Kineting modeling of hazelnut drying: effects of different cultivars and drying parameters

In this study, for the first time, six different hazelnut cultivars, characterized by different carpological traits (diameter, volume, weight, density, shell thickness, shape index, empty volume between kernel and shell), were utilized for conducting 60 experiments in a lab-scale convective dryer, in which different drying air conditions (temperatures: 20°C, 35°C, 50°C; relative humidity: 20%, 40%, 60%; airflow: 0.5 m/s) were explored with a Design of Experiment approach. The obtained drying curves where mathematically modelled and, among the tested kinetic models, the Fick’s equation proved to best fit the drying data and was chosen to estimate the equilibrium moisture content (Me) and the drying rate (k) for each experiment, based on the studied variables. The k parameter was found to be greatly affected (p < 0.01) by the carpological traits related to the hazelnut dimension, by T and RH. Conversely, a weak correlation (p ≈ 0.05) was found between the carpological traits and Me which, instead, resulted being greatly affected by T and RH (p < 0.01).