## 4 Discussion
Studies on apple slices and vegetables have shown that hybrid IR-convective systems reduce drying time by up to 57% compared to convective-only methods while maintaining high product quality [42]. Similarly, in bread baking processes, hybrid heating modes have been shown to reduce process times by up to 28% compared to conventional methods while improving product characteristics such as volume and texture [39]. The IR drying system not only reduced drying time by up to 69% but also lowered the system's energy consumption by 43.2%. This reduction in drying time is attributed to the synergistic effect of IR heating, which accelerates heat and mass transfer, leading to faster evaporation of water from the material [43]. The bread slices exhibited drying kinetics marked by an initial rapid moisture loss, which transitioned into a slower drying phase controlled by diffusion (Figure 5). Sensor data showed a sharp decrease in moisture content over the first 50 min of drying, which correlated with the removal of free water from the surface of the bread slices. Following the initial phase, the moisture loss rate decreased as the drying process transitioned to being controlled by the diffusion of water from the bread's interior to its surface. Sensors recorded the maximum WLS values over 5 min of CIRD (WLS\({}_{\text{A}}\) = 5.15 g/min, WLS\({}_{\text{B}}\) = 10.91 g/min, WLS\({}_{\text{C}}\) = 6.95 g/min and WLS\({}_{\text{D}}\) = 4.30 g/min). Towards the end of the observed period (around 100 min onwards), the WLS curves tend to flatten out, suggesting that the rate of water loss slows down significantly and approaches a steady state. Model D maintains a slightly higher WLS than the others during this phase. Samples A and C exhibit similar behavior, showing a moderate initial WLS followed by a comparable reduction in water loss over time. The observed trends in WLS are consistent with the general principles of drying processes. In Model B (Figure 6), both Maillard and caramelization reactions occurred. [PERSON] et al. observed similar browning indicators during the toasting of 10 mm thick, 25 g slices of bread [44]. At the peak of WLS, marking the onset of drying and maximum water evaporation, Maillard reactions predominantly contributed to the formation of \"burnt\" areas on the bread. In the study by [PERSON] et al. (2016), it was also noted that the color saturation of bread slices increased with rising temperature, and that IR drying resulted in more intense color reactions [43]. Figure 2 supports this claim, showing the highest average drying temperatures that the bread slices are subjected to. The color pigments formed on the surface area generally agree with the fact that the browning precursors experience caramelization and Maillard reactions which are highly influenced by the quality and quantity of the precursors, thermal processing parameters, pH, and quantitative ratio of amino nitrogen to reducing sugar during baking [45]. Bread is a raw material abundant in amino acids and reducing sugars, primarily glucose, which are formed through the breakdown of proteins and starch. The interactions between these components, combined with the reduction of water activity and the rise in the bread's surface temperature above 100 \({}^{\circ}\)C, create favorable conditions for the formation of melanoidins--the characteristic products of the Maillard reaction [46; 47]. The color correlation matrix visually represents the relationships between various independent parameters and response variables in the CIRD (Figure 7). The color intensity and size of the circles indicate the strength and direction of the correlations, where darker blue signifies strong positive correlations and darker red indicates strong negative correlations [48; 49]. Water loss parameters (WLm, WLi) exhibit strong positive correlations among themselves and with drying time (t), indicating that higher drying times result in greater water loss, consistent with established drying kinetics.