Mean Kinetic Temperature (MKT) is a simplified way of expressing the overall effect of temperature fluctuations during storage or shipment of perishable goods. Consider the following example:
A dozen eggs sat:
In a 20°C room for 2 hours
In a 2°C refrigerator for 4 hours
And on a 25°C loading dock for 1 hour
Using MKT we can calculate that the temperature profile of the eggs was “thermally equivalent” to storing them at 10.096°C for 7 hours.
How is Mean Kinetic Temperature Calculated?
Technically speaking, MKT is an expression of cumulative thermal stress experienced by a product at varying temperatures during storage and distribution. In other words, MKT is a calculated, single temperature that is analogous to the effects of temperature variations over a period of time.
MKT is not a simple weighted average. The calculation of MKT gives the higher temperatures a greater weight when computing the average than would a simple numerical average or an arithmetic mean. This weighting is determined by a geometric transformation— the natural logarithm of the absolute temperature.
The International Conference on Harmonization (ICH) stability testing guidelines define MKT as ‘a single derived temperature which, if maintained over a defined period, would afford the same thermal challenge to a pharmaceutical product as would have been experienced over a range of both higher and lower temperatures for an equivalent defined period’. By using this unequal weighting pf the higher temperatures in a temperature series, MKT takes into consideration the accelerated rate of thermal degradation of materials at these higher temperatures. Therefore, MKT provides for the non-linear effect of temperature.