Researchers develop tags that change colour when food has spoiled

18 March 2014 (Last Updated March 18th, 2014 18:30)

Consumers could soon know whether a carton of milk has turned sour without opening the container, using a new colour-coded smart tag developed by Chinese researchers.

Smart Tags

Consumers could soon know whether a carton of milk has turned sour without opening the container, using a new colour-coded smart tag developed by Chinese researchers.

The report on the food deterioration tags was presented as part of the 247th National Meeting & Exposition of the American Chemical Society (ACS). It revealed that tags appearing on packaging could also be used to determine if medications and other perishable products were still suitable for consumption.

Peking University scientist and lead researcher of the study Chao Zhang said that consumers can use the tags to estimate how much time food would remain fresh in packs.

"This tag, which has a gel-like consistency, is really inexpensive and safe, and can be widely programmed to mimic almost all ambient-temperature deterioration processes in foods," Zhang added.

If food comes in contact with higher temperatures then the tag will indicate possible spoilage to manufacturers, grocery-store owners and consumers.

Around the size of a kernel of corn, the tags would appear in various colour codes on packaging. If the tags stay red or reddish orange, its means that the food is fresh. Food spoilage is indicated by changes in colour from orange to yellow to green. An orange colour means that the product is only roughly half as fresh, and is edible for only for a period of another seven days if kept refrigerated.

The tags were tested and developed using E coli in milk as a reference model.


Image: Smart tags in packaging could let consumers know about food spoilage. Photo: courtesy of Chao Zhang, Ph.D.