Indicator element of solid constituents

摘要

Hitherto, it has not been possible to make the state "thawed" simply and clearly visible in individual packages of deep frozen goods, in particular foods. According to the invention, this problem is solved by one or more indicator elements being integrated into the individual packages; the build up, in principle, of such an element is shown in Figure 1. Such elements contain solid materials 2 which permanently change colour, for example from green via yellow to red, when liquid, in particular pH-neutral water, acts on the elements from outside (corresponding to the arrows in Figure 1). These materials 2 are covered by one or more layers 1 which comprise material which is swellable and/or soluble in water, for example gelatine and/or cellulose film. The period of time which elapses from the commencement of the action of water until the material 2 changes colour can be preset within wide limits by selection of the materials and the composition of the layer or layers 1. The elements are generally suitable for monitoring water-sensitive goods. <IMAGE>