Solar tunnel dryer and slice thickness effect on the chemical composition and functional properties of taro corms flour

The effect of solar tunnel drying zones and slice thickness on the physicochemical, anti-nutritional, and functional properties of taro flour was investigated. Taro corms were sliced into three thicknesses (2, 4, and 6 mm) and dried under three zones of a solar tunnel dryer (Zones 1, 2, and 3), with open-sun drying used as the control. The dried samples were milled into flour and evaluated for physicochemical composition, anti-nutritional factors, and functional properties. Drying zone and slice thickness significantly influenced the quality characteristics of taro flour. The moisture content of flour samples ranged from 11.0 to 12.5%, while crude protein content varied from 4.53 to 8.14%. The highest-temperature drying zone (Zone 3), particularly for 2 mm slices, resulted in improved flour quality, with the lowest phytate (4.54 mg 100 g −1 ) and condensed tannin (57.1 mg 100 g −1 ) contents, together with enhanced functional properties, including the highest oil absorption capacity (0.925 g g −1 ) and swelling power (6.58%). In comparison, open-sun drying resulted in longer drying times, requiring up to 2012 min for 6 mm slices, compared with 331 min for 2 mm slices dried in Zone 3. Overall, drying 2 mm taro slices in Zone 3 of the solar tunnel dryer was identified as the most effective condition for producing high-quality taro flour with improved nutritional, functional, and processing characteristics. The findings demonstrate the potential of solar tunnel drying as an efficient and sustainable approach for taro flour production, particularly for smallholder and rural processing systems.