Optimization of Drying Conditions for Chamchwi (Aster scaber Thunb.) Using the Response Surface Methodology with a Central Composition Design

Abstract

This study aimed to establish the optimal drying conditions that minimize quality changes during hot air drying for Chamchwi, a leafy vegetable. Drying temperature (50, 60, 70°C) and time (60, 150, 240 min) were set as independent variables, and the physicochemical characteristics were analyzed after drying. A central composite design was used to design 13 experimental points, and the dependent variables included moisture content, water absorption capacity, chromaticity, strength, total polyphenols, total flavonoids, β-carotene, total chlorophyll, chlorophyll a, chlorophyll b, and volatile aroma components. The optimization variables were moisture content, water absorption capacity, leaf, and stem strength, a* value, and total flavonoid content with a model P-value of 0.05 or less and R 2 values of 80% or more. The optimized drying conditions were a temperature of 56.87°C and a time of 156.36 minutes. The corresponding predicted values were moisture content 10.27%, water absorption capacity 12.54%, leaf strength 47.44 kg/cm 2 , stem strength 51.86 kg/cm 2 , a* value of −2.54, and total flavonoid contents 11.25 μg/mL.