Optimizing Microwave-Assisted Extraction of Snow Chrysanthemum Polysaccharides

Both the single-factor experimental design and Box–Behnken experimental design were also applied for the optimization of the microwave-assisted extraction (MAE) conditions. Briefly, the snow chrysanthemum powder (1.0 g) was firstly refluxed with 10 mL of 80% (v/v) ethanol at 80 °C for 2 h to remove most of the small molecules. Subsequently, the extract residue was extracted with deionized water by MAE (MKJ-J1-3, Qingdao Makewave Microwave Applied Technology Co., Ltd., Shandong, China), and the effects of the microwave power (240, 320, 400, 480, and 560 W), extraction time (2, 4, 6, 8, and 10 min), and ratio of water to raw material (30, 40, 50, 60, and 70 mL/g) on the yield of SCPs were investigated using a single-factor experimental design. Finally, the crude snow chrysanthemum polysaccharides (SCP-M) were obtained according to the same treatment processes as described in Section 2.2.1.
Furthermore, based on the results of the single-factor experiments, a three-level Box–Behnken experimental design (BBD) with three factors was also applied to optimize the MAE conditions. The microwave power (X₂₁, W), extraction time (X₂₂, min), and ratio of water to raw material (X₂₃, mL/g) were preferred for the independent variables. The variables and their levels, with both coded and actual values, were also presented in Table 1. Statistical analysis was performed the same as described in Section 2.2.2.