Hence, traditional procedures for extraction
begin with powders of raw materials being defatted by organic solvents
or with 80% aqueous ethanol to eliminate low molecular
weight compounds. After that, the material is successively
extracted with water (e.g., 100 C for 3 h), or with saline and
diluted alkali solutions at different temperatures (e.g., 2% ammonium
oxalate at 100 C for 6 h, and 5% sodium hydroxide at 80 C
for 6 h). The hot water extraction yields water-soluble polysaccharides;
on the other hand, extraction with alkali solution yields
water-insoluble ones (