## 1 Introduction  
Drying involves the movement of heat from its source to a given material in order to remove a specific amount of water from said material. This can be achieved solely by radiation, convection, or conduction, as well as by using two of the aforementioned methods at the same time, or all of them simultaneously. As a result, a product with reduced water content is obtained, which reduces the risk of moisture-mediated spoiling reactions [1, 2, 3]. In infrared drying (IR), infrared radiation energy (as electromagnetic wave) is delivered directly to the surface of the material being dried without heating the surrounding air. This energy is absorbed mainly by the surface layers of the material, but depending on the properties of the matrix and IR wavelength, it can penetrate to a small depth. The infrared wavelength radiation produced by the source interacts with the internal structure of the material, which undergoes the drying process. An increase in the material's surface temperature increases the vapor pressure, which intensifies the diffusion of water molecules from deeper layers of the material towards its surface. The induced molecular excitationsprovide rapid heating of the material, which, in turn, increases mass transfer. Compared to conventional convective drying (CD), also called hot-air drying (HAD) because of the use of hot air as the drying medium, infrared drying is generally characterized by higher drying efficiency, which results from a higher energy transfer rate. In addition, reduced energy consumption, more efficient transmission through the air (less energy waste), and better product quality should also be acknowledged [1; 2; 3; 4; 5; 6; 7; 8; 9]. Combining both techniques as a hybrid method (IR and CD/HAD) appears to be superior to other methods due to its synergistic effect. The surface of the material being dried absorbs infrared radiation, which, in turn, results in an increase in its temperature. Subsequently, there is an intense movement of water molecules towards the surface, from where they are evaporated by a flow of air (which additionally reduces the temperature of the material's surface, simultaneously reducing the risk of burning it) [8]. Regarding this hybrid method, it is worth considering using a relatively slow air flow to reduce the risk of a cooling effect [5]. It is also necessary to take into account the risk of thermal degradation of the material in the event of incorrect selection of the radiation intensity or the distance between the infrared source and the material being dried [4; 6; 10]. Both the course of infrared-convective drying and the properties of the dried product obtained in this way can be adjusted by appropriately modifying the tissue at the pretreatment stage. So far, among the nonthermal pretreatments, mainly the effect of ultrasound (US) on IR-CD of matrices such as blackberry [11], kiwi [12], strawberry [13], and scallion stalk [14] has been studied. The results are promising: shortening of the drying time of strawberries; lightening of their color and increasing their redness; higher retention of anthocyanins and total phenols [13]; increased drying efficiency in the case of kiwi [12]; and reducing the color difference in relation to both fresh blackberry [11] and scallion stalk (additionally shortening the drying time of this material) [14]. Loosening of the apple tissue, subjected to IR-CD via electroporation, the primary mechanism of pulsed electric fields (PEF), has not yet been comprehensively analyzed. This is another promising nonthermal pretreatment that, unlike US, which creates microscopic channels in solid-like matrices [13; 15], generates pores in the cell membrane [16; 17]. Despite the many benefits of assisting convective drying with infrared radiation, there are many process parameters whose incorrect settings may cause undesirable effects.