If anyone should have learned the lessons of the 2008 scandal over baby milk formula tainted with melamine, which killed six mainland children and caused 300,000 to fall ill, it is Fonterra, the New Zealand dairy export giant. Fonterra sounded the alarm to the New Zealand government, which alerted Beijing, after its mainland partner, the state-owned Sanlu Group, failed to comply with a request for a full product recall. The result was one of the darkest chapters of China product safety, involving more than 20 companies.

The industrial chemical was introduced in China and trust in Fonterra's product emerged intact. Incredibly, the company has lost it in one stroke in circumstances that are not dissimilar. Fonterra has revealed that a whey product used to make infant formula and sports drinks had been contaminated with bacteria that can cause potentially fatal botulism. According to New Zealand Prime Minister John Key, tests last year showed problems with three batches of whey. He has accused Fonterra of delaying sounding the alarm. The company says it acted promptly once the seriousness of the bug was confirmed. But the apparent cover-up in the hope that the problem would go away does not reflect the lessons of the melamine scandal.

China, New Zealand's biggest dairy product customer, has halted all imports and ordered a product recall. Perhaps fortunately, only a small handful of drinks and baby-formula companies were found to have used the contaminated product. But Key is rightly concerned at the impact on his farm-reliant country's reputation as a supplier of "clean, green" dairy products, particularly in Asia. Fonterra needs to come clean as a first step towards restoring its credibility and reputation.