Processs for production and purification of fermentation derived organic acids

A method of producing and purifying an organic acid by producing an aqueous solution of the ammonium salt of the organic acid through fermentation and/or bioconversion and neutralization. The solution is heated to thermally crack the ammonium salt of the organic acid producing a vapor phase of ammonia and water and organic acid which is thereafter passed in contact with a membrane permeable to water and ammonia and substantially impermeable to the organic acid vapor to concentrate the aqueous solution of organic acid, and remove the ammonia and excess water.