Drying of prickly pear cactus cladodes (Opuntia ficus indica) in a forced convection tunnel

In this work we evaluated the kinetics of drying of Opuntia’s cladodes observing two conditions: complete cladode with the protective cuticle of the intact product and with reduced cuticle (partially removed), using a drying tunnel with forced flow. The temperature of the air was set at 35, 45, and 60 °C with velocities of 1.5 and 3.0 m/s. The conditions of the environment were controlled and maintained at 22 °C and 30% of relative humidity. The results show that the drying time was considerably reduced when approximately 30% of the cuticle that protects the product was removed. Additionally, the temperature had greater influence than the velocity of the air. The numerical model that best describes the behavior of the drying process is the double logarithmic one, with the imposed restrictions of r close to the unit, the lowest possible χ2 and the RSEM tending to zero. The characteristic drying function of the product resulted in a third-grade exponential curve, where r and SD were the corresponding selection criteria.