A mixed-mode solar drying was developed to evaluate the physicochemical and colorimetric properties of Zompantle (Erythrina americana). A 2²-factorial design was used; the operation mode (mesh shade and direct) and airflow (natural convection and forced convection) were established as factors in this design. The initial moisture content in the Zompantle flower was reduced from 89.03% (w.b) to values that ranged from 3.84% to 5.84%; depending on the operation mode of the dryer, the final water activity ranged from 0.25 to 0.33. The Zompantle’s components as proteins (4.28%), antioxidant activity (18.8%), carbohydrates (4.83%), fat (0.92%), fiber (3.71%), ash (0.94%), and total soluble solids (3°Brix) increased as the water was evaporated during the drying. The increment in the Zompantle’s components depends on the operation mode; in direct mode and natural convection, the proteins, antioxidant activity, carbohydrates, fat, fiber, ash, and total soluble solids were 6.99%, 61.69%, 79.05%, 1.20%, 3.84%, 8.70%, and 45 °Brix, respectively. The total drying efficiency was 14.84% with the direct mode and natural convection (DM-NC) and 17.10% with the mesh shade and natural convection (MS-NC). The Hue angle measures the property of the color; the indirect mode and natural convection keep the hue angle close to the initial value (29.2 °). The initial chroma value of the Zompantle flower was 55.07; the indirect mode and natural convection kept high saturation (37.58); these dry conditions ensured a red color in the dehydrated Zompantle. Dehydrated Zompantle’s flowers could have several practical applications, such as an additive in traditional Mexican cuisine.

Marigold (Tagetes erecta L.), commonly known as Cempasúchil, is a significant symbol of Mexico's Day of the Dead celebrations. However, once the festivities conclude, the flowers and petals are frequently discarded as waste, contributing to environmental pollution. Cempasúchil was dehydrated using an active mixed-type solar dryer to address this issue. This method establishes an environmentally friendly, easy-to-use, cost-effective, and practical preservation technique for rural communities. The maximum drying temperature was 69.65 °C, and the maximum solar irradiance was 1080.60 W/m². The initial moisture content began at 87.35% and finished at 4.93%. The initial colorimetric parameters were: lightness 65.44, a 32.43, b 78.38, Chroma 84.83, and Hue angle 67.53°. The antioxidant activity of the marigold flower was 93.51%, ascorbic acid 27.86 mg/100 g, total phenols content 28.06 mg GAE/g dry mass (gallic acid equivalents), total flavonoids content 6.34 QE/g (quercetin equivalent) and carotenoid content 2.07 mg/g. After drying it was observed an increment in vitamin C (from 27.86 to 75.675 mg/100 g), carotenoids content (from 2.073 to 18.947 mg/100 g.), and antioxidant activity (from 93.513 to 98.178%). No significative changes in total phenols content with a value of 28.488 QE/g for dried marigold samples and flavonoid content from 6.348 QE/g and 6.622 QE/g were observed. Dried flowers and petals can be used in practical applications, such as in agriculture. They serve as a natural insecticide, providing an alternative for pest management, and can also act as a fertilizer, enhancing the soil's physical, chemical, and biological conditions.