GB653188A - Improvements in and relating to the extraction of protein from seeds - Google Patents

Abstract

Vegetable proteins are extracted from protein-containing seeds by means of an aqueous alkaline liquid containing both alkali metal ions and aluminate (AlO2-) ions and having a pH value within the range of 8.5 and 11.5, the liquid extract is separated from the undissolved material and the protein in the extract precipitated by addition of an acid. The extraction may be effected by adding an alkali metal aluminate as such to the extraction liquid or by forming such an aluminate in situ by pretreating the seeds with a solution of an aluminium salt and then adding an aqueous solution of an alkali metal hydroxide to extract the protein and to form the alkali metal aluminate in the solution by reaction between the aluminium salt and the alkali hydroxide; in the latter method, it is preferred to add a salt, such as sodium sulphate, to the pretreating solution which will increase the solubility of the protein, decrease the solubility of impurities and reduce the swelling of the final precipitate. The alkaline extracting liquid is preferably an aqueous solution of an alkali metal hydroxide. Also the seeds are preferably used in the finelyground oil-free condition. Examples illustrate the extraction of protein from pea-nut meal by both of the above methods, dilute sulphuric acid being used to precipitate the protein; the same extraction in absence of the aluminate gives a darker product more susceptible to oxidation in alkaline solution. The extraction of vegetable casein from bean meal, pea meal, and castor bean meal is referred to. According to the Provisional Specification, the extraction is effected by means of an alkaline liquid at a pH value of not less than 8.5 and in the presence of an alkali aluminate.