Freezing-Out Technique Applied to the Concentration of Biologically Active Materials

When applied to a dilute solution of folic acid and glucose, a freezing-out (with agitation) technique was shown to be an effective method of achieving a 20-fold reduction in volume with a loss of 10% of the active material being concentrated. Concentration of a stimulatory factor forLactobacillus casei produced byCandida albicans in a complex medium was limited by the total solute concentration. Salts in the medium were concentrated to levels inhibitory forL. casei . The process is not selective and all solutes are concentrated.