Local scientists have devised an inventive way of identifying fake milk powder being sold on the international market as a New Zealand product.
Scientists from the University of Otago and GNS Science have conducted preliminary work that shows they can read the powder's geographical information.
The discovery is timely as a recent increase in the - often dangerous - imitation of dairy products in China is highlighting the need to protect the New Zealand brand.
The scientists found that the identification can be made through the fact that New Zealand rainfall has a "distinctive natural isotope signature" that passes from pasture into dairy products.
Troy Baisden, of GNS Science, said progress was made possible by having the ability to look at the hydrogen isotopes in rainfall from each storm during the growing season when the milk is produced.
"We work with monthly rainfall samples from all over New Zealand. We turn information derived from these samples into a map of daily rainfall chemistry using climate data from NIWA," Baisden said.
The milk powder research was carried out by Otago University PhD student Emad Ehtesham.
University of Otago associate professor Russell Frew said the new technique opened the possibility of verifying the origin of the milk component of mixtures like infant formula. It would also be ideal for products such as butter and cheese.
While the use of similar technology to verify the origin of whole foods was already well established, the advantage of the new research would link the milk data to the rainfall map - identifying the product's origin, Frew said.
Baisden said the work was very promising and was being developed further.
"We can also apply this type of science to other important problems, such as where insects and other biological material breaching New Zealand's biosecurity have come from."