GB804013A - Improvements in or relating to the preparation of protein products from fish materials - Google Patents

Abstract

In the production of protein preparations free from undesirable smell and taste, partially dehydrated fish material having a fat content of less than 4 per cent is treated, preferably between 20 DEG C. and 80 DEG C. under reduced pressure, with a solution of an alkali, e.g., caustic alkali, alkali and alkaline earth metal and ammonium compounds having an alkaline reaction, and/or a solution of an acid, e.g., hydrochloric acid in an organic solvent, e.g., ethanol or acetone. When both alkali and acid treatments are employed they may be in either order and, if desired, in repeated alternation. Partial dehydration involves reducing the water content of the fish material to 60 per cent or below, by, e.g., vacuum drying or treatment with water-miscible organic solvents. If necessary, the fat content is first reduced to below 4 per cent by treatment with organic solvents. After the alkali and/or acid treatment the protein is isolated by adding alkali or acid to reach the iso-electric point thereof, the solvent then being removed by e.g., pressing, centrifuging or distillation. The separated protein is purified by washing with one or more organic solvents and is then dried, preferably below 60 DEG C. under reduced pressure. Steam treatment may replace, or be combined with, washing with an organic solvent.ALSO:In the production of protein preparations free from undesirable smell and taste, partially dehydrated fish material having a fat content of less than 4 per cent is treated, preferably between 20 DEG and 80 DEG C., under reduced pressure, with a solution of an alkali, e.g. caustic alkali, alkali and alkaline-earth metal and ammonium compounds having an alkaline reaction, and/or a solution of an acid, e.g. hydrochloric acid, in an organic solvent, e.g. ethanol or acetone. When both alkali and acid treatments are employed they may be in either order and, if desired, in repeated alternation. Partial dehydration involves reducing the water content of the fish material to 60 per cent or below, by, e.g., vacuum drying or treatment with water-miscible organic solvents. If necessary, the fat content is first reduced to below 4 per cent by treatment with organic solvents. After the alkali and/or acid treatment the protein is isolated by adding alkali or acid to react the isoelectric point thereof, the solvent then being removed by, e.g., pressing, centrifuging or distillation. The separated protein is purified by washing with one or more organic solvents and is then dried, preferably below 60 DEG C., under reduced pressure. Steam treatment may replace, or be combined with, washing with an organic solvent.