Microbiologist battles against E. coli

Related tags Microbiology

A Kansas State University microbiologist is using a series of
ground breaking methods which it is claimed will help to facilitate
the detection of E. coli and other foodborne pathogens in processed
foods.

A Kansas State University microbiologist is using a series of ground breaking methods which will help to facilitate the detection of E. coli and other foodborne pathogens in processed foods.

Daniel Fung is currently evaluating a new instrument for processing food samples for microbiological analysis. The instrument, the PULSIFIER, allows researchers to obtain bacteria and pathogens from food without breaking up the food extensively.

According to Fung, there is no lack of high-power technology available today for use by microbiologists to detect organisms. But with technology comes problems, such as getting the organisms to interact with the advanced systems. He cites as an example current requirements that call for food microbiologists to be able to detect salmonella in 25 grams of meat.

"There is no way on Earth right now that you can take a bio sensor or probe, stick it into the meat, stir it around and say 'I have salmonella',"​ Fung said. " So the problem right now is to find better ways to make samples better for food microbiologists."​ Fung pointed out how previously microbiologists used a device called a stomacher to "beat up" and "homogenise" the food samples. However, the problem with the stomacher is that it does its job a bit too well.

"When you beat the sample up, there are many other things that come into the liquid,"​ Fung said. "Those inhibitors can really hamper new technologies and interfere with polymerase chain reactions. So the fewer inhibitors in the food the better your sample."

Fung said scientists can do filtration on the samples to filter but with that process you still have the inhibitors in the liquid, which may in turn lead to false reads because the inhibitors will alter the PCR reaction.

"The less inhibitor the better,"​ Fung said.

Where the stomacher pulverises the sample, Fung said the pulsifier literally shakes pathogens into the liquid without breaking up the food extensively. In turn, the pulsified samples are much cleaner in terms of the turbidity and much easier to operate.

"This is the first step of testing in food microbiology - to blend your food first,"​ Fung said. "This method will give you the same number of pathogens but the liquid is much clearer."

Fung said that while many people study pathogens in relation to meat and poultry contamination, the study of contamination in vegetables is often neglected.

"We make zillions of salads and send to the grocery stores, but there is no control,"​ Fung said. "The only control of little packages of salad is low temperatures but some pathogens can survive and grow in low temperatures."

As opposed to foods that are cooked, Fung said prepared salad mixes are just opened - sometimes washed - and dumped into a bowl and eaten.

"This is an interesting experiment,"​ Fung said "From a scientific standpoint, we're going to find out how and why the organisms are shaken into the liquid. We will be using an electron microscope to look at lettuce leaves to find out the difference between the pulsified and the stomacher samples and see if they are giving the same numbers (of pathogens). Because of our previous data I think it will show that they are."

Related topics Processing & Packaging

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