New Technology May Detect Spoiled Food

Cutting Edge

New Technology May Detect Spoiled Food

When we shop for groceries, we have every intention of using and consuming everything we buy. We take our groceries home and put them away in the refrigerator. Later you find something hidden in the back of the fridge, forgotten, and maybe not so good. It has happened to all of us at least once in our life. Sadly we never got to finish all the milk in the gallon or we forgot about that yogurt that somehow got pushed way to the back of the shelf. Usually, when we find something like that and we are not sure if it is still good, we resort to the smell test. If that fails to help, the dreaded taste test is the last resort. Everyone has accidentally gotten a taste of sour milk and nobody wants to repeat that mistake. But, what if because of new technology you never had to go by the date on the product or do a smell test again?

old tech smelling food

Advances in Technology

Researchers in China have been working to get rid of the need for a smell test or worse, taste test to see if food is still good or if it has gone bad. With all the new technology at their disposal, they have come up with a way to take the guess work out of knowing when food has gone bad. Dr. Chao Zhang is the lead researcher and scientist on the project. He, along with other scientists in Beijing at the Peking University are working with nanorod technology to recognize spoiled food while it is still in the container.

Color Changing Tags

What the researchers have come up are tiny little tags that will be attached to food packaging. These gel-like tags are color coded so you will be able to tell if perishable food items are expired without ever having to open them. The color changes as the freshness of the item changes. The smart tags start out a red color that means the food is fresh. They change from the original reddish color to orange, yellow, blue, violet, and finally green meaning the food is no longer good.

smart food tag

Metallic nanorods are in the small and non-toxic tags, which do not pose any known safety concerns, according to the researchers. When the tiny metallic nanorods are exposed to chemicals in the air, they react and change color. The tags can tell when something is spoiled even before the jar or can is open. These nanorods are red naturally, which is why they start out red and change to other colors as food starts to lose its freshness and go bad. The scientists have timed the nanorods to match expiration dates on the attached food item.


Scientists developed the tags and originally tested them on E. coli bacteria that is found in milk. The tags could detect the growth of the bacteria. Dr. Chao Zhang reported that they synchronized the bacteria growth process in milk with the process of chemical evolution in the tags at several temperatures during testing. The testing that was done using the nanorods on milk was successful.

Presenting the Technology

food tag

On Monday, March 17, 2014, Dr. Chao Zhang along with fellow researchers and scientists went before a meeting of the American Chemical Society and presented the new technology. They explained that the tags could be used on other perishable products. Because the smart tags are programmed so they notice ambient-temperature deterioration they can be attached to items such as medicine. According to the scientists, the tags would be beneficial to customers as well as retailers in helping to figure out the expiration date of products. Researchers say the new smart tags would be inexpensive to produce. They would cost less than one penny per tag.

While the smart tags are not on the market yet, they seem to be in our future. With these tiny tags on food, you will be able to tell at a glance if the food in your fridge is still good. No more smell tests or worse, taste tests that have your risking a mouthful of sour milk. Less food waste is another benefit we will see with the use of the color changing tags. With advances being made and new technology becoming available, great inventions like the small smart tags may soon be in our homes to help us reduce food loss. Although, it is not know when the smart tags might be available, they are patented in China now.

About The Author
Terri Chapman
Terri Chapman is a freelance writer living in the Midwest. She enjoys writing and being able to work from home. She has 3 sons and 7 grandchildren. In her spare time she loves reading and spending time with her family.