Waste water may be purified using a shaped porous structure comprising natural or synthetic polymeric material or lipoids having enzymes or micro-organisms containing enzymes embedded therein.ALSO:Reactions effected by an enzyme or enzyme-containing micro-organism embedded in a porous matrix (see also Division C3) are (1) the production of l-alanine by treatment of an l-glutamic acid-pyorocemic acid system with glutamic acid-pyorocemic acid trans-aminase embedded in cellulose nitrate, optionally containing castor oil; (2) the production of d and l methionine from dl-acetylmethionine by preferential hydrolysis of the l-isomer by aminoacid acylase I embedded in cellulose nitrate, and subsequent separation and hydrolysis of the d-isomer; (3) the splitting of saccharose into glucose and fructose by invertase embedded in polyvinyl alcohol.ALSO:A shaped porous structure for effecting enzymatic processes in liquid media comprises natural or synthetic polymeric material or liquids having embedded therein an enzyme or an enzyme-containing micro-organism, the pores of the matrix being of such a size as to be permeable to the liquid medium or substances dissolved therein but not to the enzymatic material. Matrices specified are polyamides, polyvinyl acetate, polyvinyl alcohol, polyurethanes, cellulose nitrate, cellulose acetate, ethyl cellulose, rubber hydrochloride, or mixtures thereof alone or with lipoids.  The structures may be utilized in the form of hollow balls, coatings or lamellae, and are prepared by forming a solution, emulsion or suspension containing the enzymatic material, and subsequently drying and if necessary hardening; during solidification the structure may be given its final form by coating, brushing or spray-drying. Conventional additives, e.g. ion-exchanges, Redox substances, curing or cross-linking agents or substances which influence permeability may be added.  Enzymes used in specific examples are glutamic acid-pyroracemic acid trans-aminase, amino-acid acylase I, a mixture of glucose oxidase and peroxidase, a mixture of glucose oxidase and catalase, and invertase.  An example discloses the treatment of chicken egg albumen with cellulose nitrate lamellae containing a glucose oxidase-peroxidase mixture, the b -d-glucose in the albumen being converted to g -d-gluconic acid lactone.ALSO:A shaped porous structure for carrying out enzymatic processes in liquid media comprises natural or synthetic polymeric material or lipoids with enzymes or micro-organisms containing enzymes embedded therein, the pores of the matrix being of such a size that the matrix is permeable to the liquid medium and substances dissolved therein but not to the enzymatic material.  Matrices specified are polyamides, polyvinyl acetate, polyvinyl alcohol, polymethanes, cellulose nitrate, cellulose acetate, ethyl cellulose, rubber hydrochloride, or mixtures thereof alone or with lipoids.  The structures may be utilized in the form of hollow balls, coatings or lamellae, and are prepared by forming a solution, emulsion or suspension containing the matrix material and the enzymatic material, and subsequently drying and, if necessary, hardening; during solidification the structure may be given its final form by coating, brushing or spray-drying. Conventional additives, e.g. ion-exchangers, Redox substances, curing or cross-linking agents or substances which influence permeability may be added.  The structures may be utilized in preparation of amino-acids, treatment of proteins, splitting of polysaccharides, preservation of foods and purification of waste waters.ALSO:Mayonnaise is protected against oxidation by storage in preserve cans lined with a polyurethane foil in which is embedded a glucose oxidase-catalase enzyme system.