Effect of Foam-Mat Drying Methods on Quality Attributes of Green Chili Powder

This study evaluated foam-mat drying methods (sun, cabinet, and vacuum) for green chili powder production. Fresh chilies (86.21% moisture) contained 6.24% protein, 412.81 mg GAE/100g phenolics, 141.43 mg/100 g vitamin C, and 1666.27 μg/g capsaicin, with strong antioxidant activity (DPPH: 145.21 μM Trolox eq./g; FRAP: 236.74 mM Fe(II)/100 g). Foamed chili foamed paste supplemented with 5%–15% albumin and 2% starch was dried, with vacuum drying showing optimal kinetics (diffusion coefficient: 9.15 × 10⁻¹⁰ m²/s) and nutrient retention: highest protein (11.78%), phenolics (965 mg GAE/100g), flavonoids (395.43 mg QE/g), and β-carotene (985.16 μg/100 g). It preserved chlorophyll (2.67 mg/100 g chlorophyll a; 3.71 mg/100 g chlorophyll b), minimized vitamin C loss, and maintained capsaicin content. Vacuum-dried powder exhibited superior antioxidant activity (DPPH: 338.78 μM Trolox eq./g; FRAP: 553.63 mM Fe (II)/100 g) and color stability, alongside excellent functional properties (water absorption: 178 g/100 g; oil absorption: 111 g/g). Microstructure analysis revealed compact, smooth particles, confirming structural integrity. In contrast, cabinet drying and sun drying caused higher nutrient degradation and color deterioration. The results demonstrate that vacuum drying combined with foaming is the most effective method for producing nutrient-rich, high-quality green chili powder with enhanced bioactivity and functional quality.