In the production from animal tissue of oils, fats and waxes, including cholesterol and other sterols &c., in order to break down the cell membranes of the tissue and free the intra cellular contents by autolysis or by fermentation by added ferments, the p raw material is brought to a pH of 4-5 by addition of mineral acid, then incubated at 30-40 DEG C. in an oxygen-free atmosphere and finally treated to remove fibrous tissue or other undesirable matter. The treatment of fish liver to which hydrochloric acid is added is described. The material may be sterilized prior to digestion by addition, for example, of sulphurous acid or sodium benzoate, or mammalian spleen tissue may be added to inhibit bacterial growth. The sterilization may be effected after the digestion, for example by repeated heating to 80 DEG C. in the absence of air, in nitrogen or other inert gas. Connective tissue may be removed by sieving and may be extracted with alcohol or other solvent and the extract added to the autolyzed product. When treating with different ferments, the ferment action may be controlled by adjustment of the pH valve and the temperature, for example in treating fish liver proteolytic decomposition by autolysis is first obtained by acidifying to pH 4-5, and then by adding dilute caustic soda to give a pH value of 7.5-8.5 lipolytic autolysis is facilitated. The oil is separated from the digested fish liver by centrifuging, clarified by filtering through anhydrous sodium sulphate, and then concentrated by cooling, e.g. to -10 DEG C., and removing the solidified fatty acids and neutral fats by centrifuging. Specifications 17732/93 and 19431/12, [both in Class 49, Food &c.], are referred to.ALSO:In the production from animal tissue of concentrated nitrogenous edible products, edible products rich in vitamins, or oils, fats and waxes, including cholesterol and other sterols &c., in order to break down the cell membranes of the tissue and free the intra cellular contents by autolysis or by fermentation by added ferments the raw material is brought to a pH of 4-5 by addition of mineral acid, then incubated at 30-40 DEG C. in an oxygen-free atmosphere and finally treated to remove fibrous tissue or other undesirable matter. The treatment of ox and fish liver to which hydrochloric acid is added is described. The material may be sterilized prior to digestion by addition, for example, of sulphurous acid or sodium benzoate, or mammalian spleen tissue may be added to inhibit bacterial growth. The sterilization may be effected after the digestion, for example by repeated heating to 80 DEG C. in the absence of air, in nitrogen or other inert gas. Connective tissue may be removed by sieving and may be extracted with alcohol or other solvent and the extract added to the autolysed product. When treating with different ferments, the ferment action may be controlled by adjustment of the pH value and the temperature, for example in treating fish liver proteolytic decomposition by autolysis is first obtained by acidifying to pH 4-5, and then by adding dilute soda to give a pH value of 7,5-8,5 lipolytic autolysis is facilitated. The oil is separated from the digested fish liver by centrifuging. The aqueous portion containing amino acids, water soluble vitamins, &c. is concentrated by evaporation. The materials may be treated with ultraviolet light at any convenient stage to convert any ergosterol present into vitamin. Specifications 17732/93, [Class 49, Food &c.], and 19431/12, [Class 2 (iii), Dyes &c.], are referred to.ALSO:In the production from animal tissue of concentrated nitrogenous edible products, edible products rich in vitamins, or oils, fats and waxes, including cholesterol and other sterols &c., usable for animal food in order to break down the cell membranes of the tissue and free the intra cellular contents by autolysis or by fermentation by added ferments the raw material is brought to a pH of 4-5 by addition of mineral acid, then incubated at 30-40 DEG C. in an oxygen-free atmosphere and finally treated to remove fibrous tissue or other undesirable matter. The treatment of ox and fish liver to which hydrochloric acid is added is described. The material may be sterilized prior to digestion by addition, for example, of sulphurous acid or sodium benzoate, or mammalian spleen tissue may be added to inhibit bacterial growth. The sterilization may be effected after the digestion, for example by repeated heating to 80 DEG C. in the absence of air, in nitrogen or other inert gas. Connective tissue may be removed by sieving and may be extracted with alcohol or other solvent and the extract added to the autolyzed product. When treating with different ferments, the ferment action may be controlled by adjustment of the pH valve and the temperature, for example in treating fish liver proteolytic decomposition by autolysis is first obtained by acidifying to pH 4-5, and then by adding dilute caustic soda to give a pH value of 7.5-8.5 lipolytic autolysis is facilitated. The oil is separated from the digested fish liver by centrifuging, clarified by filtering through dry anhydrous sodium sulphate, and then concentrated by cooling, e.g. to -10 DEG C., and removing the solidified fatty acids and neutral fats by centrifuging. The aqueous portion containing amino acids, water soluble vitamins, &c. is concentrated by evaporation. The materials may be treated with ultra-violet light at any convenient stage to convert any ergosterol present into vitamin. The autolyzed product may be brought to solid jelly, thin paste or other form. Colouring and flavouring materials may be added. Specifications 17732/93, [Class 5, Agricultural appliances, Farmyard &c.], and 19431/12, [Class 49, Food &c.], are referred to.ALSO:In the production from animal tissue of concentrated nitrogenous edible products, edible products rich in vitamins, or oils, fats and waxes, including cholesterol and other sterols &c., in order to break down the cell membranes of the tissue and free the intracellular contents by autolysis or by fermentation by added ferments the raw material is brought to a pH of 4-5 by addition of mineral acid, then incubated at 30-40 DEG C. in an oxygen-free atmosphere and finally treated to remove fibrous tissue or other undesirable matter. The treatment of ox and fish liver to which hydrochloric acid is added is described. The material may be sterilized prior to digestion by addition, for example, of sulphurous acid or sodium benzoate, or mammalian spleen tissue may be added to inhibit bacterial growth. The sterilization may be effected after the digestion, for example by repeated heating to 80 DEG C. in the absence of air, in nitrogen or other inert gas. Connective tissue may be removed by sieving and may be extracted with alcohol or other solvent and the extract added to the autolysed product. When treating with different ferments, the ferment action may be controlled by adjustment of the pH value and the temperature, for example in treating fish liver proteolytic decomposition by autolysis is first obtained by acidifying to pH 4-5, and then by adding dilute caustic soda to give a pH value of 7,5-8,5 lipolytic autolysis is facilitated. The oil is separated from the digested fish liver by centrifuging, clarified by filtering through dry anhydrous sodium sulphate, and then concentrated by cooling, e.g. to -10 DEG C., and removing the solidified fatty acids and neutral fats by centrifuging. The aqueous portion containing amino acids, water soluble vitamins, &c., is concentrated by evaporation. The materials may be treated with ultra-violet light at any convenient stage to convert any ergosterol present into vitamin. The autolysed product may be brought to solid jelly, thin paste or other form, and is usable as a human or animal food. Colouring and flavouring materials may be added. Specifications 17732/93 and 19431/12, [both in Class 49, Food &c.], are referred to.