Smart tag can identify spoiled food: Scientists

Washington: Scientists have developed a new colour-coded smart tag that can tell consumers whether a carton of milk has turned sour or a can of green beans has spoiled even without opening the containers. 

"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," said Chao Zhang,Researcher. Use of tags could potentially solve the problem of  knowing how fresh packaged, perishable foods remain over time. The tags can also be customised for a variety of other foods and beverages.   The tags contain tiny metallic nanorods that, at   different stages and phases, can have a variety of colours:   red, orange, yellow, green, blue and violet.

Scientists also stated, ‘The tag that will appear on the packaging and help in determining if medications and other perishable  products were still active or fresh.’.  This tag will also help manufacturers, grocery-store owners and consumers to get a reliable indication of the quality of any food  product.  The tags, which are about the size of a kernel of corn, would appear in various colour codes on packaging.   "In our configuration, red, or reddish orange, would mean   fresh," said Zhang, from Peking University in Beijing, China. 

"Over time, the tag changes its colour to orange, yellow  and later green, which indicates the food is spoiled," added Zhang.The colours signify a range between 100 per cent fresh   and 100 per cent spoiled.   If the label says that the product should remain fresh for 14 days under refrigeration, but the tag is now orange, it means that the product is only roughly half as fresh.   In that case, the consumer would know the product is edible for only another seven days if kept refrigerated, Zhang   said.   

Researchers developed and tested the tags using E coli (food-spoiling bacteria that cause gastrointestinal problems) in milk as a reference model.   "We successfully synchronised, at multiple temperatures, the chemical evolution process in the smart tag with microbial growth processes in the milk," concluded Zhang.