Patent ID: 8454833

Claim:
A method of filtering a liquid protein mixture, the method comprising: providing a liquid mixture at a first pressure (P 1 ), the liquid mixture comprising a carrier liquid, a protein at a first concentration (C 1 ) relative to the carrier liquid, and a dispersed contaminant; passing the liquid mixture through a filter to form a filtrate at a second pressure (P 2 ), the filtrate comprising the carrier liquid and the protein at a second concentration (C 2 ) relative to the carrier liquid, wherein P 1 is greater than ambient pressure and less than about 1 bar gauge, P 2 is greater than ambient pressure and less than P 1 , and the filter is sized to remove at least a portion of the dispersed contaminant from the liquid mixture; and, applying a counter pressure to the filtrate to ensure that a pressure differential between the first and second pressures (P 1 −P 2 ) is not more than about 300 mbar, wherein at least about 85% of the protein present in the liquid mixture is recovered in the filtrate.