Assessing the Interaction of Blanching and Drying Parameters in Yam Drying through Response Surface Methodology

Blanching facilitates thermal energy utilization in yam drying by softening the tissue structure, so that heat penetrate more efficiently to minimize drying time. Higher drying temperatures further improve thermal energy utilization by accelerating moisture removal, though excessively high temperatures may reduce energy efficiency and product quality. The aforementioned conditions, including blanching time, has not been collectively run in any Response Surface Methodology (RSM) tool prior to this study, to test their effect on yam drying. In this study, Central Composite Design (CCD) in Design Expert 7.0 software was employed to assess the moisture content as response variable. Yam slices of 7–8 mm thickness were blanched at varying temperatures (70–90℃) and durations (15–35 min) and subsequently dried in a hot air tray dryer at temperatures between 50–70℃ for 4–10 h. The quadratic model showed an excellent fit with an R2 value of 0.9750 and 95% confidence intervals. Among the tested interactions, the combination of blanching temperature and blanching duration exhibited a strong synergistic effect on moisture removal efficiency. The optimal conditions – blanching at 90℃ for 23.9 min and drying at 70℃ for 10 h, resulted in a minimum moisture content of 3.99% with a desirability of 0.812. It further signifies a high thermal efficiency and minimal energy loss. Hence, the findings demonstrate the process’s potential for yam flour production, due to its effective dehydration, nutrient preservation, and energy-efficient drying performance. Attention must be given to differences in yam types, which currently includes, white yam, yellow yam, bitter yam, water yam and three-leaved yam, when opting for drying RSM, kinetics and thermodynamic studies.