This tiny patch can tell you if your food has gone bad. Engineering Research Assistant Hanie Yousefi (left) and Tohid Didar, Assistant Professor Mechanical Engineering at McMaster University show off the “Sentinel Wrap” patch. Photo credit: McMaster University

Trying to figure out if a food has gone bad? For food safety, simply looking at the food or doing a little “sniff test” isn’t a reliable or accurate way of determining food spoilage. But what if there was something on the food package itself that indicated whether a food has gone bad. Now there is!

A team of mechanical and chemical engineer researchers at McMaster University in Hamilton, Ontario have developed a thin, plastic transparent patch – about the size of two postage stamps – called the “Sentinel Wrap” to detect harmful bacteria and pathogens on food. The patch has tiny droplets of DNA molecules printed on one side that act as sensors to signal the presence of E. Coli, a type of types of bacterium that can cause food poisoning.

In Canada, about 4 million (1 in 8) Canadians are affected by a foodborne illness every year. Because it doesn’t affect the food at all, the Sentinel Wrap patch could be installed on the inside of a food package such as raw meat or raw poultry. If harmful bacteria are present on the food, the DNA molecules on the patch would light up under ultraviolet light. Shoppers could use a handheld device such as a smart phone, to scan the patch and immediately know whether there are any harmful bacteria present in the food.

The invention can still take two years before it comes to market. Until then, prevent food poisoning by following the four principles of food safety: clean, separate, cook and chill…and ditch the “sniff test”!