Optimization Of Processing Conditions To Extract Bioactive Compounds From Eggplant Peel

Abstract

Eggplant peel is notable for high bioactive compounds. In this study, Plackett Burman design was used for screening with the aim of achieving three significant factors among seven factors including ethanol concentration, extraction duration, solvent/solid ratio, extraction temperature, pH, and drying temperature. As a result, ethanol concentration (70-90%), solvent/solid ratio (30-50mL/g), and drying temperature (50-70°C) were proved to be significant. The optimal range of levels from the three significant parameters were then chosen to conduct the Box-Behnken design. Then Box-Behnken design was used to attain optimal levels of the three significant parameters. The responses were total phenolic content, anthocyanin content, and antioxidant activity. Statistical analysis showed that these three factors significantly affected the three responses, and drying temperature was the most crucial factor. For total phenolic content, anthocyanin content, and antioxidant activity, the predicted maximum yield were 21.98 mg GAE/g dry basis, 0.67 mg CGE/g dry basis, and 27.04 mg TE/g dry basis, respectively, and the optimal conditions were drying temperature at 53°C, ethanol 78%, and solvent/solid ratio at 44 mL/g. In the validation, TPC, anthocyanin content, and antioxidant activity of the eggplant peel were 21.43±0.62 mg GAE/g dry basis, 0.64±0.02 mg CGE/g dry basis, and 25.51±0.38 mg TE/g dry basis, respectively. In conclusion, eggplant peel is a good source of bioactive compounds, and the combination of Plackett-Burman design and Box-Behnken design were proved to be effective in screening and optimization.