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Cambridge University Science Magazine
To avoid this unpleasant experience, a new product was designed to indicate if a carton of milk is spoiled. This product from China is a Color-coded smart tag made of a gel-like material which can be placed on the container without having to open it.

The tag which simply indicates to the consumer the quality status of the product The tag which simply indicates to the consumer the quality status of the product
The tag glued to the container then changes colour from red to green over time depending on the temperature it is stored in, thereby indicating the freshness of the product (red being the freshest). In fact, this gel-like product uses a time-temperature technology containing metallic nanorods  which react together with time.

This technology allows to “record” the various temperatures the product went through during the manufacturer-to-consumer chain. Then, depending on the temperature history of the product, the nanorods interact together which provokes a gradual colour change on the tag which simply indicates to the consumer the quality status of the product. This very small tool is only made of nontoxic reagents and would cost less than 5 pence to produce.

This new technology could therefore be used easily for various types of products and potentially medications.  Therefore, this tag seems like an affordable, user-friendly and easy product with many applications which could revolutionize the food and pharmaceutical industries.

DOI: 10.1021/nn401266u

Written by Laetitia Schwab.