A biocompatible and edible colorimetric timer is obtained by exploiting the dynamic color modifications of the cholesteric liquid crystalline mesophases of hydroxypropyl cellulose (HPC) in aqueous suspensions. The edible timer is encapsulated between semi permeable membranes made from shellac. The cholesteric organisation of the HPC supplies vibrant colouration, whereas the shellac layers enable tuning of the evaporation charge of water from the mesophase, which ends up in a color change. As a result of biocompatibility of the elements and the direct read-out of the system, i.e. the color change may be visually detected, and the developed timer may be applied as a colorimetric sensor with potential for use in meals packaging, and as a wise labelling system.
