Optimization of extraction conditions for functional compounds from thinned unripe apple using β-cyclodextrin-based ultrasound-assisted extraction

Unripe apples contain more functional compounds than ripe apples and thus demonstrate significant potential for use as functional food materials. In this study, the conditions for the extraction of functional compounds from unripe apples were optimized using the response surface methodology. A Box-Behnken design was used to investigate the effects of three independent variables (β-cyclodextrin concentration, extraction time, and extraction temperature) on the total polyphenol content (TPC), chlorogenic acid content (CAC), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (RSA). The corresponding optimal extraction conditions were found to be 40 mg/mL, 53.03 min, and 60°C for TPC; 40 mg/mL, 46.67 min, and 60°C for CAC; and 20 mg/mL, 30 min, and 40°C for DPPH RSA. The experimental values obtained under these conditions were consistent with the predicted values, indicating that the model was suitable for optimizing the extraction of functional compounds from unripe apples.