Freeze Indicator with Proteinaceous Ice-Nucleating Agent
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Solution Overview
Problem
Existing freeze indicators often have freeze onset temperatures that are depressed by supercooling, limiting their effectiveness in detecting exposure to freezing temperatures, and they may not maintain a high response temperature after storage.
Innovation Solution
A freeze indicator comprising an aqueous liquid medium with organic indicator particles and a proteinaceous ice-nucleating agent, stabilized by a nucleating agent stabilizer, which exhibits a high freeze onset temperature above −1.9°C and remains effective after storage for several weeks, with a distinct appearance change upon freezing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an aqueous liquid medium is used in the freeze indicator, then the indicator can provide a clear visual signal upon freezing, but the freezing point is depressed by supercooling, resulting in a lower freeze onset temperature
Solution Approach 1:
An ice-nucleating agent is introduced as an intermediary substance in the aqueous liquid medium. This agent acts as a mediator that facilitates ice crystal formation at temperatures closer to the normal freezing point of water, thereby preventing supercooling and elevating the freeze onset temperature while maintaining the reliability of the visual signal.
Solution Approach 2:
The chemical composition parameters of the aqueous liquid medium are modified by adding specific ice-nucleating agents. This parameter change alters the freezing behavior of the medium, enabling it to freeze at a higher temperature (above -1.9°C) while still providing the desired visual indication.
2Duration of action of stationary object
If the freeze indicator is stored at room temperature for extended periods, then it remains available for use, but the freeze onset temperature decreases and effectiveness is reduced
Solution Approach 1:
The ice-nucleating agent is pre-incorporated into the aqueous liquid medium during manufacturing, performing the nucleation function in advance. This preliminary action ensures that when the indicator is stored and later used, the freeze onset temperature remains elevated without requiring additional treatment or preparation.
Solution Approach 2:
The freeze indicator formulation is designed to be self-stabilizing through the incorporated ice-nucleating agent. The agent continuously maintains the elevated freeze onset temperature throughout storage periods, allowing the indicator to serve itself without external intervention or degradation of performance over time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The freeze indicator provides a reliable and irreversible visual signal of freezing exposure, maintaining a high freeze onset temperature and consistency across multiple samples, even after extended storage, addressing the limitations of existing technologies.
Implementation Method 1
a proteinaceous ice-nucleating agent, stabilized by a nucleating agent stabilizer, which exhibits a high freeze onset temperature above −1.9°C
Implementation Method 2
The indicator element can change appearance irreversibly upon exposure to freezing temperatures, for example as a result of coagulation of the dispersed solid particles
Data Source
AI summary
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.