during milk storage – elevated microbiological results will remain until the source of the contamination has been removed.
- Milk is an ideal breeding ground for bacteria. The sooner milk is cooled, the less likelihood there is of the bacteria multiplying.
- Knowing your milk cooling rate capability is critical in controlling the safety and quality of your product.
- A consistent and effective wash procedure for the milking machine, milk vat & other milking equipment is the best way to achieve good quality milk – verified by consistent low micro results.
- Regular monitoring of water temperature & dosage rates for the detergent wash (acid & alkaline chemicals) – to determine that the process meets the recommendations for the chemicals in use – results in more effective & efficient cleaning.
- There are always parts of a milking machine or milk vat that may prove difficult to keep clean – at the end of a milk line, the agitator in a milk vat, or the plate cooler.
- A pro- active approach to monitoring cleanliness of milking machine and vat components may identify areas that may require regular manual cleaning.
- Don’t wait to receive a high bacteria result to investigate.
The milk cooling rate controls spoilage bacteria known as Pseudomonads, which are very good at spoiling protein foods by breaking down protein into shorter chain molecules and causing bitter tastes and eventually, off odours.
They get their nutrition by sending enzymes outside their body to break down the big milk proteins into bite-sized chunks that they can bring back through the cell wall and eat.
These are called extracellular enzymes and they are very heat stable, so persist through dairying processes such as pasteurisation.
These enzymes cause gelling of UHT milks, reduced casein yield for cheesemaking, and shorten the shelf life of pasteurised milk.
Dairysafe Early Milk Collection Index (EMCI) webinar
A Dairysafe webinar on the application of the Early Milk Collection Index EMCI, held in October 2020, had around 20 participants representing most major processors. Professor Tom Ross of the University of Tasmania delivered the webinar via Zoom.
Feedback indicated the webinar was rated highly and met the expectations of participants. Participants said the workshop provided sufficient background information to enable better understanding of EMCI, particularly the microbiological aspects, and it answered many of the questions regarding the limits of the EMCI tool.
The EMCI was initially designed to quickly and simply determine whether milk picked up early at above 5 degrees C will meet the Food Standards Code and/or EU requirements (Tool #1). Version 2 (Tool #2) of the EMCI is more complex, allowing additional inputs to be used in a detailed risk assessment for milk falling above the milk cooling curve.
The EMCI webinar is now available on the Dairysafe website at https://dairy-safe.com.au/food-safety-toolbox/
The focus of Dairysafe’s webinar/workshop program will now turn to HACCP and also Labelling, ID and Traceability.