Fractionation of soybean proteins with pressurized carbon dioxide as a volatile electrolyte.
Fractionation of specific proteins from plant material is a complex and involved science, yet pure protein extracts are in high demand by a wide range of food and pharmaceutical industries. In this study carbon dioxide has been used as a volatile electrolyte to isoelectrically precipitate two major protein constituents of soybean. Carbon dioxide was shown to be effective in purifying glycinin and beta-conglycinin in a three-step process as 95% and 80% concentrated fractions with precipitation yields of 28% and 21%, respectively. Recycling of the mixed precipitate of the intermediary step enables complete separation into the concentrated fractions. Fractionation acidity was precisely controlled by a simple modification of pressure. In addition, the occurrence of a pH overshoot was prevented at any point in the fractionation vessel, as the pH minimum was defined by its equilibrium relationship with carbon dioxide operating pressure. The removal of the glycinin precipitate was an important factor in the purification procedure. The yield of the individual concentrated glycinin and beta-conglycinin precipitate fractions was a function of carbon dioxide pressure, extract concentration and, to a much lesser extent, temperature.
Laboratory for Process Equipment, Delft University of Technology, Leeghwaterstraat 44, 2628 CA, Delft, the Netherlands. R.Thiering@unse.edu.au
R
R
Thiering
G
G
Hofland
N
N
Foster
G J
GJ
Witkamp
L
L
van de Wielen
D052179:Antigens, Plant; D019149:Bioreactors; D002245:Carbon Dioxide / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D019649:Food Industry; D005590:Fractional Precipitation; D005916:Globulins / Q000032:analysis / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D008854:Microscopy, Electron; D011312:Pressure; D055314:Seed Storage Proteins; D030262:Soybean Proteins / Q000737:chemistry*; D013025:Glycine max / Q000737:chemistry*; D013696:Temperature
D052179:Antigens, Plant; D004573:Electrolytes; D005916:Globulins; D055314:Seed Storage Proteins; D030262:Soybean Proteins; C013894:beta-conglycinin protein, Glycine max; D002245:Carbon Dioxide; C011474:glycinin