Optimization of Subcritical Water Extraction of Polysaccharides from Inonotus Obliquus and their Antioxidant Activities

Subcritical water extraction (SWE) of Inonotus Obliquus polysaccharides (IOP) was investigated using response surface methodology (RSM) with a design by Box–Behnken design (BBD). Results showed that the optimum SWE conditions for IOP production were as follows: extraction temperature 194°C, residence time 5.36 min and liquidsolid ratio 53 mL/g, yielding 168.80 ± 0.59 mg/g of IOP, which was in close agreement with the values predicted by the mathematical model. FT-IR spectra of the polysaccharides extracted by SWE and hot water extraction (HWE) were compared as well. Moreover, in vitro antioxidant assays revealed that SWE-IOP exhibited stronger scavenging activity that HWE-IOP. This investigation suggests that polysaccharides of Inonotus Obliquus extracted by SWE could be further developed as a potential antioxidant resource for dietary supplements of functional food.