VALORIZATION OF WINE LEES: DRYING BEHAVIOR AND MATHEMATICAL MODELLING

In recent years, the management of winery waste processing has emerged as a major concern. This study evaluated the drying kinetics of wine lees, with a view to exploiting its technological potential toward the valorization of winery by-products and waste reduction in wine industries. The wine lees samples were placed in an electric dryer with forced air recirculation at 40°C until constant mass. The curves obtained were expressed in moisture (dry basis) as a function of time (minutes). Drying rate values were calculated as the average of the angular coefficients obtained in the adjusted linear equations and expressed in g of water/g of dry solid. The curves for modeling were dimensionless and expressed as a moisture ratio (MR) per time (min). The parameters of Page´s model were obtained using non-linear fitting. The wine lees drying time was 420 minutes. Initially, the moisture of the wine lees sample was 73.83% (2.821 g of water / g of dry solids) and reached final moisture of 8.32 ± 1.62 % (0.091 ± 0.019 g of water / g of dry solids). Therefore, the sample showed a water removal of 88%. The average values of the critical humidity of the wine lees were 0.84 ± 0.03 g of water/ g of dry solids. The time in which this moisture condition was reached was 180 minutes. When the sample reached critical moisture in 180 minutes, the average moisture content removed was 44%. The mean value of the drying rate in the constant rate region was 0.0112 ± 0.001 g of water/g of dry solid.min. The experimental data fitted perfectly to the Page model that showed a coefficient of determination (R²) of 0.9969, with values for parameter n greater than 1, ranging between 1.37 and 1.44. Therefore, wine lees represent an interesting potential for technological applications.