Construction of cold‐triggered/heat‐destroyed emulsions for use as a practical cold‐storage thermal history indicator

Abstract

AbstractBACKGROUND: To provide a record of the occurrence of a high‐temperature event during a cold‐chain system in the range from 1 to 10 °C, an indicator material that undergoes an irreversible temperature‐related visual change in response to high temperatures is needed.RESULTS: In order to obtain the required indicator, we attempted to construct highly thermo‐sensitive cold‐triggering and heat‐destructive emulsions that could start monitoring a high‐temperature event just by cooling, and after triggering provide an irreversible visual change over the upper limitation of the monitoring temperature. Emulsions composed of oil mixtures of triacylglycerols and fatty acid esters provided a 1 °C triggering and 10 °C destructive emulsion. The effect of the oil‐phase composition was studied by differential scanning calorimetry, nuclear magnetic resonance and microscopy with a cooling/heating system.CONCLUSION: The emulsion was triggered by cooling at 1 °C and was immediately destroyed by heating to 10 °C, with clear visible phase separation. For cold‐triggering, crystalline structures of frozen oils should work to destroy the interfaces of the emulsion droplets. This could be used as a thermal indicator that would trigger in cold‐chain distribution systems and be destroyed in these systems. Copyright © 2009 Society of Chemical Industry