The Ministry for Primary Industries says it is happy to continue discussions with Port Chalmers dairy farmer Merrall MacNeille over options for his milk.
Mr MacNeille was ordered to stop selling raw milk after a tuberculosis-positive heifer was discovered on his property, prompting widespread support from his customers.
He was keen to see a pilot programme set up involving him, the University of Otago and MPI in an attempt to keep selling his milk.
He had previously been supplying milk to the university for research on the pulsed electric field effect on enzyme inactivation, quality and bacteria count.
An MPI spokesman said yesterday it had not seen details of that research so could not comment on whether it might be an acceptable substitute for pasteurisation.
"In general, though, any alternative treatment to pasteurisation must be proven to achieve the same results as pasteurisation so it's safe for consumers,'' he said.
MPI had a process to recognise alternative treatments to pasteurisation that would require scientific evidence to show the proposed method was effective in making the milk safe for consumption.
Asked to comment why it would take six years before Mr MacNeille was able to sell his raw milk again, the spokesman said sometimes an animal might be infected for many years, without any obvious symptoms.
During that time, the infected animal could spread the disease to the rest of the herd before it began to show any signs of illness.
Because Mr MacNeille did not pasteurise his milk, which would kill potential Tb-causing pathogens, and he only sold raw milk, there was a risk his customers could consume Tb-infected milk.
To ensure that did not happen, MPI required his herd to be Tb-free for five years before raw milk could be sold again.
That was to reflect the slow course of Tb in cattle and the fact that it could take many years to eradicate the disease.
