Peach is a fruit highly appreciated by consumers; however, it is highly perishable, so drying is an alternative to preserve its physical and chemical properties. In this study, the effect of drying in natural and forced convection at three different temperatures (40 °C, 45 °C and 50 °C) and solar drying with two air velocities (1 m/s and 3 m/s) on the color, texture, total phenol content and antioxidant capacity of peach (Prunus persica (L.) Batsch), were evaluated. The experimental data of the drying kinetics were adjusted to five different mathematical models (Page, Logarithmic, Two-term exponential, Wang and Singh, and Verma et al.). The model that best represented the experimental data in natural convection was the Wang and Singh model (r² > 0.998; RMSE < 0.016; χ² < 2.85 × 10⁻⁴); in forced convection (45 °C and 50 °C), it was the Verma et al. model (r² > 0.997; RMSE < 0.025; χ² < 8.12 × 10⁻⁴); and finally, for solar drying, it was the Logarithmic model at 3 m/s (r² = 0.999; RMSE < 0.012; χ² < 1.12 × 10⁻⁴) and Wang and Sing model (1 m/s) (r² = 0.998; RMSE = 1.31 × 10⁻⁴; χ² = 1.92 × 10⁻⁴). The highest color difference was in samples dried by the natural convection method. The highest values of hardness were obtained by the solar drying method. The value of chlorogenic acid increased with the temperature of natural convection, while the concentration of neochlorogenic acid increased with the temperature at forced convection. For solar drying, the values of chlorogenic acid were greater at 3 m/s; in contrast, the neochlorogenic acid was greater at 1 m/s.

As one of the main chili varieties in Mexico, Yahualica chili requires year-round availability. This study examines the feasibility of five drying methods (open-air, solar, microwave, freeze-drying and shade drying) used to preserve this culturally and economically valuable product. The results show the drying duration and rate for solar drying with varying air temperatures (40, 50, 60, and 70 °C) and airflows (150, 200, 250, and 300 m³/h) and microwave drying with varying power levels (90, 160, 360, and 600 W). Convection drying efficiency increased with temperature and airflow, according to the findings. Microwave drying significantly reduced drying time, and higher powers further accelerated moisture removal. Open sun and shade drying was the slowest, and open sun drying was also susceptible to factors compromising quality. Total Phenolic Content (TPC), Total Capsaicinoids Content (TCC), and antioxidant activity had a positive effect, since the drying methodologies favored the release of these compounds.

The quality effects of spectral irradiance conditions during papaya (Carica papaya L.) drying were investigated using three different dryers: a solar dryer with dynamic irradiance control (SDIC), a cylindrical solar dryer (CSD), and a solar simulator dryer (SSD). This study builds upon previous PDLC film applications in solar drying by specifically examining its impact on phytochemical preservation and color degradation, addressing gaps in spectral-specific effects on food quality parameters. The drying conditions were as follows: a temperature of 50 °C for each method, 700 w/m² for both SDIC and solar simulator dryers (SSD), and full solar irradiance for the cylindrical solar dryer (CSD). The cylindrical solar dryer exhibited 210 min of drying time due to higher solar irradiance than SDIC (300 min), while SSD lasted 180 min. Drying rates were highest for CSD (0.056 g H₂O/g d.m. min⁻¹), followed by SDIC (0.027 g H₂O/g d.m. min⁻¹). Color analysis revealed that CSD resulted in the most significant color degradation, followed by SSD and SDIC. This was attributed to the varying spectral composition of radiation in each method. The CSD, with a full solar spectrum, including higher UV and visible radiation, induced more pronounced color changes than SDIC, which received lower intensity radiation in these ranges. Chemical analyses showed that SSD samples had the highest antioxidant activity (1432.91 µmol TE/g dw by ABTS) and phenolic content (58.92 mg GAE/100 g), suggesting simulated conditions may better preserve certain phytochemicals. SDIC maintained better carotenoid-related color parameters while showing intermediate antioxidant levels (1084.09 µmol TE/g dw). These results demonstrate that irradiance control significantly impacts drying efficiency and quality parameters.

In this study, a novel adaptive solar dryer with a coating of polymer-dispersed liquid crystals (PDLC) was designed, built, and characterized to evaluate its optical properties and thermal performance by modulating the transmission of solar radiation toward the drying chamber. PDLC films can electrically switch between opaque and transparent states, making them ideal for controlling solar radiation. Unlike conventional direct dryers, the proposed solar drying system takes advantage of direct solar radiation, known for its rapid drying process, while minimizing the impact on product properties. The results show that the PDLC coating exhibited a significant difference in transmittance between the “on” and “off” states under ambient conditions. At 400 nm, the transmittance varied by 20 %, increasing to 30 % at 450 nm. The solar dryer with dynamic control of solar irradiance constantly maintained a temperature range of 52.19 °C–57 °C. Lower relative humidity values were achieved compared to the uncontrolled solar dryer, resulting in a uniform irradiance distribution within the drying cabinet. The solar dryer with dynamic control of solar irradiance (acrylic and PDLC film) presents a total thermal resistance (0.02817 mK/W) exhibiting better heat permanence inside the drying cabinet compared to polycarbonate (one of the materials most used for drying systems). The system's thermal efficiency ensures reliable operation regardless of weather conditions, efficiently capturing and converting solar energy into heat.

Post-harvest food loss significantly threatens global food security, and solar drying offers a sustainable preservation solution. The effectiveness of solar drying depends on consumer acceptance, in which color is a critical quality attribute. This study investigated how solar irradiance and temperature affect color degradation during the drying of pineapple (Ananas comosus), orange (Citrus × sinensis), and beet (Beta vulgaris L.). Experiments conducted in Zacatecas, Mexico, compared a Solar Dryer with Dynamic Irradiation Control (SDIC), which limited irradiance to 700 W/m², against an uncontrolled Cylindrical Solar Dryer (CSD). The results indicate that the controlled SDIC environment promotes gradual and uniform color preservation by minimizing rapid thermal stress. In contrast, the fluctuating high irradiance and temperature of the CSD caused faster, less uniform color changes. Statistical analyses confirmed that both irradiance and temperature significantly impacted color parameters (p < 0.05). The SDIC method reduced the total color change (ΔE) by 30–47% in pineapple and beet compared to the CSD. Regression models identified temperature as the primary driver of redness (a*) degradation, while irradiance was strongly correlated with changes in yellowness (b*). This research highlights the necessity of optimizing solar drying conditions to enhance the quality of dried produce. By improving visual appeal, this optimized green technology can help reduce food waste and support the transition to more sustainable fod processing systems. This controlled approach reduced the total color change (ΔE) by 30–47% in pineapple and beet compared to the CSD, demonstrating its significant potential for quality preservation.