Freeze indicators with a controlled temperature response
AssigneeTemptime Corporation
InventorsDawn E. SMITH, Carl M. LENTZ, Dene H. TAYLOR, Yvonne OSUNGA, Brian HUFFMAN
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Abstract
A freeze indicator can include an indicator dispersion having an aqueous liquid medium and organic material indicator particles dispersed in the aqueous liquid medium. The indicator dispersion can have an initial appearance before freezing and an irreversibly different appearance after freezing and can exhibit a freeze-onset temperature of about −1.9° C. or higher. Some factors helpful to providing a relatively high freeze onset temperature are employment of a proteinaceous ice-nucleating agent, control of pH, use of a protein stabilizer and control of the ratio of protein stabilizer to ice-nucleating agent.
Claims31
A freeze indicator including an indicator dispersion, the indicator dispersion comprising:
- an aqueous liquid medium having a melting temperature and a freezing temperature, the freezing temperature being below the melting temperature;
- and
- organic material indicator particles dispersed in the aqueous liquid medium;
- wherein the indicator dispersion has an initial appearance before freezing and an irreversibly different appearance after freezing, and wherein the freeze indicator can exhibit a freeze-onset temperature of about −1.9° C. or higher.
A freeze indicator including an indicator dispersion, the indicator dispersion comprising:
- an aqueous liquid medium having a melting temperature and a freezing temperature, the freezing temperature being below the melting temperature;
- organic material indicator particles dispersed in the aqueous liquid medium;
- a proteinaceous ice-nucleating agent to elevate the freezing temperature;
- and
- a nucleating agent stabilizer to enhance the thermal stability of the nucleating agent;
- wherein the indicator dispersion has an initial appearance before freezing and an irreversibly different appearance after freezing and comprises a weight of proteinaceous ice-nucleating of from about 1 μg to about 2 mg and a proportion of stabilizer for the ice-nucleating agent of from about 0.05 percent to about 5 percent by weight based on the weight of the indicator dispersion.
A freeze indicator including an indicator dispersion, the indicator dispersion comprising:
- an aqueous liquid medium having a melting temperature and a freezing temperature, the freezing temperature being below the melting temperature;
- and
- organic material indicator particles dispersed in the aqueous liquid medium;
- wherein the indicator dispersion has an initial appearance before freezing and an irreversibly different appearance after freezing and wherein the aqueous liquid medium has a pH in the range of from about pH 7.5 to about pH 8.5.
Dependencies are inferred from the claim text.