Examination of the effect of Spirulina platensis microalgae on drying kinetics and the color change of kiwifruit pastille

In this study, the effects of various concentrations of Spirulina platensis microalgae on drying kinetics and the color change of kiwifruit pastille were investigated. S. platensis was applied to the samples at three 0, 0.5 and 1(g/100 g sample) concentrations and the samples were dried at 70, 80 and 90 °C. Eight models of the entire drying thin layer models were fitted into the moisture ratios obtained during experiments. Coefficient of determination (R2), sum squared error, and root mean squared error were used in order to choose the best model. Different concentrations of S. platensis had no effect on the drying process. An ascending trend and descending trend were observed for a* and L* values, respectively. The Midilli model was selected as the best among the fitted mathematical models, with R2 = 0.9942. Effective moisture diffusivity was calculated and was between 1.83 × 10−9 and 2.29 × 10−9 m2/s within the studied temperature range. An Arrhenius relation with an activation energy value of 11.503 kJ/mol expressed the effect of temperature on diffusivity.