2.4. Central Composite Design (CCD) and Response Surface Methodology (RSM)

Response surface methodology (RSM) using central composite design (CCD) was used to evaluate the effect of the selected independent variables on the EAE extract yields, Trolox equivalent antioxidant capacity in the ABTS^•+ assay (TEAC_ABTS), and total phenolic content (TPC), and to identify the optimal conditions for EAE. Design-Expert version 12.0.8.0 (Stat–Ease Inc., Minneapolis, MN, USA) was used to establish the models and analyze the results. All extraction experiments were performed in random order. One-way analysis of the variance (ANOVA) and statistical significance of the model and each variable was determined using the Student’s t-test (p-value) at a 5% probability level (p < 0.05). The model’s adequacy was determined by evaluating the ‘lack of fit’ coefficient and the Fisher test value (F-value) obtained from ANOVA.