Low-cost, easy-to-read stickers that get attached on the outside of food pallets-boxes and change color if the food is exposed to unsuitable temperatures during transportation. The FreshStrip is a thin layer of liquid crystals printed on a plastic/paper adhesive label. The liquid crystals form a helical structure at a nanometre scale. When this structure is exposed to high temperatures for a specific amount of time it expands, which causes an irreversible shift in color from green to red. The FreshStrips get attached on the outside of food boxes. If during transportation these boxes are exposed to unsuitable heat the FreshStrips switch color and act as an alarm for potential food-borne outbreaks. On the other hand, if only a handful of boxes in a shipment are heat-affected we save the rest of the boxes from being discarded as they would be currently.