## 5 Future Perspectives and Challenges  
Emerging drying technologies represent innovative and promising alternatives for the dehydration of plant-based products, promoting the preservation of nutritional, sensory, and functional attributes. In addition to improving energy efficiency and process selectivity, these techniques play a crucial role in retaining bioactive compounds such as phenolics, flavonoids, carotenoids, and vitamins, which are highly susceptible to thermal and oxidative degradation. Despite significant progress, technical challenges remain, especially regarding the optimization of operational conditions to ensure the maximum retention of these compounds. The precise control of parameters such as the temperature, exposure time, and thermal radiation intensity is essential to avoid significant losses. In this context, hybrid approaches that combine different technologies have proven particularly effective in maintaining the chemical and functional stability of bioactives. Among the analyzed technologies, freeze-drying stands out as one of the most effective for preserving bioactive compounds, particularly due to the absence of heat during drying. Although this is a costly and low-throughput process, the reviewed studies highlight its high retention capacity for heat-sensitive compounds, especially when combined with pretreatments or rapid freezing techniques [73]. However, freeze-drying presents challenges such as prolonged drying times, which can extend from several hours to days, and high overall costs, making it unsuitable for low-cost food products [71]. Radiofrequency drying has shown promise due to its volumetric penetration and uniform heating, resulting in reduced thermal degradation and the enhanced release of antioxidant compounds [64], although its industrial application remains limited. Microwave technology has demonstrated a high efficiency with significantly reduced processing times, ensuring a good retention of crocin, phenolic compounds, and volatiles. This makes it a more accessible alternative compared to freeze-drying and infrared. However, challenges related to thermal uniformity and industrial scalability still limit its widespread adoption [55]. Infrared radiation can be an effective tool for preserving bioactive compounds during the drying process, especially phenolics and flavonoids, which exhibit strong antioxidant activity. The main advantage of IR lies in its ability to rapidly heat materials, releasing bioactives without prolonged heat exposure, thereby protecting these sensitive substances. Nonetheless, using IR in heat-sensitive foods presents challenges, as its high thermal efficiency and application conditions may not always be suitable. Excessive IR heating may result in quality deterioration, such as over-roasting or undesired alterations during fruit peeling, potentially affecting the texture, color, and bioactive content [110; 111; 114]. Ultrasound, mainly used as a pretreatment, has demonstrated beneficial effects by enhancing the drying process through microstructural changes in plant matrices that favor moisture diffusion and the preservation of bioactive metabolites [2]. Lastly, cold plasma emerges as an innovative non-thermal approach with a potential for the surface modification of foods, microbial inactivation, and possible improvements in the stability of bioactive compounds. However, it remains an exploratory technology requiring further research into its efficacy, safety, and scalability for industrial applications [101]. Continued scientific and technological investigation is essential to consolidate these techniques and enable their transition from laboratory-scale to commercial applications. Future studies should also deepen the understanding of the relationship between drying methods and the bioavailability of bioactive compounds, ensuring not only their retention during processing but also their effective functionality in the human body.