There was a significant difference in a* values (P < 0.05) between fresh and dried leaves. Dried leaves showed an increase in a* values (1.9300 ± 0.1414, 7.2850 ± 0.3041 and 7.8367 ± 0.4506 at 40 °C, 50 °C and 60 °C, respectively), and their colour became less green. The natural green colour of green plants or leaves is created by a mixture of chlorophyll a and chlorophyll b, which are directly linked to magnesium. During the drying process, magnesium molecules are converted to pheophytin and pyropheophytin ( Krokida et al., 2001 and Buchaillot et al., 2009). Therefore, greenness is reduced at the higher temperatures in the study range. Visually, the dark green colour of the leaves appeared to turn dull green-yellow due to chlorophyll degradation, which was accelerated at higher temperatures.