Abstract: The process consists of manufacturing milk acid from milk sugar by lactic fermentation process. The milk sugar is obtained as permeate from ultra-filtration of milk or from cheese or casein whey both in liquid, concentrate or dry form. The milk acid is separated and purified by a combination of membrane technology i.e., ultra-filtration/micro-filtration and nano-filtration. The purified milk acid is concentrated by evaporation, distillation or reverse osmosis.