Impact of organic PCM on drying kinetics and nutritional quality of sweet potato in indirect solar dryer

This study aims to investigate the drying kinetics and nutrient retention of the sweet potato without Phase Change Material (PCM) (Case 1) and with PCM (Case 2) in the drying chamber of an indirect type of Solar Air heater (SAH). The trapezoidal-shaped absorber plates and PCM containers were treated using a shot-blasting mechanism. This surface modification improves roughness, thereby increasing solar radiation absorption and heat transfer. The augmented surfaces contribute to advanced drying efficiency and thermal energy storage throughout sweet potato drying. The proposed SAH reduced the moisture content of sweet potato from 69.94 % (wet basis) to 7.83 % and 6.67 % in Cases 1 and 2. The drying efficiency of Case 2 is 1.51 % higher than Case 1. Shrinkage was 1.94 % in Case 2 against 3.35 % in Case 1, indicating less physical deformation and steadier moisture loss. With PCM, Case 2 attained 6.68 % moisture in 12 h, 1.15 % lower than Case 1, signifying extended drying time and better thermal performance for enhanced moisture removal. The drying rate was indicated at 12.16 kg/h for Case 1 and 13.37 kg/h for Case 2 in the afternoon. PCM usage in Case 2 displayed greater retention of nutritional components, with crude protein rising to 2.82 % and crude fat to 1.40 %, compared to 2.23 % and 0.92 % in Case 1, respectively. Eventually, drying with PCM increases drying rate, efficiency, and keeps product quality higher, retaining nutrients, sinking moisture, lessening color loss, and confirming better microstructural integrity compared to drying without PCM. • The drying kinetics of sweet potatoes using an indirect solar dryer were studied. • A trapezoidal shape with a shot-blasted absorber plate was employed. • The incorporation of OM49 PCM offered the highest nutrient quality in solar drying. • Average dryer efficiency of 53.35 % was attained with the integration of OM49 PCM.