11 Aug 2016

'Milk on a disc'

From Our Changing World, 9:06 pm on 11 August 2016

Canny consumers may soon be able to buy their milk the way they do their wine. A handy device being developed at the University of Auckland aims to give buyers full knowledge of the age, origin and flavour of their milk, as well as its nutritional content.

 ‘Milk-on-a-Disc’ is a project by Professor David Williams and Associate Professor Cather Simpson, who are both at the MacDiarmid Institute. It uses lasers, spinning transparent discs and a spectrometer to quickly and accurately analyse the properties of milk samples.

“We call it ‘value-added spectroscopy’,” says Simpson. “We use the spinning discs to move the fluids around, and use the spectroscopy to do the analysis.”

An example of a transparent disc, with carved channels and wells visible, used to analyse milk samples.

An example of a disc used to analyse milk samples. Photo: University of Auckland

An image of Associate Professor Cather Simpson.

Associate Professor Cather Simpson. Photo: ScienceLens

The transparent discs have channels and wells carved into them which mix the milk samples with various reagents. The discs are then spun at high speed to separate and measure different components within the milk.

“As far as the user is concerned,” says Williams, “It’s just like playing a CD on your music player.”

The discs allow the team to test the protein and fat content of milk, as well as the health and pregnancy status of each cow. When they need to run other kinds of tests, they simply swap discs.

“For us it’s like changing from Classical to Pop. You just change the disc in your reader.”

Professor David Williams.

Professor David Williams. Photo: University of Auckland

The eventual aim is for farmers to be able to individually test every cow in their herd at every milking and for the results to be available straight away. This information can then be used to adjust the care of the cow, as well as determine the best use of the milk, a process Simpson and Williams call ‘point of cow diagnostics’.

“Different types of milk are better for cheese or yoghurt or drinking or for turning into milk powder,” says Simpson. “So we’ll be looking at those things.”

The team can already identify milk from different parts of the country and also accurately distinguish our milk from that produced overseas. New Zealand cows are largely pasture-fed and as a result their milk has different qualities to barn-raised, grain-fed foreign cows. It’s hoped that Milk-on-a-Disc will be able to give very accurate information about those differences and so provide a marketable point of difference for our milk.

Consumers may also soon be able to choose their milk based upon where it came from by applying an almost terroir idea to dairy. One consumer might prefer the dryer, mineral quality of Canterbury milk to drink, while another chooses fattier, richer milk from, say, Taranaki or Southland to feed their baby.

The device could also help people concerned with food safety. As reported by RNZ, in 2008 four children in China died and at least 63,000 needed medical treatment for kidney complaints after drinking milk formula contaminated with melamine.

Melamine, a chemical compound used in the manufacture of plastics, was added to baby formula to artificially boost its protein levels. Sanlu, the dairy company responsible, was partly owned by Fonterra. By increasing the accuracy of the information available to consumers, Milk on a Disc will hopefully inspire greater confidence in our milk products. 

There’s also, potentially, an environmental payoff. Better information on milk quality, animal health and best use of the milk should lead to an emphasis on quality over quantity when it comes to herd size, reducing the impact of dairy cows upon the land.

Using funding from central government, Simpson and Williams have formed a company called Orbis Diagnostics Limited to develop the project further. They expect to have a small, hand-held unit available for sale within a year.

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