Proteases are widely used in the food industry for deproteinization of protein-containing foods. Alkaline pro- tease immobilization on cross-linked chitosan beads was performed for deproteinization of natural rubber. Com- pared to other techniques, using immobilized alkaline pro- tease reduced the total nitrogen level in the rubber up to 96 % and enzyme system could be used five times without losing more than 10 % of the initial enzyme activity (Praserkittikul et al. 2013). A novel cysteine protease, Procerain B, was immobilized on glutaraldehyde- activated chitosan matrix by covalent attachment for use in food industry. The capacity of substrate loading and reusability were improved and even after tenth use, 50 % of enzyme activity remained (Singh et al. 2011).