Q10 factor

The Q10 factor is a quick rule of thumb for how much faster a reaction goes when you raise the temperature by ten degrees. It answers a homely question — if I store this somewhere ten degrees warmer, roughly how much faster will it spoil? — with a single multiplier.

Formally, Q10 is the ratio of the degradation rate constant at one temperature to the rate constant at a temperature ten degrees lower. For many pharmaceutical degradations Q10 lies between about 2 and 5, with a value of around 2 to 3 often assumed as a default; a Q10 of 3 means the reaction runs three times faster for each 10-degree rise, and conversely roughly three times slower for each 10-degree drop.

Its appeal is speed and intuition: knowing Q10, you can make a back-of-envelope estimate of how a shelf life shifts with storage temperature, or how long a brief excursion (say a fridge product left out warm for a day) might cost, without solving the full Arrhenius equation.

Caveats are important. Q10 is a simplification of Arrhenius and is strictly valid only for one mechanism and only near the temperatures from which it was derived; it ignores humidity and physical changes. Using a guessed Q10 to justify a real shelf life would be cavalier — it is best for rough thinking and triage, with proper studies for the actual claim.