Drying of sicilian lemon residue: influence of process variables on the evaluation of the dietary fiber produced

Abstract

In this study, the effect of the process variables of the air-drying of Sicilian lemon residues on some technological properties of the fibers produced was studied. The determination and modeling of desorption isotherms were used to establish the equilibrium moisture content at 60, 75, and 90 degrees C using the static method with 8 saturated salt solutions. The best fit was obtained with BET and GAB models. The drying process was conducted in a vertical tray dryer and delineated according to a central composite experimental design (2(2)) using the following as factors: air velocity (0.5, 0.75 and 1 m/s) and temperature (60, 75, and 90 degrees C), and it presented a good fit to the exponential model (R-2 > 99.9%). The experimental design responses evaluated were the technological properties of the fibers: water-holding, oil-holding, and swelling capacity. Since these properties were present in high levels, the lemon residues could be used to increase content of fibers in foods resulting in the addition of nutritional benefits for the consumers.