This document specifies an in vitro method for the digestion (IVD) of milk and milk products allowing the assessment of milk protein digestibility and the measurement of in vitro digestible indispensable amino acid score (DIAAS) values. DIAAS has been recommended by FAO for assessing protein quality. The method is applicable to milk and reconstituted milk products. It is also applicable to fermented milk products and cheese. The method is also applicable to other matrices, such as meat, legumes and insects. The method was validated on skim milk powder, whey protein isolate, whole milk powder, yoghurt (freeze dried), gruyere cheese (freeze dried), as well as soy protein isolate and chickpea (freeze dried).