**1. Introduction**

Convective drying removes water from a wet product by the simultaneous transfer of heat and mass [1, 2]. The process involves using a stream of hot air (provided by an electrical resistance and a propeller fan) that distributes the temperature to one or more drying chambers containing trays with samples [3]. The hot air increases the energy transfer over the product surface by convection and can reach the product interior by conduction or diffusion depending on the product structure and dimensions [4, 5]. At the same time, product moisture is transferred from the product surface to the air by convection and from the product interior by diffusion, convection or capillarity [1]. Thus, the drying rate and the quality of the dried product depend on the external conditions (temperature, relative humidity, airflow speed and direction) and internal conditions (geometry, thickness, porosity and chemical composition of the product) of the process [6].

The main advantages of the industrial use of convective drying are that it allows processing large quantities of foods, the heat distribution within the system is uniform, and the cost of the equipment is relatively low [7, 8]. However, drawbacks include low process speed, significant loss of product quality (shrinkage, deformation, water holding capacity, color and flavor) and high energy consumptions when working at high temperatures [4, 9–11]. Damage to product quality could be minimized by using low process temperatures, reducing detrimental reactions, and improving the quality of dried foods. Unfortunately, this increases the duration of treatment and the energy costs of the process [12]. On the other hand, osmotic dehydration, blanching or ultrasound are pre-treatments used to prevent enzymatic browning, morphometrical changes, or add solutes foy modify flavor, color, texture, etc. [13–15].

Osmodehydration of fruits and vegetables is a mass transfer process in which food is immersed in a hypertonic solution (of one or more solutes) known as osmotic solution. During this process, the product undergoes partial dehydration, thereby increasing its solids content [16]. However, the mass transfer process stops when the difference between the water activity of the osmotically dehydrated sample and the osmotic solution is not significant [17, 18]. This pre-treatment of drying is widely used because it helps to reduce consumption of energy and drying time [19, 20].

The kinetics of the dehydration process is a complex heat and mass transfer phenomenon [21]. Models of dehydration of food materials provide simple representations of a complex geometric solid process, which have proven to be very useful for drying system's design, construction, and operation. To this end, these transport properties can be monitored through kinetic models of drying [22].

Theoretical, empirical, and semi-theoretical models have been reported to describe dehydration process kinetics for biological materials. The choice of the model is influenced by the behavior of experimental data of the process according to the type of material, product geometry, equipment technology and process conditions [23]. Theoretical models take into account the internal resistance to heat and energy transfer; in contrast, empirical and semi-theoretical models, only consider the external resistance to transfer at the interface of the food matrix and the drying system [24], also provide greater understanding of the transport processes by better fitting the experimental data [25].

Therefore, this work used different mathematical models to describe the drying kinetics of osmodehydrated apple cubes (Granny Smith var.) with sucrose solution.
