Drying Characteristics and Process Simulation of Hot-Air Drying of Nostoc commune Vaucher

PurposeTo study the characteristics of hot-air drying of Nostoc commune Vaucher, providing theoretical reference for its industrial application.

MethodsThe effects of different sizes (10, 20, 30, 40 mm) and different temperatures (50, 60, 70, 80 ℃) on the drying process of fresh N. commune were investigated. The non-linear fitting of the drying curve of N. commune was evaluated by using the Page equation and Weibull function. The scale parameter (α), shape parameter (β), water diffusion coefficient (D_eff and D_cal), activation energy (E_a) and geometric parameter (R_g) were analyzed.

ResultsThe higher the temperature of hot-air, the faster the drying rate and the shorter the drying time. The size of N. commune had little effect on drying time. Weibull function could better predict the variation of moisture ratio with the size and the temperature during the hot-air drying process of N. commune. In Weibull function, the α value was related to hot-air temperature and the size of N. commune, and the hot-air temperature had a greater effect on it. The β value ranged from 1.945 0 to 1.254 4, and the R_g value was less than 1. The D_eff value was between 2.513 2×10⁻⁹ and 9.965 6×10⁻⁸ m²/s, and the D_cal value calculated according to Weibull function was between 1.835 2×10⁻⁹ and 8.357 2×10⁻⁸ m²/s. The E_a value of N. commune ranged from 19.332 0 to 31.575 6 kJ/mol.

ConclusionFresh N. commune is easy to dry, Weibull function can describe the variation of water content in hot-air drying process of N. commune. The results can provide a theoretical basis for hot-air drying of N. commune.