Researchers at McMaster University in Canada have developed a transparent test patch called “Sentinel Wrap” that can be incorporated into food packaging to monitor for pathogens such as Salmonella and E. coli. The patch, which is printed with harmless molecules that can detect food pathogens, would trigger a signal if it detects bacteria that could be read by a smartphone. The patch doesn’t affect the food.
The new material was developed in biochemist Hingfu Li’s labs at McMaster. Chemical engineer Carlos Filipe and mechanical-biomedical engineer Tohid Didar collaborated on the project. The researchers say that the patch can be incorporated into the production process by food manufacturers.
The patch contains tiny drops of DNA sensors that will light up when it finds a pathogen. Any smart phone camera with a specialized filter, or a hand held device that reads fluorescence can scan the sensors.
Lead author Hanie Yousefi, a graduate student and research assistant, said, “In the future, if you go to a store and you want to be sure the meat you’re buying is safe at any point before you use it, you’ll have a much more reliable way than the expiration date.” The patch has been tested to find E. coli bacteria on chicken, meat, water, sliced apples, apple juice, and milk.
Until the Sentinel Wrap was developed, people relied on “best by” dates on meats to determine whether or not the food was safe. But these foods can be contaminated with pathogenic bacteria whether or not that date has come and gone.
And cooking products to a safe final internal temperature may not make contaminated foods safe. Some pathogenic bacteria produce toxins as they grow that are not destroyed by heat. Those toxins can make you sick.
Did told The Star, “Right now, if you want to know if there’s any contamination in a food sample, you need to bring it into a lab. And it takes at least a day or two to find out if there’s any pathogen present.”
