can make sure safe food products aren't unduly discarded
of Article: http://insciences.org/article.php?article_id=3766
Published on 26
March 2009, 13:08 Last Update: 2 hour(s) ago by Insciences
| Food Science
WEST LAFAYETTE, Ind. -
A tiny chip developed at
Purdue University can detect harmful bacteria in food products more
accurately and significantly quicker than more traditional tests.
Arun Bhunia, Purdue professor of food science, found a way
to use human cell receptors in biochips to detect the presence of Listeria
monocytogenes, a bacterium common in deli meats and some unpasteurized
cheeses. Listeria monocytogenes can cause sickness and death in people with
weakened immune systems. Bhunia's findings were reported this week in the
early online version of the journal Analytical Chemistry.
"If you want to modify this, you could use different
receptors to detect salmonella, E.coli or any other pathogenic
bacteria," Bhunia said. "There are many potential uses."
Bacteria in a fluid are passed over the biochip and attach
to the cell receptors, changing the conductivity of the solution. The chip
senses the conductivity change and signals to a computer that bacteria are
Researchers, including Bhunia, had previously developed a
chip that used antibodies instead of cell receptors. The antibody chips
also detected benign forms of bacteria, however. Without being able to tell
whether the bacteria were harmful, food producers were forced to discard
products that were suitable for consumption.
"Companies could be wasting resources because current
testing methods don't show whether the bacteria is pathogenic," said
Ok Kyung Koo, a Purdue graduate student working with Bhunia.
When bacteria come into contact with the specific human cell
receptor, the bacteria attach to that cell, causing sickness. Benign
versions of those bacteria do not bond with receptors, making them better
for bacteria detection in food products.
"Most of the tests you have now may not be specific.
There's a chance it could give you a false positive," Bhunia said.
"The test we have set up would only detect pathogenic listeria."
Bhunia said current tests for listeria and other pathogens
take between one day and 10 to obtain results. His biochips take less than
12 hours, and he believes that time can be shaved to less than eight hours.
Since the chips are so small — about the size of a postage
stamp — they require only a small sample. And Bhunia said that since the
chips can be hooked up to a computer, tests could be done on-site,
eliminating the need to send samples to outside labs.
The U.S. Department of Agriculture funded Bhunia's research.
The biochips worked with samples of bacteria in a fluid that was passed
over the chips. The next step is to test the chips using samples taken from
Contact: Brian Wallheimer, (765) 496-2050, firstname.lastname@example.org, Sources: Arun
Bhunia, (765) 494-5443, email@example.com,
Ok Kyung Koo, (765) 496-7356, firstname.lastname@example.org,
Ag Communications: (765) 494-8415; , Steve Leer, email@example.com