Assessment of the effects of drying temperatures on effective moisture diffusion and quality properties of purple carrot slices dried by hot air method

This study examined the influence of hot-air drying temperature on the moisture ratio (MR), drying rate (DR), effective moisture diffusivity (Deff), color characteristics (L, a, b, C, and ΔE), and hardness (N) of purple carrot slices. A clear temperature-dependent response was observed for both the drying behavior and the quality attributes of the samples. Increasing the drying-air temperature resulted in a shorter drying period. The mean DR values obtained under the different drying conditions ranged from 0.0062 to 0.0201 g moisture/g dry matter·min. The calculated Deff values were within the range of 9.66 × 10⁻⁹ to 3.37 × 10⁻⁸ m²/s. Temperature also altered the color characteristics of the fresh purple carrot slices; specifically, the L and b values differed significantly from those of the fresh samples (p < 0.05). The α color values of fresh samples were preserved at 55 ºC and 65 ºC, the C color value at 55 ºC, and the ΔE color value at 55 ºC (p>0.05). The N values of fresh purple carrot slices are preserved at 75 ºC (p<0.05). Based on the findings, a temperature of 75 °C is recommended for the MR, DR, Deff, and N parameters, while a temperature of 55 °C is recommended for color characteristics.