Optimization of complex enzyme‐ultrasonic synergistic extraction of water‐soluble polysaccharides from Perilla frutescens seed meal: Purification, characterization and in vitro antioxidant activity

The new feasible complex enzyme-ultrasonic synergy extraction (CEUE) was optimized by response surface methodology (RSM) for extracting Perilla seed meal polysaccharides (PSMP), the optimum extraction conditions were: compound enzyme dosage (X1) of 6.6%, liquid–solid ratio (X2) of 25 ml/g, extraction time (X3) of 61 min, extraction temperature (X4) of 62°C, the verified yield was 7.711 ± 0.201% at the optimum extraction conditions. The RSM results confirmed that the effects of X1 and X4 on CEUE yield were more significant than X2 and X3. The maximum weight loss rate of PSMP and purified component PSMP-1 due to degradation of polysaccharides were −4.84%/min (295.33°C) and −8.47%/min (313.67°C) according to thermogravimetry and differential thermogravimetry (TG-DTG) curves. PSMP and PSMP-1 were β-D-glucopyranose compounds, composed of rhamnose, arabinose, xylose, mannose, glucose, galactose, with relative molar ratios 6.07:40.78:10.91:1.34:1.00:5.12 and 0.69:11.13:5.55:0.90:1.00:4.71. This study determined physicochemical and antioxidant activities properties of Perilla polysaccharides. Practical applications As hot water extraction (HWE) process is a traditional method for polysaccharide extraction, high cost of manipulating with respect to duration and energy consumption limit the promotion of this technology. In this work, the CEUE process optimized by RSM is more suitable for research and development of highly active natural ingredients and is a promising alternative method for HWE of polysaccharides for advantages of high efficiency and energy saving. If the one-time fixed investment cost of the equipment was put aside, CEUE can effectively decrease subsequent operating costs by reducing the extraction temperature, shortening extraction time, and increasing raw material utilization.