Dried turmeric is used as a spice and traditional medicine. The common drying methods for turmeric (Curcuma longa L.) are sun drying and solar drying. In this study, turmeric slices with a thickness of 2 mm were dried at 40, 50, 60, and 70 °C in a laboratory hot-air dryer with a simulated solar radiation applied through transparent polycarbonate cover (UV impermeable) and PMMA cover (UV permeable). Air velocity and relative humidity of drying air were fixed at 1.0 M·s⁻¹ and 25 g H₂O kg⁻¹ dry air, respectively. Light significantly increased the sample temperature under both covers. Page was the best model to predict the drying characteristics of turmeric slices. Drying rate correlated with the effective moisture diffusivity, which increased at higher temperature. The hue angle (h°) of turmeric was distinctly lower at 70 °C under both covers. The dried products were of intensive orange color. Curcumin, demethoxycurcumin, and total curcuminoids were affected by the cumulated thermal load (CTL). The lowest curcumin content was found at 40 °C under PMMA (highest CTL). The optimum drying condition was 70 °C under polycarbonate cover due to shorter drying time and better preservation of color and curcuminoids in the dried product.

Cassava is grown because of its starchy roots, but the leaves being rich in protein are mostly underutilized. For protein recovery, mechanical juice extraction from cassava leaves and the extraction process was evaluated using computational fluid dynamics (CFD) simulation. The influence of input variables such as nozzle diameter and rotational speed of the screw was investigated in relation to process efficiency. The highest green juice extraction yield (81.0%) from cassava leaves and dry matter of press cake (61.3%) were achieved by using 4 mm nozzle diameter and 18 rpm screw speed. The protein content of the cassava leaves, press cake, juice sediment, and juice supernatant was found to be 31.5%, 27.7%, 26.2%, and 12.4%, respectively. The crude protein, cellulose, hemicellulose, lignin, and total phenolic content mainly accumulated in the press cake. The screw pressing concentrated the amino acids in the press cake and the juice sediment.

Particle characteristics are crucial knowledge to improve the process chain of cassava flour. Wet and dry grits, as the intermediate products, were investigated in this study. With respect to particle size, wet grits were predominately (66.7%) obtained between mesh size 0.50 and 1.00 mm, while dry grits (28.4%) were between 0.09 and 0.25 mm. Higher moisture content of wet grits generally resulted in higher bulk density, static and dynamic angle of repose, but lower particle density and porosity than dry grits. Plywood typically led to the highest coefficient of static friction of both, wet and dry grits. The transported mass and air velocity fitted well into a sigmoidal model. Due to particle size, terminal velocity of wet and dry grits ranged from 1.07 to 4.25 m/s and from 0.88 to 2.87 m/s, respectively, whereas conveying velocity ranged from 1.23 to 6.47 m/s and from 1.02 to 3.70 m/s.Practical Applications: Physical characteristics of wet and dry cassava grits were compared and studied. Particle size distribution relies on moisture change before and after drying. Effect of particle size on the aerodynamic properties was investigated. Homogeneity of particle size before flash drying should be controlled using sieves.