The new technology — dubbed Bardot, for bacterial rapid detection using optical scatter technology — uses a red diode laser to scan colonies on an agar plate. When light penetrates, it produces a scatter pattern of rings and spokes resembling the iris of an eye. The pattern is matched against an image library to identify the bacteria type.
“This could ultimately help provide safer food to consumers,” Arun Bhunia, a professor of food science who collaborated with then-Purdue engineer Daniel Hirleman to create the machine, said in a news release.
The research was published in mBio, a journal of the American Society for Microbiology.
Bardot, about the size of a large microwave oven, can also detect E. coli, listeria and other pathogens. It can be operated with minimal training and resources.
The researchers grew bacteria from rinses of contaminated spinach, chicken and peanut butter on agar plates for about 16 hours. The plates were covered with bacteria and placed inside Bardot. Identification of salmonella was to an accuracy of 95.9%.
The machine also distinguished eight salmonella serovars — variations of the bacteria — according to the release. Serovar identification helps trace contamination to a source.
Atul Singh, one of the study’s authors, said Bardot could be an effective preliminary screening tool, especially for food processors testing a large number of samples.
The study’s authors included researchers from Indiana State University. Funding was from the U.S. Department of Agriculture, the National Institute of Allergy and Infectious Diseases and the Center for Food Safety Engineering at Purdue.