Can cheese get the flu? The simple answer is yes, according to a UCC microbiology lecturer, Dr Douwe van Sinderen. And while the cheese doesn't display the equivalent of a temperature and a runny nose, it is definitely a little off after the flu strikes.
Cheese flu is probably not any more prevalent today than a century ago. It's only that cheese is made in much larger quantities nowadays, so when the bug strikes, the cost for producers can be very high, he explained at a Science Week lecture in UCC last night.
Many people believe dairy products arise in a mysterious way from the conversion of milk to cheese or yoghurt. "It doesn't just happen. You need specific bacteria to perform the conversion (a form of fermentation) into the desirable products, which are sometimes healthy for us. Usually, the products are then safer and can be stored longer."
It is also assumed the process goes on without any problems. But difficulties can take the form of a virus attacking the lactic acid (converter) bacteria which are essential for full conversion and the creation of distinctive flavours.
This happens in a similar way to the flu virus affecting the human body, but the viral aggressors killing the bacteria are known as bacteriophage or phage.
The first disruption of "starter cultures", which are essential to fermenting the food and releasing the flavours, was recorded in 1935, but it was only in the past 30 years that the exact causative agent was identified: the dreaded bacteriophage.
Phage "illness" as far as the cheese is concerned is manifest in the form of reduced acidity and off flavours, so much so that the quality is impaired. Often the cheese does not coagulate properly. It doesn't become a viral cess-pit and is not particularly dangerous to eat, but a batch may have to be condemned.
Given that 100,000 gallons of milk may be used at a time, it amounts to a considerable loss.
There is little that can be done to eliminate phage, as they circulate in the air. Scientists at UCC are establishing which of the numerous strains of lactic acid bacteria used in food production and found in nature have in-built "resistance systems" to phage.
They are using natural genetic-exchange techniques to transfer phage resistance ability into cheese-making strains, Dr van Sinderen said.
Thus, cheese can be made with the equivalent of a flu vaccine to protect it.
