The invention concerns a process for the hydrolysis of protein biomass in which, in the first step, the biomass is mixed with water and subjected to hydrolysis in an acidic environment of carbon acids with a dissociation constant pKa of less than 4, under an inert atmosphere and at a pressure of at least 0.1 MPa and a temperature from 90 to 150 ° C for at least 0.5 hours to form a hydrolyzate containing low molecular weight water-soluble proteins, amino acids, acylglycerols and free aliphatic fatty acids, followed by subsequent enzymatic catalyzed hydrolysis at up to 60 °C, the enzyme being a protease to form a liquid hydrolyzate comprising a mixture of amino acids, low molecular weight proteins with a relative molecular weight of up to 10 kD, acylglycerols where the acyl is preferably derived from C12 to C24 fatty acids, and C12 to C24 aliphatic fatty acids. The invention also includes a protein biomass hydrolyzate containing keratin and / or collagen and its use.