Abstract: A thermal history indicator comprising a temperature sensitive material, a sensing device, a heat insulating material functioning to buffer the temperature sensitive material against temperature change, and an activation means. The triggering of the activation means allows a molten phase of the temperature sensitive material to interact with the sensing device, or cease interacting with the sensing device, thereby altering its chemical, biochemical or microbiological.

Abstract: A temperature history indicator means for affixing to goods. A temperature related phase change in a material within the indicator leads to an indication that a high temperature event has occurred. A preferred format has a water-soluble, lipid-insoluble dye immobilised within a lipid selected to have a melting point at a particular temperature and has all components made from edible materials. Upon melting, the dye dissolves in water present in a secondary phase or the goods themselves giving a visual indication. Another format has a primary reagent within a solid lipid and a secondary reagent held with a secondary phase such that melting of the lipid allows the primary reagent to react with the secondary reagent, providing an indication of a high temperature event. Time-dependent formats are also considered.