Ultrasonic composite acidic water extraction method for cordyceps polysaccharide and cordycepin in Cordyceps militaris

An ultrasonic composite acidic water extraction method for a Cordyceps polysaccharide and cordycepin in Cordyceps militaris, comprising the following specific steps:

• (1) culturing and harvesting:
• culturing Cordyceps militaris fruiting bodies in a solid medium, harvesting after 40-45 days of the culturing, and storing the harvested Cordyceps militaris fruiting bodies under refrigeration at 4° C.;
• (2) washing and drying:
• drying the harvested Cordyceps militaris fruiting bodies for 5 hours in a hot-air drying oven at 60-65° C. during which the Cordyceps militaris fruiting bodies are arranged evenly and kept ventilated;
• and collecting and storing same in a cool and dry place after drying to a constant weight;
• (3) pulverizing:
• crushing a dry sample of Cordyceps militaris, and passing through a 60-mesh sieve;
• (4) degreasing:
• placing the pulverized sample in a reflux device, performing reflux extraction with 95% ethanol at a material-liquid ratio of 1:5 (w:v) in a boiling water bath for 3 hours, centrifugation, collecting the precipitate, and drying at 60-65° C. to a constant weight, to obtain a degreased cordyceps powder;
• (5) ultra-low temperature freezing-microwave defrosting cycle:
• adding distilled water into the degreased cordyceps powder at a material-liquid ratio of 1:40 (w:v), to obtain an extract;
• stirring and titrating the extract with 1 mol/L of a diluted acid solution to obtain a pH of 4.8±0.2;
• freezing the extract for 2 hours at −80° C.;
• taking out the extract, and defrosting for 2-3 min using microwaves with a power of 300-400 W;
• and repeating the freezing and the defrosting operations three times, to obtain a crude extraction mixture of Cordyceps militaris;
• (6) ultrasonic-assisted extraction:
• after obtaining the crude extraction mixture of Cordyceps militaris, extracting for 35-40 min at 65-70° C. with the assistance of ultrasonic waves having a frequency of 20-30 KHZ and a power of 300-400 W;
• and after the ultrasonic-assisted extraction is complete, centrifuging for 15 min at 4,000 r/min, and filtering the supernatant to obtain a crude water extract of the Cordyceps militaris fruiting bodies;
• (7) evaporation and concentration:
• concentrating, by rotary evaporation at 60-65° C. and at 0.095 MPa, the crude water extract of the Cordyceps militaris fruiting bodies to 1% of the original volume, until it finally becomes a viscous and thick slurry;
• collecting the concentrated crude water extract of the Cordyceps militaris fruiting bodies, and freezing for 24 hours at −70° C.;
• and
• (8) freeze-drying to prepare powder:
• performing freeze-drying on the frozen concentrated crude water extract of the Cordyceps militaris fruiting bodies for 3 hours in a cold trap at −55° C., to obtain a dry powder of the crude water extract of the Cordyceps militaris fruiting bodies.