The US group, lead by Lisa Mauer, said the method uses infrared spectroscopy to cut the time to identify E.coli to just hours instead of days as with current testing methods.
The associate professor of food science from Purdue University, told FoodProductionDaily.com the breakthrough technique had the potential to become an industry standard and her team was already working on adapting it to detect other pathogens such as Salmonella.
Using Fourier transform infrared spectroscopy FT-IR, Mauer said E.coli had been detected in ground beef in one hour compared to the 48 hours needed by conventional plating technology carried out in laboratories. She added the same labs could use the compact spectroscopy equipment to get results in a fraction of this time.
The technique is also able to differentiate between strains of E. coli 0157:H7, meaning outbreaks could be tracked more effectively and quickly. Current tests are multi-step and take almost one week to get results.
"Even with all the other bacteria present in ground beef, we could still detect E. coli and recognize different strains," said Mauer.
The study – Detection of E.coli 0157:H7 from Ground Beef Using Fourier Transform Infrared Spectroscopy and Chemometrics – was published in the Journal of Food Science.
The research showed two methods for separating bacteria from ground beef for testing. An antibody-capture method, which binds bacteria to antibodies attached to magnetic beads, gave results in four hours, while a filtration method achieved results in about an hour.
Infrared spectroscopy could detect just one E. coli cell if the bacteria were cultured for six hours. Conventional plating techniques used for E. coli detection require culturing cells for 48 hours. The faster feedback is achieved as the FT-IR is able to read the E.coli’s specific infrared spectrum by interpreting the combination of energy that has been absorbed and energy that has been reflected back when infrared light is scanned over a sample.
"Energy is only absorbed by certain components of a sample," Mauer said. "If that component or bacteria isn't there, the energy is reflected back."
The testing methods can also distinguish between living and dead E. coli cells, something current testing methods cannot. While dead cells are not harmful, their presence could indicate something about the quality of the product, said the study.
“The FT-IR technology has been used since the 1990s for pure samples,” explained Mauer. “We have moved this forward by capturing bacteria from meat samples and analysing them. We have demonstrated the general principle works and that there is an opportunity for more rapid detection using instrumentation that is already available.”
Using samples from products, companies could build up a spectral library of micro-organisms and create a database. Subsequent tests would then be compared against the reference material to see if a micro-organism was present in the product, with the FT-IR being used as a micro fingerprint detection device, said Mauer.
Detection of E.coli 0157:H7 from Ground Beef Using Fourier Transform Infrared Spectroscopy and Chemometrics by Reeta Davis, Joseph Irudayaraj, Bradley L. Reuhs, and Lisa J. Mauer is published in the Journal of Food Science Doi: 10.1111/j.1750-3841.2010.01686.x