Washington State University scientists developed a new sensor technology that could detect if a box of milk is still good or has gone bad.

The sensor was developed by the Department of Biological Systems Engineering (BSE) and the WSU/UI School of Food Science and other departments and is comprised of nanoparticles coated with chemicals. It can detect spoilage through the reaction of this sensor to the gas produced and bacterial growth. The milk does not come in contact with the sensor. The main author is a professor in BSE Shyam Sablani.

"If it's going bad, most food produces a volatile compound that doesn't smell good," Sablani said. "That comes from bacterial growth in the food, most of the time. But you can't smell that until you open the container."

Sabiana and his team published their results in the journal Food Control. The sensor can detect volatile gases and can change color.

The team aims to develop the visual representation of how long a product is before spoilage. The sensor is limited to showing whether the milk is spoiled or not.

Sabiani targets to incorporate his sensor into the plastic cap of a milk bottle to indicate whether the product is spoiled or not.

Expiration dates are only accurate if the conditions are optimal.

"The expiration date on cold or frozen products is only accurate if it has been stored at the correct temperature the entire time," Sablani said.

These conditions could either be that the product is stored above the optimum temperature during delays in shipment or during travel from the store to the house.

"We'll have to work with the industry to make this work," Sablani said. "But we're confident that we can succeed and help improve food safety and shelf life for consumers."