Impacts of two-stage drying techniques on drying characteristics, physical and nutritional quality of maize

Abstract

This research aimed to evaluate the effect of two-stage drying techniques on drying characteristics and selected physical parameters, colour, and nutritional qualities of dried maize. To execute this study, the maize sample was dried by (i) fluidized bed drying at 120–160 °C temperatures followed by sun drying at 32 °C (Technique 1), (ii) fluidized bed drying using higher temperatures (120, 140, and 160 °C) at first stage followed by lower temperature (65±2 °C) at the second-stage (Technique 2), and (iii) sun drying method (∼32 °C) (control). Results signposted that lower drying time was attained in the second approach (1.5 h) compared to the drying Technique 1 (4.5 h) while the sun drying method took 10 h for plummeting high moisture (25.43%, wb) to a safe level (<14%, wb). Data analysis revealed that the dried product's bulk density and porosity diverged between two-stage drying and sun drying techniques. The colour properties of the dried products changed significantly (P ≤ 0.05) with the drying arrangements. The results of nutritional values of the dried product did not change significantly with the first-stage drying temperature but did change significantly with the drying techniques. Even though both techniques yielded almost the same quality dried product, Technique 2 is superior for rapid drying. Therefore, the proposed two-stage drying techniques can be familiarized as alternative drying for high-moisture maize in a commercial drying complex.

Keywords

• Maize
• Two-stage drying
• Fluidized bed drying
• Physical property
• Nutrition