A food-grade glycol (chemical designation: propane-1,2-diol) used in cold chain monitoring as the thermal buffer medium in glycol-buffered temperature probes, and separately in food production as a humectant, solvent, and preservative (E1520 in EU, GRAS status FDA).
Cold Chain Application
Propylene glycol’s value in temperature monitoring comes from its physical properties:
At 50/50 concentration with water, the freezing point is approximately -33°C — it remains liquid in a standard -18°C freezer, allowing the probe to measure continuous temperature changes.
Specific heat of approximately 3.4 kJ/kg·K places it between water (4.18) and frozen food (1.5-2.5), making it a reasonable thermal simulant for food products.
Non-toxic and food-safe, eliminating contamination risk if a probe container leaks in a food storage environment.
Stable across repeated freeze-thaw cycling at monitoring temperatures, ensuring long-term reliability.
Practical Specifications
Only 50-200ml is needed per probe. Available from chemical suppliers across South Africa at approximately R150-300 per litre for food-grade material. Ensure food-grade specification (USP/NF or equivalent) — not industrial propylene glycol, which may contain contaminants.
When mixed 50/50 with distilled water, the solution provides reliable thermal buffering across the full range of frozen food storage temperatures (-18°C to -25°C). No special handling or disposal requirements beyond standard chemical safety practices.
Not to Be Confused With
Ethylene glycol (automotive antifreeze) — toxic, never appropriate for food environment applications. Always specify propylene glycol for cold chain monitoring applications.
Related Terms: Glycol Buffered Probe, Food Simulant Sensor, Air Temperature vs Product Temperature
Related Articles: Your Freezer Says -15°C. Your Product Says -6°C. Both Are Correct.