The Korea Research Institute of Chemical Technology on Tuesday announced that it has invented a cold-chain safety sticker that allows one to tell whether frozen food products have been mishandled during delivery.

The nanofiber-film sticker, which costs around 120 won (1 cent) to produce, can be used when transporting different types of frozen foods, as well as expensive medicines and medical supplies, the research team said.

The cold-chain sticker is designed to indicate how long frozen food products have been exposed to room temperature.

At low temperatures, the film stays opaque because the fiber structure scatters the light. But when exposed to room temperature, the nanofiber film starts to melt and becomes transparent.

Once the sticker is transparent, it stays transparent even if the goods are refrozen, the research team said.

The research team also found a way to control the exposure time required for this nanofiber film to become transparent, so distributors can choose different stickers for different types of products.

There is no risk of chemical leakage even if the sticker is damaged during delivery, the research team added.

By Shim Woo-hyun (ws@heraldcorp.com)