Abstract: According to a first aspect, hydrolysis of a protein-containing raw material and separation of amino acids/peptides is carried out, wherein the hydrolysis is effected by using the endogenous enzymes of the protein-containing raw material. The hydrolysate is passed through a membrane filter, wherein peptide/amino acids follow a permeate stream, while the active enzymes continuously break down any protein residues that are deposited on the membrane surface. The enzymes are passed together with retentate back to the hydrolysis. Furthermore, an amino acid and peptide product and an oil product are described and the use thereof is disclosed.