The nutritional protein quality of lactose-hydrolysed milk after some industrial processes was studied with N balance experiments on growing rats. Ultra-high-temperature sterilization and evaporation at 25 °C did not influence the nutritional value significantly, whereas spray-drying under conditions usually used for ordinary milk gave a considerable reduction in protein quality.The protein quality of cow's milk and nondairy beverages was calculated based on the Digestible Indispensable Amino Acid Score (DIAAS). The DIAAS scores the digestibility of amino acids in the ileum and is a measure of both protein content and absorption