Whilst some companies were "exempt", it was after they had convinced the food safety authority that they tested the products according to agreed standards. I think they had to show testing was acceptable for three batches. However, the industry only routinely checks for biological markers of product quality, such as bug counts, not illegal adulteration..
The issue is that the testing is based on typical measurements of the quality of dairy milk, not illegal adulturation of the milk. The Kjeldahl method is a fast and effective indicator of protein but, like other tests, it's compromised by deliberate criminal activities.
The suggestion that protein testing would have detected the melamine is true, however it would not have detected other forms of adulteration involving cheap protein sources from animal processing waste products that have also been found in dairy products in the past, along with the easily-detected urine and urea wastes..
The solution is to make the supply chain honest, not try to outsmart criminals by testing. That's what quality systems try to achieve, and assurance testing should be part of that process.
One of the issues in this tragic case is that regional authorities had major incentives to meet economic growth targets, and hence hide any inconvenient facts that might compromise that regional growth.
Also loyal party members were given major positions in industry, whilst still retaining positions in the govt - which enabled them to prevent the release of embarrassing information.
Despite recent news items coming out of China suggesting that Chinese govt agencies uncovered the criminal fraud, it's clear that it was New Zealand Prime Minister's direct message to the Chinese central government in early September that triggered the Chinese govt's response, as the Chinese govt food quality agencies had known about the adulteration since early August.
That's the same time at the NZ shareholder ( Fonterra ) was first informed, and they immediated pushed for a public recall, but were overridden by the majority shareholders and local authorities, and the Chinese govt quality agency still did nothing - hence the departure of the agency head once publicity appeared.
The NZ shareholder eventually decided they escalate it to high political levels, and asked the NZ govt to convey their concerns. The tragedy shows why quality systems have to be clearly separated from business and political interests, and must be systemic from grower to consumer.
As the adulteration issue disappears, it's likely that melamine found will come from residual insecticide degradation, such as from cyromazine, and may highlight yet another common aspect of inadequate control of food quality.
Once again, the acceptable and responsible usage of such chemicals should rest with the initial user, with quality checks to ensure all is well, rather than trying to outsmart criminals.
Bruce Hamilton