There are four methods of enzyme immobilisation: adsorption, covalent bonding, entrapment and membrane separation. Adsorption involves mixing the enzyme with an immobilising support so the enzyme molecules will bind to it because of hydrophobic interactions and ionic links. The support is called an adsorbing agent and could be porous carbon, glass beads or clays. Covalent bonds between enzyme molecules and an insoluble material, such as clay, are formed using cross-linking agents (e.g. Sepharose). Entrapping the enzyme molecules in a network or gel beads or cellulose fibres allows the enzyme to be immobilised in their natural state (not attached to another molecule). Membrane separation physically separates the enzyme and substrate solutions with a partially permeable membrane. Both the substrate and product molecules are small enough to pass through the membrane. These immobilized enzymes have a wide range of applications. These include applications in the sugar, fish, and wine industries, where they are used for removing organic compounds from waste water. Immobilized enzymes also find significant application in drug metabolism, biodiesel and antibiotic production, bioremediation, and the food industry. The widespread usage of immobilized enzymes is largely due to the fact that they are cheaper, environment friendly, and much easier to use when compared to equivalent technologies. Several immobilized enzymes are used for the complete hydrolysis of the protein present in food. The protein is hydrolysed for changing the digestibility of the protein. It is related to the quality of protein. For this purpose, the enzymes such as pepsin, trypsin, chymotrypsin, and intestinal mucosal peptidases are used in the immobilized form.