Modelling the change in colour of potassium sorbate powder during heating

Colour change of potassium sorbate caused by heating was statistically modelled to examine its potential as a time–temperature process indicator. A full factorial design with five levels of heating time (t) and temperature (T) was used. L, a and b values were measured by a HunterLab colorimeter, and second-order polynomial models were developed. Heating significantly reduced L and increased b values, causing the potassium sorbate powder to turn dark yellow, possibly because of non-enzymatic browning reactions. Statistically significant models with good fit were developed for L and b, and their response surfaces were generated. This potassium sorbate-based system may be a suitable indicator for high-temperature heating processes such as dry heat sterilizers or baking ovens.