Production of protein isolates in good yield and purity using an extraction process which involves the use of a gradient of protease concentration, pH and temperature

摘要

A protein isolate is produced from a protein-containing substance using an extraction process which involves at least two stages of contact with a protease. A gradient of pH, temperature and protease concentration operates between the stages. Preparation of a protein isolate from a substance which contains protein comprises: (a) grinding the substance to a powder; (b) suspending the powder in an aqueous solution; (c) bringing the protein into solution from the powder using at least one protease which is passed in countercurrent to the suspension; and (d) precipitating the protein and neutralizing it by addition of a mineral acid. The protein is brought into solution by a treatment with the protease which involves at least two stages and takes place at a pH above 8 and a temperature of 30-60 deg C. In the first stage, the powder is treated at a lower concentration of protease (based on the weight of the protein), a lower pH and a higher temperature than those used in the second stage. After the first stage, a first supernatant of a powder-containing fraction is separated. The protein is precipitated from this. After the second stage, a second supernatant from a powder-containing fraction is separated. This is recycled to the first stage.