German researchers have found that the addition of a bacterium during cheese production may be a simple answer to preventing Listeria in unpasteurised produce.
Their findings appear in March 2003 issue of the journal of Applied and Environmental Microbiology.
In the study, cheese was ripened with or without the bacterium Lactobacillus plantarum. The results showed complete inhibition to listeria bacteria in the cheese produced with L. plantarum. The reason for the inhibition appears to be a compound produced by L. plantarum called pediocin. The authors did express a mild concern over an observation that in some cases listeria may become resistant.
"The addition of a L. planatarum culture is a potent measure for combating listeria in a contaminated production line, but because of the potential development of resistance, it should not be used continuously over a long time in a production line," the researchers said.
The results of the research could have major implications for cheese producers, if the method can be translated into mass cheese production. The pasteurisation of cheeses can be both a time consuming and relatively expensive procedure. Furthermore, the discovery could come as a major boon to a host of cheese makers, particularly in France, where the pasteurisation of cheeses is not considered to be a valid part of the production process.