Clostridium botulinum causes problems for Fonterra

Fonterra, New Zealand's largest dairy manufacturer, last week issued a warning that Clostridium botulinum had been found in three batches of whey protein, (approximately 40 tonnes), which can be used to boost the protein content of many foods, including infant feeding formula.

The warning caused a New Zealand manufacturer of infant feeding formula to recall certain batches of product.  Fonterra Chief Executive, Theo Spierings also flew to China to discuss the issue with Chinese food safety authorities.

Apparently, the source of the bacteria has been traced to a dirty pipe in a processing factory.  If this is true, it's a serious lapse in process control and obviously should not have occurred.

The whey was made in May 2012 and it is unclear why the contamination has taken so long to come to light and why the company has been so slow to inform the government and the public.  The company became aware of the contamination in March, but it was not until Wednesday 31st July 2013 that tests confirmed the presence of the bacteria. 

There are some possible explanations for the delay: third parties may have tested the product at some point in their own manufacturing operations and found it;  the contamination levels may be very low, resulting in a requirement to test large amounts of product before the contaminants were found.  Certainly, once the bacteria had been isolated, using modern methods,it should not have taken long to confirm the identification.

It is not usual to test dairy products for the presence of Clostridium botulinum.  When bacteria occur in a product at very low level and very infrequently, testing is ineffective in assuring safety and the cost is prohibitive.  An Australian specification for whey protein concentrate does not mention Clostridia.

The concern about the presence of C. botulinum is real and justified.  The bacteria can produce a potent neurotoxin that causes paralysis and death.  There have been only a couple of cases in New Zealand in the last 35 years.  The toxin is released when the cells sporulate, so growth of the bacteria is necessary for toxin production.  Bacteria cannot grow at the low water activity conditions in whey protein powder, but spores could germinate and grow if infant formula containing the contaminated whey protein were made up and then held warm for some period.  The other very serious scenario is that infants fed the contaminated formula might then suffer botulism when the spores grow in the intestinal tract.

This story is not over yet and Safe Food will monitor the developments.