AgResearch test narrowed down botulinum strain in whey, since disproved

AgResearch, a Crown Research Institute, played a key role in identifying bacteria in batches of Fonterra Cooperative Group whey protein concentrate as a strain that could cause botulism, according to an initial report by the Ministry for Primary Industries.

The test result has since been contradicted by a barrage of secondary tests commissioned by MPI and released today, which showed the bacteria to be clostridium sporogenes, which isn't typically a food safety risk, not clostridium botulinum.

"We sought additional testing at both local and international laboratories, seeking the most robust results we could get. Scientists used a range of methods - all came back negative for clostridium botulinum," MPI acting director-general Scott Gallacher said in a statement. A total of 195 tests were conducted in the US and New Zealand.

The MPI report says that initial tests by Fonterra identified the bacteria were either C. sporogenes or C. botulinum though further testing was needed to narrow down the strain.

"On 26 June, Fonterra formally engaged AgResearch to undertake a mouse bioassay test," the report says. "On 31 July, AgResearch reported to Fonterra the mouse bioassay results for all three isolates from the WPC80 as presumptively confirmed positive for C. botulinum."

MPI said it considered that the AgResearch diagnosis needed to be validated, using independent, internationally recognised laboratories and test methods.

The news that the Fonterra whey protein concentrate posed no botulism risk was welcomed by both Fonterra and by the Food & Grocery Council.

"From a food industry perspective Fonterra did exactly the right thing - they put public safety first, council chief executive Katherine Rich said in a statement.

"Faced with positive test results from Crown Research Institute AgResearch, Fonterra had no choice - morally, ethically, or commercially - but to issue a full recall of the batches in question to eliminate all possibility of risk to consumers," she said.

"In the coming days the science which underpinned that research may come under scrutiny," she said.

MPI said a failure of hygiene during processing "remains a concern for customers incorporating WPC into their products." Clostridium sporogenes at elevated levels can be associated with food spoilage.

The ministry's "Whey Protein Concentrate Incident Tracing and Verification Report" concludes that the contamination affected only the last three days of the 2012 season WPC80 manufacture on May 17, 18 and 22, 2012.

Investigations by ministry officials "strongly suggest" no other ingredients or products were contaminated. A temporary pipe identified as the cause of the contamination has been decommissioned.