Background. Quality of dried foods is aff ected by the drying method and physiochemical changes in tissue. The drying method aff ects properties such as colour. The colour of processed food is one of the most important quality indices and plays a determinant role in consumer acceptability of food materials and the processing method. The colour of food materials can be used as an indirect factor to determine changes in quality, since it is simpler and faster than chemical methods. Material and methods. The study focused on the kinetics of colour changes of plum slices, under infrared vacuum and microwave conditions. Drying the samples was implemented at the absolute pressures of 20 and 60 kPa, drying temperatures of 50 and 60°C and microwave power of 90, 270, 450 and 630 W. Colour changes were quantifi ed by the tri-stimulus L* (whiteness/darkness), a* (redness/greenness) and b* (yellowness/ blueness) model, which is an international standard for color measurement developed by the Commission Internationale d’Eclairage (CIE). These values were also used to calculate total colour change (ΔE), chroma, hue angle, and browning index (BI). A new model was used for mathematical modelling of colour change kinetics. Results. The drying process changed the colour parameters of L*, a*, and b*, causing a colour shift toward the darker region. The values of L* and hue angle decreased, whereas the values of a*, b*, ΔE, chroma and browning index increased during exposure to infrared vacuum conditions and microwave drying. Comparing the results obtained using the new model with two conventional models of zero-order and fi rst-order kinetics indicated that the new model presented more compatibility with the data of colour kinetics for all colour parameters and drying conditions. Conclusion. All kinetic changes in colour parameters can be explained by the new model presented in this study. The hybrid drying system included infrared vacuum conditions and microwave power for initial slo
