Patent GB-692101-A (GB)
Title: Treatment of fish livers
IPC: C11B1/00
Filed: 1950-08-03
Abstract: Fish liver oil and undenatured protein are recovered from fish livers by macerating the livers, adjusting the temperature of the macerated livers to between 45 DEG  and 70 DEG  C., adjusting the pH of the mass to between 7.5 and less than 8.5, and then separating the oil so liberated from the protein-water components.  The pH may be adjusted before the heating step.  After the liver has been macerated, heated and treated with the required amount of alkali, the mass is allowed to cool.  On cooling to a critical temperature, the protein-water film surrounding the oil droplets in the treated mass is ruptured and separation of the oil and protein-water components takes place rapidly.  In the alternative method of working by adjusting the pH before the heating step, when heating from below 45 DEG  C., separation of the oil from the protein-water occurs when the critical temperature is reached. The separation of the oil phase from the protein-water components is then completed by settling, floating or centrifuging.  The pH of the mass may be adjusted by adding calcium hydroxide, caustic potash, caustic soda, sodium carbonate or bi- and tri-sodium phosphate or mixtures of caustics with the salts mentioned. Corresponding compounds of lithium and caesium may also be used. In the treatment of livers low in oil, a vegetable or fish liver oil may be added to the material after or before the alkali and heat treatment, e.g. cod liver oil or a vegetable oil is added to halibut liver.  The small amount of oil left in the protein-water-phase may be recovered by re-mixing the separated protein-water phase with another oil and recentrifuging.  The protein may be acidified and then neutralized.  Cod, halibut, dogfish and tuna fish livers are specified.ALSO:Fish liver oil and undenatured protein are recovered from fish livers by macetating the livers, adjusting the temperature of the macerated livers to between 45 DEG and 70 DEG C, adjusting the pH of the mass to between 7.5 and less than 8.5, and then separating the oil so liberated from the protein-water components.  The pH may be adjusted before the heating step.  After the liver has been macerated, heated and treated with the required amount of alkali, the mass is allowed to cool.  On cooling to a critical temperature, the protein-water film surrounding the oil droplets in the treated mass in ruptured and separation of the oil and protein-water components takes place rapidly.  Such a temperature may be as low as 45 DEG C and does not exceed 70 DEG C. In the alternative method of working by adjusting the pH before the heating step, when heating from below 45 DEG C, separation of the oil from the protein-water occurs when the critical temperature is reached.  The separation of the oil phase from the protein-water components is then completed by settling, floating or centrifuging. The pH of the mass may be adjusted by adding calcium hydroxide, caustic potash, caustic soda, sodium carbonate or bi- and trisodium phosphate or mixtures of caustics with the salts mentioned. Corresponding compounds of lithium and caesium may also be used.  The alkali may be added as solid or preferably in aqueous solution and does not exceed 1.5 per cent of the weight of the macerated livers. The amount of water added with the alkali varies with the amount of natural water of the livers but should not exceed 7 or 8 per cent of the weight of the livers and is preferably kept below 3 per cent.  In the treatment of livers low in oil, a vegetable or fish liver oil may be added to the material after or before the alkali and heat treatment, e.g. cod liver oil or a vegetable oil is added to halibut liver.  The small amount of oil left in the protein-water phase may be recovered by remixing the separated protein-water phase with another oil and re-centrifuging.  The protein may be acidified and then neutralized.  Cod, halibut, dogfish and tuna fish liver are specified.