Preserving bioactive compounds in avocado peel through convective drying: RSM-based optimization and multivariate modeling

• Page model predicted avocado peel drying kinetics exceptionally (R²>0.99) • 3 mm thickness maximizes phenolics; chlorogenic acid peaks at 181.53 µg·g⁻¹ db • PCA revealed 46.6% for PC1, which links antioxidants to shorter drying times • Optimal conditions: 45°C, 3 mm, 1.85 m·s⁻¹ airflow (desirability = 0.724) • Multivariate framework enables circular valorization of avocado’s processing waste Industrial avocado processing generates underutilized byproducts rich in bioactive compounds with potential functionality. This study evaluates convective drying for stabilization, focusing on the effects of temperature (45 to 75°C), airflow (0.5 to 2.5 m·s⁻¹), and thickness (3 to 9 mm). Results demonstrated that sample thickness was the dominant kinetic regulator: 3 mm samples dried fastest (100–270 min), while 6 mm exhibited extreme variability (165–810 min) due to inconsistent moisture pathways. The Page model successfully described the drying kinetics (R 2 >0.995), while effective moisture diffusivity ranged from 2.79 × 10⁻ 10 to 2.25 × 10⁻ 9 , driven by enhanced molecular mobility at higher temperatures. Bioactive conservation showed thickness dependence; chlorogenic acid peaked at 181.53 µg·g⁻¹ under high-temperature short-time conditions (75°C, 3 mm, 1.5 m·s⁻¹). Principal component analysis (PCA) segregated variance into three principal components: PC1 (46.6% variance) grouped antioxidant metrics (TPC, DPPH, ABTS) with chlorogenic acid and quercetin, linking preservation to short drying times; PC2 (16.5%) revealed kinetic-bioactivity trade-offs; and PC3 (15.6%) highlighted ferulic acid’s unique behavior. Multivariate optimization identified 45°C, 3 mm, and 1.85 m·s⁻¹ as the optimal conditions (desirability = 0.724), balancing bioactive integrity with process efficiency. These insights enable scalable valorization of waste streams through potentially energy-efficient protocols that mitigate thermal degradation and align with circular economy principles.