Indicating device

A device for indicating breaks in the refrigeration chain of a frozen product, comprising the following layers:

• (a) a surface layer (1) impermeable to moisture;
• (b) an indicator layer (2) comprising at least one indicator;
• (c) an activator layer (3) comprising at least one activator;
• and
• (d) an optional delaying layer (4), wherein
• the surface layer is positioned over the indicator layer, the activator layer and the delaying layer,
• the surface layer prevents moisture from penetrating from the outside to the indicator layer and/or the activator layer,
• the device does not comprise a moisture reservoir, and
• the indicator layer is positioned between the surface layer and the optional delaying layer, and
• wherein the device is configured such that, when applied to an upper surface of a packaging surrounding the frozen product, the surface layer of the device is the furthest away from the frozen product packaging, and, upon sufficient heating of the frozen product to above a freezing point of the frozen product, moisture originating from the product penetrates into the device through the product packaging and from below the device and migrates upwardly from the product packaging through the device towards the surface layer, thereby mobilizing the indicator and/or activator to bring components of the indicator layer and the activator layer together, and
• wherein at least one layer comprises a cellulose derivative selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), hydroproxypropyl cellulose (HPC), carboxymethyl cellulose (CMC) and mixtures thereof.