Studies on Drying characteristics of Beetroot Slices at varied Temperatures and its Quality Evaluation

Drying characteristics of beetroot slices was investigated by convective hot air drying method at the temperature 40°C, 50°C, 60°C and 70°C of 4 mm thickness beetroot slices. Beetroot has the many medicinal, pharmaceutical, nutraceutical applications. Five drying model i.e. Newton, Page, Modified Page, Thompson, Modified Page Equation II were fitted to the experimental data on moisture ratio with respect to time. Modified Page Equation II drying model best fitted with r² ≥ 0.9691; MSE ≤ 0.000840; χ² ≥ 0.1015 to experimental moisture ratio with respect to time. Effective moisture diffusivity for beetroot slices dried at different temperature was 2.10962 ×10^-9 m²/s, 5.03063 ×10^-9 m²/s, 1.03858 × 10^-8 m²/s, 1.34691 × 10^-8 m²/s at 40°C, 50°C, 60°C and 70°C respectively. The activation energy (E_a) for moisture diffusion was found to be 0.8160 kJ/mole. Effect of quality parameter i.e. acidity, TSS, pH, reducing sugar, total sugar, moisture, hardness and colour (L, a and b value) on fresh beetroot slices and dried beetroot slices after drying at 40°C, 50°C, 60°C and 70°C respectively were also determined and discussed.