Abstract:

Different cultivated species of Ganoderma from different geographic origins were analyzed for their chemical components, and Ganoderma lucidum from Zhejiang province was found to contain higher content of non-reducing sugars and lower contents of protein and ash and therefore, it was the selected raw material for extracting polysaccharides. The extraction process with water as extraction solvent on an ultrasonic-microwave synergistic extractor was optimized using response surface methodology based on Box-Behnken experimental design. Meanwhile, the structural change of Ganoderma lucidum before and after extraction was observed under scan electron microscope (SEM) and the extraction method developed in this study and the conventional water bath extraction method were compared for differences in the extraction yield of polysaccharides and the infrared spectral characteristics of the extraction products. The optimum conditions for the ultrasonic-microwave synergistic extraction of polysaccharides were found to be: raw material amount 100 g, microwave power 284 W, extraction duration 12 min, and material-to-liquid ratio 1:11.6 (g/mL). Ultrasonic-microwave synergistic extraction was time saving and gave a higher extraction yield of polysaccharides, 3.27%, when compared with the conventional water bath extraction method (115.6% extraction yield of polysaccharides).

Key words: ultrasonic-microwave synergistic extraction, conventional water bath extraction, Ganoderma lucidum polysaccharides, yield