Lipoid-soluble vitamins and other physiologically active substances are obtained by treating animal tissue with \ba1/2\be-\ba1/50\be per cent of papain at 60-80 DEG C. at PH 4.5-5. The papain may be added as an aqueous suspension. The juice leaves or sap of the papaw plant may also be employed. The lipoid-soluble vitamins together with fat may be separated out from the digested tissue by gravity or by centrifuging, if desired after adding water, the fat being extracted at temperatures above its melting point, or by means of solvents such as petroleum ether which are immiscible with water, or by a combination of these means. Saponifiable or non-saponifiable oils, fats, and waxes, e.g. spermaceti, may be added to facilitate the extraction of these substances and concentration may be effected by saponifying. In an example, finely minced animal tissue, e.g. mammalian liver, is subjected to the papain digestion until liquefaction occurs. After adding an equal bulk of water the mass is filtered hot, the aqueous filtrate obtained containing polypeptides, amino acids and water-soluble physiologically active principles. The solid residue is mixed with sufficient water to bring the volume up to that of the original tissue and sodium or potassium hydroxide is added to give a PH of 8,5-9. Saponification is allowed to proceed for a half-hour, and an oil, fat, or wax is then added and the mixture agitated for 5-15 minutes at above melting point of the added fat. The unsaponified fat is next separated by gravity or centrifuging. The concentration of the active substances may be increased by agitating in an aqueous solution of alkali and then washing with distilled water. Cyanogen and sulphydryl compounds which act as accelerators may be added in the digestion. Specification 378,399 is referred to.ALSO:Oils, fats, and waxes are separated from animal tissue, and fat from cream by treating the material with \ba1/2\be-\ba1/50\be per cent of papain at 60-80 DEG C. at PH4.5-5. The process may also be used for treating cream to separate out the fat. The materials are sterilized and freed from obnoxious flavours and odours by the digestion treatment, and the papain inhibits the development of rancidity in the extracted oils and fats. The papain may be added as an aqueous suspension. The juice leaves or sap of the papaw plant may also be employed. The oils, fats, and waxes, may be separated out from the digested tissue by gravity or by centrifuging, if desired after adding water, the fats being extracted at temperatures above their melting-points. The PH value may be obtained by adding dilute hydrochloric acid. Cyanogen or sulphydryl compounds which act as accelerators may be added in the digestion. Specification 378,399 is referred to.ALSO:Concentrated edible products are obtained by treating animal tissue with 1/2 -\ba1/50 per cent of papain at 60-80 DEG C. at pH 4.5-5. The process may also be used for treating cream to separate out the fat. From the animal tissue concentrated nitrogenous products are obtained and the extraction of oils, fats and waxes and lipoid-soluble and water-soluble vitamins and other physiologically active principles from the cells of the tissues is facilitated. The materials are sterilized and freed from obnoxious flavours and odours by the digestion treatment, and the papain inhibits the development of rancidity in the extracted oils and fats. The papain may be added as aqueous suspension. The juice, leaves or sap of the papaw plant may also be employed. The pH value may be obtained by adding dilute hydrochloric acid. Oils, fats, waxes and lipoid-soluble vitamins may be separated out from the digested tissue by gravity or by centrifuging, if desired after adding water, the fats being extracted at temperatures above their melting points. The fat-soluble physiologically active principles including the lipoid-soluble vitamins may also be separated from the digested proteins by the aid of solvents such as petroleum ether which are immiscible with water. Saponifiable or non-saponifiable oils, fats and waxes, e.g. spermaceti, may be added to facilitate the extraction of these substances and concentration may be effected by saponifying. In an example, finely minced animal tissue, e.g. mammalian liver, is subjected to the papain digestion until liquefaction occurs. After adding an equal bulk of water the mass is filtered hot, the aqueous filtrate obtained containing polypeptides, amino acids and water-soluble physiologically active principles. The solid residue is mixed with sufficient water to bring the volume up to that of the original tissue and sodium or potassium hydroxide is added to give a pH of 8.5-9. Saponification is allowed to proceed for a half hour, and an oil, fat or wax is then added and the mixture agitated for 5-15 minutes at above the melting point of the added fat. The unsaponified fat is next separated by gravity or centrifuging. The concentration of the active substances may be increased by agitating in an aqueous solution of alkali and then washing with distilled water. In a further example, a mixture of lean meat and liver is subjected to papain digestion followed by heating to 100 DEG C. to sterilize, and drying to give a concentrated nitrogenous food. The concentration of vitamins and other active principles in the food can be modified by varying the amount of liver used. A balanced ration can be obtained by adding carbohydrates and fats. In another example, meat is digested and after sterilizing at 100 DEG C. and filtering the filtrate is neutralized with sodium hydroxide and common salt and flavouring matter may then be added to it and the mixture evaporated to a thick paste. The process can be applied to heavily salted meat and for producing animal food from spoiled meat. Cyanogen and sulphydryl compounds which act as accelerators may be added in the digestion. Specifications 17732/93, 7895/04, 7896/04, 19431/12, [all in Class 49, Food &c.], and 378,399 are referred to.ALSO:Fat is separated from cream, and concentrated food for animals is obtained from animal tissue, e.g. spoiled meat, by treating with 1/2 -\ba1/50 per cent of papain at 60-80 DEG C. at pH 4,5-5. The materials are sterilized and freed from obnoxious flavours and odours by the digestion treatment, and the papain inhibits the development of rancidity in the extracted fat. The papain may be added as an aqueous suspension or the juice leaves or sap of the papaw plant may be employed. Cyanogen or sulphydryl compounds may be added as accelerators. Specifications 17732/93, [Class 5, Agricultural appliances, Farmyard &c.], 7895/04, 7896/04, 19431/12, [all in Class 49, Food &c.], and 378,399 are referred to.