Patent ID: 7226765

Claim:
A process for extracting polyhydroxyalkanoates from a biomass containing the polyhydroxyalkanoates comprising: a) combining the biomass containing the polyhydroxyalkanoates with a single main solvent to form a biomass liquor; b) heating the biomass liquor to at least partially solubilize the polyhydroxyalkanoates from the biomass containing the polyhydroxyalkanoates to form a PHA liquor; c) separating the biomass from the PHA liquor to form a PHA-enriched liquor; d) evaporating from 0% to about 50% of the single main solvent from the PHA-enriched liquor to form a solvent vapor and a concentrated PHA-enriched liquor; and e) cooling the concentrated PHA-enriched liquor to form precipitated polyhydroxyalkanoates and an impure solvent liquor and recovering the precipitated polyhydroxyalkanoates from the impure solvent liquor by filtration under pressure after cooling said cooling; wherein the polyhydroxyalkanoates comprise at least two randomly repeating monomer units, wherein the first randomly repeating monomer unit has the structure: and the second or higher randomly repeating monomer unit has the structure: wherein R is a C3 to C7 alkyl or a mixture thereof; wherein from about 75 mol % to about 99 mol % of the randomly repeating monomer units have the structure of the first randomly repeating monomer unit and from about 1 mol % to about 25 mol % of the randomly repeating monomer units have the structure of the second randomly repeating monomer unit; and wherein the single main solvent is a butanol, a pentanol or a mixture thereof and wherein the process further comprises adding from about 3% to about 8% by weight of acetone to the biomass liquor before heating the biomass liquor.