Modulated Solar Irradiation: Impact on Drying Behavior and Quality Attributes of Chile de Agua (Capsicum annuum L.) Peppers Harvested at Different Maturity Stages

Drying chili peppers is a crucial technique for their preservation, as it extends shelf life while minimizing the degradation of high-value bioactive compounds. This study evaluated the impact of modulated solar irradiation on the drying kinetics and quality retention of “Chile de Agua” (Capsicum annuum L.) peppers across three maturity stages (unripe, ripe, and overripe). Two cylindrical solar dryers were employed: a conventional solar dryer (CSD) and a novel Solar Dryer with Dynamic Irradiance Control (SDIC) utilizing Polymer Dispersed Liquid Crystal (PDLC) technology. Drying behavior was analyzed through moisture ratio and drying rate, while quality attributes were assessed via color parameters, capsaicinoid content, and flavonoid profiling using UPLC-PDA-ESI-MS. Results demonstrated that the maturity stage significantly influences drying kinetics; unripe fruits exhibited the fastest dehydration rate, reducing drying time by approximately 14% compared to overripe fruits. Regarding quality, the CSD better preserved color (ΔE of 15.29 for ripe chilies). At the same time, the SDIC system significantly favored the retention of bioactive compounds, maintaining higher concentrations of total capsaicinoids (up to 1700 µg/g DW) and flavonoids such as luteolin (15.9 mg/100 g DW) and quercitrin (11.5 mg/100 g DW), especially in ripe fruits. The findings suggest that optimal processing requires selecting the drying method based on the targeted final use: CSD for color preservation in unripe chilies, or SDIC for maximizing bioactive retention in ripe fruits.