Evaluation of Drying Performance, Energy Consumption, and Quality of Two-Stage Dried Maize Grain

In this paper, the effect of two options (first option: fluidized bed drying (120–160 °C) + sun drying; second option: fluidized bed drying (120–160 °C) + again fluidized bed drying (65 ± 2 °C)) of two-stage drying on kinetics, energy consumption, quality of dried maize as color, nutritional properties, and hardness was evaluated to assess the drying performance. First stage drying for both options was executed by FBD at 7.0 cm bed thickness within the temperature range of 120–160 °C for 1.5–4 min. Then, the samples were tempered for 45 min in a closed container after completion of first stage drying. Second stage drying was then done by sun drying method (temperature: 33–36°C, RH: 52–65%, air velocity 0.4–0.6 m/s) for first option while for second option, it was accomplished again by FBD (65 ± 2°C). Drying time was shorter in the case of second option (2.23 h) than first option (4.98 h). Effective moisture diffusivity was found higher in both options of two-stage drying (10.5 × 10−09 m2/s to 63 × 10−09 m2/s) than control drying. Specific energy consumption was lower in first option compared to second option. Color of dried maize in two-stage options deteriorated markedly. However, nutritional qualities of dried grain for two-stage drying technique were similar to control sample. Hardness of the two-stage dried maize was lesser than control product. The two-stage drying options of maize drying instead of conventional sun drying method can be considered an alternative drying technique for the commercial maize drying industries.