The absorbance with extraction time reached a maximum after approximately 40 min of heating. Similar results are found for the TPH concentration in the extracts. The results indicate that under the given experimental conditions an optimum concentration already is reached after 30–40 min extraction time. Prolonged extraction does not result in further increase in concentration of coloured matter, also the TPH concentration stabilises. The slight decrease in both, absorbance and TPH concentration indicates that losses of colouring matter occur when extraction time is prolonged substantially over 60 min.