Extraction optimization by response surface methodology of mucilage polysaccharide from the peel of Opuntia dillenii haw. fruits and their physicochemical properties.

In this study, response surface methodology (RSM) was employed to optimize microwave-assisted extraction (MAE) technology of mucilage polysaccharide from the peel of Opuntia dillenii haw. fruits (OFPP), and the physicochemical characteristics of OFPP were also investigated. The three parameters were the ratio of water to raw material (30-40ml/g), microwave power (300-400W) and extraction time (120-180s). The results indicated that the yield of OFPP was 15.62±0.37% under the optimum extraction conditions. Compared with MAE, the OFPP yield by hot water extraction (HWE) was 13.36±0.71%. In addition, the rheological properties of OFPP were also explored. The OFPP obtained by HWE exhibited a lower viscosity compared with that by MAE. The FT-IR spectra analysis, scanning electron microscopy (SEM) observation and thermogravimetric analysis (TGA) revealed that there were strong interactions between Ca(2+) and OFPP, which resulted in the high viscosity, different microstructure and thermal stability of OFPP.