Modeling and optimization of thin‐layer drying data of pretreated taro (Colocasia esculenta) corm slices

Drying, an important but energy‐intensive unit operation, is necessary to ensure that perishable food produce is preserved for diverse industrial uses. Hence, modeling and optimizing this unit operation is vital. This study was carried out with the view of modeling and optimizing the thin‐layer drying of pretreated taro corm slices using three‐level factorial design of response surface methodology. Factors studied included different pretreatments (using either or a combination of sodium metabisulfite at concentrations of 1–4% w/w, steam‐blanching for durations of 1–6 min, and varying drying air temperature from 50 to 70°C). Seven responses (total drying time (TDT), specific energy consumption (SEC), final moisture content (FMC), activation energy (Ea), effective moisture diffusivity (Deff), percentage change in thickness (%∆TH) and percentage of moisture loss (%ML) were investigated. The optimum drying condition was further investigated for model fitness using nine existing drying models. The results showed that responses such as TDT and FMC ranged from 395.6 to 699.9 min and 5.29–12.4% wb, respectively. SEC was between 25.7 and 50.6 kWh/kg. Deff and Ea values ranged from 0.88 × 10−10 to 2.96 × 10−10 m2/s. and 33.9–40.9 kJ/mol, respectively. However, %∆TH and %ML ranged from 37.5 to 60.9% and 83.9 to 97.5%, respectively. The models generated were reliable and reproducible. Finally, optimization studies showed that pretreating taro slices by sulfiting at a concentration of 1.73% and blanching at a time of 2.37 min and drying at a temperature of 57.7°C would be optimum and fit Henderson and Pabis model best. In conclusion, the information provided by this study would be beneficial in designing and analyzing drying systems for taro products. Practical applications Taro (Colocasia esculenta) corm is an underutilized tuber crop with promising potentials for use in different food applications especially in the production of taro flour. Taro corm is however perishable, having high moisture content, hence, drying is an important unit operation in the production of flour from the corms. There is a need to establish optimum drying conditions to ensure that the drying process is efficient and economical. This study, therefore, was conducted to generate data that would provide information useful for drying pretreated taro slices.