Abstract: A process for efficient purification of magnesium lactate from fermentation broths derived from non-homogeneous feedstocks that contain soluble and insoluble impurities is provided. The fermentation broth, having high amounts of impurities and containing magnesium lactate in a soluble form, is separated from insoluble impurities, concentrated to particularly high concentrations of the magnesium lactate at elevated temperatures, and subsequently cooled by gradual and controlled cooling such that magnesium lactate crystals of high purity are formed.