Method for purifying and separating gamma-polyglutamic acid from fermentation liquor

The invention discloses a method for purifying and separating gamma-polyglutamic acid from fermentation liquor. Through the utilization of the characteristic that only the gamma-polyglutamic acid can be separated out in a fermentation liquor filtrate with low pH value, the purpose of separating and purifying high-purity gamma-polyglutamic acid is achieved. The method comprises the following steps: adjusting the pH value to be 3.0-6.0 with acid, performing filtration sterilization, then, decolorizing with activated carbon, adjusting the pH value to be 2.0-5.0 with acid, leaving to stand, separating out sediments, performing solid-liquid separation, dissolving the sediments in purified water to obtain a high-concentration water solution, finally, performing band drying, and smashing, so as to obtain the gamma-polyglutamic acid finished product. According to the invention, the process route is novel and simple, an organic solve is completely avoided, the product has no organic solvent residue, the production cost is low, the cost is reduced by 30% or above, the yield is as high as 85% or above, the product quality is excellent, the purity reaches 95% or above, and the method is more suitable for industrial production.