Researchers in the United Kingdom have developed a technology that can identify contaminated meat in seconds using infrared spectroscopy and genomic algorithms.
The technology is so fast that it could be used on a production line, the scientists say. The technique incorporates infrared spectroscopy and software algorithms to identify spoiled meat in just 60 seconds, as opposed to the hours it typically takes using current methods.
By then "the carcasses could have been dressed and delivered to a retailer," said David Ellis, a researcher in the school of chemistry at the University of Manchester, who helped develop the technique. "You ideally want something that measures in real time."
Rather than detecting the bacteria itself, the new method detects biochemicals produced when microbes break down food. Food spoils when the concentration of bacteria reaches a certain threshold (10 million bacteria per square centimeter for chicken, 1 million for beef), and they break down nitrogenous compounds. "That's when spoilage really kicks in ... stuff starts to get smelly," Ellis said.
The technology emits an infrared beam, which bounces off the sample. The resulting spectrum shows the level of biochemicals. Software designed to read the spectrum then determines whether the meat is bad.
The researchers created the software using genetic algorithms. First, they collected the spectra of meat samples kept at room temperature every hour for 24 hours, and simultaneously measured the actual bacterial count. They fed the data into a computer, where genetic algorithms boiled down the thousands of wavelengths to two or three that would best indicate that the bacterial concentration has crossed the spoilage threshold. The software sniffs out bad meat by searching for these wavelengths in meat samples.
The new technique detected bacteria concentration as low as 1 million for chicken and 10,000 for beef. But it didn't identify ideal wavelengths for beef, Ellis said, so the research team plans to refine the method for beef as well as expand it to dairy products and other foodstuff. They presented their research on Sept. 14 at the Society for General Microbiology meeting at Keele University in the United Kingdom.
"Tools for quantitative detection of microbial count are very important," said Andrew Proctor, a food sciences professor at the University of Arkansas in Fayetteville, who has developed a way to use infrared spectroscopy to detect nerve tissue in minced meat, which can lead to the fatal disease bovine spongiform encephalopathy, or mad cow disease. "There's certainly a need for this new approach," he adds, "especially if it can be put on (the production) line."
The technology to create handheld spectroscopic detectors for food inspection is already being used for weapons and toxic material detection, Ellis said.
But the new technology will likely have to work for a variety of food products before the industry invests in it, according to Randy Huffman, vice president of scientific affairs at the American Meat Institute in Washington, D.C. Detecting bacteria concentration of 10 million is sufficient for chicken, but detecting contamination in eggs or milk requires more sensitivity. "You would want to have a device that gives you lower than that -- 100 or 1,000 to the minimum," he said.
Because the technique works for chicken and beef, which are very different types of meat, Ellis believes it should work for less-complex foodstuffs as well. "Theoretically," he said, "there is absolutely no reason why our system should not detect significantly lower levels of bacteria."